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In this study, we obtained CoNi alloy nanomaterials encapsulated in N-CNTs using ZIF-67 as a carrier through high-temperature pyrolysis and reduction. The hollow structure of this material increased the exposed accessible active sites, accelerated electron transfer and mass diffusion, and enhanced structural stability. The NiCoNC synthesized in this study had SOD activity and can scavenge ROS. The simulation of SOD activity displayed by NiCoNC can effectively eliminate ROS in S. invicta and improved the sensitivity of workers to insecticides by inhibiting transcription factors and downregulating the expression of P450 genes. This study revealed the synergistic mechanism of NiCoNC and insecticides against S. invicta , providing an innovative solution for pest control applications. [Display omitted] • NiCoNC can significantly enhance the efficacy of flonicamid against S. invicta. • NiCoNC acts as SOD, CAT, and GSH-Ox activities, catalyzing H 2 O 2 to generate H 2 O and O 2. • NiCoNC can enhance insecticidal activity by entering the intestine. • NiCoNC inhibits transcription factor Maf by clearing ROS. • NiCoNC decreases expression of P450 genes, increasing sensitivity of S. invicta. to insecticides. The annual invasion of Solenopsis invicta (Buren) (Hymenoptera: Formicidae) has caused significant ecological damage. However, the use of a single type of prevention and control agents and improper use methods have resulted in S. invicta developing a tolerance to pesticides. The development of nanoparticles has shown promise in improving insecticide formulations, and increasing insecticidal efficacy. In this study, we obtained carbon nanotube grafted hexagonal star nanoparticles NiCoNC using zeolitic imidazolate framework-67 (ZIF-67) as a carrier through high-temperature pyrolysis and reduction. The CoNi alloy nanoparticles had an average size of 32.43 nm, and elements C, N, O, Co, and Ni were evenly distributed in the carbon skeleton structure. NiCoNC acted as superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GSH-Ox) activities, catalyzing H 2 O 2 to generate H 2 O and O 2. The combination of NiCoNC with S. invicta tissue fluid showed significant reactive oxygen species (ROS) scavenging ability. While NiCoNC did not show insecticidal activity against S. invicta , it enhanced the insecticidal activity of the insecticide by entering the intestine. To study the synergistic mechanism of NiCoNC and insecticide, SOD activity, ROS content, detoxification metabolic enzyme activity, and verified function by feeding silenced muscle aponeurosis fibromatosis (Maf) with double-strand RNA. The results showed that NiCoNC decreased the expression of CYP4C1, CYP6A14, and CYP9e2 by expressing SOD activity, and inhibiting the Maf pathway, ultimately increasing the sensitivity of S. invicta to insecticides. In summary, our research has led to the development of a novel nano-enzyme that can significantly enhance the efficacy of flonicamid against S. invicta. [ABSTRACT FROM AUTHOR]

Herein, based on the excellent redox ability of the transition metal oxide Mn 3 O 4 , the key strategy of introducing WO 3 was used to effectively modulate the electronic structure of the Mn active species and improve the catalyst nanozyme activity. The characterizations of transition electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS) presented that the dropping of WO 3 accelerated the electron transfer and redistribution capacity of WO 3 /Mn 3 O 4 , thus exhibiting excellent oxidase and peroxidase activities. Density functional theory (DFT) revealed that WO 3 /Mn 3 O 4 effectively increased the adsorption capacity of O 2 molecules and drastically reduced the kinetic energy potential of the reaction-limiting step in the oxidase-like activity. An "on-off-on" colorimetric and intelligent biosensing platform for epinephrine and Ag+ was successfully constructed. It was used to visualize and monitor epinephrine levels in human serum with a linear range of 0.075–65 µM and a detection limit of 0.055 µM. The mechanism of detection was revealed using infrared spectroscopy. Moreover, WO 3 /Mn 3 O 4 took more readily to obtain the electrons of epinephrine than 3,3′,5,5′-tetramethylbenzidine. Therefore, the colorimetric sensor of epinephrine on the basis of the oxidase of WO 3 /Mn 3 O 4 had a promising future in the biomedical field. • The prepared WO 3 /Mn 3 O 4 showed excellent dual enzymatic activity. • Introduction of WO 3 could modulate the electronic structure of the active site Mn. • Establish "On-Off-On" colorimetric sensor platform for intelligent detection of epinephrine and Ag+. • This method was used for the monitoring of adrenaline in human serum. • Building an intelligent sensing platform based on deep learning [ABSTRACT FROM AUTHOR]

Deep learning-assisted smartphone optical sensing platform based on CDs@Fe-Zr-MOF smart label detects SP and HIS, and meat freshness. [Display omitted] • Two-color and dual-emitter ratio fluorescence nanoprobe for agro-food was constructed. • Portable, visual, and real-time optical device with gel label was fabricated. • Deep learning-assisted self-designed smartphone WeChat mini program for real-time sensing. • CDs coupled with Fe/Zr-MOF acts as the response units. Here, a smartphone-assisted dual-color ratiometric fluorescence smart gel label-based visual sensing platform was constructed for real-time evaluation of the freshness of agro-food based on the biogenic amines responses. Green-emission fluorescence carbon dots (CDs) coupled with blue-emission fluorescence bimetallic metal–organic framework (Fe/Zr-MOF) obtained dual-color CDs@Fe/Zr-MOF fluorescence nanoprobe acts as the response units. With the increase of SP and HIS content, the green fluorescence of CDs was enhanced, while the blue fluorescence of Fe/Zr-MOF was quenched. Therefore, this dual-color probe achieved a clear fluorescence color response to biogenic amines. The nanoprobe possessed sensitive and color-responsive with the LODs of 0.17 μM for SP and 2.95 μM for HIS in a wide range of 0–937.5 µM, respectively. Besides, these fluorescent nanoprobes were immobilized on the hydrogel carrier, and the intelligent fluorescent hydrogel tag can be obtained after freeze-drying, which realizes the real-time qualitative monitoring of SP and HIS in pork and shrimp samples. [ABSTRACT FROM AUTHOR]

[Display omitted] • AGE organohydrogel was developed via micellar polymerization and solvent exchange method. • The organohydrogel exhibits soft yet tough mechanical features resembling human soft tissues. • Multi-functionalities were integrated into the organohydrogel. • The organohydrogel exhibits promising potential for soft ionotronics. To date, hydrogels with skin-like ionic conduction mechanisms are gaining popularity in fabricating soft electronics. Integrating the tissue-like mechanical properties and multi-functionalities into one hydrogel system is crucial for its practical application in diverse scenarios. Nevertheless, it remains a significant challenge to realize. Here, we present a mechanically soft tissue-like organohydrogel with ionic conduction mechanism and multiple functions via constructing plentiful "sacrificial bonds" (hydrogen bonding) between the hydrophobic association poly(acrylamide)/gelatin (HAPAM/gelatin) hydrogel and ethylene glycol/water (EG/H 2 O) clusters. By systematically optimizing the compositions, the organohydrogel displayed desired mechanical properties that fully matched human soft tissues, including the unique soft (∼77.8 kPa in Young's modulus) yet tough (3.07 MJ m−3 in toughness) features. Meanwhile, the gel is tear-resistant (∼3.15 kJ m−2 in fracture energy), strong (∼0.4 MPa in tensile and ∼4.1 MPa in compression), and ultra-stretchable (∼1324 %). In addition, the organohydrogel integrated a broad spectrum of functionalities, including optically transparent, self-healing, freezing/heating tolerant, adhesive, and deformation sensitive. By taking these advantages, applications in soft ionotronic sensors for healthcare monitoring and information encryption/decryption were presented using the organohydrogel. It is expected that this work will shed some light on developing artificial materials with mechanical features resembling soft tissues and sophisticated functionalities. [ABSTRACT FROM AUTHOR]

Dual-signal ratiometric molecularly imprinted polymer (MIP) electrochemical sensors with bimetallic active sites and high-efficiency catalytic activity were fabricated for the sensing of catechol (CC) with high selectivity and sensitivity. The amino-functionalization bimetallic organic framework materials (Fe@Ti-MOF-NH 2), coupled with two-dimensional layered titanium carbide (MXene) co-modified glassy carbon electrode provides an expanded surface while amplifying the output signal through the electropolymerization immobilization of polythionine (pTHi) and MIP. The oxidation of CC and pTHi were presented as the response signal and the internal reference signal. The oxidation peak current at +0.42 V rose with increased concentration of CC, while the peak currents of pTHi at −0.20 V remained constant. Compared to the common single-signal sensing system, this one (MIP/pTHi/MXene/Fe@Ti-MOF-NH 2 /GCE), a novel ratiometric MIP electrochemical sensor exhibited two segments wide dynamic range of 1.0–300 μM (R2 = 0.9924) and 300–4000 μM (R2 = 0.9912), as well as an ultralow detection limit of 0.54 μM (S/N = 3). Due to the specific recognition function of MIPs and the advantages of built-in correction of pTHi, the prepared surface imprinting sensor presented an excellent performance in selectivity and reproducibility. Besides, this sensor possessed superior anti-interference ability with ions and biomolecules, excellent reproducibility, repeatability, and acceptable stability. Furthermore, the proposed sensing system exhibits high specific recognition in the determination of environmental matrices and biological fluids in real samples with satisfactory results. Therefore, this signal-enhanced ratiometric MIP electrochemical sensing strategy can accurately and selectively analyze and detect other substances. Bimetallic MOF and MXene coupled with ratiometric molecularly imprinted polymers electrochemical synergy sensing CC based on the dual signal on/off ratio strategy. [Display omitted] • Bimetallic MOF and MXene decorated ratiometric MIP electrochemical sensor was proposed. • The charge transfer mechanism of the signal on/off ratiometric MIP was elucidated. • PTHi not only as a built-in signal but also as a conducting polymer in the sensor. • High sensitivity, selectivity, and reproducibility in detecting trace catechol. [ABSTRACT FROM AUTHOR]

[Display omitted] • MoS 2 /CoS 2 heterostructure nanozyme presented double enzyme-like activity. • The structure–activity relationship of MoS 2 /CoS 2 NFs was investigated deeply. • The antibacterial rate of MoS 2 /CoS 2 NFs reached up to 99%. • Insights into the antibacterial mechanism of MoS 2 /CoS 2 to drug-resistant bacteria. • MoS 2 /CoS 2 effectively treated the wounds infected with drug-resistant bacteria in vivo. Wounds infected by drug-resistant bacteria have become a worldwide health problem, and conventional antibiotics are no longer effective. On this basis, MoS 2 /CoS 2 heterostructure nanozymes was designed by simple molten salt method. Transmission Electron Microscopy confirmed that the clear interface of MoS 2 /CoS 2 was established creatively, which greatly promoted more distorted lattice generation. Benefited from the heterogeneous interfaces of MoS 2 /CoS 2, the transfer of electrons was accelerated and double enzyme-like activities were improved greatly, which had been confirmed by the experimental characterizations and theoretical calculation. Moreover, the mechanism was investigated in depth based on the electronic state change of MoS 2 /CoS 2 during the peroxidase reaction. Based on the peroxidase avtivity, MoS 2 /CoS 2 could effectively kill drug-resistant bacteria as high as 99%, including Gram-positive and Gram-negative bacteria, it proved the broad-spectrum antibacterial effect of MoS 2 /CoS 2. The results showed the superiority of the synergistic effect of the material and low concentration of H 2 O 2. In addition, MoS 2 /CoS 2 NFs greatly promoted the rapid healing of wounds in vivo and had good biocompatibility. This study provides a simple strategy to engineer nanozymes with enhanced catalytic activity and furnished a potential ideas in the treatment of bacterial infections and wound healing. [ABSTRACT FROM AUTHOR]

Herein, a novel Ba 2 SrWO 6 :Mn4+, La3+ (BSW:Mn4+, La3+) far-red phosphor was obtained by an addition strategy of La ion to negligible-luminescence BSW:Mn. Deep-red emission peaks at ∼ 664, 679 and 690 nm were observed for BSW:Mn4+, La3+ with the excitation band in the 250 ∼ 600 nm spectral range, which are well matched to the absorption of chlorophyll and phytochromes. An impressive nanorod surface micro-morphology was observed in BSW samples and the size of the surface-grown nanorods can be changed by the addition of La ions. It was speculated that the generation of oxygen vacancies in BSW:Mn probably causes the self-reduction process of Mn4+ → Mn2+, and a charge replenishment mechanism was proposed to explain the abnormal luminescence of Mn4+ ions. The BSW:0.5%Mn, 5%La phosphor showed a CIE chromaticity coordinate of (0.724, 0.276) with a high color purity of 100%. In addition, the internal and external quantum efficiency of BSW:0.5%Mn, 5%La phosphor reach as high as 51.9% and 39.5%, respectively. Finally, LED devices were fabricated by using the as-prepared BSW:0.5%Mn, 5%La phosphor and applied in the illumination on tomato seeds. It shows that the LED devices can promote the seeding of tomatoes effectively, indicating a potential application value in the plant cultivation field. [Display omitted] • Nanorod surface micro-morphology was observed in Ba 2 SrWO 6 samples. • La addition results in highly efficient luminescence of Ba 2 SrWO 6 :Mn sample. • The influence of oxygen vacancies and La3+ ions on the valence variation of Mn in Ba 2 SrWO 6 was studied. • The fabricated deep-red LED device can promote the germination of tomato seeds effectively. [ABSTRACT FROM AUTHOR]

[Display omitted] • Smartphone-based tri-color ratio fluorescent sensing system is proposed. • Visual and portable optical device integrated with machine learning was designed. • A Wechat applet based on yolov3 algorithm with six different linear fitting algorithms. • A smartphone-based handheld device for on-site and rapid detection TCs. In this work, a tri-color ratiometric fluorescent optical device integrated with machine learning-assisted smartphones is designed for the visual monitoring of tetracycline antibiotics. The trichromatic sensing probe consists of blue emitting carbon dots (BCDs) at 420 nm, and red-emitting bovine serum albumin-protected copper nanoclusters (BSA-Cu NCs) at 635 nm, as well as an emission peak at 520 nm, rises in the presence of tetracycline antibiotics (TCs), therefore, a three emission system is formed. BCDs/BSA-Cu NCs present three emission responses to TCs, which are based on the internal filtering effect (IFE) and the sensitization mechanisms with BSA. The reaction mechanism was verified by density functional theory (DFT) and a series of characterizations, such as infrared spectrum, ultraviolet absorption spectrum, and fluorescence lifetime. Interestingly, the fluorescence intensity of BCDs was quenched by TCs, and due to the sensitization between BSA and TCs, a green fluorescence rose at 520 nm, while the peak of BSA-Cu NCs remained stable, resulting in a significant color shift from red to cyan. Therefore, the ratiometric fluorescence intensity of I (635+520) /I 420 can be used to determine TCs, and the colors change can be used to identify the quantitative analysis. In addition, the deep learning of the YOLO v3 algorithm assists the integrated tri-color portable optical device of smartphones, which can realize the visual detection of TCs. In general, the sensing system has many advantages, such as good stability, specificity, and rich color changes, which provide help for the visual detection of tetracycline residues. [ABSTRACT FROM AUTHOR]

Here, a novel and portable machine learning-assisted smartphone-based visual molecularly imprinted ratiometric electrochemiluminescence (MIRECL) sensing platform was constructed for highly selective sensitive detection of 2,4-Dichlorophenoxyacetic acid (2,4-D) for the first time. Te doped CdS-coated Mn 3 O 4 (Te–CdS@Mn 3 O 4) with catalase-like activity served as cathode-emitter, while luminol as anode luminophore accompanied H 2 O 2 as co-reactant, and Te–CdS@Mn 3 O 4 decorated molecularly imprinted polymers (MIPs) as recognition unit, respectively. Molecular models were constructed and MIP band and binding energies were calculated to elucidate the luminescence mechanism and select the best functional monomers. The peroxidase activity and the large specific surface area of Mn 3 O 4 and the electrochemical effect can significantly improve the ECL intensity and analytical sensitivity of Te–CdS@Mn 3 O 4. 2,4-D-MIPs were fabricated by in-situ electrochemical polymerization, and the rebinding of 2,4-D inhibits the binding of H 2 O 2 to the anode emitter, and with the increase of the cathode impedance, the ECL response of Te–CdS@Mn 3 O 4 decreases significantly. However, the blocked reaction of luminol on the anode surface also reduces the ECL response. Thus, a double-reduced MIRECL sensing system was designed and exhibited remarkable performance in sensitivity and selectivity due to the specific recognition of MIPs and the inherent ratio correction effect. Wider linear range in the range of 1 nM–100 μM with a detection limit of 0.63 nM for 2,4-D detection. Interestingly, a portable and visual smartphone-based MIRECL analysis system was established based on the capture of luminescence images by smartphones, classification and recognition by convolutional neural networks, and color analysis by self-developed software. Therefore, the developed MIRECL sensor is suitable for integration with portable devices for intelligent, convenient, and fast detection of 2,4-D in real samples. [ABSTRACT FROM AUTHOR]

Inspired by the porous microstructure of biomass carbon (BC) and the high adsorption properties of magnetic nanomaterials. A novel electrochemical sensor was developed for the selective assay of thiamphenicol (TAP) in fresh milk, honey, and meat samples by the preconcentration with magnetic molecularly imprinted polymer (MIP) based on differential pulse voltammetry (DPV). The magnetic MIP sensor (MIP/BC/CoFe-CoFe 2 O 4 /GCE) was fabricated by coupling CoFe-CoFe 2 O 4 particles embedded loofah sponges derived BC with MIP film-decorated glassy carbon electrode (GCE). Theoretical simulation and quantum calculations based on density functional theory (DFT) accelerate the prediction and selection of rational functional monomers, as well as the ratio of template molecules to monomers. The surface structure, elemental composition, and electrochemical behavior were characterized by XRD, XPS, SEM, TEM, CV, and EIS, respectively. Various factors such as the amount of BC/CoFe-CoFe 2 O 4 , monomer/template ratio, polymerization cycles, pH value, elution time, and incubation time have been optimized to enhance the performance of the sensor. Under the optimal conditions, the current response intensities have three segments of good linear relationships with the TAP concentrations in the range of 0.01–2.0 µM (R2 =0.9930) and 2–400 µM (R2 =0.9955) as well as 400–5000 µM (R2 =0.9900) with an ultralow detection limit (LOD, S/N = 3) of 0.003 µM. Besides, the magneto-actuated electrochemical sensor exhibited outstanding analytical performance, i.e., excellent reproducibility and repeatability, ideal stability, and superior anti-interference ability. Moreover, the reliable recoveries (95.11%−105.00%) and the ideal relative standard deviations (RSDs) (1.2%−4.9%) for TAP determination in husbandry samples demonstrated that our developed sensor has good potential in the application. [Display omitted] • A novel DFT calculation optimized magnetic molecularly imprinted electrochemical sensor was constructed. • The sensitivity was dramatically promoted by magnetic preadsorption. • The electrochemical sensing of TAP on the magnetic MIP exhibits ultralow LOD of 0.003 µM. [ABSTRACT FROM AUTHOR]

A novel, portable, and smartphone-based molecularly imprinted polymer electrochemiluminescence (MIP-ECL) sensing platform was constructed for sensitive and selective determination of furosemide (FSM). In this platform, MoSe 2 nanoparticles/starch-derived biomass carbon (MoSe 2 /BC) nanocomposites as imprinted material, lucigenin (Luc) as the energy donor, CdS quantum dots (CdS QDs) were used as the luminophore (energy acceptor), and molecularly imprinted polymer (MIP) as the specificity recognition element to construct a MIP-ECL sensing system based on electroluminescence resonance energy transfer (ECL-RET) mechanism, which enhanced the sensitivity and the specificity of this system. Imprinted materials were characterized by SEM, TEM, XRD, FT-IR, etc. and the recognition performance of MIP was characterized using CV, EIS, and ECL methods. The elution and re-sorption of template molecules can be used as a switch to control ECL based on the signal that can be quenched by FSM. Interestingly, deep learning based on convolutional neural networks realizes batch processing of ECL signals. Additionally, this developed MIP-ECL method was established by using the traditional ECL analyzer detector for the assay of FSM with a detection limit of 4 nM in the range of 0.010 μM–100 μM. Besides, the consumer smartphone sensing platform based on deep learning showed an outstanding linear response between the R-value of the picture and the concentration of furosemide in the range of 1–70 μM with a detection limit of 0.25 μΜ, which is much lower than that the reported for other detection methods. More importantly, due to the transferability of deep learning, the smartphone-based MIP-ECL systems can facilitate the real-time monitoring of biochemical analytes in multiple fields. [ABSTRACT FROM AUTHOR]

A self-designed smartphone-based portable device and system for detecting Cu2+ and thiram by multi-color ratiometric fluorescence optical probe based on deep learning and density functional theory. [Display omitted] • A portable fluorescence detection device based on smartphone was designed. • Multi-color fluorescence sensing system for dual detection of Cu2+ and thiram. • Ratiometric fluorometric and colorimetric signals for on-site analysis of thiram. • Density functional theory was used to verify the detection mechanism. Dual emission ratiometric fluorescence probes have been widely used for naked visual individual detection of hazardous chemicals, but it is still limited to simultaneously detecting multiple targets in a complex system. In this work, a deep learning-assisted smartphone-integrated tricolor ratiometric fluorescence optical device has been designed for visual monitoring of Cu2+ and thiram. The tricolor sensing probes are consist of blue-emission carbon quantum dots (B-QDs), green-emission cadmium telluride quantum dots (G-QDs), and red-emission cadmium telluride quantum dots (R-QDs). The sensing system presents a three emission response to Cu2+ and thiram based on electron transfer effect, complexing effect, and inner filter effect (IFE), respectively. The reaction mechanisms were verified by density functional theory (DFT). Interestingly, the G-QDs and R-QDs' fluorescence intensity are simultaneously quenched by Cu2+, whereas the fluorescence intensity of B-QDs remained unchanged and used as the internal reference, resulting in a distinct color shift from orange-red to blue with a detection limit (LOD) of 0.05 μM. Subsequently, the addition of thiram restored the G-QDs and R-QDs' intensity while the fluorescence intensity of B-QDs was quenched accompanied by a distinguishable color transition from blue to red with LOD of 0.073 μM. Moreover, colorimetric detection of thiram is realized based on the variation of UV absorption intensity with LOD of 0.142 μM. Besides, deep learning-YOLO v3 algorithm-assisted smartphone-integrated tricolor portable optical device for in-situ monitoring of Cu2+ and thiram with ultralow LOD of 0.344 μM and 1.840 μM, respectively. In conclusion, the sensing system shows excellent stability, sensitivity, and specificity, which provides a great capacity for the convenient evaluation of Cu2+ concentration and thiram residue. [ABSTRACT FROM AUTHOR]

Pt/Co 3 O 4 nanoflowers were synthesized by precipitation and reduction methods, and they exhibited unparalleled four enzyme activities: oxidase-like, peroxidase-like, catalase-like and SOD-like activities by adjusting pH. Based on its excellent oxidase activity, a dual-functional colorimetric detection platform for pesticide residues thiram and Cu2+ had been constructed based on the turn on-off-on signal change. Combined with DFT theoretical calculations showed that Pt-Co was the active center, and in the key step of catalyzing O 2 to produce O 2 −, Pt/Co 3 O 4 needed lower energy. This study presented herein may provide an intelligent detection method to monitor environment. [Display omitted] • The pH-switchable Pt/Co 3 O 4 presented an excellent four-enzyme activity. • Establishing "on–off-on" colorimetric sensor platform to detect thiram and Cu2+ intelligently. • DFT calculation showed that the interfaces of Pt and Co 3 O 4 was the active sites. • In-depth discussion of the detection mechanism by in-situ DRIFTS. • Colorimetric detection of pesticide residues had a wide detection range and low limit of detection. Pt/Co 3 O 4 were synthesized by precipitation and reduction methods, exhibited unparalleled four enzyme activities: oxidase-like, peroxidase-like, catalase-like and superoxide dismutase activities by adjusting pH. The mechanism of enzyme activity was deeply explored, it was found that its oxidase activity originated from the oxygen vacancies of the material and O 2 −, 1O 2 , the peroxidase activity was attributed to the 1O 2 and OH formed by nanomaterials catalyzing H 2 O 2. Density functional theory calculations showed that Pt-Co with strong metal-oxide interaction interface was the active center, which needed a lower energy than others in the key step of catalyzing O 2 to produce O 2 −. Based on its excellent oxidase activity, a muti-functional colorimetric detection platform for thiram, Cu2+ and ziram had been constructed successfully. The linear ranges of thiram was 0.6–250 µM and the limit of detection was 0.065 µM. The linear ranges of Cu2+ and ziram were 10–200 µM and 5–50 µM, the limit of detection were 4.066 µM and 3.36 µM. It should be noted that the portable smart phone platforms for thiram, Cu2+ and ziram had also been established with instant and quick detection. It was worth noting that in-depth exploration of the detection mechanism combined with in situ diffuse reflectance infrared fourier transform spectroscopy revealed that hydrogen bonds can be formed between thiram and oxidation substrate. And Cu2+ would inhibit the combination. Furthermore, it also showed excellent applications in detecting pesticide and Cu2+ in environmental soil and water samples. This study presented herein may provide an intelligent detection method to monitor environment. [ABSTRACT FROM AUTHOR]

Deep learning-assisted smartphone-integrated fluorescence sensing platform successfully fabricated for the detection of Hg2+ and thiram in actual samples with satisfactory results based on the dynamic quenching mechanism by density function theory (DFT). [Display omitted] • Smartphone-based ratio fluorescence sensor for "on–off-on" Hg2+ and thiram sensing. • High sensitivity to Hg2+ and thiram with LOD of 7 nM and 0.083 μM, respectively. • The mechanism of detecting Hg2+ has been explored with the method of DFT. • Deep learning-assisted WeChat App makes the operation simple and direct forthright. Rapid, accurate, and low-cost detection of heavy metals and pesticide residues are crucial to environmental pollution control, but it is still a challenge. In this work, the fluorescence sensing platform system of the iron-based metal–organic framework (Fe-MIL-88NH 2) and gold nanoclusters (Au NCs) based on a smartphone portable device coupled with a deep learning-driven applet of WeChat to measure Hg2+ and thiram were proposed. Meanwhile, Hg2+ quenched the fluorescence mechanism of Au NCs was explored by density functional theory (DFT). Interestingly, thiram can restore the fluorescence intensity of Au NCs. As a result, the ratiometric fluorescence sensor can accurately detect Hg2+ in the "on–off" model and detect thiram in the "off–on" model, which possessed high sensitivity and low detection limits are 7 nM and 0.083 μM, respectively. Meanwhile, the visual changes of fluorescence color from red to purple and blue for determination of Hg2+ and the color returned to red when detecting thiram. Based on the RGB or HSV values reflected in the images, the linear range individually quantified of Hg2+ and thiram in the broad linear range of 0.002–30 μM and 0.083–49.910 μM, respectively, which are equivalent to or better than that attained from fluorescence spectrometer. In addition, the developed sensor in combination with deep learning can accurately predict Hg2+ and thiram concentration levels in actual samples. Besides, our strategy provides a powerful sensing platform in the analysis of water samples and crops and suggests great application potential in environmental monitoring. [ABSTRACT FROM AUTHOR]

Azodicarbonamide (ADA) in flour can be easily decomposed to semi-carbazide and biuret, exhibiting strong genotoxicity in vitro and carcinogenicity. Glutathione (GSH) can be conjugated with some ketone-containing compounds and unsaturated aldehydes to form toxic metabolites. Here, a novel ratio fluorescence probe based on blue emitting biomass-derived carbon dots (BCDs) and yellow emitting 2,3-diaminophenazine (OxOPD) was prepared for the bifunctional determination of glutathione (GSH) and ADA. This strategy includes three processes: (1) Ag+ oxidizes o-phenylenediamine (OPD) to produce OxOPD. The peak at 562 nm was enhanced, and the peak at 442 nm was reduced due to fluorescence resonance energy transfer (FRET), (2) glutathione binds Ag+ and inhibits the production of OxOPD, (3) ADA oxidizes GSH to form GSSG, resulting in the release of Ag+ by GSH. Therefore, the newly designed ratio fluorescence probe can be based on the intensity ratio (I 442 /I 562) changes and significant fluorescent color changes to detect GSH and ADA. Moreover, a smartphone WeChat applet and a yolov3-assisted deep learning classification model have been developed to quickly detect GSH and ADA on-site based on an image processing algorithm. These results indicate that smartphone ratiometric fluorescence sensing combined with machine learning has broad prospects for biomedical analysis. [Display omitted] • Smartphone ratiometric fluorescence sensing system was proposed. • Newly designed sensor possessed ultralow LODs for the detection of GSH and ADA. • A WeChat applet based on deep learning yolov3 algorithm was developed. • A smartphone-based handheld device for on-site and rapid detection. [ABSTRACT FROM AUTHOR]

A self-designed portable smartphone electrochemiluminescence molecularly imprinted polymer (ECL-MIP) device and system for detecting NFZ based on artificial neural network (ANNs) and density functional theory (DFT). [Display omitted] • A portable smartphone device for detecting NFZ based on MIP-ECL system. • Nitrofurazone was also used as a co-reaction accelerator in the ECL system. • Density functional theory was used to find the optimal monomer for nitrofurazone. • High sensitivity MIP-ECL sensing for NFZ with a nanomolar rang of LOD value. An efficient, portable and sensitive electrochemiluminescence molecularly imprinted polymer (ECL-MIP) sensor with CsPbBr 3 perovskite nanomaterials (NMs) was developed based on a smartphone point-of-care testing (POCT) system. In this system, a rechargeable lithium-ion battery served as the power supply, and Ag+@UiO-66-NH 2 /CsPbBr 3 was regarded as an ECL emitter, while the ECL signal was read-out using a smartphone. The optimal functional monomer (pyrrole) was screened by density functional theory (DFT), and then the MIP membrane was formed by the electrochemical polymerization method with template molecule (nitrofurazone, NFZ). The luminescence images were collected by the smartphone camera and the image color was analyzed by self-designed software, and the embedded artificial neural network-assisted machine learning was used for automatic analysis. Under the optimal experimental conditions, the ECL signal responded linearly to NFZ in the range of 0.5 nM ∼ 100 μM, with the detection limit of 0.09 nM. Overall, the obtained sensor exhibited good sensitivity, desirable selectivity, and favorable stability in response to NFZ. The developed smartphone-based ECL-MIP system with the portable device provided an alternative strategy for the point-of-care monitoring of biochemical analytes. [ABSTRACT FROM AUTHOR]

Transition metal sulfides (TMSs) are expected to be a new type of electrode material due to their excellent electrochemical activity. However, the poor capacity retention and stability of TMSs are obstacles to their practical application. Here, the porous hollow nickel-cobalt sulfides are fabricated via a simple water bath followed by anion exchange, which can be regulated by N-doped carbon dots (NCDs). Newly designed porous hollow structure provides more active sites, a cavity for storing electrolytes, and optimized electron/ion diffusion pathways. Then, the Ni-Co ratio and the NCDs doping mass are optimized, and the as-prepared NCDs/Ni 2 Co 1 S-50 displays a specific capacity of 764.1 C g−1 at 1 A g−1. A hybrid supercapacitor based on NCDs/Ni 2 Co 1 S-50 achieves an outstanding energy/power density (73 mWh cm−2/1.39 W cm−2) and exhibits favorable cyclic performance (96.5% maintain for 10 000 times). In addition, a glucose sensor based on NCDs/Ni 2 Co 1 S-50 modified glassy carbon electrode (GCE) is designed, with a wide detection range of 1 × 10−5-5 × 10−3 M and a low detection limit of 3.8 × 10−7 M (S/N = 3). The excellent electrochemical performance demonstrates the effectiveness of the manufacturing strategy of adjusting the properties of hollow-structured metal sulfides through carbon dots and provides a novel way to design new nanocomposite materials used for the multi-functional field. [Display omitted] • The morphologies of NiCoS were adjusted by biomass-derived NCDs. • Porous hollow NiCoS was prepared based on the Kirkendall effect. • The porous hollow structure provides optimized electron/ion diffusion pathways. • NCDs/Ni 2 Co 1 S-50 exhibited multifunction in supercapacitor and glucose sensing. [ABSTRACT FROM AUTHOR]

[Display omitted] • A three layers FeO x @ZnMnFeO y @Fe-Mn bimetallic organogel was creatively synthesized. • The four-functional sensing platforms for H 2 O 2 , citric acid, norfloxacin and gallic acid were constructed effectively. • The smartphone detection platform for CA and NOR was established successfully. • CA and NOR were detected continuously based on the turn on-off-on signal change. • The nanozyme-like activity mechanism and the detection mechanism were analyzed systematically. In this study, the FeO x @ZnMnFeO y @Fe-Mn bimetallic organogel (FO@ZMFO@FM-MOG) with three layers structure was synthesized. It presented outstanding multi-enzyme (peroxidase, oxidase and catalase) activities. The systematical characterization results showed that Zn and Mn on the surface of FO@ZMFO@FM-MOG were nearly disappeared, and thus a large amount of Fe exposed as the active species. Accordingly, the high ratio of Fe2+/Fe3+ for FO@ZMFO@FM-MOG was conductive to the electron transfer and enzyme activity. Moreover, the multiple detection platforms were constructed based on the different nanozyme activities. As for the peroxidase-mimetic activity, citric acid (CA) and norfloxacin (NOR) were monitored continuously on the basis of the turn on–off-on signal change due to the electron transfer abilities and hydroxyl radicals (•OH) formation. The linear range of 0.415–6.21 μM was obtained with a low detection limit of 79 nM, which was rarely detecting citric acid by nanozyme. And the low detection limit of 52 nM for NOR was superior to the most published NOR assays in nanozyme field. Furthermore, an oxidase platform for gallic acid (GA) was also established due to superoxide anions (O 2 •−) generation. It should be noted that the smartphone detection platforms for CA and NOR were established successfully for on-site analysis. This study provided multifunctional detection platform for valuating CA, NOR and GA in food quality and environment monitoring. [ABSTRACT FROM AUTHOR]

CuNi/CoMoO 4 with laccase-like activity showed multifunctional applications. The total antioxidant capacity of commercial beverage was measured accurately. And epinephrine could be on-site determinate by smartphone platforms based on CuNi/CoMoO 4 laccase-like activity. Moreover, CuNi/CoMoO 4 could be applied for acid fuchsin degradation due to ·OH and SO 4 ·− formation Furthermore, the laccase-like catalytic mechanism was investigated by theoretical calculation. [Display omitted] • CuNi/CoMoO 4 with laccase-like activities had multifunctional applications. • A smartphone platform was established for visual detection of epinephrine. • The laccase-like catalytic mechanism was investigated firstly by theoretical calculation. • CuNi/CoMoO 4 had a strong ability of activation PMS to produce ·OH and SO 4 ·−. • The efficiency was up to 99.45%, which was the highest value for AF degradation. In this work, CuNi/CoMoO 4 nanozyme was synthesized the hydrothermal method, followed by calcination and impregnation techniques, which had laccase-like activity and could be used as peroxymonosulfate (PMS) activator. Thus, the total antioxidant capacity (TAC) of commercial beverage measurement and phenolic pollutants degradation were studied systematically. Besides, the portable smartphone platform integrated with an intelligence analysis APP and colorimetric signals was further established for on-site determination of epinephrine (a typical phenol). Simultaneously, as PMS activator, CuNi/CoMoO 4 could activate PMS to yield ·OH and SO 4 ·−, which was applied for organic pollutants (acid fuchsin, AF) degradation, and the degradation efficiency could reach up to 99.45% within 40 min. The results displayed that CuNi/CoMoO 4 had practical value in anti-oxidant food quality evaluation and pollution degradation. Furthermore, the theoretical calculation revealed that the activation energy of the rate-determining step over Cu/CoMoO 4 was decreased from 0.819 eV to 0.524 eV due to the enhanced interaction between Cu(I) of CuNi/CoMoO 4 and 2,4-dichlorophenol (2,4-DCP). It not only provided a multifunctional catalyst for evaluating oxidative capacity in food quality and pollutant degradation, but also provided some new evidences for further study of laccase-like mechanism. [ABSTRACT FROM AUTHOR]

• A colorimetric and fluorescence turn-on dual-signal method for the detection of ascorbic acid was developed. • The established probe was used successfully for ascorbic acid detection in living cells and beverages. • A linear detection range for ascorbic acid is 1–200 μM and the LOD is 0.15 µM and 0.023 µM by fluorescence method and colorimetric, respectively. A colorimetric and fluorescence turn-on dual-signal assay was developed for the determination of ascorbic acid (AA). Because the ultraviolet absorption of the oxidized 3,3′,5,5′-tetramethylbenzidine (oxTMB) overlapped with the fluorescence emission of glutathione stabilized Au nanoclusters (AuNCs), the fluorescence of AuNCs can be quenched by oxTMB. When AA was added, the blue oxTMB was reduced to colorless TMB, and the fluorescence of AuNCs was restored simultaneously. The decrease in absorbance and increase in fluorescence signal depended on the concentration of AA. In the determination range of 0.5 to 200 μM, the detection limits (LOD) for AA were as low as 0.15 µM and 0.22 µM for fluorometric and colorimetric, respectively. The established probe was used successfully for AA detection in living cells and beverages. [ABSTRACT FROM AUTHOR]

Hollow peanut-shaped NiFe 2 O 4 /CoFe 2 O 4 twinned nano-spherical shell composite materials have interconnected electron channels and excellent electrochemical performance, which prompted the use of this unique spatial structure to fabricate efficient electrochemical sensors. In this work, N-doped carbon dots (NCDs) incorporated into magnetic NiFe 2 O 4 /CoFe 2 O 4 nanoparticle shell (NiFe 2 O 4 /CoFe 2 O 4 /NCDs) modified glassy carbon electrode (GCE) was applied to construct a dual-template molecularly imprinted polymer (MIP) based electrochemistry sensor (NiFe 2 O 4 /CoFe 2 O 4 /NCDs/MIP/GCE) for the simultaneous detection of catechin (CA) and theophylline (TPH). MIP was fabricated by an in-situ electrochemical polymerization strategy based on the theoretical exploration and density functional theory (DFT) computer directional simulation to screen out the optimal functional monomer (L-arginine) and the optimal ratio between the dual template molecules (CA and TPH) and functional monomer. The materials were characterized by SEM, TEM, XRD, XPS, and TGA. Besides, electron binding energy, binding constant, and imprinting factor were investigated. With the optimal conditions, the proposed electrochemical dual detection system showed outstanding analytical performance for the simultaneous sensing of CA and TPH, with an ultralow detection limit (LOD, S/N = 3) of 1.3 nM for CA in 0.01–1 μM (R2 = 0.9956) and 1–50 μM (R2 = 0.9928), as well as a LOD of 20.0 nM for TPH in the linear range of 0.1–100 μM (R2 = 0.9939), respectively. Also, the selectivity and anti-interference performances of the fabricated sensor were performed by differential pulse voltammetry and chronoamperometry, and successfully detected the analyte from tea drinks and human urine samples with the recovery rates ranging from 98.22% to 104.76% and relative standard deviations (RSD) were 1.19%–3.81%, demonstrated the sensor has excellent stability, repeatability, and reproducibility, which paves the way for other platforms to use this nanomaterial for the detection of antioxidant in the filed food safety. • A dual template electrochemical molecularly imprinted sensor based on DFT theory guide was proposed. • Fabricate the MIP sensor based on peanut twin-like NiFe 2 O 4 /CoFe 2 O 4 /NCDs nanospheres. • The adsorption position and the electron distribution of the bonding groups were determined by molecular modeling. • Highly sensitivity MIP sensor for the simultaneous detecting of CA and TPH with ultralow LOD. [ABSTRACT FROM AUTHOR]

• A peroxidase-like CeO 2 -CDs and CDs were developed. • The CeO 2 -CDs has higher peroxidase-like activity than CeO 2. • Coupling CeO 2 -CDs, CDs with O-phenylenediamine as a ratiometric fluorescence H 2 O 2 and cholesterol sensor. Enhanced peroxidase-like activity CeO 2 -carbon dots and carbon dots were synthesized by one-pot hydrothermal method, and application as a ratiometric fluorescence for H 2 O 2 and cholesterol detection. ga1 Carbon dots-doped CeO 2 (CeO 2 -CDs) with enhanced peroxidase-like activity and fluorescent carbon dots (CDs) were prepared by one-pot hydrothermal method in this work. The morphology, surface groups and enzymatic properties of CeO 2 -CDs and optical properties of CDs were studied in detail. The enzyme activity of CeO 2 -CDs was higher than CeO 2 due to the smaller particle size. O-phenylenediamine (OPD) as peroxidase substrate can be catalyzed to fluorescent o-phenylenediamine (oxOPD) by CeO 2 -CDs, and the UV–vis absorption of oxOPD overlapped partly with the fluorescence emission of CDs. Hence, the fluorescence intensity of CDs would be decreased by oxOPD due to the inner filter effect. Based on this, a sensitive and selective ratiometric fluorescence method for H 2 O 2 and cholesterol was developed. The detection ranges for H 2 O 2 and cholesterol are 1.67 µM-2.01 mM and 1.66 µM-1.65 mM with the detection limits are 0.35 µM and 0.49 µM (3Ϭ), respectively. Moreover, this method has been successfully used to detect cholesterol in human serum. [ABSTRACT FROM AUTHOR]

A novel sensing system was constructed by biomass carbon/MOF-derived Co 3 O 4 /FeCo 2 O 4 (BC/Co 3 O 4 /FeCo 2 O 4) composite decorated with glassy carbon electrode (GCE) for exploiting to determine dopamine (DA), acetaminophen (AC), and xanthine (XA) simultaneously. The BC/Co 3 O 4 /FeCo 2 O 4 composite was synthesized via a facile in-situ growth process and calcination treatment, coupled with hydrothermal reaction. This composite could appreciably enlarge the electrochemically active surface area of as-prepared sensor to promote electron transfer resulting in enhanced response signals. Applying BC/Co 3 O 4 /FeCo 2 O 4 /GCE sensor under the optimum conditions, the differential pulse voltammetry (DPV) current responses vs. concentration are linear in the wider ranges of 0.1–250 μM, 0.1–220 μM, and 0.5–280 μM, along with low detection limits (LOD, S/N = 3) of 0.04587 μM, 0.02886 μM, and 0.1209 μM for DA, AC and XA correspondingly. Moreover, the proposed sensor exhibited a satisfying selectivity, stability and reproducibility as well. Finally, this sensor had been utilized to detect DA, AC and XA successfully in real samples with satisfactorily apparent recoveries, providing a promising application for further sensing analysis. (A) The preparation process of BC/Co3O4/FeCo2O4 composite and (B) simultaneous detection of DA, AC and XA on BC/Co3O4/FeCo2O4/GCE. Image 1 • A novel electrochemical sensor based on MOF-derived Co 3 O 4 /FeCo 2 O 4 incorporated porous biomass carbon was constructed. • The proposed sensor showed preferable electrochemical sensitivity and practicality. • Simultaneous detection of dopamine, acetaminophen and xanthine in human serum samples could be achieved. • The detection limits (S/N = 3) were as low as 0.04587 μM, 0.02886 μM, and 0.1209 μM, respectively. [ABSTRACT FROM AUTHOR]

In this work, the carbon dots (CDs) were prepared by one-pot hydrothermal method with chitosan as a carbon source and hydrogen peroxide as an oxidant, this route is a novel, simple and green. The prepared CDs has a relatively high photoluminescence (PL) quantum yield (QY) (18.9%) and good water solubility. CdTe quantum dots (CdTe QDs) possess the characteristic of responding to pH rapidly. So a ratiometric fluorescent probe for measuring pH was constructed using the prepared CDs and CdTe QDs. Under the excitation of 330 nm, the probe shows dual (blue and red) emission with peaks at 430 and 600 nm, respectively. When the pH of the solution changes, the blue fluorescence intensity of the CDs remains stable as a reference signal, while the red fluorescence intensity of CdTe QDs changes accordingly. This method has obvious pH-sensitive feature, stable fluorescence properties, and a great linear relationship with pH values in the range of pH 3.0–11.0. What is more, the method can monitor proton-producing enzyme-catalyzed reactions by acting as a ratiometric pH probe. Carbon dots were prepared by one-pot hydrothermal method with chitosan as a carbon source and hydrogen peroxide as an oxidant, and a ratiometric fluorescence was constructed for determination of pH and enzyme reactions based on carbon dots and CdTe quantum dots. Unlabelled Image • Carbon dots were prepared by one-pot hydrothermal method with chitosan as a carbon source and hydrogen peroxide as an oxidant. • A ratiometric fluorescence was constructed for determination of pH based on carbon dots and CdTe quantum dots. • The pH sensor was used to monitor proton-producing enzyme-catalyzed reactions by acting as a ratiometric pH probe. [ABSTRACT FROM AUTHOR]

• Biomass carbon, Ag NPs and Cr-MIL-101 derived Cr 2 O 3 were used to enhance conductivity. • MOF-derived metal oxides retain the MOF morphology. • Bifunctional monomers were used to enhance the specificity of MIP for NFZ. • Wide linear range of 5 × 10−9–1 × 10−5 M were obtained, along with low detection limit of 3 × 10−9 M. In the work, a novel molecularly imprinted electrochemical sensor was proposed for sensitive and rapid detection of nitrofurazone (NFZ). The sensor was modified with Cr 2 O 3 derived from metal-organic framework (MOF), silver nanoparticles (Ag NPs) and biomass carbon (BC) from walnut shells. Among them, Ag NPs are grown on the surface of Cr-MIL-101 to obtain Cr-MIL-101/Ag, and then calcined with BC to obtain a composite material BC/Cr 2 O 3 /Ag. This material improves the effective surface area and electron transfer capability of the electrode to increase current response. Adding molecularly imprinted polymer (MIP) to the surface of composite materials can improve the specific recognition ability of modified electrodes for NFZ. MIP was prepared by precipitation polymerization using acrylamide (AM) and α-methacrylic acid (MAA) as bifunctional monomers and NFZ as the template. Under the most suitable experimental environment, the differential pulse voltammetric (DPV) current response of modified electrode (BC/Cr 2 O 3 /Ag/MIP/GCE) to NFZ showed a good linear relationship between 5 × 10−9 −1 × 10−5 M, and the detection limit was 3 × 10−9 M. This sensor has high sensitivity, selectivity, reproducibility and stability. Moreover, BC/Cr 2 O 3 /Ag/MIP/GCE was applied for the detection of NFZ in real samples. BC/Cr 2 O 3 /Ag/MIP/GCE provides a reliable approach for determination of NFZ in biological fluids. [ABSTRACT FROM AUTHOR]

In this study, using diethylenetriaminepentaacetic acid (DPTA), diethylenetriamine (DETA) and Fe (NO 3) 3.9H 2 O, Fe, N co-doped carbon dots (Fe, N-CDs) were successfully synthesized by a simple one-pot hydrothermal method. Fe, N-CDs possessed fluorescence and peroxidase-like properties. When H 2 O 2 was present, o-phenylenediamine (OPD) can be oxidized by Fe, N-CDs to oxidized phenylenediamine (oxOPD), and oxOPD further quenched the fluorescence of Fe, N-CDs because of inner filter effect. There were two peaks at 450 nm and 560 nm for the system of Fe, N-CDs and oxOPD. Results showed that the concentration of H 2 O 2 can not only affect the fluorescence intensity but also the color of the oxOPD. Considering that the xanthine oxidase can oxidize xanthine to produce H 2 O 2 , thus, a ratiometric fluorescent and colorimetric dual-signal sensor for H 2 O 2 and xanthine was developed. This new method was demonstrated to have high sensitivity and excellent selectivity for determination of H 2 O 2 and xanthine. The detection limits (LOD) for H 2 O 2 and xanthine were 0.047 μM and 0.02 μM with a ratiometric fluorescence method, and were 0.05 μM and 0.023 μM with a colorimetric method, respectively. This dual-signal sensor was used successfully for xanthine detection in human serum and urine. A ratiometric fluorescent and colorimetric dual-signal sensor for H 2 O 2 and xanthine were developed based on prepared fluorescence and peroxidase-like Fe, N-CDs. Image 1 • A bifunctional nanomaterial with both fluorescence and peroxidase-like properties were prepared. • A ratiometric fluorescent and colorimetric dual-signal sensor for H 2 O 2 and xanthine were developed. • The dual-signal sensor was used successfully for xanthine detection in human serum and urine. [ABSTRACT FROM AUTHOR]

In this paper, Bi3+ ions were co-doped into La 2 LiSbO 6 :Mn4+ phosphors for purpose of improving luminescent properties in the near ultraviolet and blue light range. A significant enhancement from 25.89% to 58.71% in quantum yield under blue light excitation was achieved. Impressively, via increasing Bi3+ concentration, the excitation spectra can be effectively tuned from double to triple bands along with the maximum excitation peak changed. Besides, particle morphology and Raman vibration modes were investigated to reveal the luminescence enhancement and the excitation evolution mechanisms. The results show that Bi3+-induced structure symmetry change may play a dominant role in tunable excitation phenomenon of the samples, which makes La 2 LiSbO 6 :Mn4+, Bi3+ may have a potential application in plant growth lighting LEDs for different kind of excitation light sources. • The quantum yield of La 2 LiSbO 6 :Mn4+ phosphor was enhanced obviously by co-doping of Bi3+. • The excitation spectra of La 2 LiSbO 6 :Mn4+, Bi3+ phosphors were tunable with Bi3+ concentration varying. • Bi3+ dopant can promote the crystal grain growth of La 2 LiSbO 6. • The variation of symmetry and lattice vibration brought by Bi3+ was discussed. [ABSTRACT FROM AUTHOR]

Biomass-carbon prepared by Kiwi peel and asymmetric carbon-based nanospheres synthesized by hydrothermally method are used as substrate to decorate NiS 2 nanoparticles to obtain NiS 2 /BC. Dropping the NiS 2 /BC dispersions on the surface of glassy carbon electrode to improve conductivity. Then we modified the electrode with N-GOQDs and AuNPs to improve the electroactive region of the surface and the electron transfer rate. Nicotinamide was used as functional monomer, MIP was prepared on the surface of Au/N-GOQDs/NiS 2 /BC/GCE by electropolymerization method in presence of DA and CPZ to enhance the selectivity and sensitivity of the sensor. After extraction of the template molecule, DA and CPZ can be specifically recognized by the imprinted cavities formed on the surface of the MIP. Quantitative electrochemical analysis is performed by differential pulse voltammetry (DPV). Demonstrate the prepared Au/N-GOQDs/NiS 2 /BC/MIP/GCE can be used for sensitive and selective determination of DA and CPZ in human serum, urine and pharmaceutical samples. • A novel imprinted polymer electrochemical sensor based on AuNPs and N-GOQDs coated on NiS 2 /BC was proposed. • Molecularly imprinting approach used for simultaneous determination of DA and CPZ. • Highly sensitive and selective determination of DA and CPZ with LODs in nanomolar range. • This sensor was successful for determination of DA and CPZ in biological samples. In this study, a dual template molecularly imprinted electrochemical sensor was fabricated for the simultaneous determination of dopamine (DA) and chlorpromazine (CPZ). Nitrogen-doped graphene oxide quantum dots (N-GOQDs) and gold nanoparticles (AuNPs) were deposited on a combination of biomass carbon and biomass-derived asymmetric carbon-based nanospheres decorated with NiS 2 nanoparticles (NiS 2 /BC), and the obtained material was used to modify glass carbon electrode (GCE). The electropolymerization of nicotinamide (NA) on Au/N-GOQDs/NiS 2 /BC/GCE via cyclic voltammetry (CV) using NA as functional monomer and DA and CPZ as template was used to produce molecularly imprinted polymer (MIP) film. Various experimental parameters, including electropolymerization cycles, template-to-functional monomer ratio, pH value, elution time, and incubation time, were optimized. Differential pulse voltammetry (DPV) response under optimized parameters show two linear ranges for DA (0.05–8 µM and 8–40 µM), and the limit of detection (LOD) is as low as 2.8 nM (S/N = 3). CPZ had a linearity range of 0.005–2 µM with very low LOD value of 0.25 nM (S/N = 3). The prepared MIP electrochemical sensor had good reproducibility and repeatability, acceptable stability, and high selectivity for DA and CPZ. Furthermore, the sensor was used in real sample analysis of human serum, urine and pharmaceutical samples, and the result of recovery (93.9%–106.15%) and relative standard deviation (RSD) (1.5%–6.6%) indicated good practicality. [ABSTRACT FROM AUTHOR]

Glucose oxidase catalyzes glucose to produce H 2 O 2 , and Fe2+ catalyzes H 2 O 2 , generating hydroxyl radicals to oxidize vitamin B 1 and statically quench C-dots fluorescence, accompanied by a color change from purplish-red to colorless. Furthermore, the fluorometric and colorimetric output was integrated with a smartphone to conduct on-site analysis of glucose without the need of spectrometer. • Ratiometric fluorometric and colorimetric sensing system for the H 2 O 2 and glucose was proposed. • The designed approach for glucose determination delivers a wide linear range and a low detection limit. • The synthesized C-dots have both fluorescent and colorimetric properties. • Ratiometric fluorometric and colorimetric signals were integrated with a smartphone platform for on-site analysis of glucose in real samples. In this work, a new strategy for ratiometric fluorescent and colorimetric determination of H 2 O 2 and glucose is proposed. The sensing system involves catalytic oxidation reaction of glucose oxidase (GOx) with glucose to generate H 2 O 2. Under the catalysis of Fe2+, the 580 nm emission of carbon dots (C-dots) upon 365 nm excitation is reduced by H 2 O 2 , while the fluorescence emission at 450 nm of thiochrome (oxVB 1) enhances with the oxidation reaction between H 2 O 2 /Fe2+system and VB 1 (thiamine). Simultaneously, the color of the carbon dots (C-dots) suspension changes from purplish-red to colorless. Thus, the fluorescence intensity ratio (I 450 /I 580) and the absorbance (A 557) can be used to quantitatively determine H 2 O 2 and glucose. Furthermore, we integrated fluorometric and colorimetric output with a smartphone platform to conduct on-site analysis of glucose without the need of spectrometer. A smartphone application (APP) was designed to take pictures and analyze R, G, B values of fluorometric and colorimetric signals, which delivered excellent analytical result for glucose. This ratiometric fluorescent and colorimetric sensing system on a smartphone platform ensures sensitive and convenient determination of glucose and H 2 O 2 , hence having great prospects in biomedical analysis. [ABSTRACT FROM AUTHOR]

The overuse and misuse of tetracycline (TCs) antibiotics, including tetracycline (TTC), oxytetracycline (OTC), doxycycline (DC), and chlortetracycline (CTC), pose a serious threat to human health. However, current rapid sensing platforms for tetracyclines can only quantify the total amount of TCs mixture, lacking real-time identification of individual components. To address this challenge, we integrated a deep learning strategy with fluorescence and colorimetry-based multi-mode logic gates in our self-designed smartphone-integrated toolbox for the real-time identification of natural TCs. Our ratiometric fluorescent probe (CD-Au NCs@ZIF-8) encapsulated carbon dots and Au NCs in ZIF-8 to prevent false negative or positive results. Additionally, our independently developed WeChat app enabled linear quantification of the four natural TCs using the fluorescence channels. The colorimetric channels were also utilized as outputs of logic gates to achieve real-time identification of the four individual natural tetracyclines. We anticipate this strategy could provide a new perspective for effective control of antibiotics., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023. Published by Elsevier Ltd.)

The effectiveness of chemokinetic therapy nanozymes is severely constrained because of the low H 2 O 2 levels in the tumor microenvironment. Unlike other self-produced H 2 O 2 nanozymes, the N-CNTs-encapsulated CoNi alloy (CoNiCoNC) with glucose oxidase and lactate oxidase activities has two ways to produce H 2 O 2 . It can facilitate the transformation of glucose and lactic acid into H 2 O 2 simultaneously. First, the H 2 O 2 generation pathway is favorable for aggravating energy metabolism. Second, some produced H 2 O 2 can be decomposed by CoNiCoNC to H 2 O and O 2 with the 4e - pathway to alleviate the TME hypoxia. Third, H 2 O 2 can be catalyzed to form OH to enhance reactive oxygen species (ROS) content. Through proteomic analysis, nanozymes substantially impact the metabolic pathways of cancer cells because of their aggravating energy metabolism. The high levels of ROS can cause mitochondrial lipid peroxidation and cellular ferroptosis. Consequently, the two-way H 2 O 2 -selective nanoenzymatic platform realizes the synergistic effect of starvation therapy and chemokinetics., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024. Published by Elsevier Inc.)

Environmental pollution caused by ciprofloxacin is a major problem of global public health. A machine learning-assisted portable smartphone-based visualized molecularly imprinted electrochemiluminescence (MIECL) sensor was developed for the highly selective and sensitive detection of ciprofloxacin (CFX) in food. To boost the efficiency of electrochemiluminescence (ECL), oxygen vacancies (OVs) enrichment was introduced into the flower-like Tb@Lu 2 O 3 nanoemitter. With the specific recognition reaction between MIP as capture probes and CFX as detection target, the ECL signal significantly decreased. According to, CFX analysis was determined by traditional ECL analyzer detector in the concentration range from 5 × 10 -4 to 5 × 10 2  μmol L -1 with the detection limit (LOD) of 0.095 nmol L -1 (S/N = 3). Analysis of luminescence images using fast electrochemiluminescence judgment network (FEJ-Net) models, achieving portable and intelligent quick analysis of CFX. The proposed MIECL sensor was used for CFX analysis in real meat samples and satisfactory results, as well as efficient selectivity and good stability., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Ltd. All rights reserved.)

This study involved the preparation of Metal Organic Frameworks (MOF)-derived Co 8 FeS 8 @Co 1-x S nanoenzymes with strong interfacial interactions. The nanoenzymes presented the peroxidase (POD)-like activity and the oxidation activity of reduced glutathione (GSH). Accordingly, the dual activities of Co 8 FeS 8 @Co 1-x S provided a self-cascading platform for producing significant amounts of hydroxyl radical (•OH) and depleting reduced glutathione, thereby inducing tumor cell apoptosis and ferroptosis. More importantly, the Co 8 FeS 8 @Co 1-x S inhibited the anti-apoptosis protein B-cell lymphoma-2 (Bcl-2) and activated caspase family proteins, which caused tumor cell apoptosis. Simultaneously, Co 8 FeS 8 @Co 1-x S affected the iron metabolism-related genes such as Heme oxygenase-1 (Hmox-1), amplifying the Fenton response and promoting apoptosis and ferroptosis. Therefore, the nanoenzyme synergistically killed anti-apoptotic tumor cells carrying Kirsten rat sarcoma viral oncogene homolog (KRAS) mutations. Furthermore, Co 8 FeS 8 @Co 1-x S demonstrated good biocompatibility, which paved the way for constructing a synergistic catalytic nanoplatform for an efficient tumor treatment., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Inc. All rights reserved.)

In this work, a colorimetric and fluorescent dual-mode probe controlled by NH 2 -MIL-88 B (Fe, Ni) nanozymes was developed to visually detect tetracycline antibiotics (TCs) residues quantitatively, as well as accurately distinguish the four most widely used tetracycline analogs (tetracycline (TC), chrycline (CTC), oxytetracycline (OTC), and doxycycline (DC)). Colorless substrate 3,3',5,5'-tetramethylbenzidine (TMB) may be oxidized to blue oxidized TMB by the Fe Fenton reaction, which was catalyzed by the NH 2 -MIL-88 B (Fe, Ni) nanozyme with POD-like activity. The colorimetric detection system allows TCs to interact with NH 2 -MIL-88 B (Fe, Ni). This inhibits the production of ·OH, weakens the oxidation process of TMB, and ultimately lightens the blue color in the system by blocking the electron transfer between NH 2 -MIL-88 B (Fe, Ni) and H 2 O 2 . Furthermore, TCs can interact with NH 2 -MIL-88 B (Fe, Ni) as a result of the internal filtering effect, which causes the fluorescence intensity to decrease as TCs concentration increases. Additionally, a portable instrument that combines a smartphone sensing platform with colorimetric and fluorescent signals was created for the quick, visual quantitative detection of TCs. The colorimetric and fluorescent dual-mode nano platform enables color change, with detection limits (LODs) of 0.182 μM and 0.0668 μM for the spectrometer and smartphone sensor, respectively, based on the inhibition of fluorescence and enzyme-like activities by TCs. Overall, the colorimetric and fluorescence dual-mode sensor has good stability, high specificity, and an efficient way to eliminate false-positive issues associated with a single detection mode., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

Environmental pollution caused by tetracycline antibiotics is a major concern of global public health. Here, a novel and portable molecularly imprinted electrochemiluminescence (MIECL) sensor based on smartphones for highly sensitive detection of chlortetracycline (CTC) has been successfully established. The high-performance ECL emitter of biomass carbon (BC) encapsulated CdZnTeS (CdZnTeS@BC) was successfully synthesized by hydrothermal. The enhanced ECL performance was ascribed to the introduction of the BC and increased the overall electrical conductivity of the nanoemitter, as well as increased the number of sulfur vacancies and doping on the surface of the emitter based on density functional theory calculations. An aniline-CTC molecular imprinted polymer was synthesized on the surface of the CdZnTeS@BC modified electrode by in-situ electropolymerization. The decrease in MIECL signal was attributed to the increase in impedance effect. The MIECL nanoplatform enabled a wide linear relationship in the range of 0.05-100 μmol/L with a detection limit of 0.029 μmol/L for spectrometer sensors. Interestingly, the light emitted during the MIECL reaction can be captured by a smartphone. Thus, machine learning was used to screen the photos that were taken, and color analysis was carried out on the screened photos by self-developed software, thus achieving a portable, convenient, and intelligent sensing mode. Finally, the sensor obtains satisfactory results in the detection of actual samples, with no significant differences from those of liquid chromatography., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 Elsevier B.V. All rights reserved.)

Ethephon (ETH) is a common pesticide, and its overuse has resulted in a variety of health problems for humans. However, the existing ETH detection methods are tedious and time-consuming, and real-time ETH identification remains a significant difficulty. To mitigate this concern, a dual-emission ratiometric fluorescent probe Ru@ZrMOF was rationally synthesized for the detection of ETH. In the presence of ETH, the emission peak at 435 nm gradually increased, while the peak at 600 nm remained constant, accompanied by the fluorescence color change from red, pink, blue-violet to blue. The fluorescence intensity ratio (F 435 /F 600 ) demonstrated two linear relations with the ETH concentration ranges at 3 - 50 μM and 50 - 500 μM, with a lowest detection limit at 1 μM. This was attributed to the formation of Zr-O-P bonds which attenuated the ligand-metal charge transfer (LMCT) process, resulting in the recovery of blue fluorescence of the ligand 2-Aminoterephthalic acid (2-APDC). To validate the practical application of the developed platform, a YOLO v5x-based WeChat applet "96 Speckles" was developed, and a 96-well plate and smartphone-embedded 3D-printed portable toolbox was designed for the real-time intelligent detection of ETH. This smart platform allows for real-time and efficient ETH analysis in various real samples including apples, pears and tomatoes., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 Elsevier B.V. All rights reserved.)

Antibiotic residues in the environment pose a serious threat to ecosystems and human health. Therefore, it is important to develop sensitive and rapid in situ detection methods. In this work, the designed nanozymes, with excellent four enzyme activities, were proved to be constituted of unique hollow nanocage structures (CoZnSe@CN HCs). Based on the peroxidase-like enzymes, a portable colorimetric sensor was constructed for the on-site determination of tetracycline (TC) in real samples. The linear range of TC detection was 0.1-100 μM, and the detection limit was 0.02 μM. At the same time, colorimetric detection and smartphones have also been combined for on-site colorimetric detection of TC. In-depth exploration of the detection mechanism showed that TC could be bound with the material, inhibiting the production of oxidized 3,3',5,5'-tetramethylbenzidine. The sensor was also used for the detection of TC in environmental soil and water samples. This study can provide an intelligent detection method for environmental monitoring., (© 2024. The Author(s), under exclusive licence to Springer-Verlag GmbH Austria, part of Springer Nature.)

We designed a novel, portable, and visual dual-potential molecularly imprinted ratiometric electrochemiluminescence (MIRECL) sensor for tyramine (TYM) detection based on smartphone and deep learning-assisted optical devices. Molecularly imprinted polymer-Ce 2 Sn 2 O 7 (MIP-Ce 2 Sn 2 O 7 ) layers were fabricated by in-situ electropolymerization method as the capture and signal amplification probe. Oxygen vacancies in Ce 2 Sn 2 O 7 not only enhance the electrochemical redox capability but also accelerate the energy transfer, thereby enhancing the luminescence of cathode ECL. Under optimal conditions, the ECL signals of MIP-Ce 2 Sn 2 O 7 at the cathode and the anode response of Ru(bpy) 3 2+ was reduced, thus a wide linear range from 0.01 μM to 1000 μM with the detection limit as low as 0.005 μM. Interestingly, combined with an artificial intelligence image recognition algorithm and the principle of optical signal reading by smartphone, the developed MIRECL sensor has been applied to the portable and visual determination of TYM in aquatic samples, and its practicability has been satisfactorily verified., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 Elsevier Ltd. All rights reserved.)

In this work, CuO/Fe 2 O 3 nanozymes with high peroxidase-like activity were synthesized by using hydrothermal and calcination methods. The high-resolution transmission electron microscopy (HRTEM) proved that the heterogeneous interface of CuO/Fe 2 O 3 was the main reason for the high enzyme-like activity. Strong interactions of CuO and Fe 2 O 3 were successfully verified by X-ray absorption near-edge structure (XANES) characterization. Experiments and density functional theory (DFT) calculations were also used to explain the increased enzyme activity. The heterogeneous interface acted as the main active center, facilitating the electron transfer from CuO to Fe 2 O 3 . A colorimetric and intelligent sensing system was constructed based on deep learning. Using the peroxidase-like activity of CuO/Fe 2 O 3 , a platform for glufosinate pesticides and chlortetracycline hydrochloride (CTC) with the signal "on-off-on" changes were established. The limit of detection (LOD) of glufosinate and CTC was 28 and 0.69 μM, respectively. It was successfully applied in the detection of environmental water and soil. This study can provide an intelligent detection method for environmental monitoring.

Since the catalyst's surface was the major active location, the inner structure's contribution to catalytic activity was typically overlooked. Here, ZnO-Co 3 O 4-v nanozymes with several surfaces and bulk oxygen vacancies were created. The O atoms of H 2 O 2 moved inward to preferentially fill the oxygen vacancies in the interior and form new "lattice oxygen" by the X-ray photoelectron spectroscopy depth analysis and X-ray absorption fine structure. The internal Co 2+ continually transferred electrons to the surface for a continuous catalytic reaction, which generated a significant amount of reactive oxygen species. Inner and outer double-layer electron cycles accompanied this process. A three-dimensional model of ZnO-Co 3 O 4-v was constructed using virtual reality interactive modelling technology to illustrate nanozyme catalysis. Moreover, the bactericidal rate of ZnO-Co 3 O 4-v for Methionine-resistant Staphylococcus aureus and Multiple drug resistant Escherichia coli was as high as 99%. ZnO-Co 3 O 4-v was biocompatible and might be utilized to heal wounds following Methionine-resistant Staphylococcus aureus infection. This work offered a new idea for nanozymes to replace of conventional antibacterial medications., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 Elsevier Inc. All rights reserved.)

Although the application of nanozymes has been widely studied, it is still a huge challenge to develop highly active and multifunctional nanozyme catalysts with a wider application prospect. Co 3 O 4 /CoFe 2 O 4 hollow nanocubes (HNCs) with oxygen vacancies were proposed in this study, which had a porous oxide heterostructure with CoFe 2 O 4 as the core and Co 3 O 4 as the shell. The Co 3 O 4 /CoFe 2 O 4 HNCs had three enzyme activities: peroxidase-like, oxidase-like, and catalase-like. Combining XPS depth profiling with density functional theory (DFT), the catalytic mechanism of peroxidase-like activity was explored in depth, which was mainly originated from ·OH produced by the synergistic effect between the outer oxygen and inner oxygen and electron transfer between Co and Fe. A colorimetry/smartphone dual sensing platform was designed based on the peroxidase-like activity. Especially, a multifunctional intelligent sensing platform based on deep learning-YOLO v3 algorithm-assisted smartphone was constructed to realize real-time and rapid in situ detection of l-cysteine, norfloxacin, and zearalenone. Surprisingly, the detection limit of norfloxacin was low at 0.015 μM, which was better than that of the newly published detection method in the field of nanozymes. Meanwhile, the detection mechanism of l-cysteine and norfloxacin was successfully investigated by in situ FTIR. In fact, it also showed outstanding applications in detecting l-cysteine in the food environment and norfloxacin in drugs. Furthermore, Co 3 O 4 /CoFe 2 O 4 HNCs also could degrade 99.24% of rhodamine B, along with good reusability even after 10-cycle runs. Therefore, this work provided an in-depth understanding of the synergistic effect between the outer and inner oxygen in the reaction mechanism and an efficient method for establishing a deep-learning-assisted intelligent detection platform. In addition, this research also offered a good guideline for the further development and construction of nanozyme catalysts with multienzyme activities and multifunctional applications.

An optical monitoring device combining a smartphone with a polychromatic ratiometric fluorescence-colorimetric paper sensor was developed to detect Hg 2+ and S 2- in water and seafood. This monitoring included the detection of food deterioration and was made possible by processing the sensing data with a machine learning algorithm. The polychromatic fluorescence sensor was composed of blue fluorescent carbon quantum dots (CDs) (BU-CDs) and green and red fluorescent CdZnTe quantum dots (QDs) (named GN-QDs and RD-QDs, respectively). The experimental results and density functional theory (DFT) prove that the incorporation of Zn can improve the stability and quantum yield of CdZnTe QDs. According to the dynamic and static quenching mechanisms, GN-QDs and RD-QDs were quenched by Hg 2+ and sulfide, respectively, but BU-CDs were not sensitive to them. The system colors change from green to red to blue as the concentration of the two detectors rises, and the limits of detection (LOD) were 0.002 and 1.488 μM, respectively. Meanwhile, the probe was combined with the hydrogel to construct a visual sensing intelligent test strip, which realized the monitoring of food freshness. In addition, a smartphone device assisted by multiple machine learning methods was used to text Hg 2+ and sulfide in real samples. It can be concluded that the fabulous stability, sensitivity, and practicality exhibited by this sensing mechanism give it unlimited potential for assessing the contents of toxic and hazardous substances Hg 2+ and sulfide.

Due to the lack of a general descriptor to predict the activity of nanomaterials, the current exploration of nanozymes mainly depended on trial-and-error strategies, which hindered the effective design of nanozymes. Here, with the help of a large number of Ni-O-Co bonds at the interface of heterostructures, a prediction descriptor was successfully determined to reveal the double enzyme-like activity mechanisms for Ni/CoMoO 4 . Additionally, DFT calculations revealed that interface engineering could accelerate the catalytic kinetics of the enzyme-like activity. Ni-O-Co bonds were the main active sites for enzyme-like activity. Finally, the colorimetric signal and intelligent biosensor of Ni/CoMoO 4 based on deep learning were used to detect organophosphorus and ziram sensitively. Meanwhile, the in situ FTIR results uncovered the detection mechanism: the target molecules could block Ni-O-Co active sites at the heterostructure interface leading to the signal peak decreasing. This study not only provided a well design strategy for the further development of nanozymes or other advanced catalysts, but it also designed a multifunctional intelligent biosensor platform. Furthermore, it also provided preferable ideas regarding the catalytic mechanism and detection mechanism of heterostructure nanozymes.

A valid strategy for amplifying the oxygen reduction reaction (ORR) efficiency of non-noble electrocatalyst in both alkaline and acid electrolytes by decorated with a layer of biomass derivative nitrogen-doped carbon (NPC) is proposed. Herein, a top-down strategy for the generally fabricating NPC matrix decorated with trace of metal oxides nanoparticles (FeO x NPs) by a dual-template assisted high-temperature pyrolysis process is reported. A high-activity FeO x /FeNC (namely Hemin/NPC-900) ORR electrocatalyst is prepared via simply carbonizing the admixture of Mg 5 (OH) 2 (CO 3 ) 4 and NaCl as dual-templates, melamine and acorn shells as nitrogen and carbon source, hemin as a natural iron and nitrogen source, respectively. Owing to its unique 3D porous construction, large BET areas (819.1 m 2 ∙g -1 ), and evenly dispersed active sites (FeN x , CN, and FeO parts), the optimized Hemin/NPC-900 catalyst displays comparable ORR catalytic activities, remarkable survivability to methanol, and preferable long-term stability in both alkali and acid electrolyte compared with benchmark Pt/C. More importantly, density function theory computations certify that the interaction between Fe 3 O 4 nanoparticles and arm-GN (graphitic N at armchair edge) active sites can effectually promote ORR electrocatalytic performance by a lower overpotential of 0.81 eV. Accordingly, the research provides some insight into design of low-cost non-precious metal ORR catalysts in theory and practice., (© 2021 Wiley-VCH GmbH.)

A dual-signal strategy is proposed based on fluorescent biomass-based carbon dots (BC-dots) and chitosan stabilized AuNPs (CS@AuNPs) to determine hyaluronidase (HAase). BC-dots can induce aggregation of CS@AuNPs nanoparticles with a colour change from red to blue. Positively charged CS@AuNPs interacted with the negatively charged hyaluronic acid (HA) through electrostatic adsorption, and CS@AuNPs maintained stability due to the semirigid coil conformation of HA. However, in the presence of HAase, due to enzymatic hydrolysis of HA by HAase, the CS@AuNPs agglomerated. Based on the change of fluorescence and colour, quantitative analysis of HAase was achieved. Linear ranges for the fluorometric and colorimetric determinations were 2.0-70 U mL -1 and 8-60 U mL -1 , respectively, with a detection limit of 0.27 U mL -1 . This dual-signal sensing system possesses high potential for determination of HAase in biological matrices., (© 2019 John Wiley & Sons, Ltd.)

In order to accelerate the reaction rate of water splitting, it is of immense importance to develop low-cost, stable and efficient catalysts. In this study, the facile synthesis of a novel rose-like nanocomposite catalyst (Ni 2 P/Fe 2 P/Fe 3 O 4 ) is reported. The synthesis process includes a solvothermal step and a phosphatization step to combine iron oxides and iron-nickel phosphides. Ni 2 P/Fe 2 P/Fe 3 O 4 performs well in catalyzing oxygen evolution reaction, with a very low overpotential of 365 mV to reach 10 mA cm -2 current density. The Tafel slope is as low as 59 mV dec -1 . Ni 2 P/Fe 2 P/Fe 3 O 4 has a large double-layer capacitance that contributes to a high electrochemically active area. Moreover, this catalyst is very stable for long-term use. Therefore, the Ni 2 P/Fe 2 P/Fe 3 O 4 catalyst has a high potential for use in oxygen evolution reactions., (© 2019 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

NH 3 emissions were limited strictly because of the threat for human health and sustainable development. Pt/Al 2 O 3 and Pt/CeZrO 2 were prepared by the impregnation method. Differences in surface chemical states, reduction ability, acid properties, morphological properties, reaction mechanisms, and ammonia oxidation activity were studied. It indicated that Pt species states were affected by different metal-support interactions. The homogeneously dispersed Pt species over Pt/Al 2 O 3 exposed Pt(111) because of weak metal-support interactions; there even existed an obvious interface between Pt and Al 2 O 3 . While obscure even an overlapped interface was observed over Pt/CeZrO 2 , resulting in the formation of PtO because of the oxygen migration from CeZrO 2 to Pt species (confirmed by CO-FTIR, the cycled H 2 -TPR and transmission electron microscopy results). It was noteworthy that different reaction mechanisms were induced by different states of Pt species; NH was the key intermediate species for ammonia oxidation reaction over Pt/Al 2 O 3 , but two kinds of intermediates, N 2 H 4 and HNO, were observed for Pt/CeZrO 2 . It consequently resulted in the obvious distinction of the NH 3 -SCO catalytic performance; the light-off temperatures of NH 3 over Pt/Al 2 O 3 and Pt/CeZrO 2 were 231 and 275 °C, respectively, while the maximum N 2 selectivity (65%) was obtained over Pt/CeZrO 2 , it was obviously better than that over Pt/Al 2 O 3 .

In this study, a colorimetric method was developed for rapid and sensitive determination of gallic acid (GA) by using floral-like magnetic Fe 3 O 4 @MnO 2 composite material with enhanced oxidase-like activity. Fe 3 O 4 @MnO 2 composite material is able to oxidize 3,3',5,5'-tetramethylbenzidine (TMB) to a blue product (oxTMB) with apparent color change and absorbance at 652 nm. GA can reduce the oxTMB yielding a fading blue color. Based on these results, a technique is proposed to detect GA quantitatively and qualitatively with UV-vis spectroscopy and bare eyes. A low detection limit of 0.105 μM and a detection range of 0.01 to 15 μM were obtained with UV-vis spectroscopy. This methodology possesses high potential for application in determination of GA., (© 2018 John Wiley & Sons, Ltd.)

Small molecule aggregators non-specifically inhibit multiple unrelated proteins, rendering them therapeutically useless. They frequently appear as false hits and thus need to be eliminated in high-throughput screening campaigns. Computational methods have been explored for identifying aggregators, which have not been tested in screening large compound libraries. We used 1319 aggregators and 128,325 non-aggregators to develop a support vector machines (SVM) aggregator identification model, which was tested by four methods. The first is five fold cross-validation, which showed comparable aggregator and significantly improved non-aggregator identification rates against earlier studies. The second is the independent test of 17 aggregators discovered independently from the training aggregators, 71% of which were correctly identified. The third is retrospective screening of 13M PUBCHEM and 168K MDDR compounds, which predicted 97.9% and 98.7% of the PUBCHEM and MDDR compounds as non-aggregators. The fourth is retrospective screening of 5527 MDDR compounds similar to the known aggregators, 1.14% of which were predicted as aggregators. SVM showed slightly better overall performance against two other machine learning methods based on five fold cross-validation studies of the same settings. Molecular features of aggregation, extracted by a feature selection method, are consistent with published profiles. SVM showed substantial capability in identifying aggregators from large libraries at low false-hit rates., ((c) 2009 Wiley Periodicals, Inc.)