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Surgical intervention is the most common first-line treatment for severe traumatic brain injuries (TBIs) associated with high intracranial pressure, while the complexity of these surgical procedures often results in complications. Surgeons often struggle to comprehensively evaluate the TBI status, making it difficult to select the optimal intervention strategy. Here, we introduce a fluorescence imaging-based technology that uses high-quality silver indium selenide-based quantum dots (QDs) for integrated TBI diagnosis and surgical guidance. These engineered, poly(ethylene glycol)-capped QDs emit in the near-infrared region, are resistant to phagocytosis, and importantly, are ultrastable after the epitaxial growth of an aluminum-doped zinc sulfide shell in the aqueous phase that renders the QDs resistant to long-term light irradiation and complex physiological environments. We found that intravenous injection of QDs enabled both the precise diagnosis of TBI in a mouse model and, more importantly, the comprehensive evaluation of the TBI status before, during, and after an operation to distinguish intracranial from superficial hemorrhages, provide real-time monitoring of the secondary hemorrhage, and guide the decision making on the evacuation of intracranial hematomas. This QD-based diagnostic and monitoring system could ultimately complement existing clinical tools for treating TBI, which may help surgeons improve patient outcomes and avoid unnecessary procedures.

A fluorescence probe based on molecularly imprinted polymers on red emissive biomass-derived carbon dots (r-BCDs@MIPs) was developed to detect tyramine in fermented meat products. The red emissive biomass-derived carbon dots (r-BCDs) were synthesized by the one-step solvothermal method using discarded passion fruit shells as raw materials. The fluorescence emission peak of r-BCDs was at 670 nm, and the relative quantum yield (QY) was about 2.44%. Molecularly imprinted sensing materials were prepared with r-BCDs as fluorescent centers for the detection of trace tyramine, which showed a good linear response in the concentration range of tyramine from 1 to 40 µg L -1 . The linear correlation coefficient was 0.9837, and the limit of detection was 0.77 µg L -1 . The method was successfully applied to the determination of tyramine in fermented meat products, and the recovery was 87.17-106.02%. The reliability of the results was verified through high-performance liquid chromatography (HPLC). Furthermore, we combined the r-BCDs@MIPs with smartphone-assisted signal readout to achieve real-time detection of tyramine in real samples. Considering its simplicity and convenience, the method could be used as a rapid and low-cost promising platform with broad application prospects for on-site detection of trace tyramine with smartphone-assisted signal readout., (© 2024. The Author(s), under exclusive licence to Springer-Verlag GmbH Austria, part of Springer Nature.)

Developing the second near-infrared (NIR-II) photoacoustic (PA) agent is of great interest in bioimaging. Ag 2 Se quantum dots (QDs) are one kind of potential probe for applications in NIR-II photoacoustic imaging (PAI). However, the surfaces with excess anions of Ag 2 Se QDs, which increase the probability of nonradiative transitions of excitons benefiting PA imaging, are not conducive to binding electron donor ligands for potential biolabeling and imaging. In this study, Staphylococcus aureus (S. aureus) cells are driven for the biosynthesis of Ag 2 Se QDs with catalase (CAT). Biosynthesized Ag 2 Se (bio-Ag 2 Se-CAT) QDs are produced in Se-enriched environment of S. aureus and have a high Se-rich surface. The photothermal conversion efficiency of bio-Ag 2 Se-CAT QDs at 808 and 1064 nm is calculated as 75.3% and 51.7%, respectively. Additionally, the PA signal responsiveness of bio-Ag 2 Se-CAT QDs is ≈10 times that of the commercial PA contrast agent indocyanine green. In particular, the bacterial CAT is naturally attached to bio-Ag 2 Se-CAT QDs surface, which can effectively relieve tumor hypoxia. The bio-Ag 2 Se-CAT QDs can relieve heat-initiated oxidative stress while undergoing effective photothermal therapy (PTT). Such biosynthesis method of NIR-II bio-Ag 2 Se-CAT QDs opens a new avenue for developing multifunctional nanomaterials, showing great promise for PAI, hypoxia alleviation, and PTT., (© 2024 Wiley‐VCH GmbH.)

MicroRNAs (miRNAs) play a key role in physiological processes, and their dysregulation is closely related to various human diseases. Simultaneous detection of multiple miRNAs is pivotal to cancer diagnosis at an early stage. However, most multicomponent analyses generally involve multiple excitation wavelengths, which are complicated and often challenging to simultaneously acquire multiple detection signals. In this study, a convenient and sensitive sensor was developed to simultaneously detection of multiple miRNAs under a single excitation wavelength through the fluorescence resonance energy transfer between the carbon dots (CDs)/quantum dots (QDs) and graphene oxide (GO). A hybridization chain reaction (HCR) was triggered by miRNA-141 and miRNA-21, resulting in the high sensitivity with a limit of detection (LOD) of 50 pM (3σ/k) for miRNA-141 and 60 pM (3σ/k) for miRNA-21. This simultaneous assay also showed excellent specificity discrimination against the mismatch. Furthermore, our proposed method successfully detected miRNA-21 and miRNA-141 in human serum samples at a same time, indicating its diagnostic potential in a clinical setting., 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.)

Florfenicol (F), an antimicrobial agent exclusive to veterinary use within the chloramphenicol class, is extensively applied as a broad-spectrum remedy for animal diseases. Despite its efficacy, concerns arise over potential deleterious residues in animal-derived edibles, posing threats to human health. This study pioneers an innovative approach, introducing a quantum dot fluorescence-based immunoassay (FLISA) for the meticulous detection of F residues in animal-derived foods and feeds. This method demonstrates heightened sensitivity, with a detection limit of 0.3 ng/mL and a quantitative detection range of 0.6-30.4 ng/mL. Method validation, applied to diverse food sources, yields recoveries from 90.4 % to 109.7 %, featuring RSDs within 1.3 % to 8.7 %, the results showed high consistency with the national standard HPLC-MS/MS detection method. These findings underscore the method's accuracy and precision, positioning it as a promising tool for swift and reliable F residue detection, with substantial implications for fortifying food safety monitoring., 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.)

Although therapeutic nanovaccines have made a mark in cancer immunotherapy, the shortcomings such as poor homing ability of lymph nodes (LNs), low antigen presentation efficiency and low antitumor efficacy have hindered their clinical transformation. Accordingly, we prepared advanced nanovaccines (CMB and CMC) by integrating carbon dots (CDs) with tumor-associated antigens (B16F10 and CT26). These nanovaccines could forwardly target tumors harbouring LNs, induce strong immunogenicity for activating cytotoxic T cells (CTLs), thereby readily eliminating tumor cells and suppressing primary/distal tumor growth. This work provides a promising therapeutic vaccination strategy to enhance cancer immunotherapy., 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.)

As biomass, rice straw (RS) is often valorized as a precursor of green products. In this respect, the RS-based carbon quantum dots (CQDs) are synthesized doped with N and S during the preparation. Synergistic doping with lipoic acid and ethylenediamine can vastly increase the yield of CQD from rice straw from 6.14 % to 62.8 %, and sulfur doping plays a more important role on the surface functional groups of the quantum dots. Further assessment is achieved toward the performance of SN-CQDs-hydroxypropyl cellulose nanocomposites. The optical behavior of synthesized SN-CQDs, and the critical concentration of its liquid crystal behaviors, at which the anisotropic phase begins to emerge, is approximately 1 %. Incorporating it into HPC, especially at 5 %, provided nanocomposite films with effective liquid crystal, tensile strength, and thermal stability. This sample's texture reveals a planar structure with colors ranging from yellow to red. The synergistic effect of incorporating SN-CQDs is shown by improving the strength to ~282.1 %, and the activation energy increased from 583.6 kJ.mol -1 to 615.1 kJ/mol. HPC-SN-CQDs can be assembled into an LED device, emitting warm light, of which CIE coordinate is (0.34,0.43)., 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.)

ASFV is the only known double-stranded insect-borne DNA virus, which can rapidly infect domestic pigs and wild boars with ticks as transmission medium. Since it was first discovered in 1921, it quickly spread to all parts of the world and brought huge economic losses to the pig industry all over the world. At present, there is still no safe and effective vaccine for ASFV. Here, we developed a quantum-dot labeled antibody test strip for the detection of antibodies against ASFV pp62. The pp62 protein was labeled with quantum dots, and the antibody test strip was developed uses it in a detection mode of labeled antigen-SPA interceptor-monoclonal antibody quality control. The test strip showed high sensitivity, the positive detection limit of the strip was 1: 10 6 by continuous multiple dilution using the positive standard serum of ASFV antibody as reference. The test strip showed good specificity, and there was no cross reaction with other swine diseases virus (PCV2, PRRSV, CSFV, PPV). Using the detection results of commercialized kit for African swine fever virus as reference, 80 ASFV antibody negative serum and 4 different ASFV antibody positive serum were detected using the ASFV pp62 quantum-dot labeled antibody test strip. The results were consistent with the commercial kit. This study provides a new detection method for the prevention and control of African swine fever., Competing Interests: Declaration of competing interest The authors declare that they have no competing interests., (Copyright © 2024. Published by Elsevier B.V.)

Efforts to prolong the blood circulation time and bypass immune clearance play vital roles in improving the therapeutic efficacy of nanoparticles (NPs). Herein, a multifunctional nanoplatform (BPP@RTL) that precisely targets tumor cells is fabricated by encapsulating ultrasmall phototherapeutic agent black phosphorus quantum dot (BPQD), chemotherapeutic drug paclitaxel (PTX), and immunomodulator PolyMetformin (PM) in hybrid membrane-camouflaged liposomes. Specifically, the hybrid cell membrane coating derived from the fusion of cancer cell membrane and red blood cell membrane displays excellent tumor targeting efficiency and long blood circulation property due to the innate features of both membranes. After collaboration with aPD-L1-based immune checkpoint blockade therapy, a boosted immunotherapeutic effect is obtained due to elevated dendritic cell maturation and T cell activation. Significantly, laser-irradiated BPP@RTL combined with aPD-L1 effectively eliminates primary tumors and inhibits lung metastasis in 4T1 breast tumor model, offering a promising treatment plan to develop personalized antitumor strategy.

The carbon dots (CDs) with excellent optical properties and their hydrogel complex are of great significance in biomedicine, healthcare and biochemical detection fields. This paper reports the preparation of green-emitting CDs (MA-CDs) through one-step hydrothermal route with citric acid as reducing agent, L-malic acid as carbon source and N-(2-hydroxyethyl)ethylenediamine as nitrogen source. To expand its application in biology, MA-CDs were coupled with vancomycin to obtain multifunctional CDs (VMA-CDs). The prepared VMA-CDs exhibit selective antibacterial behavior to Gram-positive bacteria, and it could be used as a fluorescent probe to selectively label Staphylococcus aureus (S. aureus). Moreover, thanks to the excellent optical properties of VMA-CDs, it has been used as a fluorescent sensor to detect Au 3+ with detection range of 6.50 nM-21.93 μM and detection limit 3.98 nM. By introducing the fluorescence of CDs as the reference signal, and VMA-CDs as a response signal, the hydrogel (V-SP) was prepared and realized the detection of Au 3+ in microfluidics with assistance of a smartphone to collect and analyze data., 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.)

Nifedipine (NIF), as one of the dihydropyridine calcium channel blockers, is widely used in the treatment of hypertension. However, misuse or ingestion of NIF can result in serious health issues such as myocardial infarction, arrhythmia, stroke, and even death. It is essential to design a reliable and sensitive detection method to monitor NIF. In this work, an innovative molecularly imprinted polymer dual-emission fluorescent sensor (CDs@PDA-MIPs) strategy was successfully designed for sensitive detection of NIF. The fluorescent intensity of the probe decreased with increasing NIF concentration, showing a satisfactory linear relationship within the range 1.0 × 10 -6  M ~ 5.0 × 10 -3  M. The LOD of NIF was 9.38 × 10 -7  M (S/N = 3) in fluorescence detection. The application of the CDs@PDA-MIPs in actual samples such as urine and Qiangli Dingxuan tablets has been verified, with recovery ranging from 97.8 to 102.8% for NIF. Therefore, the fluorescent probe demonstrates great potential as a sensing system for detecting NIF., (© 2024. The Author(s), under exclusive licence to Springer-Verlag GmbH Austria, part of Springer Nature.)

Photosynthetic inorganic biohybrid systems (PBSs) combining an inorganic photosensitizer with intact living cells provide an innovative view for solar hydrogen production. However, typical whole-cell biohybrid systems often suffer from sluggish electron transfer kinetics during transmembrane diffusion, which severely limits the efficiency of solar hydrogen production. Here, a unique biohybrid system with a quantum yield of 8.42% was constructed by feeding bismuth-doped carbon dots (Bi@CD S ) to Escherichia coli ( E. coli ). In this biohybrid system, Bi@CD S can enter the cells and transfer the electrons upon light irradiation, greatly reducing the energy loss and shortening the distance of electron transfer. More importantly, the photocatalytic hydrogen production of the E. coli -Bi@CDs biohybrid system reached up to 0.95 mmol within 3 h under light irradiation (420-780 nm, 2000 W m -2 ), which is 1.36 and 2.38 times higher than that in the E. coli -CDs biohybrid system and the E. coli system, respectively. In addition, the mechanism of enhanced hydrogen production was further explored. It was found that the accelerated decomposition of glucose, the accelerated production of pyruvate, the inhibition of lactic acid, and the increase of formic acid were the reasons for the increase of hydrogen production. This work provides a novel strategy for improving the hydrogen production in photosynthetic inorganic biohybrid systems.

Telomerase is an important biomarker for early diagnosis of cancers, but current telomerase assays usually rely on measuring the extension products of telomerase substrates, which increases the assay complexity. More evidence indicates that human telomerase RNA (hTR), as a core component of telomerase, is positively correlated with the telomerase activity. Herein, we demonstrate the development of a duplex-specific nuclease (DSN)-propelled 3D quantum dot (QD) nanoassembly with two-step Föster resonance energy transfer (FRET) for the one-step sensing of hTR in breast cancer cells and tissues. This assay involves only one hairpin probe modified with a Cy5 at the sixth base from the 5'-biotin end and a BHQ2 at the 3'-terminus, which integrates three functions of target recognition, target recycling amplification, and signal readout. The anchoring of the hairpin probe on the 605QD surface results in the formation of a 3D 605QD-Cy5-probe-BHQ2 nanoassembly in which two-step FRET occurs among the 605QD, Cy5, and BHQ2 quencher. Notably, the formation of 605QD-Cy5-probe-BHQ2 nanoassembly facilitates the reduction of background signal and the increase of signal-to-background ratio due to its dense, highly oriented nucleic acid shell-induced steric hindrance effect. This assay can achieve one-step and rapid detection of hTR with a detection limit of 2.10 fM, which is the simplest and most rapid hTR assay reported so far. Moreover, this assay can efficiently distinguish single-base mismatched sequences, and it can discriminate the hTR level between breast cancer patients and healthy donors with a high accuracy of 100%, with great prospects for early diagnosis of cancers.

A facile method which combines the advantages of carbon quantum dots and molecular imprinting technology to design a fluorescence molecular imprinting sensor for the high sensitivity and selective detection of chloramphenicol. The fluorescent molecule imprinted polymers are synthesized by sol-gel polymerization using carbon quantum dots as functional monomers and fluorescent sources, TEOS as crosslinkers, breaking with the traditional understanding of an additional functional monomer. Under optimal experimental, as the concentration of chloramphenicol increases, the fluorescence intensity of the fluorescence molecule imprinting sensor gradually decreases. The concentration of chloramphenicol is linear in the range of 5-100 µg/L and the detection limit is 1 µg/L (N/S = 3). The sensor is able to detect chloramphenicol in milk, enabling the application of real samples. The results show that this work provides an easy method to preparing fluorescent molecular imprinting sensors for the detection of chloramphenicol in milk., (© 2023. The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature.)

Lomefloxacin (LMF), a third-generation fluoroquinolone antibacterial agent, is often used to treat bacterial and mycoplasma infections. However, due to its prolonged half-life and slow metabolism, it is prone to residues in animal-derived foods, posing a potential food safety risk. Therefore, it is particularly urgent and important to establish a method for detecting lomefloxacin. In this study, direct and indirect competitive fluorescence-linked immunosorbent assay (dc-FLISA and ic-FLISA) based on quantum dots (QDs) was established for the detection of LMF. As for dc-FLISA, the half-maximal inhibitory concentration (IC 50 ) and limit of detection (LOD) were 0.84 ng/mL, 0.04 ng/mL, respectively, the detection ranges from 0.08 to 9.11 ng/mL. The IC 50 and LOD of ic-FLISA were 0.43 ng/mL and 0.03 ng/mL, respectively, meanwhile the detection ranges from 0.05 to 3.49 ng/mL. The recoveries of dc-FLISA and ic-FLISA in animal-derived foods (milk, fish, chicken, and honey), ranged from 95.8% to 105.2% and from 96.3% to 103.4%, respectively, with the coefficients of variation less than 8%. These results suggest that the dc-FLISA and ic-FLISA methods, which are based on QD labelling, are highly sensitive and cost-effective, and can be effectively used to detect LMF in animal-derived foods.

Based on the use of CQDs as fluorescent probe and covalent coupling method to detect biological molecules with amino groups, to deeply analysis and detect the metabolism of Microcystis aeruginosa. The metabolic changes of carboxyl biomolecules in Microcystis aeruginosa were analyzed by covalent coupling method, including GSH, phycocyanin and SOD enzyme. The changes of GSH content and its correlation between phycocyanin, SOD were analyzed. The content of phycocyanin and SOD reached the maximum on the 65th day, and GSH was more sensitive to the growth and metabolism of microalgae. GSH plays an important role in reducing the external oxidative damage of microalgae cells. The synthesis of glutathione (GSH), GSH/GSSG mutual transformation, the production of phytochelating peptide (PC), the ASA-GSH cycle, and other physiological processes are interconnected. These interactions are crucial for preserving the antioxidant properties of microalgae and regulating redox-sensitive signal transduction., 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.)

Recently protein binders have emerged as a promising substitute for antibodies due to their high specificity and low cost. Herein, we demonstrate an electrochemical biosensor chip through the electronic labelling strategy using lead sulfide (PbS) colloidal quantum dots (CQDs) and the unnatural SARS-CoV-2 spike miniprotein receptor LCB. The unnatural receptor can be utilized as a molecular probe for the construction of CQD-based electrochemical biosensor chips, through which the specific binding of LCB and the spike protein is transduced to sensor electrical signals. The biosensor exhibits a good linear response in the concentration range of 10 pg mL -1 to 1 μg mL -1 (13.94 fM to 1.394 nM) with the limit of detection (LOD) being 3.31 pg mL -1 (4.607 fM for the three-electrode system) and 9.58 fg mL -1 (0.013 fM for the HEMT device). Due to the high sensitivity of the electrochemical biosensor, it was also used to study the binding kinetics between the unnatural receptor LCB and spike protein, which has achieved comparable results as those obtained with commercial equipment. To the best of our knowledge, this is the first example of using a computationally designed miniprotein receptor based on electrochemical methods, and it is the first kinetic assay performed with an electrochemical assay alone. The miniprotein receptor electrochemical biosensor based on QDs is desirable for fabricating high-throughput, large-area, wafer-scale biochips.

In this work, we report a new concept of upconversion-powered photoelectrochemical (PEC) bioanalysis. The proof-of-concept involves a PEC bionanosystem comprising a NaYF 4 :Yb,Tm@NaYF 4 upconversion nanoparticles (UCNPs) reporter, which is confined by DNA hybridization on a CdS quantum dots (QDs)/indium tin oxide (ITO) photoelectrode. The CdS QD-modified ITO electrode was powered by upconversion absorption together with energy transfer effect through UCNPs for a stable photocurrent generation. By measuring the photocurrent change, the target DNA could be detected in a specific and sensitive way with a wide linear range from 10 pM to 1 μM and a low detection limit of 0.1 pM. This work exploited the use of UCNPs as signal reporters and realized upconversion-powered PEC bioanalysis. Given the diversity of UCNPs, we believe it will offer a new perspective for the development of advanced upconversion-powered PEC bioanalysis.

The abnormal level of xanthine oxidase (XOD) often causes pathological changes, which are related to a series of diseases. Herein, a novel and sensitive ratiometric fluorescent sensing platform based on WO 3 nanosheets and carbon dots (CDs) was constructed to detect XOD activity for the first time. Under the catalytic oxidation of xanthine by XOD, hydrogen peroxide (H 2 O 2 ) was generated. In the presence of H 2 O 2 , WO 3 nanosheets were able to catalyze the oxidation of o-phenylenediamine to generate 2,3-diaminophenazine (DAP) with a yellow fluorescence signal at 570 nm due to its great peroxidase-like activity. The oxidation product DAP was capable of quenching the fluorescence of CDs at 430 nm through the inner filter effect. Therefore, the fluorescence intensity ratio F 570 /F 430 can be used for quantitative analysis of XOD activity. This assay displayed good linear relationships in the range of 0.005-0.05 U/L and 0.5-40 U/L with a detection limit of 0.002 U/L. In addition, this ratiometric fluorescent sensing platform was successfully applied to the determination of XOD in human serum samples and XOD inhibitor screening, demonstrating significant potential in disease diagnosis and drug-screening applications., 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.)

Two different models of electrochemiluminescence (ECL) immunosensors for the sensitive and quantitative detection of the CP4-EPSPS protein in genetically modified (GM) crops were proposed in this study. One was a signal-reduced ECL immunosensor based on nitrogen-doped graphene, graphitic carbon nitride and polyamide-amine (GN-PAMAM-g-C 3 N 4 ) composites as the electrochemically active substance. The other model was a signal-enhanced ECL immunosensor based on a GN-PAMAM modified electrode for the detection of CdSe/ZnS quantum dots (QDs)-labeled antigens. The ECL signal responses of the reduced and enhanced immunosensors linearly decreased as the increase of the soybean RRS and RRS-QDs content in the range of 0.05% to 1.5% and 0.025% to 1.0%, with the limits of detection of 0.03% and 0.01% (S/N = 3), respectively. Both of the ECL immunosensors showed good specificity, stability, accuracy, and reproducibility in the analysis of real samples. The results indicate that the two immunosensors provide an ultra-sensitive and quantitative approach for the determination of the CP4-EPSPS protein. Due to their outstanding performances, the two ECL immunosensors could be useful tools for achieving the effective regulation of GM crops., 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.)

Influenza virus, existing many subtypes, causes a huge risk of people health and life. Different subtypes bring a huge challenge for detection and treatment, thus simultaneous detection of multiple influenza virus subtypes plays a key role in fight against this disease. In this work, three kinds of influenza virus subtypes are one-step detection based on microbead-encoded microfluidic chip. HIN1, H3N2 and H7N3 were simultaneously captured only by microbeads of different magnetism and sizes, and they were further treated by magnetic separation and enriched through the magnetism and size-dependent microfluidic structure. Different subtypes of influenza virus could be linearly encoded in different detection zones of microfluidic chip according to microbeads of magnetism and size differences. With the high-brightness quantum dots (QDs) as label, the enriched fluorescence detection signals were further read online from linearly encoded strips, obtaining high sensitivity with detection limit of HIN1, H3N2, H7N3 about 2.2 ng/mL, 3.4 ng/mL and 2.9 ng/mL. Moreover, a visual operation interface, microcontroller unit and two-way syringe pump were consisted of a miniaturized detection device, improving the detection process automation. And this assay showed strong specificity. This method improves a new way of multiple pathogens detection using microbead-encoded technologies in the microfluidic chip., 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.)

The combination of phototherapy and chemotherapy holds great potential for cancer treatment, while hypoxia in tumor as well as unexpected drug release largely restricts anticancer therapy. Inspired by the natural intelligence, herein, for the first time, a "bottom-up" protein self-assembly strategy mediated by near-infrared (NIR) quantum dots (QDs) with multicharged electrostatic interactions is presented to develop a tumor microenvironment (TME)-responsive theranostic nanoplatform for imaging-guided synergistic photodynamic therapy (PDT)/photothermal therapy (PTT)/chemotherapy. Catalase (CAT) possesses diverse surface charge distribution under different pH conditions. After modification by chlorin e6 (Ce6), the formulated CAT-Ce6 with patchy negative charges can be assembled with NIR Ag 2 S QDs by regulating their electrostatic interactions, allowing for effective incorporation of specific anticancer drug oxaliplatin (Oxa). Such Ag 2 S@CAT-Ce6@Oxa nanosystems are able to visualize nanoparticle (NP) accumulation to guide subsequent phototherapy, together with significant alleviation of tumor hypoxia to further enhance PDT. Moreover, the acidic TME triggers controllable disassembly through weakening the CAT surface charge to disrupt electrostatic interactions, allowing for sustained drug release. Both in vitro and in vivo results demonstrate remarkable inhibition of colorectal tumor growth with a synergistic effect. Overall, this multicharged electrostatic protein self-assembly strategy provides a versatile platform for realizing TME-specific theranostics with high efficiency and safety, promising for clinical translation., (© 2023 Wiley-VCH GmbH.)

Herein, a direct-contact photocurrent-direction-switching photoelectrochemical (PEC) biosensing platform for the ultrasensitive and selective detection of soluble CD146 (sCD146) is reported for the first time via in situ formation of carbon nitride quantum dots (CN QDs)/titanium dioxide (TiO 2 ) nanodiscs with the double-supported 3D DNA walking amplification. In this platform, metal organic frameworks (MOFs)-derived porous TiO 2 nanodiscs exhibit excellent anodic photocurrent, whereas a single-stranded auxiliary DNA (ssDNA) as biogate is absorbed onto the TiO 2 nanodiscs to block active sites. Subsequently, with the help of intermediate DNAs from target sCD146-induced double-supported 3D DNA walking signal amplification, the ssDNA can leave away from the surface of TiO 2 nanodiscs due to the specific hybridization with intermediate DNAs. Afterward, the successful direct contact of CN QDs on TiO 2 nanodiscs by porosity and electrostatic adsorption, leads to the effective photocurrent-direction switching from anodic to cathodic photocurrent. Based on direct-contact photocurrent-direction-switching CN QDs/TiO 2 nanodiscs system and double-supported 3D DNA walking signal amplification, sCD146 is detected sensitively with a wide linear range (10 fg mL -1 to 5 ng mL -1 ) and a low limit of detection (2.1 fg mL -1 ). Also, the environmentally friendly and direct-contact photocurrent-direction-switching PEC biosensor has an application prospect for cancer biomarker detection., (© 2023 Wiley-VCH GmbH.)

In present work, blue carbon dots (b-CDs) were derived from ammonium citrate and guanidine hydrochloride, and red carbon dots (r-CDs) were stemmed from malonate, ethylenediamine and meso‑tetra (4-carboxyphenyl) porphin based on facile hydrothermal method. Eco-friendly ratiometric fluorescence probe was innovatively constructed to effectively measure Hg 2+ utilizing b-CDs and r-CDs. The developed probe displayed two typical emission peaks at 450 nm from b-CDs and 650 nm from r-CDs under the excitation at 360 nm. Mercury ion has strong quenching effect on the fluorescence intensity at 450 nm due to the electron transfer process and the fluorescence change at 450 nm was used as the response signal, whereas the fluorescence intensity at 650 nm kept unchangeable which resulted from the chemical inertness between Hg 2+ and r-CDs, serving as the reference signal in the sensing system. Under optimal circumstances, this probe exhibited an excellent linearity between the fluorescence response values of ΔF 450 /F 650 and Hg 2+ concentrations over range of 0.01-10 µmol/L, and the limit of detection was down to 5.3 nmol/L. Furthermore, this probe was successfully employed for sensing Hg 2+ in practical environmental water samples with satisfied recoveries of 98.5%-105.0%. The constructed ratiometric fluorescent probe provided a rapid, environmental-friendly, reliable, and efficient platform for measuring trace Hg 2+ in environmental field., 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 B.V.)

Antibacterial nanomaterials provide promising alternative strategies to combat the bacterial infection due to deteriorating resistance. However, few have been practically applied due to the lack of clear antibacterial mechanisms. In this work, we selected good-biocompatibility iron-doped CDs (Fe-CDs) with antibacterial activity as a comprehensive research model to systematically reveal the intrinsic antibacterial mechanism. Through energy dispersive spectroscopy (EDS) mapping of in situ ultrathin sections of bacteria, we found that a large amount of iron was accumulated inside the bacteria treated with Fe-CDs. Then, combining the data of cell level and transcriptomics, it can be elucidated that Fe-CDs could interact with cell membranes, enter bacterial cells through iron transport and infiltration, increase intracellular iron levels, trigger increased reactive oxygen species (ROS), and lead to disruption of Glutathione (GSH)-dependent antioxidant mechanisms. Excessive ROS further leads to lipid peroxidation and DNA damage in cells, lipid peroxidation destroys the integrity of the cell membrane, and finally leads to the leakage of intracellular substances resulting in bacterial growth inhibition and death. This result provides important insights into the antibacterial mechanism of Fe-CDs and further provides a basis for the deep application of nanomaterials in biomedicine., 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.)

Fluorescence carbon quantum dots (CQDs) have been widely applied to sensing and bioimaging. In this paper, near-infrared carbon quantum dots (NIR-CQDs) were prepared through a simple one-step hydrothermal approach using reduced glutathione and formamide as raw materials. Based on NIR-CQDs, aptamer (Apt) and graphene oxide (GO) has been applied to fluorescence sensing cortisol. NIR-CQDs-Apt adsorbed to the surface of GO through π-π stacking and an inner filter effect (IFE) occurred between NIR-CQDs-Apt and GO leading to NIR-CQDs-Apt fluorescence "off". The IFE process is disrupted in the presence of cortisol, allowing NIR-CQDs-Apt fluorescence "on". This led us to construct a detection method with excellent selectivity over other cortisol sensors. The sensor can detect cortisol from 0.4 to 500 nM and has a detection limit as low as 0.13 nM. Importantly, this sensor can be used to detect intracellular cortisol with excellent biocompatibility and cellular imaging capabilities, which is promising for biosensing., 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 B.V.)

Herein, we reported the room-temperature fabrication of ionic liquid-modified carbon dots encapsulated in bionic antibodies (IL-modified CDs@BAs) by one-pot green synthesis. In order to enhance the fluorescence intensity of CDs, imidazole ILs and lemon rich in heteroatoms were selected as CDs modifiers and sources. The resulting IL-modified CDs@BAs showed good selectivity and capture toward urea and obviously induced fluorescence quenching by template-binding. The inhibition rate ofIL-modified CDs@BAs on the urea pathway of ethyl carbamate was about 29.07% in the simulated Huangjiu system, indicating a good inhibitory effect. The IL-modified CDs@BAs system was also reproducible after five consecutive uses, thus reducing the economic cost. This research would expand the application fields of BAs-based optical sensing system from the perspectives of energy conservation, environmental protection and resource recovery, focusing on their application in the field of food safety control., 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.)

Focused ultrasound, as a protocol of cancer therapy, might induce extracellular adenosine triphosphate (ATP) release, which could enhance cancer immunotherapy and be monitored as a therapeutic marker. To achieve an ATP-detecting probe resistant to ultrasound irradiation, we constructed a Cu/N-doped carbon nanosphere (CNS), which has two fluorescence (FL) emissions at 438 and 578 nm to detect ultrasound-regulated ATP release. The addition of ATP to Cu/N-doped CNS was conducted to recover the FL intensity at 438 nm, where ATP enhanced the FL intensity probably via intramolecular charge transfer (ICT) primarily and hydrogen-bond-induced emission (HBIE) secondarily. The ratiometric probe was sensitive to detect micro ATP (0.2-0.6 μM) with the limit of detection (LOD) of 0.068 μM. The detection of ultrasound-regulated ATP release by Cu,N-CNS/RhB showed that ATP release was enhanced by the long-pulsed ultrasound irradiation at 1.1 MHz (+37%, p < 0.01) and reduced by the short-pulsed ultrasound irradiation at 5 MHz (-78%, p < 0.001). Moreover, no significant difference in ATP release was detected between the control group and the dual-frequency ultrasound irradiation group (+4%). It is consistent with the results of ATP detection by the ATP-kit. Besides, all-ATP detection was developed to prove that the CNS had ultrasound-resistant properties, which means it could bear the irradiation of focused ultrasound in different patterns and detect all-ATP in real time. In the study, the ultrasound-resistant probe has the advantages of simple preparation, high specificity, low limit of detection, good biocompatibility, and cell imaging ability. It has great potential to act as a multifunctional ultrasound theranostic agent for simultaneous ultrasound therapy, ATP detection, and monitoring.

A simple and sensitive fluorometric assay based on nitrogen-doped carbon dots (N-CDs) was developed for the determination of thrombin (TB) activity in human serum samples and living cells. The novel N-CDs were prepared by a facile one-pot hydrothermal method using 1,2-ethylenediamine and levodopa as precursors. Such N-CDs exhibited green fluorescence with excitation/emission peaks at 390/520 nm and a high fluorescence quantum yield of approximately 39.2%. H-D-Phenylalanyl-L-pipecolyl-Larginine-p-nitroaniline-dihydrochloride (S-2238) was hydrolyzed by TB to produce p-nitroaniline which was capable of quenching the fluorescence of N-CDs due to an inner filter effect. This assay was used to detect TB activity with a low detection limit of 11.3 fM. The proposed sensing method was then expanded to the TB inhibitor screening and exhibited excellent applicability. As a typical TB inhibitor, argatroban was determined in a concentration as low as 1.43 nM. The method has also been successfully employed for the determination of TB activity in living HeLa cells. This work showed significant potential for TB activity assay in clinical and biomedicine applications., 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.)

The frequent use of Zirconium (Zr) and Hafnium (Hf) in modern industries may result in serious environment issues, and thus developing analytical methods to facilitate the control of these two resembled metal elements is urgently needed. However, up to now, rapidly and conveniently detecting Zr 4+ and Hf 4+ is still full of challenge. In this study, nitrogen and sulfur co-doped carbon dots (N, S-Cdots) with aggregation-induced emission enhancement (AIEE) were prepared and used for turn-on detection of Zr 4+ and Hf 4+ within 10 min. The photoluminescent intensity of N, S-Cdots showed a good linear correlation with Zr 4+ and Hf 4+ concentrations ranging from 0 to 30 μM with the limit of detection (LOD) of 0.47 and 0.53 μM, respectively. Furthermore, this fluorometric assay was successfully used for quantitative analysis of Zr 4+ and Hf 4+ in real water samples with satisfactory recoveries in the range of 91.16-108.50% and 90.28-106.49%, respectively. Finally, the developed N, S-Cdots sensing system was used for assay PTP1B activity and screening its inhibitor with Zr 4+ as the medium. Our work demonstrated that the as-prepared N, S-Cdots with AIEE can offer a simple and reliable alternative for rapid detection of Zr 4+ and Hf 4+ in water samples, in addition to being potential useful in phosphatase analysis and drug discovery., 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.)

Streptococcus agalactiae is a significant pathogen that can affect both human beings and animals. The extensive current use of antibiotics has resulted in antibiotic resistance. In our previous research, we found that zinc oxide quantum dots (ZnO QDs) had inhibitory effects on antibiotic-resistant microorganisms. In this study, a strain of Streptococcus agalactiae WJYT1 with a broad antibiotic-resistant spectrum was isolated and identified from Lama glama at Sichuan Agricultural University Teaching Animal Hospital. The genome for the resistance and virulence genes was analyzed. Additionally, the antibacterial effects and anti-virulence mechanism of ZnO QDs for S. agalactiae WJYT1 were investigated. The results showed that the genome of S. agalactiae WJYT1 is 1,943,955 bp, containing 22 resistance genes and 95 virulence genes. ZnO QDs have a good antibacterial effect against S. agalactiae WJYT1 by reducing bacterial growth and decreasing the expression of virulence genes, including bibA , hylB , sip , and cip , which provides a novel potential treatment for S. agalactiae .

Amino- and sulfhydryl- functionalized biomass carbon dots (BCDs) were prepared by one-pot reverse microemulsion for specific recognition of ferric ions (Fe 3+ ) and L-cysteine (L-Cys). Green grapefruit peel was used as the carbon source while aminosilane and mercaptosilane were used as N- and S-supplier. Following the adsorption of Fe 3+ on the surfaces of BCDs-NH 2 and BCDs-SH, the fluorescence responses was quenched step by step, while adding L-Cys to the BCDs-NH 2 /Fe 3+ system restored the fluorescence. The BCDs-NH 2 and BCDs-SH system exhibited extremely low limits of detection for Fe 3+ of 3.2 and 3.0 nM, respectively, within a wide linear ranges of 0.006-200 μM and 0.004-200 μM, respectively. The BCDs-NH 2 /Fe 3+ systems were used as an optosensor for L-Cys in the concentration ranges of 0.08-30 and 30-1000 μM with a detection limit of 65 nM. Developed BCDs-NH 2 and BCDs-SH were able to respond to Fe 3+ in water samples with satisfactory recoveries of 100.1%-103.1% and 94.6%-108.5%, respectively, and the BCDs-NH 2 /Fe 3+ system was also able to respond to BCDs-NH 2 /Fe 3+ in actual lake water samples with recoveries from 87.3% to 98.8%. Meanwhile, The BCDs-NH 2 exhibited good photoluminescence and stability, and the with a fluorescence quantum yield was as high as 25%. This work demonstrates the feasibility of using such materials to remove hazardous ions from water and employing the resulting complexes for optosensing in a sustainable manner., (© 2022. The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature.)

Bisphenol A (BPA) is an endocrine disrupting chemical and poses a grave threat to the human health. Herein, a fluorescent probe constructed with molecularly imprinted polymers decorated carbon dots (CDs@MIPs) was proposed for determination of BPA with high selectivity. The CDs@MIPs were constructed using BPA, 4-vinylpyridine and ethylene glycol dimethacrylate as template, functional monomer and cross linker, respectively. The obtained fluorescent probe not only owned a highly selective recognition function derived from MIPs but also displayed an excellent sensitivity for sensing BPA stemmed from CDs. The fluorescence intensity of CDs@MIPs was varied before and after the removal of BPA templates. The fluorescent decrease fraction of the fluorescent probe demonstrates a nice linearity in BPA concentration range of 10-2000 nM (r 2  = 0.9998) and the detection limit is as low as 1.5 nM. The fluorescent probe was triumphantly utilized to sense the level of BPA in real aqueous and plastic samples with good results. Moreover, the fluorescent probe offered a wonderful means for fast identification and sensitive detection of BPA from environmental aqueous samples., 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 an effort to fulfill the strategy of sustainable development, Rhodamine B, a common and toxic organic pollutant in the textile industry, was reported for the first time as a single precursor to develop a kind of novel hydrophobic nitrogen-doped carbon dot (HNCD) through a green and facile one-pot solvothermal method. The HNCDs with an average size of 3.6 nm possess left and right water contact angles of 109.56° and 110.34°, respectively. The HNCDs manifest excitation wavelength-tunable and upconverted fluorescence from the ultraviolet (UV) to the near-infrared (NIR) range. Furthermore, the PEGylation of HNCDs enables them to be used as an optical marker for cell and in vivo imaging. Notably, the HNCDs with solvent-dependent fluorescence can be used for invisible inks with a wide range of light responses from UV-vis-NIR spectra. This work not only provides an innovative way to recycle chemical waste but also expands the potential application of HNCDs in NIR security printing and bioimaging.

We constructed a smartphone-integrated optosensor with inexpensive, reversible, environmental friendly, and rapid adsorption to detect Cu(II) and L-cysteine (L-Cys). The key part of this study was to prepare a red-to-blue colorimetric probe from herbaceous andrographis paniculata using one-pot polymerization at room temperature. When Cu(II) existed, the red fluorescence on the surface of the core-shell probe was quenched, while the blue fluorescence of the core did not respond, because the colorimetric probe interacted with the Cu(II) on the surface of red CDs. After L-Cys added, it interacted with the Cu(II) to strip it from the surface of red CDs, resulting in the recovery of fluorescence response. Under optimal conditions, the detection limits of this method for Cu(II) and L-Cys were 71 nM and 12 nM, respectively. Further, the red-to-blue colorimetric probe was integrated into smartphone with a software application to convert fluorescent color images into specific red (R), green (G), and blue (B) values. The spiked recovery of Cu(II) and L-Cys in lake water was verified the feasibility of the developed optosensors with a recovery of 98.2-101.6 % and 103.3-121.6 %. This method for detecting Cu(II) and L-Cys can not only recognize metal ions from actual samples, but also effectively protect CDs from quenching and restore fluorescence., 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 © 2022 Elsevier B.V. All rights reserved.)

Significance: Double-helix point spread function (DH-PSF) microscopy has been developed for three-dimensional (3D) localization and imaging at super-resolution but usually in environments with no or weak scattering. To date, super-resolution imaging through turbid media has not been reported., Aim: We aim to explore the potential of DH-PSF microscopy in the imaging and localization of targets in scattering environments for improved 3D localization accuracy and imaging quality., Approach: The conventional DH-PSF method was modified to accommodate the scanning strategy combined with a deconvolution algorithm. The localization of a fluorescent microsphere is determined by the center of the corresponding double spot, and the image is reconstructed from the scanned data by deconvoluting the DH-PSF., Results: The resolution, i.e., the localization accuracy, was calibrated to 13 nm in the transverse plane and 51 nm in the axial direction. Penetration thickness could reach an optical thickness (OT) of 5. Proof-of-concept imaging and the 3D localization of fluorescent microspheres through an eggshell membrane and an inner epidermal membrane of an onion are presented to demonstrate the super-resolution and optical sectioning capabilities., Conclusions: Modified DH-PSF microscopy can image and localize targets buried in scattering media using super-resolution. Combining fluorescent dyes, nanoparticles, and quantum dots, among other fluorescent probes, the proposed method may provide a simple solution for visualizing deeper and clearer in/through scattering media, making in situ super-resolution microscopy possible for various demanding applications., (© 2023 The Authors.)

The preparation of functional long-wavelength-emitting nanomaterials and the researches on their applications in antibacterial and antibiofilm fields have important significance. This paper reports the preparation of yellow-green-fluorescent and high- quantum yield carbon dots (4-ACDs) with 4-aminosalicylic acid and polyethylene imine as raw materials through one-step route, and the impacts of raw material structure and the reaction conditions upon the optical properties of the products have been investigated. 4-ACDs exhibit excellent broad-spectrum antibacterial activity, and their good biocompatibility ensures them as ideal fluorescent nano-probe for cell imaging. However, 4-ACDs could not effectively eliminate the biofilm of Staphylococcus aureus (S. aureus). CDs-LZM complex was prepared through the coupling between 4-ACDs and lysozyme (LZM) and the complex showed strong antibacterial activity against Gram-positive bacteria, particularly with MIC against S. aureus at 5 μg mL -1 . Besides, CDs-LZM showed excellent ability against the biofilm of S. aureus. At the concentration of 60 μg mL -1 , its inhibition rate against the growth of biofilm was 86 %, and elimination rate against biofilm reached 76 %. CDs-LZM exhibited obvious antibiofilm ability through removing extracellular matrix of biofilm, greatly reducing the thickness of biofilm under confocal microscopy. The application of novel long-wavelength-emitting nanomaterial in eliminating pathogenic bacteria is of great significance., Competing Interests: Declaration of competing interest There are no conflicts of interest to declare., (Copyright © 2023 Elsevier B.V. All rights reserved.)

A novel colorimetric and fluorescent dual-mode sensing system based on molybdophosphoric heteropoly acid (PMA) and fluorescent microspheres (FMs) was established for monitoring the activity of alkaline phosphatase (ALP). In the presence of ALP, L-ascorbic acid-2-phosphate (AAP) could be hydrolyzed catalytically to ascorbic acid (AA), which could reduce PMA to phosphorus molybdenum blue (PMB), accompanied by the generation of colorimetric signals depending on the level of ALP. Meanwhile, the fluorescence of FMs was quenched markedly by the PMB produced due to the inner-filter effect, which constituted the response mechanism for the dual-mode sensing systems of ALP. On this basis, a PMA-FMs based dual-mode sensing system was used for the detection of ALP, which not only possessed remarkable sensitivity, with a limit of detection of 0.27 U L -1 and 0.11 U L -1 , but also exhibited good analytical performance in biological samples with satisfactory results. Moreover, a simple and portable test kit for the visual detection of ALP in real serum samples was fabricated utilizing a smartphone with image-recognition and data-processing capabilities as a visual-detection platform.

Altered DNA methylation in the form of 5-methylcytosine (5-mC) patterns is correlated with disease diagnosis, prognosis, and treatment response. Therefore, accurate analysis of 5-mC is of great significance for the diagnosis of diseases. Here, an efficient enhanced photoelectrochemical (PEC) biosensor was designed for the quantitative analysis of DNA 5-mC based on a cascaded energy level aligned co-sensitization strategy coupling with the bridged DNA nanoprobe (BDN). Firstly, Au nanoparticle/graphite phase carbon nitride/titanium dioxide (AuNPs/g-C 3 N 4 @TiO 2 ) nanocomposite was synthesized through in situ growth of AuNPs on g-C 3 N 4 @TiO 2 surface as a matrix to provide a stable background signal. Next, BDN with a high mass transfer rate synthesized from a pair of DNA tetrahedral as nanomechanical handles was used as a capture probe to bind to the target sequence. The polydopamine nanosphere was applied to load with CdTe QDs (PDANS-CdTe QDs) as a photocurrent label of 5-mC antibodies. When the 5-mC existed, a large number of PDANS-Ab-CdTe QDs were introduced to the electrode surface, the formed CdTe QDs/AuNPs/g-C 3 N 4 @TiO 2 co-sensitive structure could effectively enhance the electron transfer capability and photocurrent response rate due to the effective cascade energy level arrangement, leading to a significantly enhanced photocurrent signal. The proposed PEC biosensor manifested a wide range from 10 -17  M to 10 -7  M and a detection limit of 2.2 aM. Meanwhile, the excellent performance indicated the practicability of the designed strategy, thus being capable of the clinical diagnosis of 5-mC., 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 © 2022. Published by Elsevier B.V.)

A visual and digital platform was constructed by peptide-based molecularly imprinted polymers (PMIPs) for specific recognition and detection of ethyl carbamate (EC). Here, the optosensing core was creatively constructed by the covalent assembly of dipeptides (H-Phe-Phe-OH) and genipin biomolecules for high fluorescence quantum yield and dual-signal response capability. MIPs were wrapped in the shell of the optosensing core for selectivity of EC from actual samples of alcoholic beverages. The genipin-FF nanoparticles (GFPNs)@PMIPs exhibited dual-band red-blue fluorescence image with a low detection limit of 0.817 and 1.65 μg L -1 , respectively, in the optimal linear range of 2-240 μg L -1 . The accuracy of this method was verified by the spiked recovery experiment, and a good recovery from 83.97 to 106.75% of the proposed optosensing method was obtained. In addition, a smartphone application was coupled with GFPNs@PMIPs to realize online real-time detection of EC. With the addition of EC, the color change of G and B values was negligible compared with the R value. This work also provides a potential method for on-site visual detection of analytes.

In this study, two ultrashort dipeptides, diphenylalanine (FF) or C-terminal amidated diphenylalanine (DPA), were covalently self-assembled with genipin to obtain two well-defined supramolecular peptide nanoparticles for the detection of pyrethroids. DPA-genipin nanoparticles (PNPs) demonstrated excellent dual-emission fluorescence characteristics, tunable particle size, and robust photostability. Parallel to this, PNPs showed a ratiometric fluorescence response to λ-cyhalothrin (LC) with a distinct green-to-red color transition. The satisfactory self-calibration capability of the ratiometric system enabled PNPs to respond sensitively to LC in a wide range (5-800 μg/L) with a lower limit of detection of 0.034 μg/L. The introduction of a smartphone application made it easy to develop an intelligent evaluation platform based on PNPs, which had been proven to be applicable for on-site visualization of LC in agricultural products. The platform proposed here may be a new application of peptide self-assembly in sensing, with both important food safety implications and great economic value.

A novel and facile method was proposed for preparation of red emissive N-doped carbon dots encapsulated within molecularly imprinted polymers (RNCDs@MIPs) using a one-pot room-temperature reverse microemulsion polymerization. RNCDs used citric acid and urea as carbon and nitrogen sources by one-step solvothermal synthesis with the optimum emission of 620 nm. Unique optical properties of RNCDs coupled with high selective MIPs make the RNCDs@MIPs conjugate capable to adsorb specific targets of pyrraline (PRL), such a binding event was then transduced to quench fluorescence response signal of the RNCDs. RNCDs@MIPs for PRL showed linearity from 0.1 to 40 μg/L, with a detection limit of 65 ng/L. The RNCDs@MIPs exhibited a good reproducibility of 4.67% obtained from four times of rebinding for PRL. The optosensing probe was successfully applied to the detection of PRL in fatty foods with the spiked recovery of 85.93-106.96%., (© 2023. The Author(s), under exclusive licence to Springer-Verlag GmbH Austria, part of Springer Nature.)

Myeloperoxidase (MPO) has been demonstrated to be a biomarker of neutrophilic inflammation in various diseases. Rapid detection and quantitative analysis of MPO are of great significance for human health. Herein, an MPO protein flexible amperometric immunosensor based on a colloidal quantum dot (CQD)-modified electrode was demonstrated. The remarkable surface activity of CQDs allows them to bind directly and stably to the surface of proteins and to convert antigen-antibody specific binding reactions into significant currents. The flexible amperometric immunosensor provides quantitative analysis of MPO protein with an ultra-low limit of detection (LOD) (31.6 fg mL -1 ), as well as good reproducibility and stability. The detection method is expected to be applied in clinical examination, POCT (bedside test), community physical examination, home self-examination and other practical scenarios.

The fibrillization and abnormal aggregation of β -amyloid (A β ) peptides are commonly recognized risk factors for Alzheimer's disease (AD) brain, and require an effective strategy to inhibit the A β deposition and treat AD. Herein, we designed and synthesized nitrogen-doped carbon dots (N-CDs) as an A β -targeted probe, which exhibits the capacity of inhibiting the 1-42 A β (A β 1-42 ) self-assembly in vitro. The N-CDs exhibited orange emission with an emission wavelength of 570 nm, which demonstrates their excellent optical properties with excitation-independent behavior. Meanwhile, the N-CDs have spherical morphologies with an average size of 2.2 nm, whose surface enriches the amino, carboxyl, and hydroxyl groups. These preparties are conducive to improving their biological water solubility and provide a large number of chemical bonds for further interaction with proteins. Contrary to this, the kinetic process, size evolutions, and morphologies changes of A β 1-42 were inhibited in the presence of N-CDs in the determination of a thioflavin T assay, dynamic light scattering, transmission electron microscope, etc. Finally, the safety application of N-CDs on A β 1-42 -induced cytotoxicity was further demonstrated via in vitro cytotoxicity experiments. This work demonstrates the effective outcome of suppressing A β aggregation, which provides a new view into the high-efficiency and low-cytotoxicity strategy in AD theranostics.

The fibrillization and deposition of the human islet amyloid polypeptide (hIAPP) are the pathological hallmark of type 2 diabetes mellitus (T2DM), and these insoluble fibrotic depositions of hIAPP are considered to strongly affect insulin secretion by inducing toxicity toward pancreatic islet β-cells. The current strategy of preventing amyloid aggregation by nanoparticle-assisted inhibitors can only disassemble fibrotic amyloids into more toxic oligomers and/or protofibrils. Herein, for the first time, we propose a type of cysteine-derived chiral carbon quantum dot (CQD) that targets plasmin, a core natural fibrinolytic protease in humans. These CQDs can serve as fibrinolytic activity regulators for plasmin to cleave hIAPP into nontoxic polypeptides or into even smaller amino acid fragments, thus alleviating hIAPP's fibrotic amyloid-induced cytotoxicity. Our experiments indicate that chiral CQDs have opposing effects on plasmin activity. The l-CQDs promote the cleavage of hIAPP by enhancing plasmin activity at a promotion ratio of 23.2%, thus protecting β-cells from amyloid-induced toxicity. In contrast, the resultant d-CQDs significantly inhibit proteolysis, decreasing plasmin activity by 31.5% under the same reaction conditions. Second harmonic generation (SHG) microscopic imaging is initially used to dynamically characterize hIAPP before and after proteolysis. The l-CQD promotion of plasmin activity thus provides a promising avenue for the hIAPP-targeted treatment of T2DM to treat low fibrinolytic activity, while the d-CQDs, as inhibitors of plasmin activity, may improve patient survival for hyperfibrinolytic conditions, such as those existing during surgeries and traumas.

The studies on the preparation of high-quality and long-wavelength-emitting silicon quantum dots and their application in biochemical detections have attracted increasing interests from researchers. In particular, the exploration of the effect of SiQDs and their complex in antibacterial and inhibition of biofilm areas, is of great significance to human health. This paper reports the fast synthesis of green-fluorescent SiQDs (TC-SiQDs, QYs=25%, Em=520 nm) with the synergistic effect of thiourea and catechol through microwave-assisted one-step hydrothermal route. Based on internal filtering effect, TC-SiQDs were then successfully employed as selective probes to detect vitamin B 12 , with detection range at 0.05-30 μM and limit of detection at 50 nM. Thanks to the excellent biocompatibility and fluorescence property of TC-SiQDs, they have been applied in bacterial imaging. The prepared TC-SiQDs also exhibit certain antibacterial ability with their minimum inhibitory concentration (MIC) against Staphylococcus aureus (S. aureus) at 250 μg/mL, but their inhibitory ability is effective to the growth of S. aureus biofilm only when the concentration reaches 1.3 mg/mL. TC-SiQDs-lysozyme complex were prepared, based on the effects of singlet oxygen, charge effect and lysozyme hydrolysis of peptidoglycan in the cell wall, the complex exhibits high inhibiting activity with MIC against S. aureus at 10 μg/mL and exhibits superior inhibition activity against S. aureus biofilm at a concentration of only 62.5 μg/mL. This paper provides good theoretical and practical basis for the synthesis of long-wavelength emission and ultra-bright SiQDs and their applications in detection, antibacterial and biofilm growth inhibition, and other biomedical fields., 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. Conflicts of Interest There are no conflicts of interest to declare., (Copyright © 2022 Elsevier B.V. All rights reserved.)

The development of highly efficient photocatalysts is vital for solvinge the problem of environmental pollution. In this study, a novel zero-/two-dimensional (0D/2D) S-scheme heterojunction was fabricated by integrating 0D copper phosphide (Cu 3 P) quantum dots (QDs) with a size in the range of 3-8 nm onto 2D bismuth oxychloride (BiOCl) nanosheets using a self-assembly tactic. The Cu 3 P/BiOCl presented intimate interface contact and high photocatalytic activity for the degradation of antibiotics (tetracycline hydrochloride (TC), oxytetracycline, ofloxacin). The optimal sample exhibited the highest photocatalytic TC degradation, with a total removal rate of 86% after 6 min under full-spectrum irradiation, which was higher than that of compared to individual BiOCl. The improved activity of the Cu 3 P/BiOCl heterojunction was attributed to the enhanced separation of the photogenerated carriers due to the S-scheme mode which can promote the recombination of useless photogenerated carriers and maintain photogenerated carriers with stronger redox potentials for photocatalytic reaction. In addition, employing Cu 3 P QDs and BiOCl nanosheets to construct an S-scheme composite can offer abundant active sites for antibiotic degradation. In brief, this study demonstrates that Cu 3 P QDs are an effective cocatalyst for degrading organic pollutants, which provides novel inspiration for the future design of green recycling photocatalysts for wastewater remediation., 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 © 2022 Elsevier Ltd. All rights reserved.)

A ratiometric fluorescence strategy was proposed based on carbon dots (CDs) and self-assembled copper nanoclusters (CuNCs) driven by Al 3+ ions for S 2- detection. Si-CDs/CuNCs@Al 3+ exhibits blue and red emission under single excitation. Interestingly, the red emission of the CuNCs was regularly quenched while the blue fluorescence emission of the CDs was preserved after continuous addition of S 2- . The fluorescence spectrometer-based S 2- linear range is from 0.5 to 40 μM, with a low detection limit (LOD) of 0.16 μM. The fluorescence response of Si-CDs/CuNCs@Al 3+ to S 2- exhibits a distinct color change process (red to pink to blue), implying feasibility of visual analysis. A portable fluorescence sensing platform was established using the color-to-value conversion function of a smartphone for accurate visualization and quantitative identification of S 2- without spectrometer. The fluorescent test strips prepared with Si-CDs/CuNCs@Al 3+ can conduct on-site visual analysis of S 2- in the water environment more conveniently and quickly. The linear range of S 2- detection based on the smartphone-integrated test strip sensing platform is 1-40 μM, and the LOD is 0.42 μM. This work provides a new horizon for target on-site analysis in environmental samples., 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 © 2022. Published by Elsevier B.V.)

A sensitive and efficient fluorescence sensor based on dual-emission molecularly imprinted polymers (Dual-em-MIPs) was successfully developed using the random forest (RF) machine-learning algorithm for the rapid detection of pretilachlor. SiO 2 coatings on red-emitting CdSe/ZnS quantum dots (r-SiO 2 @QDs) as intermediate light-emitting components are non-selective for pretilachlor, whereas molecularly imprinted layers coated with blue-emitting nitrogen-doped graphene quantum dots (N-GQD S ) are selective. Fluorescence images of the Dual-em-MIPs were acquired. The red (R), green (G), and blue (B) color values of the image were analyzed using an RF algorithm, and the classifier was trained using 103 fluorescent images for automatic analyses. Under optimized conditions, an excellent linear relationship between the sensor and pretilachlor was obtained in the range of 0.001-5.0 mg/L (R 2 , 0.9958). Additionally, the satisfactory recoveries of Dual-em-MIPs ranged between 92.2 % and 107.6 % for the real samples, with a relative standard deviation (RSD) under 6.5 %. The satisfactory recoveries of the RF model based on the fluorescence sensor were 84.2-108.2 % with the RSD under 6.4 %. Overall, the proposed fluorescence sensor based on Dual-em-MIPs and machine learning methods was successfully used to determine pretilachlor in the environment and in aquatic products., 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 © 2022 Elsevier B.V. All rights reserved.)

Stable molybdenum disulfide quantum dots (MoS 2 QDs) were synthesized using a simple method and embedded into chitosan (Chit) films with glucose oxidase (GOD) on the surface of a polyaniline (PANI) pre-electrodeposited ITO electrode, designated as Chit-MoS 2 -GOD/PANI. At the prepared film electrode, the fluorescence property of MoS 2 QDs as well as the catalytic properties of MoS 2 QDs and GOD were well maintained and could be reversibly regulated by external stimuli, such as pH, potential, and the concentrations of glucose and ascorbic acid (AA) in the solution. By controlling the redox state of PANI with an externally applied voltage, the color of the film electrode switched between violet blue and nearly transparent, simultaneously quenching/dequenching the fluorescence signals from MoS 2 QDs through Fӧster resonance energy transfer (FRET). The electrocatalytic signals toward hydrogen peroxide (H 2 O 2 ), a product formed by biocatalysis between glucose and GOD, could be tuned through the catalytic capacity of MoS 2 QDs in the films. Thus, an intelligent platform was built based on the film electrode with pH, potential, glucose and AA as inputs and UV-vis extinction (E), photoluminescent intensity (PL), and amperometric current (I) as outputs. Combinational logic operations such as a 4-input/5-output logic network and sequential logic operations such as a keypad lock and a reprogrammable delay/data (D) flip flop was first simulated in a biocomputing system with the film-modified electrode. This work demonstrated the construction of a multiple stimulus-responsive system with dual-functional nanomaterials and provided a new approach for sequential logic operations for further applications in the information storage., (Copyright © 2022 Elsevier B.V. All rights reserved.)