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The electrocatalytic reduction of nitrogen (N2) to ammonia (NH3) has broad prospects for green and sustainable NH3 production. Due to the electrocatalytic nitrogen reduction reaction (eNRR) performance of transition metal compound may be restricted with low yield rate, we develop transition metal interface engineering to improve the eNRR performance. Although the edge of MoS2 catalyst is active, the MoS2(0 0 1) surface is inert for N2 electroreduction. Through the hydrothermal and electrodeposition methods, Fe(OH)3 as N2 and H+ channels coated on MoS2 nanosheets array (MoS2@Fe(OH)3/CC) is synthesized. Such catalyst exhibits excellent eNRR performance in 0.1 M Na2SO4 with high Faradaic efficiency (2.76%) and NH3 yield rate (4.23 × 10−10 mol s−1 cm−2) at − 0.45 V (vs. RHE). This work may provide a new electrocatalyst synthesis pathway for artificial N2 fixation. Density functional theory calculations show that electrodeposition Fe(OH)3 can accelerate eNRR process rate of MoS2.

Interesting double-channel microfluidic chip integration with a sandwich-type cathodic photo-electrochemical (PEC) biosensor is utilized for ultrasensitive and efficient detection of cardiac troponin I (cTnI) based on a signal amplification strategy. The Pd nanoparticles loading on the I-doped bismuth oxybromide with oxygen vacancies (Pd/I:BiOBr-OVs) as a sensing platform can effectively enhance cathodic photocurrent response by improving the visible light absorption ability with I doping, facilitating the efficiency separation of photogenerated electron-hole pairs with OVs, and increasing the electron-transfer rate with Pd loading, where the photogenerated electron could be captured by dissolved O2 to boost generation of a superoxide anion radical (•O2-). To further enhance the PEC response, a novel superoxide dismutase loaded on gold@polyaniline (SOD-Au@PANI) as a signal amplification label is developed for incubating the detection antibody (dAb). It is particularly noteworthy that SOD can effectively catalyze dismutation of the •O2- to produce H2O2 and O2, and Au@PANI with a good reduction and catalytic property can catalyze the produced H2O2 into H2O and O2. Then, the produced O2 that has been dissolved or adsorbed can capture more photogenerated electrons, resulting in more electron-hole pairs to separate, so as to the cathodic photocurrent signal of this system which can be amplified more significantly. Therefore, a signal amplification cathodic PEC biosensor is prepared for sensitively detecting cTnI, in which a good linearity ranging from 0.1 pg/mL to 100 ng/mL with a low detection limit of 0.042 pg/mL is obtained. Furthermore, the proposed biosensor exhibits excellent sensitivity and high selectivity, which could be extended to detect other disease markers in biological analysis and early disease diagnosis.

The development of stable, low-cost, and highly efficient electrocatalysts for the N2 reduction reaction (NRR) process is challenging but crucial for ammonia production. Herein, we demonstrate the synthesis of pyrite nanoparticles wrapped by graphene oxide (FeS2@GO) acting as a highly efficient NRR catalyst in a wide pH range. The FeS2 nanoparticles are uniformly dispersed across the GO nanosheet, thus leading to the fine exposure of active sites, the promotion of charge transfer, and the increment of a contact surface area, which are all beneficial for a desired catalyst. In the meantime, the low-coordinated Fe atoms are activated as highly active sites, which is in favor of the enhanced electrochemical performance for the NRR. Furthermore, density functional theory (DFT) calculations illustrated that the high activity of N2 reduction over the FeS2@GO catalyst arises from the well-exposed Fe active sites and the increment of charge density at the valence band edge. Benefiting from the well-optimized interface, the barrier of the addition of the first hydrogen atom to N2 forming *NNH species as the potential-determining step is as low as 0.93 eV in N2 electroreduction. The electrochemical test results reveal that, as expected, FeS2@GO exhibits high Faradaic efficiencies (4.7% in 0.1 M HCl solution and 6.8% in 0.1 M Na2SO4 solution) and advanced NH3 yields (78.6 and 27.9 μg h-1 mgcat.-1 in 0.1 M HCl and 0.1 M Na2SO4 solutions, respectively) in both acid and neutral conditions. This work offers a new avenue for exploring novel electrocatalysts, which has great promise to accelerate the practical application of the NRR.

The nitrogen reduction reaction (NRR) has become an ideal alternative to the Haber‐Bosch process, as NRR possesses, among others, the advantage of operating under ambient conditions and saving energy consumption. The key to efficient NRR is to find a suitable electrocatalyst, which helps to break the strong N≡N bond and improves the reaction selectivity. Molybdenum disulfide (MoS2) as an emerging layered two‐dimensional material has attracted a mass of attention in various fields. In this minireview, we summarize the optimization strategies of MoS2‐based catalysts which have been developed to improve the weak NRR activity of primitive MoS2. Some theoretical predictions have also been summarized, which can provide direction for optimizing NRR activity of future MoS2‐based materials. Finally, an outlook about the optimization of MoS2‐based catalysts used in electrochemical N2 fixation are given.

Integrating a microfluidic sensor with a ratiometric photoelectrochemical (PEC) strategy to build a bioanalysis device for actual sample testing is often limited to large-volume space-resolution equipment and wavelength-dependent or potential-dependent paired photoactive materials. This work reports a microfluidic ratiometric magnetic-photoelectrochemical (M-PEC) biosensor on the photochromic composite platform to solve the above problems. In particular, as a proof-of-concept study, the platform Bi2WO6-x/amorphous BiOCl nanosheets/Bi2S3 (p-BWO-s) mediated by photochromic color centers and the magnetic photoactive secondary antibody marker ZnFe2O4@Ag2O are integrated on the microfluidic biosensor. By enhancement of the photochromic color centers, p-BWO-s outputs a considerable photocurrent signal. Meanwhile, the photoactivity of the secondary antibody marker can be changed with a magnetic field; thus, different photocurrent signals can be obtained to realize ratiometric detection. The quenching photocurrent signal without the magnetic field and the difference photocurrent signal under the magnetic field are quantitatively related to the target concentration, which unfolds a novel general strategy for bioanalysis. Different from traditional ratiometric PEC biosensors, this work characterizes the first ratiometric PEC biosensor based on an external magnetic field. Generally speaking, combined with different biorecognition cases, this scheme with good expansibility brings a unique new perspective.

Metal nanoclusters (NCs) possess high light stability and biocompatibility because of their unique quantum size effect, which has gradually become a new type of electrochemiluminescence (ECL) nanomaterial for immunoassays. However, the luminescence efficiency of metal NCs is too low to meet the needs of trace analysis, which limits its application. Herein, Ag NCs served as signal probes and Pd-Cu2O hybrid nanoconcaves served as coreaction promoters, developing a highly efficient peptide-based biosensor for neuron-specific enolase (NSE) detection. Utilizing the reversible cycle of Cu+/Cu2+ and the reduction characteristics of Pd NPs, Pd-Cu2O greatly accelerates the reduction of S2O82-. Meanwhile, Pd-Cu2O has good hydrogen evolution activity, which promotes the generation of oxygen by improving the redox efficiency of the overall reaction, thus increasing the yield of active intermediates (OH•) to promote the reduction of S2O82-. Specially, this is an effective attempt to use the hydrogen evolution reaction (HER) to accelerate the ECL emission of the S2O82- system. In addition, a short peptide ligand (NARKFYKGC, NFC) was developed to implement the targeted immobilization of antibodies, which can specifically bind to the Fc fragment of antibodies, thereby avoiding the occupation of the antigen binding site (Fab fragment). The introduction of NFC not only improves the binding efficiency of antibodies but also protects its bioactivity, thus significantly improving the sensitivity of the biosensor. Based on these strategies, the proposed biosensor provides a new perspective for the applications of metal NCs in ECL systems.

A class of water-soluble electrochemiluminescence (ECL) nanodots were prepared by encapsulating ECL-active iridium complexes into biocompatible horse spleen apoferritin (apoHSF) nanocages for immunoassays. The preparation feasibility was achieved based on the pH-induced disassembly/reassembly nature originated from apoHSF. Two iridium nanodots (1 and 2) with high ECL efficiency were separately prepared by directing the self-assembly of two water-insoluble luminescent complexes, Ir(ppy)3 (ppy = 2-phenylpyridine) and Ir(ppy)2(acac) (ppy = 2-phenylpyridine and acac = acetylacetonate), in the apoHSF cavity. Using tri-n-propylamine (TPrA) as a coreactant, the electrochemistry and "oxidative-reductive" ECL mechanisms for nanodots 1 and 2 were investigated, respectively. After demonstrating the spectroscopic property and relative ECL efficiency, the ECL emission of nanodots 1 and 2 quenched by TPrA• radicals at high potential was further studied and circumvented by optimizing the potential range and TPrA concentration for generating strong and stable ECL emission in aqueous media. The well-inherited biological functions of apoHSF in nanodots allow the convenient external modification of an antibody to act as a signal probe, thus a versatile ECL immunoassay paradigm was established. Acceptable results from this assay enabled the rapid and accurate detection of biomarkers in real samples. The unprecedented use of apoHSF is feasible and applicable for water-insoluble iridium complexes to fabricate a wide variety of biocompatible ECL nanodots for potential bioanalysis.

Herein, a split-type immunoassay strategy instigated by cation exchange (CE) and changing the capacity of an electron donor in an electrolyte solution is optimized, namely, for differentiating the biological-specific binding assay and photoelectrochemical (PEC) analysis. MoSe2/CdSe, a Z-scheme heterojunction with efficient visible light absorption and a low recombination of carriers, is used as a photoelectrode substrate. Silver ions (Ag+) as the initiator of CE are generated by the acidolysis of evenly loaded silver nanoparticles on mesoporous silica nanospheres (MSNs). The theoretical calculation and experimental results confirm that Ag+ replaces Cd2+ in CdSe and retains the crystal structure of MoSe2. However, this behavior destroys the perfectly matched heterojunction structure and introduces defects, which led to the reduction of the photocurrent response. In addition, ascorbate oxidase in combination with MSNs can be used as a consumptive agent of the electron donor, which further improves the sensitivity and reliability of the sensor. As a proof of principle, neuron-specific enolase was applied to elucidate the potential application of the PEC immunoassay in clinical diagnosis, and the obtained linear range of the sensor was from 0.0001 to 100 ng/mL with a detection limit of 28 fg/mL (S/N = 3).

Steady and efficient sensitized emission of Eu2+ to Eu3+ can be achieved through a rare mixed-valence Eu-MOF (L4EuIII2EuII). Compared with the sensitization of other substances, the similar ion radius and configuration of the extranuclear electron between Eu2+ and Eu3+ make sensitization easier and more efficient. The sensitization of Eu2+ to Eu3+ is of great assistance for the self-enhanced luminescence of L4EuIII2EuII, the longer luminous time, and the more stable electrochemiluminescence (ECL) signal. Simultaneously, L4EuIII2EuII possesses near-infrared (NIR) fluorescence of around 900 nm and a mighty self-luminous characteristic, which render it useful as a NIR fluorescent probe and as a luminophore to establish a NIR ECL biosensor. This NIR biosensor can greatly reduce the damage to the detected samples and even achieve a nondestructive test and improve the detection sensitivity by virtue of strong susceptibility and environmental suitability of NIR. In addition, the CeO2@Co3O4 triple-shelled microspheres further enhanced the ECL intensity due to two redox pairs of Ce3+/Ce4+ and Co2+/Co3+. The NIR ECL biosensor based on these strategies owns an ultrasensitive detection ability of CYFRA 21-1 with a low limit of detection of 1.70 fg/mL and also provides a novel idea for the construction of a highly effective nondestructive immunodetection biosensor.

Extracellular matrix (ECM) exerts a series of biological functions and contributes to almost 30% of the osteogenic process. Periostin is a secreted protein that can alter ECM remodeling in response to vascular injury. However, the role of periostin in vascular calcification has yet to be fully investigated. As found in this study, recombinant periostin accelerated the thoracic aortas calcification, increased the expression of glycolysis key enzymes, and disturbed the normal oxidative phosphorylation (OXPHOS) ex vivo, which could be alleviated by the peroxisome proliferation-activated receptor γ (PPARγ) agonist pioglitazone. In vascular smooth muscle cells (VSMCs), periostin promoted VSMC-osteoblastic phenotype transition and calcium deposition and suppressed PPARγ expression. Mechanistically, periostin caused overactivation of glycolysis and mitochondrial dysfunction in VSMCs as assessed by extracellular acidification rate, oxygen consumption rate, and mitochondrial respiratory chain complex activities. Targeted glycolysis inhibitors reduced mitochondrial calcium overload, apoptosis, and periostin-induced VSMCs calcification. PPARγ agonists preserved glycolysis and OXPHOS in the stimulated microenvironment and reversed periostin-promoted VSMC calcification. Furthermore, plasma periostin, lactate, and matrix Gla protein levels were measured in 274 patients undergoing computed tomography to determine coronary artery calcium score (Agatston score). Plasma periostin and lactate levels were both linked to an Agatston score in patients with coronary artery calcification (CAC). There was also a positive correlation between plasma periostin and lactate levels. This study suggests that downregulation of PPARγ is involved in the mechanism by which periostin accelerates arterial calcification partly through excessive glycolysis activation and unbalanced mitochondrial homeostasis.

Biomarker expression both on the cell surface and in serum is directly related to the pathological process of tumor. Based on the interaction between the ligand and the protein receptor, a label-free photoelectrochemical (PEC) biosensing interface with good antifouling ability was proposed for tumor cell detection. TiO

Herein, a dual-mode sensing platform using cationic N,N-bis(2-(trimethylammonium iodide)propylene)perylene-3,4,9,10-tetracarboxydiimide (PDA+)-assembled DNA strands as a quencher was suggested for estradiol (E2) detection. The aptamer chain was initially anchored with the Ru(II) novel molecule (Ru complex), which was recombined with carbohydrazide (CON4H6) and tris(4,4'-dicarboxylicacid-2,2'-bipyridyl)ruthenium(II) dichloride [Ru(dcbpy)32+] modified on copper oxide (CuO) nanospheres. Intramolecular electrochemiluminescence (ECL) occurring between CON4H6 and Ru(dcbpy)32+ effectively improved the reaction rate and increased the ECL efficiency. By employing effective van der Waals' force, PDA+ was endowed with an efficient ECL quenching probe on an electrode. The signal on the ECL interface can be converted into quenching because of energy transfer between the intercalator and the emitter. Notably, cationic PDA+ possessing a large planar π-π skeleton improved advantageous activity of redox and DNA aptamer indurative loading capacity and directly generated a well-defined cathodic peak to execute the EC bio-detection. This method not only avoids the difficulty of assembling various signal indicators but also improves the sensitivity greatly using the quenching mechanism. In addition, disparate double-response signals coming from different principles of transduction are in a position to verify each other to improve the accuracy. Hence, examination areas of 0.001-100 nM with E2 for ECL and EC were obtained, supplying a novel sensing strategy with promising ideas and perspectives of detection platform construction.

Surface engineering of electrochemiluminescence (ECL) emitters with capping agents is highly important, yet it remains a challenge. Herein, using N-acetyl-L-cysteine and cysteamine as model capping...

A novel ratiometric electrochemical (EC) sensing platform was established for sensitive immunoassay of target cytokeratin 19 fragment 21-1 (CYFRA21-1) biomarker by combining competitive immunoreact...

Herein, a label-free electrochemical immunosensor based on differential pulse voltammetry (DPV) and amperometric i-t curve (i-t) dual-mode analysis is proposed for early quantitative detection of procalcitonin (PCT). Due to the advantages of high chemical stability and biocompatibility, graphite carbon nitride (g-C3N4) was adopted as a high-capacity sensing interface to carry signal indicators. As an effective indicator of chronoamperometry, nickel cobalt sulfide (NiCo2S4) was uniformly dispersed on the surface of g-C3N4 through in-situ hydrothermal synthesis, which not only promotes the activation of bimetallic activity, but also effectively prevents the aggregation of NiCo2S4. At the same time, in order to establish a dual-mode analysis platform to improve accuracy and sensitivity, highly conductive carbon nanotubes (CNTs) were hybridized with composite materials to load Ag nanoparticles (Ag NPs), which have excellent oxidizing properties and are used as indicators of DPV. On account of this advanced sensing strategy, a wide linear response (DPV: 0.05 ng mL-1-50 ng mL-1 and i-t: 1.00 pg mL-1-10.00 ng mL-1) and a low detection limit (DPV: 16.70 pg mL-1 and i-t: 0.33 pg mL-1) are demonstrated. The immunosensor synthesized by this method has good stability and sensitivity, which could be applied in clinical diagnosis and treatment.

As a carbon-free reaction process, the electrocatalytic nitrogen reduction reaction (eNRR) under mild conditions has broad prospects for green and sustainable NH3 production. In this work, bimetallic RhRu nanoalloys (NAs) with cross-linked curly nanosheets were successfully prepared and exhibited exciting results in the eNRR process. Furthermore, the composition effect of RhRu NAs on eNRR activity was studied systematically, and the results showed that Rh0.6Ru0.4 NAs/CP exhibited the highest NH3 yield rate of 57.75 μg h−1 mgcat.−1 and faradaic efficiency of 3.39%. As an eNRR catalyst with great potential, Rh0.6Ru0.4 NAs extend the possibility of alloy-nanomaterials in the eNRR field and further provide an idea for the precise structure of more effective and stable electrocatalysts.

In comparison with the traditional Haber–Bosch process, the electrocatalytic nitrogen reduction reaction (NRR) with high purity and sustainability became a popular process to satisfy the demand of ammonia. However, the strong competing reaction (hydrogen evolution reaction, HER) and low reaction efficiency hinder the practical applications of NRR. Thus, the development of advanced NRR catalysts by regulating the electronic structure and the activity of single active sites is urgent. Here, in our study, vanadium-doped NiS2 (V–NiS2) nanospheres with abundant active sites were first proposed in the NRR field, which exhibited excellent catalytic activity with a high NH3 yield (47.63 μg h−1 mg−1cat., at −0.45 V) and good faradaic efficiency (FE) (9.37% at −0.35 V) in a 0.1 M HCl solution. Moreover, V–NiS2 also performed desired selectivity and stability. This study provides a pathway to design advanced NRR catalysts for practical applications.

The industrial-scale NH3 production still heavily depends on the Haber–Bosch process, which not only demands high energy consumption but also emits a large amount of CO2. The electrochemical fixation of N2 to NH3 under ambient conditions is regarded as an eco-friendly and sustainable approach, but stable and efficient electrocatalysts are demanded for the N2 reduction reaction under ambient conditions. In this communication, ReS2 nanosheet array on carbon cloth (ReS2/CC) is first utilized in NRR. This ReS2/CC exhibits high catalytic activity and strong long-term electrochemical durability. The Faraday efficiency of ReS2/CC is 0.78% and the NH3 yield of ReS2/CC is 3.61 × 10−10 mol s−1 cm−2 at −0.4 V versus reversible hydrogen electrode in 0.1 M HCl.

Electrocatalytic nitrogen reduction reaction (NRR), as a green and sustainable method for ammonia synthesis, has become one of the candidates to substitute industrial Haber-Bosch ammonia synthesis in the near future. In this work, gold nanoparticles (Au NPs) were successfully anchored on bismuth sulfide nanorods (Bi

Two novel two-dimensional metal-organic frameworks (2D MOFs), 2D-M2 TCPE (M=Co or Ni, TCPE=1,1,2,2-tetra(4-carboxylphenyl)ethylene), which are composed of staggered (4,4)-grid layers based on paddlewheel-shaped dimers, serve as heterogeneous photocatalysts for efficient reduction of CO2 to CO. During the visible-light-driven catalysis, these structures undergo in situ exfoliation to form nanosheets, which exhibit excellent stability and improved catalytic activity. The exfoliated 2D-M2 TCPE nanosheets display a high CO evolution rate of 4174 μmol g-1 h-1 and high selectivity of 97.3 % for M=Co and Ni, and thus are superior to most reported MOFs. The performance differences and photocatalytic mechanisms have been studied with theoretical calculations and photoelectric experiments. This study provides new insight for the controllable synthesis of effective crystalline photocatalysts based on structural and morphological coregulation.

Photoanode sensing platforms with remarkable photoelectrochemical (PEC) response and satisfying visible-light absorption have become the most promising detection systems. Nevertheless, their inevitable electrophilic character limits their expansion in the bioassay because of reductive substances in serum or other body fluids that can severely interfere with the photocurrent to be read. To solve it, a PEC platform-assembled dual-active electrode is designed to realize the separation of biological monitoring from the photoanode. The ferricyanide ([Fe(CN)6]3-)-mediated redox cycle is first proposed to meet the gain and loss electron requirements of the PEC system. It can avoid the self-reaction in the electrolyte caused by the addition of a traditional electron donor and acceptor, for instance, ascorbic acid and hydrogen peroxide. As a consequence, the traditional counter electrode (Pt wire) is replaced by Fe2O3/AgInS2 heterojunction, which can amplify the PEC response of the cathode to meet the requirement of trace analysis. An aptasensor fabricated by the above strategies exhibits convincing data for 17β-estradiol (E2) detection from which a wide detection range is obtained in 10 fg/mL to 1 μg/mL with a detection limit of 2.74 fg/mL (S/N = 3). These advanced elements show a rosy prospect for environmental monitoring and point-of-care biomarker diagnosis.

The transient gene expression of protoplasts in plant is a considerable tool for gene functional research that has been widely used in gene analysis and functional characterization. Therefore, the objectives of this study were to develop a protocol for the isolation and purification of sugarcane protoplasts (Saccharum spp. hybrids), conduct transient PEG-mediated protoplast transfection with D27, and localize the D27 protein in sugarcane protoplasts. Total yield and viability of protoplasts were optimized for enzyme combination, mannitol concentration, and duration and temperature of enzymatic hydrolysis. High production of intact protoplasts (10.94 × 106 protoplasts g−1 FW) and a survival rate of > 80.0% was achieved through enzymatic hydrolysis at constant temperature of 28 °C, 60–70 rpm min−1 for 8 h in a solution containing 2.0% cellulase R-10, 0.5% macerozyme R-10, 0.6% pectolyase Y-23, 20 mM 2-(N-morpholine) ethanesulfonic acid (MES), 20 mM KCl, and 400 mM mannitol (pH 5.7). Using GFP as the reporter gene, the protoplasts were transformed most efficiently with 25% PEG 4000 for 25 min and the ScD27 protein was localized in the chloroplasts. The localization of ScD27 protein in sugarcane protoplast demonstrated that the newly developed protocol was functionally effective. This optimized sugarcane protoplast isolation, purification, and transient expression protocol lays a foundation for future molecular biology research in sugarcane.

In this work, a mussel-inspired polydopamine (PDA) nanoparticle with biocompatible and reactive surface characteristics was desirably incorporated with high loading capacity and pH-induced disassembly-releasing behavior toward Fe(III) ions to develop an enzyme-free colorimetric immunoassay. The catechol functional network of PDA can act as a scaffold to coordinate with large amounts of Fe(III) ions to form the PDA-Fe(III) NPs whose coordination state can be tailored by changing the pH values. In detail, PDA-Fe(III) NPs can be maintained in a disassembled tri-coordinate state under alkaline conditions while the highly loaded Fe(III) ions can be easily released under acid conditions to react with ferrocyanide for the in situ generation of Prussian blue (PB) NPs. The detection sensitivity of prostate-specific antigen (PSA) was significantly improved, owing to the high peroxidase-like activity of PB NPs that triggered excellent catalytic effect by the colorimetric reaction. In addition, favorable linearity was found in the range of 0.0005-20 ng mL

This work outlines an electrochemiluminescence (ECL) platform with versatile and high-performance, which using the complex luminescent molecules [Ru(Ⅱ) complex] formed by carbohydrazide (...

An ultrasensitive controlled release system electrochemical aptasensor (CRSEA) has been developed for supersensitive determination of mercury ions (Hg2+), using gold nanoparticle-linked specific single-stranded DNA (Au NPs-ssDNA) as a molecular gate and mesoporous silica nanocontainers (MSNs) as containers. MSNs have a rich porous structure, thus entrapping the toluidine blue (TB) molecules inside. It is worth noting that Hg2+ binds to the ssDNA with multiple thymine (T) and induces the ssDNA to form a hairpin structure, which makes the separation of the Au NPs-ssDNA from the MSNs. Eventually, the stored TB molecules were released from MSNs. The electron transfer signals of TB were detected stably by a differential pulse voltammetry (DPV) detection method, which are correlated with the concentration of Hg2+. Therefore, the wide linear range (10 pM-100 μM) and low limit of detection (2.9 pM) were obtained, and the system also displayed an apparent electrochemical signal response in real sample detection and showed a promising possibility in actual monitoring.

α-Terpineol, terpinen-4-ol, and δ-terpineol, isomers of terpineol, are among the compounds that give Cinnamomum longepaniculatum leaf oil its distinguished pleasant smell. The objective of this study was to evaluate the antimicrobial activity of these three isomeric terpineols. The determination of antibacterial activity was based on the minimum inhibition concentration (MIC) and minimum bactericide concentration (MBC). Changes in time-kill curve, alkaline phosphatase (AKP), UV-absorbing material, membrane potential, and scanning electron microscopy (SEM) were measured to elucidate the possible antimicrobial mechanism. α-Terpineol, terpinen-4-ol, and δ-terpineol demonstrated good inhibitory effects against several gram-negative bacteria, particularly Shigella flexneri. MIC and MBC of α-terpineol and terpinen-4-ol were similar (0.766 mg/mL and 1.531 mg/mL, respectively) for S. flexneri, while the MIC and MBC values of δ-terpineol were 0.780 mg/mL and 3.125 mg/mL, respectively. Time-kill curves showed that the antibacterial activities of the tested compounds were in a concentration-dependent manner. Release of nucleic acids and proteins along with a decrease in membrane potential proved that α-terpineol, terpinen-4-ol, and δ-terpineol could increase the membrane permeability of Shigella flexneri. Additionally, the release of AKP suggested that the cell wall was destroyed. SEM analysis further confirmed that S. flexneri cell membranes were damaged by α-terpineol, terpinen-4-ol, and δ-terpineol. Our research suggests that these three isomeric terpineols have the potential of being used as natural antibacterial agents by destroying the cell membrane and wall, resulting in cell death. However, the specific antibacterial activity differences need further investigation.

A novel luminol electrochemiluminescence (ECL) sensing platform was developed based on the closed indium tin oxide bipolar electrode (ITO BPE) for detecting the biomarkers of squamous cell carcinomas named cytokeratin 19 fragments (CYFRA 21-1). A strategy of in situ-generated coreactant H2O2 and O2 was proposed to enhance luminol ECL intensity. CaO2, possessing a high capacity of self-supplying H2O2 and O2, was encapsulated by ZIF-67, glucose oxidase, and horseradish peroxidase (GOD/HRP-loaded ZIF-67@CaO2). In the presence of glucose, gluconic acid and H2O2 were generated via the catalytic effect of GOD; then, gluconic acid induced the degradation of ZIF-67, leading to the hydrolysis of the unprotected CaO2 to produce both O2 and H2O2. Therefore, the generated coreactants O2 and H2O2, via the oxidation of glucose and the hydrolysis of CaO2, can effectively enhance the luminol ECL behavior. According to the luminol ECL reaction occurring on the anode surface of the ITO BPE, a sandwich immunosensor was fabricated on the anodic ITO BPE and GOD/HRP-loaded ZIF-67@CaO2 as labels incubated with secondary antibodies. Owing to the cathodic reaction rate influencing the anodic reaction rate, Au nanoparticles were electrodeposited on the cathode surface of the ITO BPE, which not only meliorated oxygen reduction but also further enhanced the ECL intensity of luminol. Under optimal experiments, an ECL immunosensor for detecting CYFRA 21-1 with a wider linear range from 0.0075 to 50 ng mL-1 and a detection limit of 1.89 pg mL-1 (S/N = 3) was obtained.

An intramolecular photoelectrochemical (PEC) system is designed from the novel electron donor YYYHWRGWV (Y3-H) peptide ligand for the first time. The bifunctional nonapeptide cannot only rely on the HWRGWV sequence as a site-oriented immobilizer to recognize the crystallizable fragment (Fc) domains of the antibody but also acts as electron donors for PEC generation via three tyrosine (Y) of the N-terminal. The Bi2WO6/AgInS2 heterojunction with a significant visible-light absorption is utilized as a photoelectric generator, and the motivation is ascribed to a proven proposition, namely, that short-wavelength illuminant radiates proteins, causing a decline in bioactivity of immune protein. An innovative biosensor is fabricated using the above strategies for the detection of CYFRA21-1, a biomarker of squamous cell lung carcinoma. This sort of PEC-based sensing platform shows convincing experimental data and could be an effective candidate for clinical application in the future due to their extremely skillful conception.

Oxygen vacancies (OVs) enhanced electrochemiluminescence (ECL) biosensing strategy using luminol thermally encapsulated in apoferritin (Lum@apoFt) as an efficient transducer was investigated for ultrasensitive biomarker detection. By applying the oxygen-defect engineering (ODE) strategy, the OVs enriched cobalt-iron oxide (r-CoFe2O4) was fabricated as the sensing substrate to boost the electron mobility and catalyze the generation of superoxide anion radical (O2•-) for signal amplification. It should be noted that r-CoFe2O4 with higher OVs density dramatically accelerated the ECL reaction between O2•- and luminol anionic radicals, achieving 6.5-fold stronger ECL output than CoFe2O4 with no or low OVs density. Moreover, facile encapsulation of approximate 412 luminol molecules in a single apoFt cavity was first realized by an efficient thermal-induction method. The obtained Lum@apoFt complexes exhibited well-maintained ECL efficiency and excellent biocompatibility for biological modifications. On this basis, a biosensor was developed for early diagnostics of squamous cell carcinomas by detecting its representative biomarker named cytokeratin 19 fragment 21-1 (CYFRA 21-1), from which excellent linearity was achieved in 0.5 pg/mL to 50 ng/mL with a detection limit of 0.14 pg/mL. This work not only put forward a novel idea of creating OVs enriched sensing interface with excellent signal-amplification function but also proposes a facile and robust methodology to design apoFt-based transducers for developing more practical nanoscale biosensors in early diagnostics of diseases.

The carbon layer with good electrical conductivity and outstanding mechanical stability are essential in designing high-performance silicon/carbon (Si/C) anodes to replace the commercial graphite in lithium-ion batteries (LIBs). In terms of solving the two inherent defects of poor conductivity and big volume change of silicon, we fabricate a spongy carbon matrix derived from ZIF-8 to anchor saclike silicon synthesized by molten salt magnesiothermic reduction method. This spongy matrix can anchor saclike silicon to provide a stable reaction interface and support fast electronic transmission. At the same time, buffer space in saclike Si nanoparticles and spongy matrix can synergistically accommodate the volume change of Si to maintain the integrity of the electrode. The resulting composite with a high Si content of 77.58% exhibits good capacities of 1448 mAh g−1 at 2 A g−1 and 848 mAh g−1 at 4 A g−1 after 500 cycles. High initial coulombic efficiency of 84% at 0.2 A g−1 is also exhibited in the first three activation cycles. Therefore, this novel multifunctional N-doped spongy matrix can supply multifaceted benefits in accommodation of volumetric variation, enhancement of conductivity, and integrity of structure during cycling.

This study proposes a competitive photoelectrochemical (PEC) immunosensor for detecting diethylstilbestrol (DES). The PEC sensing platform uses a zinc and molybdenum codoped BiVO4 nanoarray ((Zn,Mo):BiVO4) as the photoactive matrix and manganese hexacyanoferrate hydrate loading silicon dioxide layer composite nanocubes (MHCF@SiO2 NCs) as the signal quencher. The (Zn,Mo):BiVO4 nanoarray demonstrated brilliant PEC behavior, by virtue of the local electric field formed by the codoped Zn and Mo. This doping accelerated the electron transfer and improved the photoelectric conversion efficiency in BiVO4 nanoarray under visible light. Furthermore, the nanoarray structure with its large surface area provided abundant binding sites for the immune response. As the MHCF@SiO2 NCs-anti-DES competitively bonded with either free DES or bovine serum albumin conjugated DES (BSA-DES), hydrogen peroxide (H2O2) as electron donor was competitively consumed and meanwhile steric resistance blocked electrons transfer. For the above reasons, the photocurrent signal was reduced. Thus, the standard sample free DES was accurately detected, and the fabricated PEC immunosensor displayed an outstanding photocurrent response from 0.1 pg/mL to 50 ng/mL with a detection limit of 0.05 pg/mL. Simultaneously, the acceptable stability, selectivity, and reproducibility of the designed dual-competitive sensing platform suggest its applicability to small molecule detection.

An original dual signal amplification immunoassay for N-Terminal pro-brain natriuretic peptide (NT-proBNP) detection is developed based on Au NPs and Zn doped CdS nanoparticles (Zn0.02Cd0.98S) co-sensitized Bi2MoO6 nanosheet photoelectrochemical (PEC) platform, the target is a good myocardial marker for diagnosing heart failure (HF). Bi2MoO6 as an outstanding photocatalysis material is successfully used in PEC analysis in this work, and the nanosheet structure provide a preponderance to capture superior Zn0.02Cd0.98S in order to achieve anticipant PEC response. The doping of Zn makes the energy band of CdS matched more compatible with Bi2MoO6, and improves the narrow band gap of CdS, making the surface plasma resonance (SPR) effect of Au NPs more significant, thus further improving the PEC response, as well as elevated the detection sensitivity of biological targets. The constructed PEC platform for NT-proBNP provides a wide detection range of 0.0001–1000 ng mL−1 and gives the minimum detection value of 0.037 pg mL−1. Great stability, high selectivity, and good reproducibility are also achieved. The proposed PEC immunoassay provides more possibilities for other protein ultra-sensitivity detection.

Dual-functional NiCo2S4 polyhedral architectures with outstanding electrochemical performance for supercapacitors and lithium-ion batteries (LIBs) have been rationally designed and successfully synthesized by a hydrothermal method. The as-synthesized NiCo2S4 electrode for supercapacitor exhibits an outstanding specific capacitance of 1298 F g−1 at 1 A g−1 and an excellent rate capability of ~80.4% at 20 A g−1. Besides, capacitance retention of 90.44% is realized after 8000 cycles. In addition, the NiCo2S4 as anode in LIBs delivers high initial charge/discharge capacities of 807.6 and 972.8 mAh g−1 at 0.5 C as well as good rate capability. In view of these points, this work provides a feasible pathway for assembling electrodes and devices with excellent electrochemical properties in the next generation energy storage applications.

In this work, a triple-amplified biosensor with a bioactivity-maintained peculiarity was constructed for quantitative procalcitonin (PCT) detection. As everyone knows, a strong electrochemiluminescence (ECL) signal is the premise to ensure high sensitivity for trace target detection. Hence, a valid tactic was developed to achieve signal amplification of luminophor by using Co2+-based metal-organic frameworks (ZIF-67) and silver-cysteine (AgCys). The ZIF-67 particles, which have more atomically dispersed Co2+, could play the role of a co-reaction accelerator to catalyze S2O82- to generate abundant Co3+ and sulfate radical anions (SO4•-). Afterward, a mass of Co3+ was reduced to more hydroxyl radicals (OH•) by H2O, thus ulteriorly reducing S2O82- to generate more SO4•-. Remarkably, S2O82- was reduced to SO4•- continuously with the recycling of Co2+ and Co3+, which realized an effective signal amplification. Meanwhile, the AgCys complex with superior catalysis and biocompatibility was prepared to further improve the ECL signal and maintain the bioactivity of the biomolecule. Furthermore, HWRGWVC, a heptapeptide that was used for combining the Fc fragments of an antibody by Au-S bonding to achieve the fixed point fixation, could not only maintain bioactivity of an antibody but also improved its incubation efficiency, thus further enhancing biosensor sensitivity. Under optimum conditions, the proposed biosensor realized highly sensitive assay for PCT with a wide dynamic range from 10 fg/mL to 100 ng/mL and a detection limit as low as 3.67 fg/mL. With superior stability, selectivity, and repeatability, the prepared biosensor revealed immense potential application of ultrasensitive assay for PCT in human serum.

Thrombin is a marker of blood-related diseases, and its detection is of great significance in the fields of medical and biological research. Herein, a novel chemiluminescence (CL) sensor for thrombin detection was prepared based on dual-aptamer biorecognition and mesoporous silica encapsulated with iron porphyrin. Mesoporous silica encapsulated with hematin by aptamer1 (Apt1/hematin/M-SiO2) and magnetic microspheres modified with aptamer2 (Apt2/NH2-MS) were successfully prepared, and the two materials were used to construct a CL sensor to detect thrombin. Primarily, Apt2/NH2-MS is used for pretreatment separation of thrombin samples by the biorecognition effect between the aptamer (Apt2) and target (thrombin). Then, thrombin/Apt2/NH2-MS is again recognized with Apt1 on the surface of Apt1/hematin/M-SiO2 and Apt1/thrombin/Apt2/NH2-MS is formed, so dual-aptamer biorecognition is realized. Meanwhile, the generated Apt1/thrombin/Apt2/NH2-MS makes Apt1 shed off the surface of M-SiO2 and release hematin. The released hematin can catalyze the luminol-H2O2 CL reaction. Therefore, a sandwich-type CL sensor was constructed based on dual-aptamer biorecognition and hematin catalysis for the detection of thrombin. The sensor has a linear range of 7.5 × 10-15 to 2.5 × 10-10 mol·L-1 and a detection limit of 2.2 × 10-15 mol·L-1 and also exhibits excellent selectivity, reproducibility, and stability. The sensor was successfully used for the detection of thrombin in serum samples, which makes it possible to apply the sensor in the detection of thrombin in actual samples.

Curcumin (CURC) is a hydrophobic molecule and its water solubility can be greatly improved by liposome encapsulation. However, investigations on the stability of pH-sensitive molecules incorporated into liposomal membranes are limited. In this study, CURC-loaded liposomes with varied internal pH values (pH 2.5, 5.0, or 7.4) were prepared and designated as CURC-LP (pH 2.5), CURC-LP (pH 5.0), and CURC-LP (pH 7.4). Physical properties including particle size, ζ-potential, morphology, entrapment efficiency, and physical stabilities of these CURC-LPs were assessed. In addition, the chemical stability of liposomal CURC to different external physiological environments and internal microenvironmental pH levels were investigated. We found that among these CURC-LPs, CURU-LP (pH 2.5) has the highest entrapment efficiency (73.7%), the best physical stabilities, and the slowest release rate in vitro. Liposomal CURC remains more stable in an acid external environment. In the physiological environment, the chemical stability of liposomal CURC is microenvironmental pH-dependent. In conclusion, we prove that the stability of liposomal CURC is external physiological environment- and internal microenvironmental pH-dependent. These findings suggest that creating an acidic microenvironment in the internal chamber of liposomes is beneficial to the stability of liposomal CURC, as well as for other pH-sensitive molecules.

Bone implant materials have been widely used in bone therapy. However, bone infections caused by bacteria can damage the healing and repairing ability of bone tissue, which remains a major problem to be solved in clinical bone regeneration with implants. In this study, silver nanoparticles (Ag-NPs) were uniformly distributed on the inner of Polylactic acid and Gelatin composite fibers (PLLA and Gel, biological macromolecules) by co-electrospinning for improving anti-infection ability and osseointegration. The optimized experimental conditions for this method were having PLLA/Gel mass ratio of 90:10 and Ag content of 7%. Ag-NPs acted as heterogeneous nucleation sites for promoting the nucleation and growth of calcium phosphorus on the surface of composite fiber. Bone marrow-derived mesenchymal stem cells adhered and proliferated well on the surface of the composite fiber, and the positive fluorescence staining indicated the existence of osteoblasts. Vascular endothelial cells had a good adherence and proliferation on the surface of composite fiber, showing good angiogenic properties. Antibacterial rate of the composite fiber was all over 97% against Monilia albicans, Escherichia coli, Staphylococcus aureus and Pseudomonas aeruginosa, showing good antibacterial property. A multi-functional biomacromolecules composite fiber was constructed and shown good bioactivity, osteoinductivity, angiogenic and antibacterial properties.