An electrochemiluminescence sensor based on Ag NPs amplifying PDDA-modified TbPO4:Ce NWs signal for sensitive detection of lincomycin.

The residue of lincomycin in water will not only aggravate the drug resistance of bacteria but also cause damage to the human body through biological accumulation. In this work, an electrochemiluminescence (ECL) aptasensor for the detection of lincomycin was constructed based on polydimethyldiallylammonium chloride (PDDA) functionalized Ce-doped TbPO4 nanowires (PDDA-TbPO4:Ce NWs) and silver nanoparticles (Ag NPs). TbPO4:Ce NWs were used as the luminophore, and PDDA was used to functionalize the luminophore to make the surface of the luminophore positively charged. The negatively charged silver nanoparticles were combined with PDDA-TbPO4:Ce NWs by electrostatic interaction. Ag NPs accelerated the electron transfer rate and promoted the ECL efficiency, which finally increased the ECL intensity of TbPO4:Ce NWs by about 4 times. Under the optimal conditions, the detection limit of the ECL sensor was as low as 4.37 × 10-16 M, and the linear range was 1 × 10 - 15 M to 1 × 10 - 5 M, with good selectivity, stability, and repeatability. The sensor can be applied to the detection of lincomycin in water, and the recovery rate is 97.7-103.4 %, which has broad application prospects.

A zinc-air battery assisted self-powered electrochemical sensor for sensitive detection of microcystin-RR.

Building a high-performance sensing platform is the key to developing sensitive sensors. Herein, a highly sensitive self-powered electrochemical sensor (SPES) was constructed using a WO3·H2O film as the cathode prepared by a hydrothermal method and Zn as the anode, and it could be applied to sensitive detection of microcystin (MC-RR). The WO3·H2O film with a larger specific surface area could boost the oxygen reduction reaction (ORR), which could achieve signal amplification and significantly increase the sensitivity of the sensors. Under the optimal conditions, there was a good linear relationship between the increased electrical power density and the logarithm of MC-RR concentration with a detection limit of 1.31 × 10-15 M (S/N = 3). This method had good anti-interference ability and stability when applied to the determination of MC-RR content in actual samples, which could boost the potential application of electrochemical sensors in the field of environmental monitoring.

Supersensitive detection of lincomycin with an ECL aptasensor based on the synergistic integration of gold-functionalized upconversion nanoparticles and thiolated 3,4,9,10-perylene tetracarboxylic acid.

In this work, the supersensitive and selective determination of lincomycin (Lin) was achieved using a novel electroluminescent (ECL) aptasensor based on the synergistic integration of gold functionalized upconversion nanoparticles (UCNPs) and thiolated 3,4,9,10-perylene tetracarboxylic acid (PTCA). The integration of two luminophores of UCNPs and PTCA combined the merits of the cathodoluminescence stability of UCNPs and the high quantum yield of PTCA, which significantly promoted the ECL signal and analytical performance of the proposed sensor. The introduction of gold nanoparticles in UCNPs can not only improve the conductivity and ECL performance of UCNPs but also cause them to easily integrate with thiolated PTCA (t-PTCA) via an Au-S bond. The ECL signal of UCNPs@Au/t-PTCA/GCE was almost twice as strong as that of t-PTCA/GCE and tenfold higher than that of UCNPs@Au/GCE. Because of the non-conductive protein of the Lin aptamer, the ECL intensity of apt/UCNPs@Au/t-PTCA/GCE noticeably decreased. In the presence of Lin, the aptamer was pulled down from the sensing interface, resulting in the recovery of the ECL intensity of the sensor. Under optimal conditions, our proposed sensor can quantify the concentration of Lin in the range from 1.0 × 10-15 to 1.0 × 10-7 M with a low detection limit of 2.4 × 10-16 M (S/N = 3), exhibiting high sensitivity and specificity for the determination of Lin.

A molecularly imprinted polypyrrole electrochemiluminescence sensor based on a novel zinc-based metal-organic framework and chitosan for determination of enrofloxacin.

Nowadays, bacterial resistance caused by the abuse of antibiotics has become a worldwide problem. In this work, a quinolone antibiotic, enrofloxacin (ENR), was rapidly monitored by combining a selective molecular imprinting polymer (MIP) with the electrochemiluminescence (ECL) method. Zn-PTC, a novel zinc-based metal-organic framework (MOF) that has a large specific surface area and ultra-high luminous efficiency, was used as the ECL luminophore. Chitosan (CHIT) was used to contact the specific surface area of molecularly imprinted polymer films and further improved the detection sensitivity. Subsequently, the molecularly imprinted polypyrrole was electropolymerized on the surface of the Zn-PTC and CHIT modified glassy carbon electrode (GCE). The specific sites that could target recombining ENR were shaped on the surface of MIP after extracting the ENR templates. The specific concentrations of ENR could be detected according to the difference in ECL intensity (ΔECL) between the eluting and rebinding of ENR. After optimization, a good linear response of ΔECL and a logarithm of specific ENR concentrations could be obtained in the range of 1.0 × 10-12-1.0 × 10-4 mol L-1, with a detection limit of 9.3 × 10-13 mol L-1 (S/N = 3). Notably, this study provided a rapid, convenient, and cheap method for the detection of ENR in actual samples.

Evaluation of Bacterial Activity Based on the Electrochemical Properties of Tetrazolium Salts.

This study focused on the electrochemical properties of tetrazolium salts to develop a simple method for evaluating viable bacterial counts, which are indicators of hygiene control at food and pharmaceutical manufacturing sites. Given that the oxidized form of 3-(4,5-di-methylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT), which has excellent cell membrane permeability, changes to the insoluble reduced form of formazan inside the cell, the number of viable cells was estimated by focusing on the reduction current of MTT remaining in the suspension. Dissolved oxygen is an important substance for bacterial activity; however, it interferes with the electrochemical response of MTT. We investigated the electrochemical properties of MTT to obtain a potential-selective current response that was not affected by dissolved oxygen. Real-time observation of viable bacteria in suspension revealed that uptake of MTT into bacteria was completed within 10 min, including the lag period. In addition, we observed that the current response depends on viable cell density regardless of the bacterial species present. Our method enables a rapid estimation of the number of viable bacteria, making it possible to confirm the safety of food products before they are shipped from the factory and thereby prevent food poisoning.

Novel inner filter effect-based near-infrared electrochemiluminescence sensor mediated by well-matched AgBr-nitrogen-doped Ti3C2 MXene and nonmetallic plasmon WO3•H2O.

The development of innovative and efficient strategy is of paramount importance for near-infrared (NIR) electrochemiluminescence (ECL) sensing, which can substantially promote ECL detection in a wide range of situations. Herein, the inner filter effect (IFE) strategy was designed to construct an ultrasensitive NIR ECL biosensor based on the well-matched AgBr nanocrystals (NCs) decorated nitrogen-doped Ti3C2 MXene nanocomposites (AgBr-N-Ti3C2) and hydrated defective tungsten oxide nanosheets (dWO3•H2O). Specifically, the AgBr-N-Ti3C2 nanocomposites displayed extremely effective NIR ECL emission because N-doping could accelerate electron transfer and boost the red-shift of the ECL spectrum. The nonmetallic plasmon dWO3•H2O was used as an absorber due to its facile tuning of the spectra overlap and higher molar extinction coefficients. Time-resolved emission decay curves proved that the decreased ECL intensity was ascribed to the IFE-based steady quenching mechanism. With the support of tetracycline (TC) aptamer and the complementary DNA chain, the fabricated NIR ECL-IFE biosensor performed a wide linear range of 100 nM âˆ¼ 10 fM with a low detection limit of 2.2 fM (S/N = 3), and it exhibited excellent stability, sensitivity, and reproducibility, so as to be applied to real samples. This strategy opens a new avenue to constructing an efficient NIR ECL-IFE system and shows excellent practical potential in actual sample analysis.

A novel molecularly imprinting polypyrrole electrochemiluminescence sensor based on MIL-101-g-C3N4 for supersensitive determination of ciprofloxacin.

Ciprofloxacin (CIP), a quinolone antibiotic, was rapidly and sensitively detected by integrating the molecularly imprinted polymer (MIP) with an ultra-sensitive electrochemiluminescence (ECL) method. g-C3N4, a typical polymer semiconductor, exhibited outstanding ECL efficiency and excellent ECL stability after combining with an iron-based metal-organic framework (MIL-101). Subsequently, the molecularly imprinted polypyrrole was electropolymerized on the composites of MIL-101-g-C3N4 modified glassy carbon electrode (GCE). The specific sites that could target rebinding the CIP molecules were formed on the surface of MIP after extracting the CIP templates. The determination of specific concentrations of CIP could be realized according to the difference in ECL intensity (△ECL) between the eluting and rebinding of the CIP. Under optimal conditions, a good linear response of △ECL and the logarithm of CIP concentrations was obtained in the range 1.0 × 10-9 ~ 1.0 × 10-5 mol/L, with a detection limit of 4.5 × 10-10 mol/L (S/N = 3) (the working potential was -1.8 ~ 0 V). The RSD of all points in the calibration plot was less than 5.0% and the real samples recovery was between 98.0 and 104%. This paper displays satisfactory selectivity and sensitivity, providing a rapid, convenient, and cheap method for the determination of CIP in real samples.

Ultrasensitive self-powered photoelectrochemical sensing for enrofloxacin detection by coupling piezoelectric effect with nonmetallic surface plasmon resonance based on ZnO nanorod arrays/WO3-x.

Exploring efficient strategy for high-efficiency photoelectric conversion is quite important to design sensitive self-powered photoelectrochemical (PEC) sensing platform. This work designed a high performance self-powered PEC sensing platform by the integration of piezoelectric effect with localized surface plasmon resonance (LSPR) effect based on ZnO-WO3-x heterostructures. Due to the fluid eddy induced piezoelectric effect by magnetic stirring, the piezoelectric semiconductor ZnO nanorod arrays (ZnO NRs) can facilitate the transfer of electrons and holes by generating piezoelectric potentials under external forces, thereby contributing to the performance of self-powered PEC platforms. Such working mechanism of the piezoelectric effect was studied by using the COMSOL software. Moreover, the introduction of defect engineered WO3 (WO3-x) can further broaden the light absorption and promote the charge transfer owing to the nonmetallic surface plasmon resonance effect. Remarkably, due to the synergizing piezoelectric and plasmonic effect, the photocurrent and maximum power output of ZnO-WO3-x heterostructures were enhanced by 3.3-fold and 5.5-fold than that of bare ZnO, respectively. After the immobilization of the enrofloxacin (ENR) aptamer, the self-powered sensor demonstrated an excellent linearity (1 × 10-14 M to 1 × 10-9 M) with a low detection limit of 1.8 × 10-15 M (S/N = 3). This work undoubtedly holds great promise to provide the innovative inspiration for the formation of high-performance self-powered sensing platform, which opens up a new horizon of potential in food safety and environmental monitoring.

Hydrovoltaic Effect Coupling with Capacitor Amplification: A Mode for Sensitive Self-Powered Electrochemical Sensing.

Self-powered electrochemical sensors, which can function without external electricity, are incredibly valuable in the realm of sensing. However, most of the present testing methods are normally confined to high environmental requirements, restricted lighting conditions, and temperature differences. Herein, an innovative self-powered electrochemical sensor was successfully developed based on hydrovoltaic effect coupling with capacitor amplification. Due to the combined merits from the two-dimensional transition metal carbides and nitrides (MXene)-polyaniline (PANI) with high surface potential and good hydrophilicity, and the capacitor amplification strategy, the device could harvest electric energy from water evaporation and displayed a high short circuit current value. Under optimal conditions, the proposed self-powered electrochemical sensor presented excellent sensitivity and high specificity for enrofloxacin (ENR) detection in the concentration range from 1 fM to 1 nM with a detection limit of 0.585 fM. Such a proposed sensor also has the advantages of environmental friendliness and ease of use, which is an ideal choice for accurately and precisely detecting ENR in real samples. The mode of such electrochemical detection outlined in this technical note implements a breakthrough in designing self-powered electrochemical sensors, providing a rational basis for development of a diversified sensing platform.

Highly efficient near-infrared electrochemiluminescence resonance energy transfer system for biosensing: Nonmetallic plasmon Mediated well-matched energy donor-acceptor pair.

Herein, a well-matched energy donor-acceptor pair strategy was designed to construct highly efficient NIR ECL-RET system. In detail, an ECL amplification system consisting of SnS2 quantum dots decorated Ti3C2 MXene nanocomposites (SnS2 QDs-Ti3C2) as the energy donor were developed via a one-pot method, and the nanocomposites exhibited highly efficient NIR ECL emission due to the surface-defect effect generated by the oxygen-containing functional groups in MXene. Nonmetallic plasmon hydrated defective tungsten oxide nanosheets (dWO3•H2O) were utilized as energy acceptors because of its strong surface plasmon resonance effect in Vis-NIR absorption range. Compared with non-defective tungsten oxide hydrate nanosheets (WO3•H2O), the overlapping area between ECL spectrum of SnS2 QDs-Ti3C2 and UV-vis spectrum of dWO3•H2O was increased by 2.1 times, and the results showed that more efficient quenching effect was obtained. As a proof of concept, tetracycline (TCN) aptamer and its complementary chain were served as a bridge to connect the energy donor and acceptor, achieving the successful construction of NIR ECL-RET aptasensor. The as-fabricated ECL sensing platform exhibited a low detection limit of 6.2 fM (S/N = 3) within a wide linear range from 10 fM to 10 µM. Besides, the NIR ECL-RET aptasensor also showed excellent stability, reproducibility and selectivity, providing a promising tool to detect TCN in real samples. This strategy offered a universal and effective method in constructing highly efficient NIR ECL-RET system for developing rapid, sensitive and accurate biological detection platform.

Fast cathodic electrodeposition of ZnTCPP-functionalized metal-organic framework films for preparation of a fluorescent aptamer sensor for microcystin determination.

A one-step electrodeposition-assisted self-assembly technique has been developed for preparation of ZnTCPP@MOF films with three-dimensional mesoporous structure in a three-electrode system. The internal structure of the ZnTCPP@MOF films was tuned by adjusting the electrochemical deposition voltage, deposition time, and the concentration of ZnTCPP at room temperature. The ZnTCPP@MOF films under different deposition conditions were characterized by scanning electron microscopy, Fourier transformation infrared spectroscopy, and X-ray photoelectron spectroscopy. The prepared ZnTCPP@MOF films exhibited excellent fluorescence properties, in which ZnTCPP molecules were encapsulated inside the MOF as fluorescent signal probes and structure-directing agents, which affected the electrochemical response of the ZnTCPP@MOF films. The sensing platform based on ZnTCPP@MOF film was used to detect microcystin with a wide determination range (1.0 × 10-12 mol/L ~ 1.0 × 10-5 mol/L), low determination limit (3.8 × 10-13 mol/L), and high sensitivity. More importantly, the strategy is simple, low-cost, green, and environmentally friendly, and it provides a new strategy for the direct use of MOFs films as signaling components.

Plasmonic heterostructure Bi2S3/Ti3C2 with continuous photoelectron injection mediated near-infrared self-powered photoelectrochemical sensing.

Herein, a novel near-infrared (NIR) self-powered photoelectrochemical platform was constructed based on nonmetallic plasmon Ti3C2 MXene coupled with sulphur vacancy engineered Bi2S3. The continuous photoelectron injection from Bi2S3 to Ti3C2 MXene induced a stable SPR effect and high photoelectric conversion efficiency, which is beneficial for developing high-performance NIR self-powered biosensors. As a proof of concept, a sensitive NIR self-powered sensor was constructed by conjunction with an aptamer using Microcystin-RR as a model analyte, which is one of the most common and toxic hepatotoxins released by cyanobacteria.

Dual-binding domain electrochemiluminescence biosensing platform with self-checking function for sensitive detection of synthetic cathinone in e-cigarettes.

Current single signal electrochemiluminescence (ECL) sensors are susceptible to false positive or false negative phenomena due to experimental conditions. Therefore, sensors with "self-checking" function are attracting democratic attention. In quick succession, a highly sensitive single-cathode dual ECL signal aptasensor with self-checking function to improve the shortcomings mentioned above was designed. This aptasensor used In-based metal-organic framework (MIL-68) as load and stabilizer to effectively attenuate the aggregation-induced quenching (ACQ) effect of porphyrin derivatives (Sn-TCPP) while improve ECL stability. The introduction of cooperative-binding split-aptamers" (CBSAs) aptamers increased the specificity of the aptasensor and its unique double-binding domains detection accelerated the detection efficiency. When analyzing 3,4-methylenedioxypyrovalerone (MDPV), we could calculate two concentrations based on the strength of ECL 1 and ECL 2. If the concentrations are the same, the result would be obtained; if not, it should be retested. Depending on the above operation, the results achieve self-check. It was found that the designed aptasensor could quantify the concentration of MDPV between 1.0 × 10-12 g/L and 1.0 × 10-6 g/L with the limit of detection (LOD) of 1.4 × 10-13 g/L and 2.0 × 10-13 g/L, respectively (3 σ/slope). This study not only improves the detection technology of MDPV, but also explores the dual-signal detection of porphyrin for the first time and enriches the definition of self-checking sensor.

Self-powered photoelectrochemical aptasensor for sensitive detection of Microcystin-RR by integrating TiO2/S-doped Ti3C2 MXene photoanode and MoS2/S-doped Ti3C2 MXene photocathode.

Screening sufficient Fermi level differentiation of photoeletrodes is significantly meaningful for developing high-performance self-powered photoelectrochemical (PEC) sensors. In this work, a dual-photoelectrode self-powered system was fabricated for sensitive detection of Microcystin-RR (MC-RR) by integration of the TiO2/S-doped Ti3C2 photoanode and MoS2/S-doped Ti3C2 photocathode. The introduction of S-doped Ti3C2 nanosheets synergistically integrated with semiconductors (TiO2 and MoS2) could generate the unique Schottky junctions, which could adjust the Fermi energy levels, facilitate the separation of electron-hole pairs and broaden light absorption, leading to high photoelectric conversion efficiency. The electric output of self-powered sensing systems was increased by the substantial inherent bias between the Fermi energy levels of various photoelectrodes and the complementary functions of Schottky junctions, which provided a necessary foundation for the development of sensitive sensors. After the immobilization of the MC-RR aptamer, a novel signal-off dual-photoelectrode self-powered sensor was constructed for sensitive detection of MC-RR based on steric hindrance effect. Moreover, the as-fabricated sensor exhibited prominent analytical performance including wide detection range (10-16 M to 10-9 M), low detection limit (3.4 × 10-17 M), good selectivity, stability and reproducibility, so as to be successfully applied to real sample analysis. The designing ideas of the proposed S-doped Ti3C2 MXene-based Schottky junctions can provide a foothold for the innovative construction of dual-photoelectrode internal-driven self-powered sensing platforms with satisfactory performance.

A novel three-dimensional molecularly imprinted polypyrrole electrochemical sensor based on MOF derived porous carbon and nitrogen doped graphene for ultrasensitive determination of dopamine.

Herein, a novel molecular imprinting polypyrrole electrochemical sensor was fabricated based on a zirconia and carbon core-shell structure (ZrO2@C) and a nitrogen-doped graphene (NPG) modified glassy carbon electrode (GCE) for ultrasensitive recognition of dopamine (DA). The NPG was prepared by a sacrificial-template-assisted pyrolysis method and ZrO2@C was synthesized via annealing treatment of a zirconium-based metal-organic framework (UiO-66). A convenient electropolymerization method was used to prepare the pyrrole (Py) conductive molecularly imprinted polymer (MIP) in the presence of DA. The elution process of DA was performed by a simple overoxidation process under alkaline conditions. Differential pulse voltammetry (DPV) was used to assess the electrochemical performance of the sensors. The MIP-based electrochemical sensor with specific binding sites could be used for selective recognition of DA. Under the optimal conditions, the linear range of such a sensor was 5.0 × 10-9-1.0 × 10-4 mol L-1 and the detection limit was 3.3 × 10-10 mol L-1 (S/N = 3). This sensor exhibited suitable selectivity, stability, and reproducibility, which suggested that it could be a promising candidate for rapid diagnostic methods in dopamine investigations.

Development of highly sensitive optical nanoantenna for bacterial detection.

Gold nanoparticles (AuNPs) are chemically stable and serve as excellent labels because their characteristic red coloration based on the localized surface plasmon resonance (LSPR) does not fade. However, it is necessary to control the structure of AuNPs to use them as labels for various analyses, because their optical properties depend strongly on their size, shape, and state of aggregation. In this study, we developed gold nanostructures (AuNSs) by encapsulating many small AuNPs within a polymer for scattering light-based bacterial detection. The AuNSs consisting of many small nanoparticles provided stronger scattered light intensity than a single AuNP of the same particle size. We found that the aggregation of the AuNSs enhanced the scattering light intensity, depending strongly on their aggregation states, and did not affect the wavelength of the scattering light observed under a dark-field microscope. By specifically binding the antibody-introduced AuNSs to the antigen on the bacterial surface, it was possible to label the target bacteria and detect them based on their light scattering characteristics. In addition, to improve the accuracy of the selective identification of the cells of interest, labels based on scattered light should ideally have a fixed wavelength of scattered light with high intensity. From these perspectives, we developed a method of constructing an optical antenna on the surface of target bacterial cells using antibody-introduced NSs.

Ultrasensitive near-infrared aptasensor for enrofloxacin detection based on wavelength tunable AgBr nanocrystals electrochemiluminescence emission triggered by O-terminated Ti3C2 MXene.

Toxic-free and easily accessible electrochemiluminescence (ECL) emitter/luminophore with near-infrared (NIR) emission is highly anticipated for ECL biosensor evolution. In this study, well-dispersed AgBr nanocrystals (NCs) decorated Ti3C2 MXene nanocomposites (Ti3C2-AgBrNCs) were prepared using a simple wet chemical technique and demonstrated highly efficient NIR ECL emission. For the first time, Ti3C2-AgBrNCs displayed wavelength-tunable ECL emission with varied Ti3C2 contents. Interestingly, further experimental data revealed that the ECL emission wavelength of Ti3C2-AgBrNCs red-shifted from 550 to 665 nm as Ti3C2 content increased, which can be attributed to the surface-defect effect generated by the oxygen-containing functional groups in Ti3C2 MXene. In particular, the ECL emission at 665 nm of Ti3C2-AgBrNCs nanocomposites not only revealed a 3.5 times increased ECL intensity but also a more stable ECL signal compared to pure AgBr NCs. As a proof of concept, a direct-type NIR ECL aptasensor with signal-on strategy was constructed with the Ti3C2-AgBrNCs nanocomposites as an ECL platform and enrofloxacin (ENR) as a model analyte. The NIR ECL aptasensor exhibited high sensitivity, a wide linear range from 1.0 × 10-12 mol/L to 1.0 × 10-6 mol/L and a low detection limit (5.97 × 10-13 mol/L). This research offered a viable alternative way for producing toxic-free and efficient near-infrared ECL luminophores in bioanalysis and wavelength-tuning light-emitting devices.

Ultrasensitive ECL aptasensing of kanamycin based on synergistic promotion strategy using 3,4,9,10-perylenetetracar-boxylic-l-cysteine/Au@HKUST-1.

Herein, a sensitive and selective electrochemiluminescence (ECL) aptasensor was designed using Au@HKUST-1 as accelerator towards the perylene derivative (PTC-Cys)/peroxydisulfate (S2O82-) system for kanamycin (KAN) assay. Firstly, the PTC-Cys was prepared by covalently binding l-cysteine to 3,4,9,10-perylenete-tracarboxylic acid, which was acted as the luminophore. Then Au@HKUST-1could play the part of effective catalyst to accelerate the electrochemical reduction process of S2O82-to produce more sulfate radical anions (SO4•-), thus the ECL signal of the compound was noticeably raised by 2.4 times in comparison with that in which only luminophore and S2O82- are present, achieving signal amplification of the ECL system. In the presence of KAN, aptamer was pulled down from the sensing interface, achieving a considerable enhancement of ECL intensity in S2O82- solution. Upon the optimal condition, our proposed strategy can quantify the concentration of KAN from 1.0 × 10-13 to 1.0 × 10-8 M with low limit of detection of 4.2 × 10-14 M (S/N = 3).Besides, our proposed ECL aptasensor exhibited excellent sensitivity, stability and specificity, and could be successfully applied to detect KAN in practical samples, which proved its potential to detect other antibiotics in food security.

Visible light-driven self-powered aptasensors for ultrasensitive Microcystin-LR detection based on the carrier density effect of N-doped graphene hydrogel/hematite Schottky junctions.

In this work, a novel visible light-driven self-powered photoelectrochemical (PEC) platform was designed based on 3D N-doped graphene hydrogel/hematite nanocomposites (NGH/Fe2O3) via a facile one-pot hydrothermal route. The coupling NGH with Fe2O3 could generate a Schottky junction, which promoted the separation of charges. Moreover, Mott-Schottky measurements validated that the carrier concentration achieved by NGH/Fe2O3 was about 3.4 × 103 times in comparison to that of pure Fe2O3, which was beneficial for efficient charge transfer. Owing to the carrier density effect and Schottky junction, the photocurrent of the as-fabricated NGH/Fe2O3 nanocomposites was 6.9-fold higher than that of pure Fe2O3. On the basis of such excellent Schottky junctions, an ultrasensitive visible light-induced self-powered PEC aptasensor was developed using a Microcystin-LR (MC-LR) aptamer. The as-fabricated PEC aptasensor displayed good analytical performance toward MC-LR detection in terms of wide linear range (1 pM-5 nM), low detection limit (0.23 pM, S/N = 3), excellent selectivity and high stability. This new strategy can provide a way for regulating nanostructures for more sensitive PEC sensors by increasing the carrier density.

Au nanoparticle plasmon-enhanced electrochemiluminescence aptasensor based on the 1D/2D PTCA/CoP for diclofenac assay.

The combination of localized surface plasmon resonance (LSPR) and electrochemiluminescence (ECL) can be an effective way to amplify the signal intensity. In this work, an ECL aptasensor with 3,4,9,10-perylenetetracarboxylic acid-decorated cobalt phosphate (denoted as PTCA/CoP) as the ECL emitter and Au nanoparticles (NPs) as plasma was proposed for diclofenac assay. The prepared PTCA/CoP with special 1D/2D structure exhibited good ability and excellent ECL performance. The diclofenac aptamer acted as a bridge to link the PTCA/CoP and Au NPs; thus, the ECL performance of PTCA/CoP was greatly improved due to the plasma effect of Au NPs. Besides, it was found that the ECL signal of the aptasensor was obviously quenched by the introduction of diclofenac, which might be due to the transformation from the LSPR process to the resonance energy transform (RET) process. Under optimal conditions, the difference of ECL intensity was negatively correlated with the concentration of diclofenac in the range 0.1 pM to 10 µM with a low detection limit of 0.072 pM at the potential of -1.8 V vs. Ag/AgCl (S/N = 3). The aptasensor was proved to be suitable for the detection of diclofenac in real samples, suggesting its great practicability.