Self-powered Photoelectrochemical Aptasensor Research Articles

A mediator and spatial-resolution induced dual-ratiometric self-powered photoelectrochemical aptasensor for accurate detection of antibiotics

This work reports a dual-ratiometric self-powered photoelectrochemical sensor (SPPS) by the combination of the photocathode with potassium persulfate (K2S2O8) as mediator and the photoanode with spatial-resolution technique. The key point is to utilize the activation and conversion of K2S2O8 as a mediator to generate two power peaks (PMax1 and PMax2) simultaneously. Spatial-resolution technique offers reference signals (PMax3 and PMax4) for two power peaks, respectively. With chloramphenicol (CAP) as model analytes, a dual-ratiometric SPPS was developed with aptamer as recognition unit. Briefly, the specific capture of CAP increased the power peaks gradually to produce sensing signals which is capable of quantifying CAP. The sensor can provide two sets of sensing signals related to the CAP concentration, i.e., PMax1/PMax3 (R = 0.997) and PMax2/PMax4 (R = 0.999) with a detection limit (S/N = 3) of 0.29 pM. Compared with single-signal or single-ratiometric SPPS, the dual-ratiometric SPPS exhibits improved analytical performances, proposing a feasible way to realize self-checking and anti-interference.

A self-powered photoelectrochemical aptasensor based on target response and Ag-CdIn2S4 photosensitive material for ultrasensitive detection of prostate-specific antigen

In this study, Ag-CdIn2S4 was selected as a photosensitive material and combined with the zeolite imidazole frame-90 encapsulated methylene blue (ZIF-90@MB) to establish a controlled release system. On that basis, a self-powered photoelectrochemical (PEC) aptasensor was constructed based on target responses to realize the highly sensitive detection of prostate-specific antigen (PSA). The self-powered sensing method was employed to effectively avoid interference from other oxidizing/reducing substances in the system and improve the accuracy of the detection method. The band gap of CdIn2S4 was adjusted by Ag doping, and the visible light absorption capacity and photoelectric conversion efficiency of the material were improved by the local surface plasmon resonance (LSPR) effect of metal Ag. The ZIF-90 porous material was used as a carrier, the MB photosensitizer as a signal molecule was loaded in the ZIF-90 pore channel. The PSA aptamer (PApt) was attached to the ZIF-90@MB surface to form a simple biological gate. In the presence of the PSA, the recognition interaction between PApt and PSA made the biological gate open, then many MB molecules were released from ZIF-90 and enhanced the photocurrent signal. Under the optimal experimental conditions, the linear range of the sensor was 0.005 ∼ 50 ng mL−1, and the detection limit was 2.35 pg mL−1. The accurate determination of PSA in human serum was achieved, which provided a novel sensing strategy for the early diagnosis of clinical biomarkers.

Self-powered photoelectrochemical aptasensor for fumonisin B1 detection based on a Z-scheme ZnIn2S4/WO3 photoanode

The incidence of esophageal cancer is positively associated with fumonisin contamination. It is necessary to develop methods for the rapid detection of fumonisins. In this work, a self-powered photoelectrochemical aptamer sensor based on ZnIn2S4/WO3 photoanode and Au@W–Co3O4 photocathode is proposed for the sensitive detection of fumonisin B1 (FB1). Among them, under visible light irradiation, the Z-type heterostructure of ZnIn2S4/WO3 acts as a photoanode to improve the electron transfer rate, which contributes to the enhancement of the photocathode signal and lays the foundation for a wider detection range. The Au@W–Co3O4 photocathode as a sensing interface reduces the probability of false positives (comparison of anode sensing platforms). The PEC sensor has a good working performance in the detection range (10 pg/mL-1000 ng/mL) with a detection limit of 2.7 pg/mL (S/N = 3). In addition, the sensor offers good selectivity, stability and excellent recoveries in real sample analysis. This work is expected to play a role in the field of analyzing environmental toxins.

Construction of a near-infrared light-assisted two-electrode self-powered photoelectrochemical aptasensor for sensitively aptasensing carbohydrate antigen and colorectal cancer CT26 cells

A novel near-infrared (NIR) light-assisted two-electrode self-powered photoelectrochemical aptasensor (SP-PECA) was established for the selective and sensitive detection of carbohydrate antigen 50 (CA 50) and colon cancer CT26 cells. For this, the mesoporous carbon embedded with TiO2 nanocrystals and Au nanoparticles (represented by TiO2/mC@AuNPs) was prepared by calcining the polymer-Ti-based MOF (polyTi-MOF) incorporated with Au NPs at a high temperature (700 °C) under nitrogen atmosphere. The TiO2/mC@AuNP hybrid comprised plenty of oxygen vacancies and possessed enhanced NIR-light absorption ability, improved separation ability of photogenerated electrons and holes, and boosted electron transfer performance, showing an amplified photocurrent signal. The developed SP-PECA based on TiO2/mC@AuNP demonstrated an ultralow limit of detection (LOD) of 60 μU mL−1 within a range of 0.1 mU mL−1 to 100 U mL−1 of CA 50, together with other superior biosensing performances. The fabricated aptasensor also showed promising practicability for the detection of CA 50 from living CT 26 cells, giving a low LOD of 16 cells mL−1 within the range of 100 to 1 × 105 cells mL−1 and high selectivity against normal L929 cells. This work provides a new NIR-assisted SP-PEC-based aptasensing strategy for the rapid and sensitive detection of cancer markers in living cancer cells.

Self-powered photoelectrochemical aptasensor based on hollow tubular g-C3N4/Bi/BiVO4 for tobramycin detection

A highly sensitive photoelectrochemical aptasensor based on phosphorus-doped hollow tubular g-C3N4/Bi/BiVO4 (PT-C3N4/Bi/BiVO4) for tobramycin (TOB) detecting was developed. This aptasensor is a self-powered sensing system which could generate the electrical output under visible light irradiation with no external voltage supply. Based on the surface plasmon resonance (SPR) effect and unique hollow tubular structure of PT-C3N4/Bi/BiVO4, the PEC aptasensor exhibited an enhanced photocurrent and favorably specific response to TOB. Under the optimized conditions, the sensitive aptasensor presented a wider linearity to TOB in the range of 0.01–50 ng mL−1 with a low detection limit of 4.27 pg mL−1. This sensor also displayed a satisfying photoelectrochemical performance with optimistic selectivity and stability. In addition, the proposed aptasensor was successfully applied to the detection of TOB in river water and milk samples.

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 self-powered photoelectrochemical oxytetracycline aptasensor: An integrated heterojunction photoanode of metal-organic framework derived ZnO nanopolyhedra/graphitic carbon nitride with high carrier density

The development of effective strategies for the detection of oxytetracycline (OTC) in soil is of great importance for preserving agri-environmental safety and human health. Herein, a novel photoactive material of metal-organic framework (MOF) derived ZnO nanopolyhedra/graphitic carbon nitride (ZnO/g-C3N4) heterojunction was designed by mixing calcination of zeolite imidazole framework-8 (ZIF-8) and melamine. A self-powered photoelectrochemical aptasensor for the sensitive and selective detection of OTC in soil was proposed using ZnO/g-C3N4 as the photoanode. The photoactivity of the MOF derived ZnO nanopolyhedra was regulated effectively by the introduction of g-C3N4, which resulted in a 7-fold increase in the photocurrent of the ZnO nanopolyhedra at a bias potential of 0 V. It was assigned to the higher carrier density of ZnO/g-C3N4. By virtue of the amplified photocurrent of ZnO/g-C3N4, the specificity of the OTC aptamer and the anti-interference ability of the self-powered sensing method, the designed aptasensor demonstrated the advantages of a wide linear range (0.005–200 nM), low limit of detection (1.49 × 10−3 nM), good selectivity and good reproducibility. For real soil sample analysis, satisfactory recoveries were obtained and further verified by ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS).

Self-powered photoelectrochemical aptasensor based on AgInS2@Co/Ni-UiO-66@CDs photoelectrode for estradiosl detection.

A self-powered photoelectrochemical (PEC) aptasensor was constructed to sensitively detect 17β-estradiol (E2). Firstly, a reasonable AgInS2@Co/Ni-UiO-66@Carbon Nanodots (CDs) photoelectrode with excellent photoelectrochemical performance was built by a simple two-step preparation method. The Co and Ni doping markedly improved the activity of UiO-66;the matched energy level of AgInS2 and Co/Ni-UiO-66 promoted the separation of electron-hole pairs, and the coupling of CDs further enhanced the conductivity and light utilization. Therefore, a steady anode-photocurrent signal output was obtained in 0.0V bias voltage, providing a reliable photoelectric translating platform for assembling a self-powered PEC aptasensor. The E2-aptamer was adopted as a recognition unit to enhance the selectivity and sensitivity of the proposed aptasensor. The specific recognition reaction between E2 and aptamer administering to a raised photocurrent signal and the concentration of E2 was quantified by counting the fluctuation of the anode-photocurrent signal. The linear response range of the PEC aptasensor was 1.0 × 10-5-10nmol/L, and the detection limit (S/N = 3) was lower than 3.0 fmol/L under optimal conditions. The fabricated aptasensor exhibited admirable selectivity, high sensitivity, rapid response, and wide linear range, demonstrating an extensive application prospect for environmental endocrine disruptor detection.

A self-powered photoelectrochemical aptasensor based on dual-photoelectrode photofuel cell for chloramphenicol detection

Inspired by the power generation mechanism of photofuel cell (PFC), a sensitive chloramphenicol (CAP) detection method was developed through the dual-photoelectrode photoelectrochemical (PEC) aptasensor. Assisted with the localized plasma resonance effect (LSPR) of AuNPs, the three-dimensional (3D) graphite carbon nitride (g-C3N4) was acted as the photoanode to output high and stable photocurrent. The photocathode used porous metal organic framework (MOF) and Cu2O to form an N doped core-shell structure, which improved the aptasensor performance by co-participating in the photoresponse with the photoanode. The oxidation-reduction reaction together with the bias voltage of two electrodes completed a PFC system, which realized spontaneously power supply capability. In addition to the sensitivity, the selectivity, stability and repeatability of the as-fabricated device were also guaranteed, which was suitable for practical application. The novel PFC-based dual-photoelectrode PEC sensing system can be regarded as a potential method for antibiotics detection.

Self-powered photoelectrochemical aptasensor based on MIL-68(In) derived In2O3 hollow nanotubes and Ag doped ZnIn2S4 quantum dots for oxytetracycline detection.

A self-powered photoelectrochemical (PEC) aptasensor was constructed based on MIL-68(In) derived indium oxide hollow nanotubes (In2O3 HNs) and Ag-doped ZnIn2S4 quantum dots (QDs) as sensing matrix for the ultrasensitive detection of oxytetracycline (OTC). The hollow tube structure of the designed photoelectric active platform provided abundant active sites and a larger specific surface area for the immobilization of target recognition unit. The coupling of Ag:ZnIn2S4 QDs and In2O3 HNs can accelerate the transmit and separation of photoinduced charge, and thus greatly increasing the intensity of photocurrent signal. Then, the well-constructed OTC-aptamer was anchored on the modified photoelectrode as an accurate capturing element, achieving the specific detection of analyte. Under optimal conditions, the photocurrent intensity of the PEC aptasensor decreases linearly, with a linear response range of 10-4 -10nmol/L, and a limit of detection (LOD) of 3.3×10-5nmol/L (S/N=3). The developed self-powered aptasensor with excellent reproducibility, stability, and selectivity, provides a potential way to detect antibiotic residues in environmental media.

Self-Powered Photoelectrochemical Aptasensor for Oxytetracycline Cathodic Detection Based on a Dual Z-Scheme WO3/g-C3N4/MnO2 Photoanode.

With the high sensitivity and anti-interference provided by a dual Z-scheme structure photoanode and a two-electrode system, a high-performance self-powered photoelectrochemical (PEC) aptasensor for oxytetracycline (OTC) detection was established in this work. Graphitic carbon nitride (g-C3N4) with excellent photoelectric properties was used to be combined with WO3 and MnO2 to form a kind of dual Z-scheme heterojunction. The designed unique structure and the complementary performances of the three materials collectively guaranteed the highly stable photocurrent output of the photoanode due to the wide range of light absorption and the high separation rate of electron-hole pairs. The aptamer-based cathode modified with reduced graphene oxide (rGO) and Au nanoparticles (Au NPs) provided high conductivity and aptamer-binding sites, which brought excellent selective recognition of OTC as well as the self-powered capacity by receiving electrons from the photoanode. In the PEC sensing of OTC, the device presented a wide detection range from 1 pM to 150 nM and a low detection limit of 0.1 pM. Besides, the developed PEC aptasenor showed good selectivity, reproducibility, and stability, so as to be applied to real samples. The proposed PEC sensing method can be considered an effective and promising direction for the detection of antibiotics in the future.

Visible light-activated self-powered photoelectrochemical aptasensor for ultrasensitive chloramphenicol detection based on DFT-proved Z-scheme Ag2CrO4/g-C3N4/graphene oxide

A visible light self-powered photoelectrochemical (PEC) aptasensor based on silver chromate particles, graphitic carbon nitride nanosheets and graphene oxide sheets (Ag2CrO4/g-C3N4/GO) for the ultrasensitive detection of chloramphenicol (CAP) was reported in this work. g-C3N4 was considered to be the fundamental photoelectric material because of its great oxidation ability of photogenerated hole as well as excellent biocompatibility and low toxicity. However, the narrow light absorption range and rapid carrier recombination rate limit the application of pure g-C3N4. Herein, Ag2CrO4 and GO as photosensitizer were introduced to improve the photoelectric properties of g-C3N4. The photocurrent of the developed ternary composite was about 3 times higher than that of pristine g-C3N4, which proves it can be used as a suitable photoelectric active material. Moreover, the mechanism of Z-scheme electron transfer path was proved by density functional theory (DFT) calculation. The fabricated PEC aptasensor exhibited high sensitivity toward CAP with a wide liner response of 0.5 pM to 50 nM and a detection limit of 0.29 pM. The specific recognition mechanism and excellent sensing performance indicated this aptasensor could serve as a useful tool for selective and ultrasensitive CAP detection in practical analysis.

Ultrathin PtNi nanozyme based self-powered photoelectrochemical aptasensor for ultrasensitive chloramphenicol detection

Nanozymes have gained increasing attention in the field of biosensing. Rationally designed nanozymes with excellent catalytic activity are accessible to substitute natural enzymes. Herein, a novel self-powered photoelectrochemical (PEC) aptasensor was constructed for ultrasensitive detection of chloramphenicol (CAP) based on ultrathin PtNi nanowires (NWs) as nanozyme and benzene-ring doped g-C3N4 (BR-CN) as the photoactive material. The prepared 1-nm-thick PtNi nanozyme acted as a peroxidase, possessing higher catalytic activity than natural horseradish peroxidase (HRP) and other Pt-based mimic enzymes. Through the biotin-streptavidin specific interaction, streptavidin modified PtNi nanozyme was introduced into the dual-stranded DNA (dsDNA) formed by complementary DNA and biotinylated CAP aptamer. The PtNi nanozyme catalyzed 4-chloro-1-naphthol (4-CN) oxidation to generate insoluble precipitation on the electrode surface, resulting in an obvious photocurrent reduction. In the presence of CAP, the CAP aptamer was released from the electrode due to strong affinity with CAP, causing the decrease of catalytic precipitation and consequently the generation of a high photocurrent signal. On the basis of PtNi nanozyme signal amplification, the developed self-powered PEC aptasensor showed a wide linear range of 0.1 pM–100 nM with an ultralow detection limit of 26 fM for the determination of CAP. This work provides a feasible strategy for the design of high-activity nanozyme and self-powered PEC biosensor to achieve the ultrasensitive detection of target analyte.

Enhanced photoelectric conversion efficiency: A novel h-BN based self-powered photoelectrochemical aptasensor for ultrasensitive detection of diazinon

This work presents a novel hexagonal boron nitride (h-BN) based self-powered photoelectrochemical (PEC) aptasensor for ultrasensitive detection of diazinon (DZN) with excellent photoelectric conversion efficiency. It was the first time that h-BN based materials were applied to PEC aptasensor, in which the construction of Z-scheme heterojunction of h-BN and graphitic carbon nitride (CN) via doping sulfur into h-BN was innovatively proposed. Meanwhile, Au nanoparticles (AuNPs) were utilized for the surface plasmon resonance (SPR) effect and the formation of new recombination centers. The charge transfer mechanism was expounded and verified by the electron spin resonance (ESR) spin-trap technique. The proposed PEC aptasensor for determination of DZN exhibited a wide linear range from 0.01 to 10000 nM and a low detection limit of 6.8 pM with superb selectivity and remarkable stability. Moreover, the constructed PEC aptasensor performed well with excellent recoveries in three different real samples. This work illustrated that PEC aptasensor is a promising alternative to conventional analytical technologies for the detection of DZN and other organophosphorus (OP) pesticides. The designing ideas of the proposed h-BN based material can provide a foothold for the innovative construction of photoactive materials for PEC bioanalysis.

Synthesis of a CdS-decorated Eu-MOF nanocomposite for the construction of a self-powered photoelectrochemical aptasensor.

A composite of CdS nanoparticles and a europium metal organic framework (Eu-MOF) (CdS/Eu-MOF) was synthesized. The unique properties of MOFs help to improve the photoelectrochemical (PEC) properties of CdS by reducing charge carrier recombination and utilizing a broader spectrum for light harvesting. Under visible light illumination, the photocurrent of the CdS/Eu-MOF composite modified electrode was about 2.5-fold higher than that of the CdS modified electrode. When an ampicillin (AMP)-binding aptamer was immobilized on the CdS/Eu-MOF modified electrode as a recognition element, a self-powered PEC aptasensor exhibiting a specific photocurrent response to AMP was constructed. Several experimental conditions such as the ratio of CdS to MOF, the coating amount of the CdS/Eu-MOF suspension and the concentration of the aptamer were studied. Under optimum conditions, the photocurrent of the developed sensor was linearly related to the logarithm AMP concentration in the range of 1 × 10-10 to 2 × 10-7 M, with a detection limit (3S/N) of 9.3 × 10-11 M. Moreover, this sensor exhibited excellent selectivity, good repeatability and desirable stability. It was successfully applied to the detection of AMP in lake water and milk samples.

Highly sensitive detection of microcystin-LR under visible light using a self-powered photoelectrochemical aptasensor based on a CoO/Au/g-C3N4 Z-scheme heterojunction.

Based on the unique photoelectrochemical properties of a CoO/Au/g-C3N4 Z-scheme heterojunction, a self-powered photoelectrochemical (PEC) aptasensor was constructed for the detection of microcystin-leucine arginine (MC-LR). Z-scheme heterojunctions can promote the separation of a photo-induced electron-hole pair, and the surface plasmonic resonance (SPR) of Au nanoparticles can significantly enhance the adsorption of visible light. Importantly, MC-LR molecules were captured by aptamers initially immobilized on the modified electrode due to their high affinity, and then oxidized by the photogenerated holes, which caused an amplified photocurrent signal, allowing the quantitative analysis of MC-LR by measuring the photocurrent intensity change. This PEC MC-LR aptasensor showed high sensitivity and selectivity within a wide linear response range from 0.1 pM to 10 nM and a detection limit of 0.01 pM. The application of this sensor in the analysis of lake water samples provided accurate results with a relative standard deviation (RSD) of 2.6%-4.2%.

Self-powered photoelectrochemical aptasensor based on phosphorus doped porous ultrathin g-C3N4 nanosheets enhanced by surface plasmon resonance effect

This work reports a facile and sensitive self-powered cathodic photoelectrochemical (PEC) aptasensor for the detection of oxytetracycline (OTC) based on Au nanoparticles-decorated phosphorus-doped porous ultrathin g-C3N4 nanosheets (Au/PCN-S). The prepared PCN-S possesses large specific surface area with abundant in-plane pores on its surface, ideal biocompatibility, and excellent visible light response. The in situ photo-reduced Au nanoparticles further enhanced the PEC performance owing to its unique surface plasmon resonance (SPR) effect. Under visible light irradiation, the photocurrent of Au/PCN-S composites was significantly enhanced, which was about 22 times higher than that of pure g-C3N4. In the self-powered PEC biosensing of OTC, the device exhibited high sensitivity toward the presence of dissolved oxygen in the electrolyte and presented a wide detection range from 0.5 to 200 nM and a detection limit of 0.34 nM, as well as certain selectivity, reproducibility and stability. The proposed Au/PCN-S nanocomposites would be considered as a promising visible light-responsive photoactive material for fabrication of PEC biosensors with high performance.