Photoelectrochemical Biosensor Research Articles

Efficient sensitization of CdTe QDs towards PTCDA for sensitive photoelectrochemical Hg2+ assay.

Herein, a sensitive photoelectrochemical (PEC) biosensor was designed for the detection of mercury ions (Hg2+) on the basis of the efficient sensitization of cadmium telluride quantum dots (CdTe QDs) towards 3,4,9,10-perylenetetracarboxylic dianhydride (PTCDA) and the significant quenching ability of a thymine-Hg2+-thymine (T-Hg2+-T) structure. The proposed CdTe QD/PTCDA sensitized structure was successfully constructed via continuous incubation of PTCDA and CdTe QDs on the glassy carbon electrode (GCE) interface, which embraced strong light absorption capacity and high carrier separation efficiency, giving rise to a remarkably improved initial photocurrent response. Notably, the PEC signal generated from the CdTe QD/PTCDA sensitized structure was almost fivefold higher than that of PTCDA owing to the efficient sensitization of CdTe QDs towards PTCDA. Once target Hg2+ ions were added, a T-rich S1 strand modified on the surface of 1-hexanethiol (HT)/S1/gold nanoparticles (Au NPs)/CdTe QDs/PTCDA/GCE immediately reacted with Hg2+ to produce multiple stable T-Hg2+-T structures. Therefore, the initial PEC signal would be considerably quenched by a high steric hindrance effect derived from the T-Hg2+-T structures. As a result, a quenched PEC response could achieve the detection of Hg2+ in concentrations ranging from 100 fM to 1000 nM. More importantly, the combination of the CdTe QDs/PTCDA sensitization structure and the T-Hg2+-T structure paves a promising pathway to developing a novel PEC biosensing platform for Hg2+ detection and also provides a favorable strategy for monitoring environmental pollution related to Hg2+.

Self-breathing strategy-enabled high-performance self-powered photoelectrochemical sensing by integrating with a perovskite Ag3BiO3/Ti3C2 plasmonic heterojunction.

An innovative photocatalytic fuel cell (PFC)-based self-powered system was developed by integrating the perovskite Ag3BiO3/Ti3C2 MXene plasmonic heterojunction with a self-breathing strategy, which was beneficial for developing high-performance self-powered photoelectrochemical biosensors.

Pyroelectric-Effect-Assisted Near-Infrared-Driven Photoelectrochemical Biosensor Based on Exponential DNA Amplifier for MicroRNA Detection.

Although near-infrared responsive photoelectrochemical (PEC) biosensors have less damage to biological components compared to UV-visible light, they still reveal an inferior response due to the rapid recombination of photogenerated electron-hole. In this study, a near-infrared-driven PEC biosensor is fabricated for microRNA (miRNA) detection via integrating photoelectricity and pyroelectricity. Upon the introduction of target miRNA-21, the exponential DNA amplifier is triggered based on enzyme-assisted strand displacement amplification (SDA), releasing multiple Ag2S reporter probes to hybridize with capture probes immobilized on a CdS-2-mercaptobenzimidazole (2MBI)-modified photoelectrode. As a result, under the stimulation of NIR, the photoelectric conversion of Ag2S NPs generates the photocurrents. In addition, due to the strong hole acceptor ability of MBI, the pyroelectric effect of CdS-2MBI nanocomposites is enhanced, which generates highly pyroelectro-induced charge separation efficiency and induces the pyroelectric current benefited from the spontaneous polarization of CdS-2MBI caused by the temperature variation under the function of Ag2S nanoheaters. Impressively, this PEC biosensor has achieved the sensitive and selective determination of miRNA-21 with a detection limit as low as 54 fM. Overall, this NIR-driven PEC biosensor based on pyroelectric and photoelectric effects opens up a new horizon for bioanalysis and early disease diagnosis.

Photoelectrochemical Enzyme Biosensor for Malate Using Quantum Dots on Indium Tin Oxide/Plastics as a Sensing Surface.

A photoelectrochemical biosensor for malate was developed using an indium tin oxide (ITO) layer deposited on a poly(ethylene terephthalate) plastic sheet as a transparent electrode material for the immobilization of malate dehydrogenase together with CdTe quantum dots. Different approaches were compared for the construction of the bioactive layer; the highest response was achieved by depositing malate dehydrogenase together with CdTe nanoparticles and covering it with a Nafion/water (1:1) mixture. The amperometric signal of this biosensor was recorded during irradiation with a near-UV LED in the flow-through mode. The limit of detection was 0.28 mmol/L, which is adequate for analyzing malic acid levels in drinks such as white wines and fruit juices. The results confirm that the cheap ITO layer deposited on the plastic sheet after cutting into rectangular electrodes allows for the economic production of photoelectrochemical (bio)sensors. The combination of NAD+-dependent malate dehydrogenase with quantum dots was also compatible with such an ITO surface.

A multiple signal amplification photoelectrochemical biosensor based on biotin-avidin system for kanamycin sensing in fish and milk via synergism of g-C3N4 and Ru@SiO2

BackgroundThe residues of kanamycin can accumulate in the human body for a long time and pose serious health risks, including hearing loss, kidney poisoning, and drug allergic reactions. Therefore, it is crucial to develop a rapid, highly sensitive, and low-cost method for detecting kanamycin residues in foods. However, the current methods have limitations such as low sensitivity, expensive instruments, and multiple steps, which make them impractical for use in resource-limited environments and emergencies. In this study, the creation of a multiple-signal amplification photoelectrochemical biosensor to address these aforementioned issues is discussed. ResultsHerein, we proposed a multiple signal amplification photoelectrochemical (PEC) biosensor based on carboxylated g-C3N4 and avidin functionalized Ru@SiO2 for the ultrasensitive detection of kanamycin. The carboxylated g-C3N4 was a highly efficient photoactive substance for amplifying photoelectric signals and a substrate for aptamer immobilization. The DOS and PDOS of g-C3N4 were studied by simulation, and the sensing mechanism of the probe at the molecular level was revealed. Meanwhile, using Ru@SiO2 as a signal amplifying unit, through the cooperative work between Ru@SiO2 and g-C3N4, the photoelectric signal could be double amplified to produce an excellent photocurrent response. Under optimized conditions, the photocurrent response of the PEC biosensor to kanamycin was obtained at concentrations from 0.1 nM to 1000 nM with a lower detection limit of 4.1052 × 10−11 mol L−1. This protocol demonstrates high sensitivity, brilliant specific recognition ability, excellent reproducibility, and acceptable stability. SignificanceThe first combination of g-C3N4 and avidin-Ru@SiO2 as photocurrent materials greatly enhanced the sensitivity of the PEC biosensors. Moreover, the specificity and sensitivity of the PEC biosensor were further improved through the specific interaction between kanamycin and aptamer. The photoelectric conversion mechanism based on g-C3N4 and two pathways for enhancing the photocurrent by Ru(byp)32+ were proposed. Through simulations of the DOS and PDOS of g-C3N4, the sensing mechanism of the probe at the molecular level was revealed. Under the optimum conditions, the PEC biosensor exhibited a wide linear concentration range and a low detection limit.

Rolling circle amplification assisted CRISPR/Cas12a dual-cleavage photoelectrochemical biosensor for highly sensitive detection of miRNA-21

BackgroundMicroRNA-21 has been determined to be the only microRNA overexpressed in 11 types of solid tumors, making it an excellent candidate as a biomarker for disease diagnosis and therapy. Photoelectrochemical (PEC) biosensors have been widely used for quantification of microRNA-21. However, most PEC biosensing processes still suffer from some problems, such as the difficulty of avoiding the influence of interferents in complex matrices and the false-positive signals. There is a pressing need for establishing a sensitive and stable PEC method to detect microRNA-21. ResultsHerein, a nicking endonuclease-mediated rolling circle amplification (RCA)-assisted CRISPR/Cas12a PEC biosensor was fabricated for ultrasensitive detection of microRNA-21. The p-p type heterojunction PbS QDs/Co3O4 polyhedra were prepared as the quencher, thus the initial PEC signal attained the “off” state. Furthermore, the target was specifically identified and amplified by the RCA process. Then, its product single-stranded DNA S1 activated the cis- and trans-cleavage abilities of CRISPR/Cas12a, leading to almost all of the PbS QDs/Co3O4 polyhedra to leave the electrode surface, the p-n semiconductor quenching effect to be disrupted, and the signal achieving the “super-on” state. This pattern of PEC signal changed from “off” to “on” eliminated the interference of false-positive signals. The proposed PEC biosensor presented a satisfactory linear relationship ranging from 1 fM to 10 nM with a detection limit of 0.76 fM (3 Sb/N). Significance and noveltyWith innovatively synthesized PbS QDs/Co3O4 polyhedra as the effective quencher for PEC signal, the CRISPR/Cas12a dual-cleavage PEC biosensor possessed excellent selectivity, stability and repeatability. Furthermore, the detection of various miRNAs can be realized by changing the relevant base sequences in the constructed PEC biosensor. It also provides a powerful strategy for early clinical diagnosis and biomedical research.

Bipedal DNA walker- CRISPR/Cas12a coupling with sulfur doped boron nitride–carbon nitride composite biosensing for the detection of miRNA-21

A novel photoelectrochemical (PEC) biosensor based on 2D–2D heterojunction S-BN/CN and dual-orbit three-dimensional (3D) bipedal DNA walker-synergized CRISPR/Cas12a signal amplification was fabricated for sensitive detection of miRNA-21. First of all, S-BN/CN, which sulfur was doped into boron nitride (BN) to construct heterojunction of 2D S-BN and 2D g-C3N4, was used as photosensitive materials to provide initial photocurrent, and combined methylene blue (MB) labeled hairpin DNA (MB-HP) as a signal probe. Secondly, after identifying the target miRNA-21, the two swing arms were simultaneously activated on two 3D orbits, cleaving along the orbit to output massive short single strand DNA (O-DNA) under the action of Nt.BsmAl endonuclease. Then trigger the trans-cleavage of CRISPR/Cas12a and cut off the hairpin DNA labeled with MB to achieve signal-off. The result showed that the proposed PEC biosensor had a good sensitivity for the detection of miRNA-21. It was a good linearity in the range of 10 fM - 100 nM, and the limit of detection was 3.98 fM (S/N = 3). The proposed PEC biosensor achieved sensitive detection with high specificity and low limit of detection for miRNA-21, while the rational design could be extended to achieve the detection of other targets.

Bienzyme photoelectrochemical biosensor for the sensitive determination of phosphatidylcholine in vegetable oil

A bienzyme photoelectrochemical (PEC) biosensor was explored for the sensitive determination of phosphatidylcholine (PC) in vegetable oil based on phospholipase D (PLD) and choline oxidase (ChOx) immobilized on an indium tin oxide (ITO) electrode. The bienzyme electrode is based on the modification with SnO2 nanoparticles (NPs) (SnO2 NPs) and polythionine (PTh). SnO2 NPs were obtained by using a hydrothermal method. Electropolymerization was performed to load the PTh layer on the ITO/SnO2 NPs electrode surface. PLD and ChOx were immobilized on the surface of modified ITO electrode using embedding and cross-linking methods. The prepared ITO/SnO2 NPs/PTh/ChOx/PLD electrode was finally applied as bienzyme PEC biosensor for PC detection. Under optimized conditions, a good linear relationship was obtained in the range of 0.01 mmol/L to 5 mmol/L with a detection limit of 0.002 mmol/L (S/N = 3). The proposed PEC biosensor exhibited remarkable reproducibility, selectivity, and stability. The prepared bienzyme biosensor was used to detect PC in soybean oil by acceptable recoveries. The results were consistent with those of liquid chromatography, confirming the suitability of this PEC sensing strategy for the rapid and sensitive determination of PC in vegetable oil.

Superoxide dismutase-like cerium dioxide hollow sphere-based highly specific photoelectrochemical biosensing for ascorbic acid

Conventional N-type semiconductor-based photoelectrochemical (PEC) sensors are difficult to achieve high selectivity for ascorbic acid (AA) detection in real samples because co-existing reducing agents act as hole sacrificial agents like AA to promote the increase of photocurrent. Cerium dioxide (CeO2) is a superoxide dismutase-like nanozyme with the reversible Ce3+/Ce4+ redox pair as well as one of alternative N-type semiconductors. To address the problem of PEC detection selectivity of AA, bifunctional CeO2 is a good choice. Herein, a novel and rational PEC biosensor for AA is constructed based on CeO2 hollow spheres as both AA superoxide dismutase-like nanozyme and the photoelectric beacon, which enable the PEC approach with high selectivity. In this protocol, AA can selectively induce a decrease in the CeO2-based photoanode current, which is significantly different from the conventional N-type semiconductor-based PEC sensor, this unique working mechanism is also proposed. The results show that the CeO2-based photocurrent response decreases linearly with AA concentrations in the ranges of 1 μM–600 μM and 600 μM–3000 μM, with a limit of detection of 0.33 μM. Moreover, the fabricated PEC biosensor has advantages of cost-effectiveness, replicability, and stability. Additionally, the sensor is competent for AA determination in practical settings and has achieved satisfactory results.

Exonuclease-catalyzed recycling and annular four-footed DNA walking amplification-assisted “on-off-super on” signal transitions for photoelectrochemical biosensing of kanamycin

Photoelectrochemical (PEC) biosensors have exhibited a promising potential for assays of a large variety of analytes; however, how to realize their low background-based “super on” signal output is still a great challenge. Herein, we report a novel multiple nucleic acid amplification-assisted “on-off-super on” signal transition mechanism for the PEC biosensing of kanamycin antibiotics. The biosensing platform was constructed on a perylene-3,4,9,10-tetracarboxylic dianhydride-based photoelectrode, and its strong photocurrent could be well inhibited by an anchored ferrocene (Fc)-labeled hairpin DNA to produce a low background signal. Two target biorecognition-triggered exonuclease III-catalytic reactions were adopted to produce an annular four-footed DNA walker (AFW) and a methylene blue (MB)-labeled DNA strand. By using their synergistic effect to release Fc quenchers and simultaneously capture MB sensitizers, a “super on” signal output was realized. As a result, a very wide linear range from 10 fg mL−1 to 10 ng mL−1 and an ultra-low detection limit of 7.8 fg mL−1 were obtained. Meanwhile, the aptamer recognition-based homogeneous reaction and AFW-based multiple nucleic acid amplification effectively simplified the assay manipulation and well ensured the repeatability of the method. The satisfactory sample experiment results indicated its good reliability and accuracy for the antibiotic residue analysis application.

Portable Visual Photoelectrochemical Biosensor Based on a MgTi2O5/CdSe Heterojunction and Reversible Electrochromic Supercapacitor for Dual-Modal Cry1Ab Protein Detection.

Reversible electrochromic supercapacitors (ESCs) have attracted considerable interest as visual display screens. The use of ESCs in combination with a photoelectrochemical (PEC) biosensor promises to improve the detection efficiency. Herein, a visual PEC biosensor is developed by introducing a circuit module between a PEC-sensing platform (PSP) and a reversible ESC for Cry1Ab protein detection. In PSP, a type II MgTi2O5/CdSe heterojunction effectively drives charge separation by their cross-matched band gap structures, generating an amplified photocurrent. Next, the circuit module is designed to connect the PSP and ESC, realizing the signal conversion from photocurrent to voltage. ESC, as a visual display screen, produces reversible color changes with different voltages. As the concentration of Cry1Ab increases, the photocurrent decreases due to the specific binding between the aptamer and Cry1Ab in PSP, while the color of the reversible ESC changes from green to blue. To improve the integrity of the device, a portable PEC biosensor is further constructed via three-dimensional printing for dual-modal Cry1Ab protein detection, thus collecting both PEC and visual signals. The linear ranges are 0.3-3000 ng mL-1 for PEC mode and 1-1000 ng mL-1 for visual mode. This work presents a portable, efficient, sensitive, and visualized detection system, providing an important reference for practical visualization applications.

Ascorbic Acid Induced the Improved Oxygen Vacancy Defects of Bi4O5Br2 and Its Application on Photoelectrochemical Detection of DNA Demethylase MBD2 with Improved Detection Sensitivity.

Oxygen vacancy defects (OVs) are one of the main strategies for nanomaterials modification to improve the photoactivity, but current methods for fabricating OVs are usually complicated and harsh. It is important to develop simple, rapid, safe, and mild methods to fabricate OVs. By studying the effects of different weak reducing agents, the concentration of the reducing agent and the reaction time on fabrication of OVs, it is found that L-ascorbic acid (AA) gently and rapidly induces the increase of OVs in Bi4O5Br2 at room temperature. The increased OVs not only improve the adsorption of visible light, but also enhance the photocurrent response. Based on this, the preparation of OVs in Bi4O5Br2 is employed to the development of a photoelectrochemical biosensor for the detection of DNA demethylase of methyl-CpG binding domain protein 2 (MBD2). The biosensor shows a wide linear range of 0.1-400ngmL-1 and a detection limit as low as 0.03ngmL-1 (3σ). In addition, the effect of plasticizers on MBD2 activity is evaluated using this sensor. This work not only provides a novel method to prepare OVs in bismuth rich materials, but also explores a new novel evaluation tool for studying the ecotoxicological effects of contaminants.

Triple-Mode Sensor Coupled by Photoelectrochemical, Electrochromic, and Spectral Signals for Sensitive Visualized Detection of Nonylphenol.

Conventional photoelectrochemical (PEC) biosensors suffer from the difficulty of visualizing rapid detection and limited accuracy due to a single-signal output. Here, we develop a PEC, electrochromic (EC), and spectral (ST) triple-mode platform for the sensitive visualized detection of nonylphenol (NP). First, the reasonably stepped Fermi energy level arrangement between the defective TiO2 anode and MoO3 cathode enables a remarkable photocurrent response (Mode 1). Then, MoO3 itself is a widely used EC candidate, which can react with free Li-ions to form a LixMoO3 intermediate, and its color will change from white to blue accordingly (Mode 2). More importantly, MoO3 is also a Li-ion host and the potential of LixMoO3 depends on the inserted Li-ion quantity deduced by spectral analysis on residual Li-ions in the electrolyte (Mode 3). The EC signal endows fast visual detection, and triple-mode cross-validation improves reliability and accuracy. As a result, this PEC-EC-ST triple-mode molecularly imprinted sensor has a wide linear range (1-5000 μg L-1), a low detection limit (0.18 μg L-1), selectivity, stability, reproducibility, and actual sample detection capability. This innovative multimode platform not only improves detection reliability but also broadens applications of electrochromic/energy storage materials in biosensors.

HOF-101-based dual-mode biosensor for photoelectrochemical/electrochemiluminescence detection and imaging of oxytetracycline

A unique hydrogen-bonded organic frameworks (HOF-101)-based photoelectrochemical (PEC) and electrochemiluminescence (ECL) dual-mode biosensor using polydopamine nanoparticles (PDAs) as quencher was constructed for ultrasensitive detection and imaging of oxytetracycline (OXY). In particular, HOF-101 was a superior ECL material and can be observed with the naked eye. Furthermore, it also had outstanding PEC signal, so HOF-101 was a new dual-signal material with excellent performance, thus it was explored to realize dual-mode detection. As the main component of natural melanin, PDAs not only had good biocompatibility, but also contained rich functional groups on the surface. Additionally, PDAs had excellent light absorption ability and poor conductivity, which made it the excellent photoquencher. In this work, PDAs were introduced on the surface of HOF-101 to quench its ECL and PEC signals by using the dual-aptamer sandwich method, achieving ultrasensitive detection of antibiotic OXY. Particularly for ECL detection, HOF-101 was firstly used to visually detect OXY. The detection range can reach 0.1 pM-100 nM, and the limit of detection (LOD) can reach 0.04 pM. This work showed a great contribution to the development of new ECL-PEC materials and ECL visualization analysis, which had outstanding application potential in the fields of food safety and biochemical analysis.

Rational design an oval heterostructure and tight linking interface of ZnS@CdS(3) for sensitively photoelectrochemical bioanalysis of PSA

Photoactive material with heterostructures could be effectively employed to promote the photoelectrochemical (PEC) property. Herein, two species heterostructured ZnS@CdS(1−2) composites derived from ZIF-8-S MOFs via a sulfofication reaction in situ using Cd(NO3)2, CdC12 cadmium reagents, and further gained the oval ZnS@CdS(3) after annealing the ZnS@CdS(2). Under irradiation, the PEC results showed that the photocurrent response of ZnS@CdS(3) signally enhanced compared to disordered heterostructures of ZnS@CdS(1), ZnS@CdS(2) and pure ZnS or CdS. It was ascribed to the staggered levels based on matching band-gap to form type II heterojunction of ZnS@CdS(3) could facilitate photo-induced electron/hole (e-/h+) separation and transfer. The obtained photoelectric material with a tight connecting interface also could reduce the carriers transport distance. Besides, the structured and well-distributed ZnS@CdS(3) was beneficial to improve synergistic effect on every component, which resulting in violently photocurrent output. This ZnS@CdS(3) modified ITO electrode to create the PEC biosensor (BSA/anti-PSA/ZnS@CdS(3)/ITO) had been successfully applied for the PSA detection with a wide linear range of 0.001 ∼ 150 ng mL−1 and ultralow detection limit of 0.27 pg mL−1. This research innovatively designed a close contact heterojunction interface with superior PEC nature for biosensor preparations.

NAD+ mediated photoelectrochemical biosensor for histone deacetylase Sirt1 detection based on CuO-BiVO4-AgNCs heterojunction and hybridization chain reaction amplification

BackgroundHistone deacetylate Sirt1 has been involved in many important biological processes and is closely related to the occurrence and development of many diseases. Therefore, the accurate detection of Sirt1 is of great significance for the diagnosis and treatment of diseases caused by Sirt1 and the development of related drugs. ResultsIn this work, a photoelectrochemical biosensor was developed for Sirt1 detection based on the NAD + mediated Sirt1 recognition and E. Coli DNA ligase activity. CuO-BiVO4p-n heterojunction was employed as the photoactive material, rolling circle amplification (RCA), hybridization chain reaction (HCR) and AgNCs were used as triple signal amplifications. As a bifunctional cofactor, NAD+ played a crucial role for Sirt1 detection, where the peptide deacetylation catalyzed by Sirt1 consumed NAD+, and the decreased amount of NAD + inhibited the activity of E. Coli DNA ligase, leading to the failure on RCA reaction, and improving the HCR reaction. Finally, AgNCs were generated using C-rich DNA as carrier. The surface plasmon effect of AgNCs and its heterojunction with CuO and BiVO4 accelerated the transfer rate of photogenerated carriers and improved the photocurrent signal. When the detection range was 0.001–200 nM, the detection limit of the biosensor was 0.76 pM (S/N = 3). SignificanceThe applicability of the method was evaluated by studying the effects of known inhibitors nicotinamide and environmental pollutant halogenated carbazole on Sirt1 enzyme activity. The results showed that this method can be used as a new platform for screening Sirt1 enzyme inhibitors, and also provided a new biomarker for evaluating the ecotoxicological effects of environmental pollutants.

Photoelectrochemical biosensor with Au@PTCA Schottky junction and multiple sandwich structures for Hg2+ sensitive detection

Herein, a novel photoelectrochemical (PEC) biosensor was built on the strength of gold nanoparticles@3,4,9,10-Perylene tetracarboxylic (Au@PTCA) Schottky junction and multiple sandwich structures caused by thymine-Hg2+-thymine (T-Hg2+-T) and base complementary pairing, realizing the highly sensitive detection of mercury ion (Hg2+). The proposed Au@PTCA Schottky junction was formed by using PTCA as carrier and Au NPs as signal enhancer, which could significantly improve photoelectric conversion efficiency, resulting in a strong initial PEC signal. The multiple sandwich structures possessed high steric hindrance effect, which could directly block external electron supply and light harvesting, giving rise to a significantly quenched PEC signal. In addition, the execution of the multiple sandwich structures could extinguish initial PEC signal produced by Au@PTCA Schottky junction, acquiring the comparison of various PEC signals, thereby fulfilling the quantitative detection of Hg2+. The experimental results showed that the PEC signal was gradually suppressed as the Hg2+ concentration increased in the range of 10 pM to 10 μM and the detection limit was 3.33 pM under optimal conditions, giving the sensor the advantages of high selectivity and excellent stability. This study demonstrated a promising method for sensitive detection of Hg2+ and offered a valuable approach with potential applications in environmental detection, biological analysis, and medical research.

Recent advances on portable photoelectrochemical biosensors for diagnostics

AbstractEfficient and accurate diagnostic methods are important for human health monitoring and prevention of major diseases, so the establishment of efficient and convenient testing methods for clinical diagnosis is urgent. Photoelectrochemical (PEC) biosensors have attracted much attention because of their high sensitivity, low detection background, and especially the advantages of combining photoexcitation and electrochemical detection. With the rapid development of integrated circuit technology many wireless transmissions of highly aggregated portable micro devices are manufactured, its small size, easy to carry, and the ability to visualize the results of the test is shown to be the potential for the application of such devices. This review aims to cover recent advances in PEC biosensing within the field of portable detection, including the principles of PEC biosensors, common photovoltaic materials, and scalable fabrication techniques for portable PEC biosensing. Future prospects in the field are also discussed.

Synergistic integration of MoOx co-catalyst with oxygen vacancies-engineered on BiVO4 for enhancing the sensitivity of photoelectrochemical DNA biosensing

Photoelectrochemical (PEC) biosensors of deoxyribonucleic acid (DNA) hybridization with simultaneously high signal-to-noise ratio and low limit-of-detection remains greatly challenging owing to the rapid recombination of photogenerated carriers of photoelectrode. Herein, we report an efficient strategy to amplify the photocurrent signal by coupling the MoOx co-catalysts and surface oxygen vacancies (Ov) of BiVO4 as photoelectrode (MoOx/BiVO4-Ov). Using a simple in situ solution impregnation method, non-noble metal MoOx nanoparticles can be grown uniformly onto BiVO4, subsequently, abundant surface Ov of MoOx/BiVO4 is induced by N2-plasma treatment. The coupling of MoOx and surface Ov on BiVO4 can efficiently promote the separation of photogenerated carriers, as a result, the optimized MoOx/BiVO4-Ov shows an excellent photocurrent response of 300.52 μA/cm2 under simulated sunlight illumination, which is 59.6 and 5.4 times higher than that of pristine BiVO4 and MoOx/BiVO4, respectively. Furthermore, the PEC biosensor based on MoOx/BiVO4-Ov demonstrates an excellent sensitivity toward DNA hybridization (10 pM to 10 μM) with a calculated detection limit down to 0.0549 pM. Moreover, this PEC biosensor exhibits specific selectivity as well as high stability. The proposed amplification strategy by the synergistic effect of co-catalysts and defects is valuable for the construction of efficient sensors for the early diagnosis of multiple diseases.

Synergistic effect of photoelectrochemical aptasensor based on staggered gap ZnO/BiFeO3 heterojunction coupled with cDNA-CdS sensitizer enabling ultrasensitive assay of kanamycin

Using staggered-gap ZnO/BiFeO3 heterojunction as photoactive materials and cDNA-CdS as the sensitizer for sensitive Kanamycin (KAN) detection, we have created a unique signal-off biosensing platform. The ZnO/BiFeO3 heterojunction provides active sites for aptamer loading and enhances photocurrent responsiveness. Rapid interfacial charge transfer and the separation efficiency of photo-generated carriers are enhanced by sensitization of the ternary heterojunction ZnO/BiFeO3/CdS. Signal-amplified quenching occurs when sensitizers are replaced with sterically hindered KAN. Because of the aptamer's greater affinity for KAN, the replacement of CdS causes a decrease in photocurrent response. Additionally, the weakly conductive aptamer-KAN complex causes steric hindrance, which exacerbates the photoelectrochemical signal-damping effect even more. The photoelectrochemical aptasensor exhibits excellent selectivity and stability, detecting KAN within the range of 0.00005825–0.233 μg/mL with a detection limit of 0.0466 ng/mL (S/N = 3). This work demonstrates the potential of perovskite oxides and their heterostructures for advanced photoelectrochemical biosensing applications.