Photoelectrochemical Biosensor Research Articles

Smartphone-based portable photoelectrochemical biosensing system for point-of-care detection of urine creatinine and albumin.

Creatinine and albumin are crucial biomarkers for health monitoring and their ratio in urine is an effective approach for albuminuria assessment. Herein, to address the challenges of point-of-care and efficient analysis of the biomarkers simultaneously, we developed a fully integrated handheld smartphone-based photoelectrochemical biosensing system. A miniaturized printed circuit board included a potentiostat for photocurrent measurements and single-wavelength light-emitting diodes (LEDs) for photo-excitation, which was controlled with a Bluetooth-enabled smartphone. Graphitic carbon nitride (g-C3N4)/chitosan nanocomposites were modified on a transparent indium tin oxide (ITO) electrode as photoactive materials. Creatinine was detected through chelate formation with copper ion probes, while albumin was recognized specifically by an antigen-antibody reaction based on immunoassay. The biosensing system demonstrated good linearity and high sensitivity, with detection ranges of 100 μg mL-1 to 1500 μg mL-1 for creatinine, and 9.9 μg mL-1 to 500 μg mL-1 for albumin. Spiked artificial urine samples with different concentrations were tested to confirm the practical validity of the biosensing system, where an acceptable recovery rate ranged from 98.7% to 105.3%. This portable photoelectrochemical biosensing platform provides a convenient and cost-effective method for biofluid analysis, which has an extensive prospect in point-of-care testing (POCT) for mobile health.

A multifunctional electrochemiluminescence and photoelectrochemical biosensor based on a quantum dot ion-exchange reaction for two-channel detection of thrombin.

Herein, a multifunctional electrochemiluminescence (ECL) and photoelectrochemical (PEC) biosensor based on exchange of Ag+ with CdTe QDs was developed for dual-mode detection of thrombin. First, CdTe QDs assembled on an electrode displayed superior ECL and PEC signals. At the same time, C-rich hairpin (HP) DNA linked to silicon spheres loaded a large amount of Ag+, and the specific binding of thrombin to an aptamer led to the release of DNA P; then, DNA P interacted with HP DNA to produce numerous Ag+ ions by an enzyme-digestion amplification reaction. Ag+ underwent ion exchange with CdTe QDs to generate AgTe/CdTe QDs, resulting in much reversed PEC and changed ECL signals for dual-mode detection of thrombin. This work takes advantage of outstanding multi-signals of QDs coupled with convenient ion exchange to achieve multi-mode detection of the target, avoiding false positive or false negative signals generated in the traditional detection process, and thus can be used for the rapid detection of various biomolecules in actual samples.

A halide perovskite/lead sulfide heterostructure with enhanced photoelectrochemical performance for the sensing of alkaline phosphatase (ALP).

For the construction of halide perovskite-based photoelectrochemical (PEC) biosensors in aqueous solution, the balance between retaining the excellent photoelectric performances of the halide perovskite and the protective modification of the halide perovskite has always been a challenging problem. In this work, a simple and sensitive photoelectrochemical biosensor based on inorganic halide perovskite CsPbBr3 as the photoactive material for the detection of alkaline phosphatase (ALP) was reported. The substrate sodium thiophosphate (Na3SPO3) can be catalyzed by ALP to produce hydrogen sulfide (H2S), which can react with the lead site on the surface of the CsPbBr3 film to form lead sulfide (PbS), resulting in a stable heterostructure and enhanced photocurrent intensity. The possible mechanism of enhanced photocurrent response of CsPbBr3/PbS heterojunctions was studied in detail. This work paves a new way for applying halide perovskites in different biosensor designs.

Synergistic enhancement effect of polydopamine–polyethyleneimine hybrid films for a visible-light photoelectrochemical biosensing interface

• This hybrid film is formed by the oxidative copolymerization of polydopamine and polyethyleneimine. • The enhanced effect of photoelectrochemical is due to the charge transfer ability of polydopamine and the electric attracting ability of polyethyleneimine. • The achieved photoelectrochemical enhancement effect is versatile for both photoanode and photocathode semiconductors. • The sensor has the ability to analyze ascorbic acid in actual samples. Photoelectrochemical (PEC) active interfaces exhibiting visible-light responses and good electron-transfer capabilities are key to the development of PEC biosensors. In this study, bioinspired polydopamine (PDA)–polyethyleneimine (PEI) hybrid films were designed to engineer inorganic semiconductors and construct PEC biosensing interfaces. The charge-transfer capability and visible-light-response property of PDA were combined with the electron-attracting ability of PEI to produce a synergistic PEC-enhancement effect. The achieved PEC-enhancement effect was versatile for photoanode and photocathode semiconductors. Further, the role of PEI doping was revealed via electrochemical investigations. Compared with the PDA sensing platform, the hybrid sensing interface offered by the PDA–PEI film exhibited enhanced analytical performances toward ascorbic acid (AA), achieving a larger detection range and a lower limit of detection.

In situ growth of TiO2/Ti3C2 MXene Schottky heterojunction as a highly sensitive photoelectrochemical biosensor for DNA detection.

In this work, a heterojunction composed of a TiO2 nanosheet and layered Ti3C2 was synthesized by directly growing TiO2 in Ti3C2 MXene. Compared with pure TiO2, TiO2/Ti3C2 composites had increased surface area, and a light absorption range that extended from ultraviolet to visible light, which greatly extended the life of photogenerated carriers. A photoelectrochemical biosensor for DNA detection was constructed based on the TiO2/Ti3C2 heterogeneous structure, which was comprehensively studied based on photocurrent responses. In the absence of the target, the CdSe QDs were close to the surface of the electrode, resulting in enhanced sensitization and increased photocurrent. In the presence of the target, the photocurrent decreases due to the formation of rigid double strands with the probe DNA, which caused the CdSe QDs to be far away from the electrode surface. The sensor had stability and sensitivity for DNA detection in the range of 10 nM-10 fM, and the lower detection limit was 6 fM. Its outstanding characteristics also provided ideas for detecting various other target DNA for early diagnosis of various diseases.

Dual II-scheme nanosheet-like Bi2S3/Bi2O3/Ag2S heterostructures for ultrasensitive PEC aptasensing of aflatoxin B1 coupled with catalytic signal amplification by dendritic nanorod-like Au@Pd@Pt nanozyme

As one of the most toxic chemical substances, aflatoxin B1 (AFB1) has a strong carcinogenic effect even at a trace level in human and animal, which severely threatens human health and even causes cancers. Therefore, ultrasensitive detection of AFB1 is of significant importance. For such analysis, dual II-scheme sheet-like Bi2S3/Bi2O3/Ag2S heterostructures were prepared by the in-situ growth method, which exhibited high separation efficiency for the electron-hole (e−-h+) pairs, prominent stability, and high photoactivity. Moreover, the dendritic nanorod-like Au@Pd@Pt (Au@Pd@Pt DNRs) nanozyme was homely synthesized, whose peroxidase-like activity was scrupulously investigated by catalytical oxidation of diaminobenzidine (DAB) in the presence of H2O2. Integration by the aptasensing strategy, a photoelectrochemical (PEC) “signal-on” aptasensor was prepared, which exhibited a broader linear range of 0.5 pg mL−1–100 ng mL−1 with a lower limit of detection (LOD = 0.09 pg mL−1, S/N = 3). This work provides a feasible strategy to develop advanced PEC biosensors for actual analysis of environmental pollutants.

Photoelectrochemical biosensor based on FTO modified with BiVO4 film and gold nanoparticles for detection of miRNA-25 biomarker and single-base mismatch

MicroRNAs (miRNAs) are of great important as non-invasive biomarkers for early diagnosis of cancer. Based on this, a photoelectrochemical (PEC) biosensor was developed to measure the concentration of microRNA-25 (miR-25), as a lung cancer biomarker. To fabricate the PEC biosensor, a suitable amino modified probe was immobilized on the surface of a florin tin oxide (FTO) electrode modified with bismuth vanadate (BiVO4) film and gold nanoparticles (AuNPs). The fabrication steps of the PEC biosensor were monitored by electrochemical impedance spectroscopy (EIS) and PEC measurements. The results indicate that the combination of BiVO4 film and AuNPs enhances the separation of photogenerated electrons and increase the photocurrent signal. Upon hybridization of the probe immobilized on the biosensor with miR-25, the photocurrent is significantly decreased. This current decrease is attributed to the fact that the hybridization processes blocks the electrode surface by creating a steric hindrance and by decrease the diffusion of AA to the electrode surface, it reduces the AA oxidation and subsequently decreases the capture photogenerated holes. Therefore, the amount of photocurrent decrease is dependent on the miR-25 concentration, and this PEC biosensor can be used to measure miR-25. The developed PEC biosensor shows good sensitivity for the determination of miR-25 in the linear concentration range of 1.0 × 10−14 M to 1.0 × 10−6 M with a detection limit of 3.4 fM, under optimal conditions. Using this biosensor, miR-25 can be detected from a non-complementary and one base mismatch sequence. It is also possible to measure miR-25 in human serum samples with satisfactory results using the PEC biosensor.

Detection of rabies virus via exciton energy transfer between CdTe quantum dots and Au nanoparticles.

Rabies is a fatal encephalitis caused by the rabies virus. The diagnosis of the disease depends in large part on the exposure history of the victim and clinical manifestations of the disease. Rapid rabies diagnosis is an important step in its prevention and control. Therefore, for accurate and timely diagnosis and prevention of rabies, we developed nanomaterials for a novel photoelectrochemical biosensing approach (PBA) for the rapid and reliable diagnosis of rabies virus. This approach uses high-efficiency exciton energy transfer between cadmium telluride quantum dots and Au nanoparticles and is low cost, and easy to miniaturize. By constructing PBA, rabies virus can be detected quickly and with a high degree of sensitivity and specificity; the minimum detection concentration limit for rabies virus is approximately 2.16 ffu/mL of rabies virus particles, or 2.53 × 101 fg/mL of rabies virus RNA. PBA could also detect rabies virus in the brain and lung tissue from rabid dogs and mice with better sensitivity than RT-PCR.

CdS-Modified TiO2 Nanotubes with Heterojunction Structure: A Photoelectrochemical Sensor for Glutathione.

The formation of heterojunction structures can effectively prevent the recombination of photogenerated electron-hole pairs in semiconductors and result in the enhancement of photoelectric properties. Using TiO2 nanotubes (prepared using the hydrothermal-impregnation method) as carriers, CdS-TiO2NTs were fabricated as a photoelectrochemical (PEC) sensor, which can be used under visible light and can exhibit good PEC performance due to the existence of the heterojunction structure. The experimental results show that the prepared CdS-TiO2NTs electrode had a linear response to 2-16 mM glutathione (GSH). The sensor's sensitivity and detection limit (LOD) were 102.9 µA·mM-1 cm-2 and 27.7 µM, respectively. Moreover, the biosensor had good stability, indicating the potential application of this kind of heterojunction PEC biosensor.

ZnO/Cu2O heterojunction integrated fiber-optic biosensor for remote detection of cysteine

Indium tin oxide, semiconductor nanomaterial ZnO, and Cu2O were first loaded on the surface of the optical fiber to form an optical fiber probe. Large-volume macroscopic spatial light is replaced by an optical fiber path, and remote light injection is implemented. Based on the optical fiber probe, a photoelectrochemical biosensor was constructed and remote detection of cysteine was realized. In this tiny device, the optical fiber probe not only acts as a working electrode to react with the analyte but also directs the light exactly where it is needed. Simultaneously, the electrochemical behavior of cysteine on the surface of the working electrode is dominated by diffusion-control, which provides strong support for quantitative detection. Then, under the bias potential of 0 V, the linear range of the fiber-optic-based cysteine biosensor was 0.01∼1 μM, the regression coefficient (R2) value was 0.9943. In spiked synthetic urine, the detection of cysteine was also realized by the integrated biosensor. Moreover, benefiting from the low optical fiber loss, the new structure also possesses a unique remote detection function. This work confirms that photoelectrochemical biosensors can be integrated via optical fibers and retain comparable sensing performance. Based on this property, different materials can also be loaded on the surface of the optical fiber for remote detection of other analytes. It is expected to facilitate the research on fiber-optic-based integrated biosensors and show application prospects in diverse fields such as biochemical analysis and disease diagnosis.

Antibody-free photoelectrochemical strategy for simultaneous detection of methylated RNA, METTL3/METTL14 protein and MazF protein based on enhanced photoactivity of MoSe2–BiOI nanocomposite

Taking advantages of the catalytic activity of METTL3/METTL14 protein towards adenine methylation in RNA sequence and the specific digestion activity of MazF protein towards unmethylated RNA sequence containing ACA bases, a novel photoelectrochemical biosensor was constructed for simultaneous detection of RNA methylation, METTL3/METTL14 protein and MazF protein. MoSe2–BiOI nanocomposite was prepared and considered as photoactive material, catalytic hairpin assembly strategy and in situ generation of electron donors catalyzed by polyaspartic acid-loaded alkaline phosphatase technique were employed as signal amplification. Under the optimum conditions, the detection ranges of methylated RNA, METTL3/METTL14 protein and MazF protein were 0.001–50 nM, 0.001–25 ng/μL, and 0.001–10 U/mL, respectively. The corresponding detection limits were 0.46 pM, 0.51 pg/μL and 0.42 U/μL with S/N = 3. In addition, the effect of drugs and composite pollutants on the activities of MazF proteins was assessed, proving the applicability of the developed method in the field of drug screening for MazF-related diseases. Moreover, the effects of pollutants on the activity of METTL3/METTL14 were also preliminarily explored, providing new information on pathogenic mechanism of pollutants.

Photoelectrochemical biosensor based on DNA aptamers and dual nano-semiconductor heterojunctions for accurate and selective sensing of chloramphenicol.

Nanosheets of anatase TiO2 and CdS quantum dots modified with thioglycolic acid (TGA-CdS QDs) were prepared and hierarchically modified on the indium tin oxides (ITO) electrodes. The heterojunction structure is formed to improve the light capture ability and carrier migration, significantly enhancing the sensitivity of photoelectrochemical (PEC) biosensors. Specific DNA sequences labeled with TGA-CdS QDs were placed on the electrodes to prepare a biosensor for the detection of chloramphenicol with ultrahigh selectivity. In addition, the heterojunction structure and the principle of photocurrent signal amplification on the electrode are described in detail. Under the optimal conditions, the photoelectrochemical biosensors showed good reproducibility and stability for chloramphenicol with a linear response in the range 10-10,000pM and a limit of detection (LOD) of 0.23pM. Due to the specific recognition of base pairs, the sensor has excellent anti-interference ability in practical applications. An effective method was developed for the accurate detection of antibiotics with far reaching prospects.

Schottky-functionalized Z-scheme heterojunction: Improved photoelectric conversion efficiency and immunosensing

Designing photovoltaic materials with good photoelectric activity is the crucial to boost the sensitivity of photoelectrochemical (PEC) biosensors. To meet this concern, a Schottky-functionalized direct Z-scheme heterojunction photovoltaic material was proposed by electrodeposition of gold nanoparticles on two kinds of bismuth oxyhalide composites surface (bismuth oxybromide and bismuth oxyiodide with different but matched band gaps) (depAu/BiOI/BiOBr). Specifically, synergistic effect was achieved through the direct Z-scheme heterojunction formed by BiOBr and BiOI as well as the gold Schottky junction, resulting in the enhanced light harvest and photoelectric conversion efficiency. Meanwhile, combined with sandwich immunotechnology, a “signal-off” PEC biosensor was fabricated for highly sensitive detection of carcinoembryonic antigen (CEA). In which, using depAu/BiOI/BiOBr modified glassy carbon electrodes both as the photoactive sensing interface and capture antibody loading matrix, polyethyleneimine copper complex encapsulated gold nanoclusters labeled detection antibody (Ab2-Au@PEI-Cu) as the quencher, the photocurrent decreased with the increasing target CEA introduced by sandwich immune reaction. The proposed smart PEC immunoassay platform exhibited a wide detection range (1.0 fg/mL-2.0 ng/mL) and a detection limit as low as 0.11 fg/mL with favorable selectivity and stability. In addition, this PEC sensing strategy can be easily extended for other tumor marker analysis, which offers a new perspective of using multiple bismuth oxyhalide as photoactive materials for early diseases diagnosis.

Ion-Exchange Reaction-Mediated Hierarchical Dual Z-Scheme Heterojunction for Split-Type Photoelectrochemical Immunoassays.

Photoelectrochemical (PEC) immunoassays with ultrasensitive detection abilities are highly desirable for in vitro PEC diagnosis and biological detection. In this paper, dual Z-scheme PEC immunoassays with hierarchical nanostructures (TiO2@NH2-MIL-125@CdS) are synthesized through epitaxial growth of MOF-on-MOF and further in situ derivatization. The dual Z-scheme configuration not only extends the light absorption range but also increases the redox ability due to the interface structure nanoengineering, which synergistically suppresses bulk carrier recombination and promotes the charge transfer efficiency at the electron level. Furthermore, a smart MOF-derived labeling probe (CuO@ZnO nanocube) is designed to develop a split-type PEC biosensor by using prostate-specific antigen (PSA) as a target biomarker. In the presence of PSA, the Ab2-labeled CuO@ZnO would specifically bond to the dual Z-scheme electrode. Then, the MOF-derived CuO@ZnO is dissolved by hydrochloric acid to release Cu2+, which could replace Cd2+ via an ion-exchange reaction, thus leading to the decrease of the photocurrent due to the destruction of the dual Z-scheme configuration. In typical applications, the split-type PEC immunoassay exhibits an excellent detection performance for PSA with a LOD as low as 0.025 pg·mL-1.

Ultrasensitive photoelectrochemical biosensor for DNA 5-methylcytosine analysis based on co-sensitization strategy combined with bridged DNA nanoprobe

Altered DNA methylation in the form of 5-methylcytosine (5-mC) patterns is correlated with disease diagnosis, prognosis, and treatment response. Therefore, accurate analysis of 5-mC is of great significance for the diagnosis of diseases. Here, an efficient enhanced photoelectrochemical (PEC) biosensor was designed for the quantitative analysis of DNA 5-mC based on a cascaded energy level aligned co-sensitization strategy coupling with the bridged DNA nanoprobe (BDN). Firstly, Au nanoparticle/graphite phase carbon nitride/titanium dioxide (AuNPs/g-C3N4@TiO2) nanocomposite was synthesized through in situ growth of AuNPs on g-C3N4@TiO2 surface as a matrix to provide a stable background signal. Next, BDN with a high mass transfer rate synthesized from a pair of DNA tetrahedral as nanomechanical handles was used as a capture probe to bind to the target sequence. The polydopamine nanosphere was applied to load with CdTe QDs (PDANS-CdTe QDs) as a photocurrent label of 5-mC antibodies. When the 5-mC existed, a large number of PDANS-Ab-CdTe QDs were introduced to the electrode surface, the formed CdTe QDs/AuNPs/g-C3N4@TiO2 co-sensitive structure could effectively enhance the electron transfer capability and photocurrent response rate due to the effective cascade energy level arrangement, leading to a significantly enhanced photocurrent signal. The proposed PEC biosensor manifested a wide range from 10−17 M to 10−7 M and a detection limit of 2.2 aM. Meanwhile, the excellent performance indicated the practicability of the designed strategy, thus being capable of the clinical diagnosis of 5-mC.

Photoelectrochemical Biosensor for Histone Deacetylase Sirt1 Detection Based on Polyaspartic Acid-Engaged and Triggered Redox Cycling Amplification and Enhanced Photoactivity of BiVO4 by Gold Nanoparticles and SnS2.

A photoelectrochemical (PEC) biosensor was established for histone deacetylase Sirt1 detection based on the polyaspartic acid (PASP)-mediated redox cycling amplification and Sirt1 catalysis deacetylation-triggered recognition of the deacetylated substrate peptide, using PASP as the recognition reagent. After BiVO4 was composited with gold nanoparticles and SnS2, the photoactivity of the composite was greatly enhanced due to the matched energy band structure. Under the catalysis of Sirt1 enzyme, the acetylated substrate peptide was deacetylated to obtain a positive peptide, which was recognized by negative PASP. In addition to the recognition function, PASP also played other triple roles. First, PASP interacted with the positive peptide to form a double-stranded structure, which led to the electrode interface changing from irregular to regular, resulting in an improved PEC response. Second, PASP was involved into redox cycle amplification due to its reduction to dehydroascorbic acid. Further, it was used for repeated preparation of ascorbic acid to provide electron donors. This process enhanced the PEC response. Third, based on the matched energy band with BiVO4, PASP effectively improved the photoactivity of BiVO4. With multiplex signal amplification, the PEC biosensor showed a wide linear range (1.83-1830 pM) and high detection sensitivity with a low detection limit of 0.732 pM (S/N = 3). The applicability of this method was evaluated by studying the effects of a known inhibitor of nicotinamide and the heavy metal ions of Cd2+ and Pb2+ on Sirt1 enzyme activity, and the results showed that this method not only provided a new platform for screening Sirt1 enzyme inhibitors but also provided new biomarkers for evaluating the ecotoxicological effects of environmental pollutants.

Self-Supplied Electron Photoelectrochemical Biosensor with PTB7-Th as a Photoelectric Material and Biotin as an Efficient Quencher.

In this work, a self-supplied electron photoelectrochemical (PEC) biosensor for sensitive determination of Pb2+ was established by utilizing donor-acceptor (D-A)-type PTB7-Th (poly{4,8-bis[5-(2-ethylhexyl) thiophen-2-yl]benzo[1,2-b,4,5-b']dithiophene-2,6-diyl-alt-3-fluoro-2-[(2-ethylhexyl)carbonyl] thieno[3,4-b]-thiophene-4,6-diyl}) as a photoelectric material coupled with biotin as an efficient signal quencher. Impressively, compared with the traditional PEC signal quenchers, biotin was first applied as a PEC signal quencher in this work and it effectively avoided a cumbersome preparation process, complex DNA sequence design, and extra reagent assistance and greatly simplified experimental steps, which could achieve an efficient PEC signal quenching toward PTB7-Th. In addition, the execution of a DNAzyme-assisted Pb2+ recycling amplification reaction could release the quencher biotin, leading to the recovery of the PEC signal, thereby realizing the quantitative detection of Pb2+. Resultantly, the submitted self-supplied electron PEC biosensor presented an extensive coverage of assay Pb2+ (50 fM to 500 nM) along with a low determination limit (16.7 fM), which exhibited the advantages of high selectivity and excellent stability. Importantly, this work provided a powerful alternative to traditional heavy metal-ion assessment methods and possessed the potential for application in environment, biomedicine, and food-safety fields.

Upconversion NaYF4:Yb/Er-TiO2-Ti3C2 Heterostructure-Based Near-Infrared Light-Driven Photoelectrochemical Biosensor for Highly Sensitive and Selective d-Serine Detection.

A near-infrared (NIR) light-driven NaYF4:Yb/Er-TiO2-Ti3C2 (NYF-TiO2-Ti3C2) heterostructure-based photoelectrochemical (PEC) biosensing platform was constructed for highly sensitive d-serine (d-ser) detection. Accurate d-ser detection depends on the model biocatalyst, d-amino acid oxidase (DAAO), which converts d-ser into hydroxypyruvate and an equimolar concentration of hydrogen peroxide (H2O2) via an enzymatic reaction. The TiO2-Ti3C2 semiconductor and NaYF4:Yb/Er optical transducer formed a Schottky junction that provided an irreversible channel for electron transfer. Infrared light was converted into absorbable multiemission light, thereby effectively increasing light absorption. Simultaneously, the generated H2O2 rapidly scavenged photogenerated holes to separate electron-hole pairs, which amplified the photocurrent signal. Under optimal conditions, the NIR light-driven PEC biosensor exhibited an excellent PEC performance for d-ser detection, with a wide linear range of 2-1650 μmol L-1 and detection limit as low as 0.286 μmol L-1. Importantly, high detection reproducibility and accuracy were achieved using this strategy for analyzing human serum and rat cerebrospinal fluid (CSF) specimens. The admirable applicability of the NYF-TiO2-Ti3C2-based PEC biosensor for detecting d-ser may lead to further opportunities for detecting other disease-related biomarkers.

Dual ligand-induced photoelectrochemical sensing by integrating Pt/MoS2 heterostructure and Au polyhedra for sensitive detection of SARS-CoV-2

The continuous evolution of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), with discovery of multiple mutants, has caused widespread panic and concern worldwide. The rapid antigen detection method via a single ligand recognition, although currently implemented in many countries, remains challenging for mutated antigens. Herein, we present a novel strategy using a dual recognition by two types of targeted ligands, based on photoelectrochemical (PEC) sensing for detection of SARS-CoV-2 spike protein. To demonstrate this strategy, the specific antibodies are modified onto the photoactive material with a supported nanostructure, created by loading the Pt nanoparticles onto MoS2 nanosheets (Pt/MoS2) to boost photon-to-electricity conversion efficiency. By subsequent binding of the targeted aptamers to the Au polyhedra, which act as a signal amplifier to suppress PEC photocurrent by competing with the Pt/MoS2 for the absorption of excitation light energy, the dual recognition is successfully achieved. The constructed biosensor not only shows satisfactory stability, high sensitivity, and selectivity, but is effective for test of the pseudovirus of SARS-CoV-2. The work provides useful advance for the development of PEC biosensors for sensitive detection of SARS-CoV-2.

Photoactive conjugated microporous polymer/carbon nanotube coupled with T-junction recycling dual-strand displacement amplification for sensing N-Gene of COVID-19

In this work, a novel conjugated microporous polymer on carbon nanotube composite (CMP-CNTs) was synthesized as photoelectrochemical (PEC) signal probe to construct sensitive PEC biosensor for sensing N-Gene of COVID-19 by integrating with an ingenious target-trigger T-junction recycling dual-strand displacement amplification (T-DSDA). The CMP-CNTs composites has an ideal photoelectrical conversion efficiency owing to the appearance of a good band matching that can effectively promote electron-hole pairs separation and accelerate carrier migration, thereby generating an extremely high initial photocurrent. Meanwhile, the T-DSDA with superior target conversion efficiency to traditional approaches could convert the small number of targets into extensive output DNAs, leading to the in-situ generation of quench agent N-GQDS decorated nanowires on electrode for significantly reducing initial photocurrent. The results demonstrated that proposed PEC biosensor had a high sensitivity towards N-Gene of COVID-19 and the detection limit was 33 aM, which provided a new way to build the simple, sensitive, and reliable sensing platform for great potential in biological analysis and early clinical diagnosis.