Photoelectrochemical Biosensor Research Articles

Single-atom ruthenium nanozyme-induced signal amplification strategy in photoelectrochemical aptasensor for ultrasensitive detection of chloramphenicol

To develop ultrasensitive and rapid antibiotics residue detection method is crucial for ensuring food safety and protecting human health. Herein, a novel photoelectrochemical (PEC) aptasensor integrated with single-atom ruthenium (Ru) nanozyme-mediated catalytic precipitation as a valuable signal amplification strategy, have been established for ultrasensitive chloramphenicol (CAP) detection. Particularly, the exceptional peroxidase-mimicking activity of single-atom Ru nanozyme is responsible for accelerating the oxidation of 4-chloro-1-naphthol (4-CN) to produce insoluble precipitate on the electrode, which in turn causes a notable reduction in the photocurrent. Whereas, when CAP is present, the aptamer is liberated away the electrode because of its potent affinity with CAP, resulting in an elevation of the photocurrent signal, enhancing the detection sensitivity. Importantly, the signal amplification strategy combines the effective photoactive material of Au nanoparticles/CdS quantum dot/TiO2 composites, a PEC aptasensor for determination of CAP with an ultralow detection limit of 4.12 pM is achieved in a self-powered mode with great selectivity and accuracy. This work proposes a novel reasonable approach utilizing high-activity single-atom nanozyme to induce signal amplification strategy for the advancement of single-atom nanozyme in ultrasensitive PEC biosensor, and further creates new avenues for ultrasensitive detection beyond antibiotics residue.

In-situ cation-exchange deposited Ag2S/In4SnS8 of Z-type heterojunction coupled with DNA recycling amplification for photoelectrochemical biosensing

Herein, a novel photoelectrochemical (PEC) biosensor was developed utilizing an in situ cation-exchange method to deposit a high-performance Ag2S/In4SnS8, a Z-type heterojunction with co-shared S atoms, as a signal indicator and using DNA recycling amplification for the sensitive and accurate detection of miRNA-141. The photosensitive Ag2S deposited on the In4SnS8 surface not only facilitated the rapid generation of photoelectrons but also formed a Z-type heterojunction with In4SnS8, effectively inhibiting electron-hole pair recombination. This resulted in a considerable improvement in the photoelectric conversion efficiency of Ag2S/In4SnS8, yielding an ∼ 120-fold increase in photocurrent compared to that of In4SnS8 under 660-nm visible-light irradiation. Furthermore, the arborescent DNA structure formed by hybrid chain reaction (HCR) enhanced the steric effect, thereby reducing the PEC response. Importantly, numerous quenchers MnPP competed for light absorption and captured photogenerated electrons in the valence bands of In4SnS8 and Ag2S, reducing electron transfer to the electrode and further considerably reducing the photocurrent. This enabled the sensitive detection of miRNA-141 across a concentration range from 10 amol·L−1 to 100 pmol·L−1, with a limit of detection as low as 3.3 amol·L−1 (S/N = 3). The proposed biosensor exhibits excellent stability and is expected to be applied for detecting clinically relevant disease markers.

Rapid Assembly of Ultrafine Palladium Nanoparticle-Decorated HOF-101 Triggered by Guest Enzyme Encapsulation.

Rapid enzyme immobilization is essential for enzyme catalysis and sensing applications, yet constructing effective immobilization systems is challenging due to the need to balance enzyme activity with the properties of the surrounding framework. Herein, taking glucose oxidase (GOx) as a model, a rapid and straightforward approach was presented for synthesizing palladium nanoparticles (PdNPs)-decorated GOx encapsulated in HOF-101 nanocomposite materials (designated as PdNPs/GOx@HOF-101) through an in situ photoreduction and enzyme-triggering HOF-101 encapsulation. The enzyme's surface residues trigger the nucleation of HOF-101 around it through the hydrogen-bonded bio interface, completing the self-assembly of HOF-101 in 0.5 h. Furthermore, the biocomposites loaded with ultrafine PdNPs show satisfactory photoelectrochemical (PEC) properties. As a proof-of-concept, a PEC biosensor was constructed by utilizing PdNPs/GOx@HOF-101 as a photoactive probe, which can quickly and sensitively detect glucose and simultaneously remain stable within the circumstance of 30-60 °C and pH 4-8. These attributes pave the way for diverse applications, including improved enzyme immobilization techniques, advanced biosensors, and more efficient biocatalytic processes.

Spring Expanding-like Polarity Reversal in Photoelectrochemical Biosensing.

Although polarity-reversal photoelectrochemical (PEC) analysis can effectively eliminate false-positive and negative signals caused by interferents, achieving high sensitivity and accuracy is still a challenge. Hence, a spring expanding-like polarity reversal strategy with bipolar signal synergistic amplification is first proposed to help build a high-performance PEC analysis system. In this study, l-cysteine (l-cys) is discovered to not only act as a polarity regulator to elaborately reverse photocurrent via its covalent bond to Cu and Bi but also provide a relatively stable electron donor to effectively consume the photogenerated holes compared with commonly used H2O2 and ascorbic acid. More importantly, the amino and electron-rich functional acridine groups in the dye acriflavine endow an electrochemical activity to accelerate electron transfer between the electrode and solution, thus enabling bipolar synergistic signal amplification for acquiring an extremely enlarged photocurrent variation that is of great significance to overcome the rigorous signal prereversal depression and reversal amplification in traditional polarity-reversal systems. Accordingly, the PEC biosensor with the proposed spring expanding-like polarity reversal strategy exhibits excellent sensitivity and accuracy, reflecting ultralow detection limits of 0.04 fM toward lead ions (Pb2+) and good anti-interference ability in the detection of natural water samples. This work provides an avenue for exploring a new polarity reversal strategy for accomplishing high-performance PEC bioanalysis, expected to be widely applied in environmental monitoring, clinical diagnosis, and food supervision.

CRISPR/Cas12a-Sheared ZIF-Based Heterojunction to Allow Polarity-Switchable Photoelectrochemical and Nanozyme-Enabled Colorimetric Dual-Modal Biosensing.

Modulating the migration of interfacial carriers in heterojunctions is critical for driving the signal response of high-performance optical biosensors. In this study, a polarity-switchable photoelectrochemical (PEC) and nanozyme-enabled colorimetric dual-modal biosensor is designed to modulate the interfacial carrier migration of the zeolitic imidazolate framework (ZIF)-based heterojunction by exploiting stem-loop DNA and the CRISPR/Cas12a system. Specifically, ZIF-hemin (ZIF-Hemin) is assembled at the CdSe/NH2-rGO interface via stem-loop DNA to form a ZIF-based heterojunction. Stem-loop DNA with a reinforcing rib effect enhances binding and accelerates the interfacial carrier migration of the heterojunction. In the presence of the target Cry1Ab, the CRISPR/Cas12a system is activated to shear the ZIF-based heterojunction, resulting in the disintegration of the heterojunction and the disappearance of interfacial carrier migration. At this point, ZIF-Hemin is released from the CdSe/NH2-rGO interface, with the photocurrent switching from the anode to the cathode. Meanwhile, due to its rich accessible active sites, the released ZIF-Hemin nanosheet shows high peroxidase-like catalytic activity and generates colorimetric signals. The dual-modal biosensor demonstrates excellent performance in selectivity and sensitivity, with low detection limits of 0.05 pg mL-1 (PEC) and 0.4 pg mL-1 (colorimetric). This work provides a general strategy to improve the performance of optical biosensors by modulating the migration of interfacial carriers in heterojunctions.

Atomically dispersed recognition unit for selective in vivo photoelectrochemical medicine detection

Continuous and long-term therapeutic monitoring of medicine molecules in biological systems will revolutionize healthcare by offering personalized pharmacokinetic reports. However, the extremely complex biological environment brings great challenges for in vivo molecule detection in living organisms. Here we introduce an in vivo photoelectrochemical biosensor following a reverse design strategy with single atoms as molecular recognition units. Atomic dispersion of Cu single atoms on TiO2-x substrate create synergistic anchoring triple-site for efficiently and selectively capturing of dual-carbonyl group and neighboring dual-hydroxyl group of tetracycline molecules. The photoelectrode is encapsulated with antibiofouling layer and implanted into the vein of living mouse to enable long-term in vivo monitoring of tetracycline in real biological environments. It is important to note that our approach was exclusively tested in male mice, and therefore, the findings may not be generalizable to female mice or other species without further research. The rationally designed biological-components-free in vivo biosensor with excellent selectivity, robustness, and stability endows possibility for enabling personalized medicine guidance through real-time feedbacking information and providing direct and authentic medicine molecular analysis.

Cerium-Modulated Zinc Oxide for enhanced Photoelectrochemical Non-Enzymatic biosensing of Cholesterol: An experimental and First Principle Analysis

Herein, we synthesized CexZn1-xO (x = 0.00, 0.01, 0.02, and 0.03) using the wet chemical method. The investigation explores photoelectrochemical (PEC) biosensors for enzyme-free detection of cholesterol, employing Ce0.03Zn0.97O (CZO3)/Nickel Foam (NF) as the active material. The investigation revealed notable enhancements in sensitivity for cholesterol detection, with a recorded activity of 2.812 mA.mM−1.cm−2, marking a twofold increase in comparison to dark mode (1.37 mA.mM−1.cm−2). The Limit of Detection (LOD) was determined to be 17 µM (light) and 28 µM (dark), while the Limit of Quantification (LOQ) was measured at 54 µM (light) and 98 µM (dark) in 0.1 M KOH solution. These findings demonstrate a linear detection range spanning from 80 µM to 2 mM. Ab-initio calculations based on Density Functional Theory (DFT) were carried out on 101 surfaces of both pristine ZnO and CZO3 to understand how the doping affected the pristine ZnO band gap. The findings indicate that CZO3 exhibits superior activity compared to pristine ZnO, underscoring its enhanced performance and potential for sensing application. The CZO3/NF photoelectrochemical (PEC) biosensor displayed notable cyclic stability, retaining 97 % of its performance over a 60-day period. This underscores its potential for reliable and enduring operation in biosensing applications. Additionally, CZO3/NF exhibited robust sensing capabilities when utilized with human serum samples, showcasing consistent performance in both dark and illuminated conditions.

Dual-Responsive MnO2-Loaded Carbonaceous Nanobottle Motors Fabricated by Interfacial Superassembly for On-The-Fly MicroRNA Sensing.

Diverse nanomotors with advanced motion manipulation have been proposed to revolutionize the way problems in many fields are solved. However, rational and controllable synthetic methods of multifunctional nanomotor are still limited. Herein, dual-responsive MnO2-loaded carbonaceous nanobottle motors (MnO2 NBMs) are developed through an interfacial superassembly strategy. Asymmetric carbonaceous nanobottles are first synthesized, and the reductive carbonaceous shell induces an oxidation-reduction reaction with KMnO4 for in-situ growth of MnO2 nanosheets, which enables the nanomotor to perform either self-diffusiophoretic or self-thermophoretic motion in response to H2O2 and near-infrared light, respectively. Inspired by bioaffinity sensing, the nanomotors are sequentially assembled with functional nanoparticles and hairpin DNA to construct swimming functional MnO2 NBMs (MnO2 FNBMs) probes. The probes can move around complex samples to improve target miRNA transport and accelerate receptor-target interaction. Coupling with the photocurrent-signal amplification, the self-assembly of photoelectrochemical (PEC) biosensors has been achieved for sensitive microRNA detection. Trace amounts of miRNA-155 can be quickly detected with a wide detection range (100 fM to 100nM). Moreover, the direct detection of microRNA in tumor cell lysates by the biosensor is demonstrated. Given the merits of automation and miniaturization, the proposed strategy provides a promising method for fast and effective self-assembly of biosensors.

Cu2O-Mediated Heterojunction Conversion from Dual Type II to Dual Z-Scheme: Its Application in Photoelectric-Colorimetric Dual-Mode Detection of Fat Mass and Obesity-Associated (FTO) Protein.

Although the construction of heterojunction has been used in photoelectrochemical (PEC) biosensors, their potential for tunable optical properties has not been deeply explored. Based on the fact that a type-II heterojunction and Z-scheme heterojunction have the same energy band structure, effective alteration of the electron transfer pathway has been achieved by introducing unique photoactive materials into the system and exploiting the interactions between the photomaterials. Based on this, we reported a novel polarity-switchable dual-mode sensor for fat mass and obesity-associated (FTO) protein analysis. Specifically, the MgIn2S4/Bi2MoO6/Bi2S3 dual type-II heterojunction was used as the sensing interface in concert with the rolling circle amplification, CRISPR/Cas12, and terminal DNA transfer enzyme multiamplification strategies, and finally, Cu2O was captured at the sensing interface. Due to the matched energy band, the introduction of Cu2O effectively changed the electron transfer pathway and realized the conversion from a dual type-II heterojunction to a dual Z-scheme heterojunction. It caused the switch of the photocurrent from the anode to the cathode. The developed PEC method showed high sensitivity and selectivity for FTO protein detection in the range of 0.0005-500 μg/L. In addition, based on the peroxidase-like activity of Cu2O to catalyze the oxidation of 3,3',5,5'-tetramethylbenzidine by H2O2, the electrode system also achieved the colorimetric detection of FTO protein using the naked eye with the change of the color of the detection solution from colorless to blue. The detection range was from 0.05 to 500 μg/L. This work developed a photoelectrochemical-colorimetric biosensing platform with consciously designed semiconductor structures, revealing the potential of semiconductor-structured transformations in future sensing fields.

A Photoelectrochemical Biosensor Mediated by CRISPR/Cas13a for Direct and Specific Detection of MiRNA-21.

Direct detection of miRNA is currently limited by the complex amplification and reverse transcription processes of existing methods, leading to low sensitivity and high operational demands. Herein, we developed a CRISPR/Cas13a-mediated photoelectrochemical (PEC) biosensing platform for direct and sensitive detection of miRNA-21. The direct and specific recognition of target miRNA-21 by crRNA-21 eliminates the need for pre-amplification and reverse transcription of miRNA-21, thereby preventing signal distortion and enhancing the sensitivity and precision of target detection. When crRNA-21 binds to miRNA-21, it activates the trans-cleavage activity of CRISPR/Cas13a, leading to the non-specific cleavage of biotin-modified DNA with uracil bases (biotin-rU-DNA). This cleavage prevents the biotin-rU-DNA from being immobilized on the electrode surface. As a result, streptavidin cannot attach to the electrode via specific biotin binding, reducing spatial resistance and causing a positively correlated increase in the photocurrent response. This Cas-PEC biosensor has good analytical capabilities, linear responses between 10 fM and 10 nM, a minimum detection limit of 9 fM, and an excellent recovery rate in the analysis of real human serum samples. This work presented an innovative solution for detecting other biomarkers in bioanalysis and clinical diagnostics.

Fluorescent and polarity-switchable photoelectrochemical dual-mode homogeneous sensing platform for ultrasensitive kanamycin detection based on EXO III-driven signal amplification.

Afluorescent and photoelectrochemical (PEC) dual-mode biosensor based on target biorecognition-triggered cyclic amplification was constructed for Kana detection. With the assistance of the catalyzed reaction of exonuclease III, a Kana-aptamer DNA duplex was designed for conducting the cyclic release of G-rich DNA sequence as well as output DNA S2. The released G-rich sequence triggers the fluorescence (FL) of thioflavin T (ThT), the intensity of which is positively correlated with the Kana concentration. The linear range is 0.2 to 30nM, and the detection limit reaches 0.07nM. Simultaneously, the released output DNA S2 was captured by Fe3O4@CdTe-probe ssDNA and then combined with methylene blue to realize the transduction of polarity-reversed PEC signal, leading to the sensitive detection of Kana with a linear range of 0.2 to 40nM and a calculated detection limit of 0.2nM. The outstanding performance endows the dual-mode biosensor a promising prospect for practical application.

Ultrasensitive miRNA-let-7a detection based on AgInS2 quantum dots co-sensitization and CRISPR/Cas12a induced strand displacement reaction for signal amplification

The evolution of breast cancer is usually accompanied by abnormal expression of miRNA-let-7a. Sensitive gauging of miRNA-let-7a is crucial for breast cancer monitoring and prognosis. Herein, a novel photoelectrochemical (PEC) biosensor was served as miRNA-let-7a detection on the basis of the coupling of co-sensitization and CRISPR/Cas12a-mediated strand displacement amplification (SDA). In short, AgInS2 quantum dots (QDs), characterized by a wide visible light absorption range and a stable photocurrent response, have an obvious sensitizing effect on TiO2/Bi2MoO6. Under the condition of without miRNA-let-7a, the AgInS2 fixed DNA probe was located near the surface of the TiO2/Bi2MoO6 electrode, forming a co-sensitive structure. During the detection process, hairpin DNA2 (HP2) specifically recognized miRNA-let-7a through base complementary pairing, triggering the SDA reaction to convert massive double-stranded DNA (dsDNA). The dsDNA product then triggered CRISPR/Cas12a lateral cleavage activity, causing AgInS2-sensitized DNA to leave the electrode surface and the co-sensitization effect to disappear, further reducing the photocurrent. Using a dual effect for signal amplification, the biosensor platform had linear detection capability within the scope of 0.01–10 nM, and the detection limit was 3.35 pM. The biosensor which was fabricated effectively provided an excellent platform for the effective monitoring of various tumor biomarkers in clinical detection.

Near-infrared light induced cathodic photoelectrochemical biosensor for duplex-specific nuclease mediated detection of miRNA166-a

The photoelectrochemical (PEC) biosensor is a new sensing platform which has the merits of low background signal, low cost, easy miniaturization and so on. However, at present, most PEC biosensors utilize visible light or ultraviolet light as the excitation light source. This type of light has high energy and may cause some light damage to the detected object and some photoelectric materials, thus limiting its application scope. Herein, based on NaYF4:Yb,Tm/BiOBr0.8I0.2 a cathode PEC biosensor that can be excited by near-infrared light was constructed to avoid the occurrence of anode false positives and light damage. Through two cycles of the miRNA cycle assisted by Duplex-Specific Nuclease (DSN) and the dissolved oxygen cycle assisted by gold nanoparticles during the detection process, the detection signal was amplified and miRNA166-a was sensitively detected. By using up-conversion materials, the near-infrared light of 980 nm can be converted into ultraviolet light and visible light, thus exciting the photogenerated carriers of BiOBr0.8I0.2. The photocurrent reaction shows a positive correlation with the quantity of gold nanoparticles present on the electrode surface, which are derived from the reporter molecules produced by the hybridization of miRNA166-a and H1. It has a good linear relationship and selectivity towards miRNA166-a, and the detection limit is 0.32 fM. This sensing method provides a cathode PEC biosensor, which can be excited by near-infrared light. The overall light damage of the system is low, and the possibility of false positive of anode PEC biosensor can be avoided, which has certain significance.

Recent advances in foodborne pathogen detection using photoelectrochemical biosensors: from photoactive material to sensing strategy

Rapid assessment and prevention of diseases caused by foodborne pathogens is one of the existing food safety regulatory issues faced by various countries, and it has received wide attention from all sectors of society. When the content of foodborne pathogens in food is higher than the limit standard and spreads in a certain way, it can cause disease outbreaks, which seriously threaten human health or life safety. Developing a novel method to detect foodborne pathogens accurately and rapidly is significant. Because of the limitations of complex steps, time-consuming, low sensitivity or poor selectivity of commonly used methods, a photoelectrochemical (PEC) biosensor based on electrochemistry is developed. Its advantages include a low background signal, fast response and simple operation. It also has broad application prospects for sensing, which has attracted wide attention. However, an organized summary of the latest PEC biosensors for foodborne pathogen sensing has not been reported. Therefore, this review introduces the recent advances in foodborne pathogen detection using PEC biosensors as follows: (i) the construction of PEC biosensors, (ii) the research status of PEC biosensors for the detection of foodborne pathogens and (iii) the direction of future development in this field. Hopefully, the study will provide some insight into developing more mature bio-sensing strategies to meet the practical needs of foodborne pathogen surveillance.

Versatile Bovine Serum Albumin as Ingenious Electron Operator-Enhanced Photoelectrochemical Biosensing for Ultrasensitive Detection of miRNA.

Bovine serum albumin (BSA) has been widely used in biosensors as a blocking agent. Herein, conformist BSA was first exploited as an ingenious operator to enhance the photocurrent response of (2Z,2'Z)-2,2'-(1,4-phenylene)bis(3-(4-(bis(4-methoxyphenyl)amino)phenyl)acrylonitrile) (TPDCN)-based photoelectrochemical (PEC) platform via manipulating the electron transfer process of the detection system. Concretely, the presence of target molecules triggered catalytic hairpin assembly reaction and subsequently powered terminal deoxynucleotidyl transferase-mediated signal amplification to produce the AgNP@BSA-DNA dendrimer nanostructure. After being treated with HNO3, a large amount of BSA could be released from the dendrimer nanostructure. When they were transferred to the TPDCN-based PEC platform, the photocurrent response of the biosensor was largely enhanced because BSA can manipulate the electrons of TPDCN via a well-matched energy level to form a new electron transfer track. Meanwhile, tryptophan (Trp) in BSA could be oxidized to quinone Trp-O under photoirradiation, which can facilitate the oxidation of ascorbate and generate more H+ to promote the migration of photogenerated electrons. As a result, the proposed PEC biosensor exhibits excellent analytical performance for detection of miRNA-21 (as a model target) over a wide linear range of 0.01 to 10,000 pM with detection limit as low as 4.7 fM. Overall, this strategy provides a new perspective on constructing efficient PEC biosensors, which expands the potential applications in bioanalysis and clinical diagnosis.

A sandwich-type photoelectrochemical biosensor based on anthocyanin-sensitized ZnO/P5FIn heterojunction for the sensitive detection of CYFRA21-1.

. A sandwich-type photoelectrochemical (PEC) immunosensor based on a ZnO/poly(5-formylindole) (P5FIn)/anthocyanin heterostructure was developed to achieve sensitive background-free detection ofthe tumor marker CYFRA21-1. ZnO with good photovoltaic properties is combined with narrow bandgap P5FIn to form a p-n type heterojunction. This structure reduces the electron-hole pair recombination, thereby enhancing the photocurrent response of the composite. Anthocyanidins are environmentally friendly natural compounds with excellent antioxidant, redox properties, and remarkable electrochemical activity. After sensitization by anthocyanins, the absorption and utilization of visible light in the composites are enhanced, further improving the PEC luminescence efficiency of the materials. Additionally, boron nitride quantum dots (BN QDs) are combined with Ab2 via polydopamine (PDA) as a secondary antibody marker, enhancing its sensitivity. The biosensor exhibited a linear detection range of 0.001-100ngmL-1 with a limit of detection (LOD) of 0.00033ngmL-1. Furthermore, this biosensor demonstrates excellent selectivity, reproducibility, and stability, as well as successful results in analyzingactual human serum samples. This approach provides a feasible method for tumor marker detection.

A Photoelectrochemical Biosensor Based on a Composite Structure of Au Nanoparticles Loaded on NiO/TiO2 Heterojunction for Sensitive Analysis of Cold-Resistant RNA in Winter Wheat

A Photoelectrochemical Biosensor Based on a Composite Structure of Au Nanoparticles Loaded on NiO/TiO₂ Heterojunction for Sensitive Analysis of Cold-Resistant RNA in Winter Wheat

CRISPR-Enhanced Photocurrent Polarity Switching for Dual-lncRNA Detection Combining Deep Learning for Cancer Diagnosis.

Abnormal expression in long noncoding RNAs (lncRNAs) is closely associated with cancers. Herein, a novel CRISPR/Cas13a-enhanced photocurrent-polarity-switching photoelectrochemical (PEC) biosensor was engineered for the joint detection of dual lncRNAs, using deep learning (DL) to assist in cancer diagnosis. After target lncRNA-activated CRISPR/Cas13a cleaves to induce DNAzyme bidirectional walkers with the help of cofactor Mg2+, nitrogen-doped carbon-Cu/Cu2O octahedra are introduced into the biosensor, producing a photocurrent in the opposite direction of CdS quantum dots (QDs). The developed PEC biosensor shows high specificity and sensitivity with limits of detection down to 25.5 aM for lncRNA HOTAIR and 53.1 aM for lncRNA MALAT1. More importantly, this platform for the lncRNA joint assay in whole blood can successfully differentiate cancers from healthy people. Furthermore, the DL model is applied to explore the potential pattern hidden in data of the established technology, and the accuracy of DL cancer diagnosis can acquire 93.3%. Consequently, the developed platform offers a new avenue for lncRNA joint detection and early intelligent diagnosis of cancer.

Self-Assembled Perylene Diimide (PDI) Nanowire Sensitized In2O3@MgIn2S4 S-Scheme Heterojunction as Photoelectrochemical Biosensing Platform for the Detection of CA15-3.

Inorganic/organic heterojunctions show promising applications as high-performance sensing platforms for photoelectrochemical (PEC) immunosensors. This work reports constructing a PEC biosensor for CA15-3 based on a self-assembled perylene diimide (PDI) nanowire sensitized In2O3@MgIn2S4 S-scheme heterojunction platform. P-type semiconductor Cu2O nanoparticles were designed as a signal burst source and were used as immunoassay labels. The carboxyl group on self-assembled PDI nanowires eliminates the step of additional surface functionalization for covalent immobilization of the capture elements. The π-π stacking of PDI enhances electron generation efficiency, while the carboxylic acid groups on PDI promote electron transfer. The performance of the constructed sensor was validated using CA15-3 as a model. The experimental results showed that the sensor based on In2O3@MgIn2S4/PDI has excellent selectivity, stability, and reproducibility, and can sensitively detect CA15-3 in the range of 0.001-100 U·mL-1 with the detection limit of 0.00056 U·mL-1. The sensor has a broad application prospect. It is hoped that this research work based on the unique advantages of the organic compound PDI will inspire other researchers to design light-responsive materials and promote the development of the field of photoelectrochemical sensing.

ZnS/MXene/CdS heterostructure modified electrode for ultrasensitive miRNA-21 assay with signal amplified photoelectrochemical strategy

The early-stage detection of microRNA (miRNA) holds significant value for clinical diagnosis of tumor. In this study, a highly sensitive miRNA detection platform is developed using a photoelectrochemical sensing system based on layer-by-layer (LBL) assembled ZnS/MXene/CdS (ZMC) heterostructure electrode. By incorporating ultrathin and highly conductive MXene, the ZMC electrode exhibits robust photocurrent signals upon exposure to light. The electrode is further modified HS-H1 DNA via disulfide bonds.With the help of auxiliary H2 DNA, a target miRNA-21 triggered catalytic hairpin assembly (CHA) amplification reaction is realized on the electrode surface through complementary base pairing. Then, manganese porphyrin (MnPP) is introduced to the formed double-stranded DNA after CHA reaction to catalyze the conversion of 4-chloro-1-naphthol (4-CN) to benzo-4-chloro-hexanedione (4-CD) precipitate in the presence of hydrogen peroxide, which leads to a significant decrease in photocurrent signals. As a result, the sensor demonstrates a reliable linear correlation in miRNA-21 detection with detection limits as low as 0.36 fM. The recoveries of miRNA-21 in human serum samples ranged from 98.27 % to 101.35 % with RSD values below 3.67 % suggest the reliability and practicality of this method. Therefore it shows great potential for the construction and application of highly sensitive photoelectrochemical biosensors in clinical sample detection.