Photoelectrochemical Biosensor Research Articles

In situ synthesis of Au nanoparticles confined in 2D sheet-like metal organic frameworks to construct competitive PEC biosensor for sensitive analysis of autism spectrum disorder miRNA

Autism spectrum disorders (ASDs) have tremendous medical and social problems in the world, which have attracted accumulated attention on the related microRNAs (miRNAs) detection by photoelectrochemical (PEC) method. Herein, 1,2,4,5-benzenetetramine tetrahydrochloride (BTA) behaved as ideal ligand to chelate with chloroauric (AuCl4-) for forming two-dimensional (2D) sheet-like metal organic frameworks (MOFs) (termed AuCl4--MOFs), followed by in situ formation of gold nanoparticles (Au NPs) embedded in metal organic frameworks (defined as MOFs@Au NPs). The resulted MOFs@Au NPs showed 5.3-time increase in the anode photocurrent over Au NPs alone by using ascorbic acid (AA) as electron donor. Then, the PEC mechanism was strictly studied by electron paramagnetic resonance (EPR) and electrochemistry. Next, a label-free “signal on” model PEC biosensor was constructed based on MOFs@Au NPs as photosensitizer to detect miRNA-23a-3p (related with ASDs), integrated by a competitive reaction associated with magnetic bead (MB) linked double-stranded DNA (dsDNA). The sensor showed a wider linear range of 200 fM ∼ 2.00 nM (R2 = 0.99) and a limit of detection (LOD) down to 78.9 fM. This analytical strategy holds huge potential for blood-based RNA detection in biomedical field.

Ultrasensitive self-driven photoelectrochemical aptasensor for lincomycin detection based on oxygen vacancy-tunable BiOBr nanosheet coupled with dual-function of N-doped Ti3C2 quantum dots

A high-performance self-driven photoelectrochemical (PEC) platform was designed based on 0D N-doped Ti3C2 quantum dots/oxygen vacancies (OVs) engineered 2D BiOBr nanosheets (N-doped Ti3C2 QDs/BiOBr) nanocomposites for sensitive detection of lincomycin (Lin). The synergistic interplay between 0D N-doped Ti3C2 QDs and 2D BiOBr can generate the fascinating interface of chemical/electronic coupling to further boost the PEC activity, including efficient charge transfer, extended the light absorption and increased carrier density. Experimental results demonstrated that the PEC response of the prepared OV-riched N-doped Ti3C2 QDs/BiOBr van der Waals (vdW) heterostructures were 9-folds stronger than that of OV-deficient BiOBr. On the basis of the such excellent PEC performance, an ultrasensitive self-driven PEC aptasensor was developed with the assistance of Lin aptamer. The proposed sensor exhibited a wide linear response (1.0 × 10−14 mol/L ∼ 1.0 × 10−8 mol/L), a low detection limit (3.57 × 10−15 mol/L, S/N = 3), excellent selectivity and good reproducibility, which provided a promising tool to detect Lin in real samples. This work not only offered a versatile protocol for a wide variety of PEC detection, but also paved the way for the development of more efficient PEC biosensor.

A Label-Free Photoelectrochemical Biosensor Based on CRISPR/Cas12a System Responsive Deoxyribonucleic Acid Hydrogel and "Click" Chemistry.

A novel label-free photoelectrochemical (PEC) biosensor is presented in this work. As a barrier, the DNA hydrogel could block the coupling between g-C3N4 and CdS quantum dots (QDs). Therefore, extremely low photocurrent signals were obtained. The presence of target microRNA-21 can initiate the rolling circle amplification (RCA) reaction, which in turn produces many repeated sequences to activate the CRISPR/Cas12a system. The trans-cleavage activity of the CRISPR/Cas12a system led to the degradation of DNA hydrogels efficiently. As a result, the g-C3N4/CdS QDs heterojunction was formed through "click" chemistry. Through the amplification of the RCA and CRISPR/Cas12a system, the sensitivity of the PEC biosensor was improved significantly with the detection limit of 3.2 aM. The proposed sensor also showed excellent selectivity and could be used to detect actual samples. In addition, the modular design could facilitate the detection of different objects. Thus, the proposed CRISPR/Cas12a system responsive DNA hydrogel provides a simple, sensitive, and flexible way for label-free PEC analysis.

Boosting the Photocatalytic Ability of TiO2 Nanosheet Arrays for MicroRNA-155 Photoelectrochemical Biosensing by Titanium Carbide MXene Quantum Dots

The electrodes of two-dimensional (2D) titanium dioxide (TiO2) nanosheet arrays were successfully fabricated for microRNA-155 detection. The (001) highly active crystal face was exposed to catalyze signaling molecules ascorbic acid (AA). Zero-dimensional (0D) titanium carbide quantum dots (Ti3C2Tx QDs) were modified to the electrode as co-catalysts and reduced the recombination rate of the charge carriers. Spectroscopic methods were used to determine the band structure of TiO2 and Ti3C2Tx QDs, showing that a type Ⅱ heterojunction was built between TiO2 and Ti3C2Tx QDs. Benefiting the advantages of materials, the sensing platform achieved excellent detection performance with a wide liner range, from 0.1 pM to 10 nM, and a low limit of detection of 25 fM (S/N = 3).

Ultrathin Covalent Organic Framework Nanosheets/Ti3C2Tx-Based Photoelectrochemical Biosensor for Efficient Detection of Prostate-Specific Antigen.

Designable and ultrathin covalent organic framework nanosheets (CONs) with good photoelectric activity are promising candidates for the construction of photoelectrochemical (PEC) biosensors for the detection of low-abundance biological substrates. However, achieving highly sensitive PEC properties by using emerging covalent organic framework nanosheets (CONs) remains a great challenge due to the polymeric nature and poor photoelectric activity of CONs. Herein, we report for the first time the preparation of novel composites and their PEC sensing properties by electrostatic self-assembly of ultrathin CONs (called TTPA-CONs) with Ti3C2Tx. The prepared TTPA-CONs/Ti3C2Tx composites can be used as photocathodes for PEC detection of prostate-specific antigen (PSA) with high sensitivity, low detection limit, and good stability. This work not only expands the application of CONs but also opens new avenues for the development of efficient PEC sensing platforms.

Development of a three-dimensional graphene-based photoelectrochemical biosensor and its use for monitoring lipase activity

In recent years, photoelectrochemical (PEC) biosensors have shown great application prospects in biological analysis and food detection. In this work, we developed and tested a new PEC biosensor. Three-dimensional graphene oxide (3DGO) was generated and deposited on an indium tin oxides (ITO) electrode. The photoelectrically active poly[Nile blue] (PNb) was formed on this electrode by electropolymerization, and glycerol dehydrogenase (GDH) was immobilised to generate the GDH-PNb-3DGO-ITO biosensor. This newly developed PEC biosensor exhibited excellent photoelectric response to lipase activity under light conditions, with a detection range of 0.1–6 U/mL and a lower detection limit of 0.069 U/mL. When the GDH-PNb-3DGO-ITO sensor was used for PEC detection of lipase activity by the standard addition recovery method, the recovery rate of the standard addition was 98.68–105.41%, and the relative standard deviation (RSD) was 2.1–3.5%, with good storage stability and repeatability. Therefore, this work provides new ideas for the design and preparation of PEC biosensors and introduces a new detection method for monitoring lipase activity.

Photoelectrochemical sensor for detection Hg2+ based on in situ generated MOFs-like structures

Trace analysis of mercury ions (Hg2+) is of great significance to human health and environmental protection. In this work, a novel photoelectrochemical (PEC) biosensor was developed for the ultrasensitive detection of Hg2+ based on the MOFs-like composite/CdS quantum dots (QDs) as photoactive substrate materials. The MOFs-like composite in situ formed by hydrophobically modified alginate (HMA) with europium ion (Eu3+) not only offered a friendly platform for bioconjugation but also resulted in enhancing sensor photocurrent response. Furthermore, the immobilized thymidine-rich probe DNA on the MOFs-like composite surface was bent to produce a T-Hg2+-T structure in the presence of Hg2+, resulting in enlarged steric hindrance on the electrode surface and decreased the proposed biosensor PEC response. This proposed photoelectrochemical sensing system displayed selective detection of Hg2+ with a linear range from 0.1 pM to 1.0 μM with a detection limit of 0.067 pM. The utilization of semiconductor quantum dots as light-harvesting components and the MOFs-like composite as sensitizers broadens the possible design ideas for photoelectrochemical sensing systems.

Photoelectrochemical immunosensor for RNA methylation detection based on the enhanced photoactivity of Bi2S3 nanorods by g-C3N4 nanosheets

As an emerging analytical technology, photoelectrochemical (PEC) biosensor have attracted widespread attentions for detection of various targets. Herein, a simple, sensitive and selective PEC immunosensor was constructed for RNA methylation detection, where g-C3N4/Bi2S3 with improved photoelectric properties was used as the photoactive material, anti-m6A antibody was employed as target recognition molecule, and the target of m6A RNA was also adopted as photocurrent inhibitor. Under optimal experimental conditions, the immunosensor presented wide linear range from 0.1 − 50 nM and low detection limit of 0.025 nM (S/N = 3). The immunosensor also possessed high stability. Considering the growing threat of heavy metal and antibiotic pollution to food security, the applicability of the develop method was assessed by investigating the effect of Pb2+-antibiotics binary pollutants on RNA methylation level in the leaves and roots of rice seedlings.

Biometric Photoelectrochemical-Visual Multimodal Biosensor Based on 3D Hollow HCdS@Au Nanospheres Coupled with Target-Induced Ion Exchange Reaction for Antigen Detection.

Three-dimensional (3D) hollow photoactive nanomaterials can enhance light capture due to the light scattering benefiting from the unique hollow nanostructures, which contributes to the decrease in energy loss and the electron-hole recombination during the process of photoelectric conversion. Herein, a 3D hollow HCdS@Au nanosphere synthesized by the templated-assisted method and photodeposition is employed to construct a multimodal sensing platform by combining the photoelectrochemical (PEC) biosensor with colorimetric analysis and photothermal imaging. In the presence of target carcinoembryonic antigen (CEA), a sandwich structure is formed on magnetic beads based on the dual-aptamer recognition, followed by the initiation of rolling circle amplification (RCA) to bind numerous CuO-DNA probes. Upon stimulation by chlorhydric acidic, a large number of Cu2+ is released from CuO, which could interact with yellow HCdS@Au on electrode to produce dark CuS by ion exchange. As a result, with increased CEA level, the photocurrent is weakened and the color of electrode interface is changed from yellow to dark, which thus facilitates the PEC and colorimetric detection of CEA. Simultaneously, the formed CuS with highly photothermal effect can achieve qualitative visual analysis of CEA using a portable infrared thermal imager. This work exhibits an excellent performance for sensitive and selective detection of CEA in the dynamic working range from 0.015 to 2.4 ng/mL with a detection limit as low as 3.5 pg/mL. Moreover, the proposed PEC biosensor is successfully applied to CEA determination in human serum, which holds great promise in accurate analysis of biomarkers and early diagnosis of diseases in the clinic.

In:Ge/Cu@calcein polyhedral nanostructure conducted photoelectrochemical biosensor for detection of IFN-gamma

A novel photoelectrochemical (PEC) biosensor based on the In:Ge/Cu@calcein polyhedral nanostructure was fabricated for ultrasensitive determination of interferon (IFN)-gamma. The calcein dye could trigger Cu nano-octahedral to transform Cu nano-polyhedral structure and attach orderly to the its surfaces by electrochemical co-deposition, and facilitate photocurrent response dramatically enhancing by five-folds. The In:Ge/Cu@calcein demonstrates excellent PEC performance resulting from the synergistic sensitization of calcein and In:Ge/Cu nanostructure, as well as supplying rich carboxy groups to couple with other biomolecules for simply fabricating biosensor, which has a wide dynamic range (from 50 fg mL −1 to 1 ng mL −1 concentrations of IFN-gamma), and a lower detection limit of 24 fg mL −1 .

Defective Se-doped In2S3 nanomaterial-based photoelectrochemical biosensor for the ultrasensitive detection of chloramphenicol

The sensitive and accurate detection of chloramphenicol is of great significance due to its environmental toxicity, which has received particular attention. Herein, a novel defective Se-doped In2S3 (In2S3-xSex) nanostructure with excellent photoelectrochemical (PEC) performance was designed to fabricate a PEC biosensor for the ultrasensitive detection of chloramphenicol (CAP). Specifically, In2S3-xSex was prepared through a one-step hydrothermal strategy by using Na2SeSO3 as the selenium source. We demonstrated that Se doping improved the separation of photocarriers and the absorption of light, resulting in a markedly enhanced photocurrent compared to that of pristine In2S3. In addition, a target-triggered recycling signal amplification procedure was designed to further develop a PEC biosensor by using In2S3-xSex as a signal indicator and SiO2 as a quencher. The fabricated CAP PEC biosensor showed high sensitivity, with a detection limit of 17 fM in a wide linear range from 50 fM to 10 nM. Importantly, the proposed PEC biosensor exhibited excellent selectivity, stability and reproducibility. This sensor was shown to offer great opportunities for the accurate detection of trace antibiotics and various environmental contaminants by altering the corresponding aptamers.

ZnIn2S4 QDs@TiO2 nanosphere-BiOI double heterojunction combined with unique tripod DNA walker amplification for photoelectrochemical biosensing of microRNA-21

In this study, a new amplified signal probe of ZnIn2S4 quantum dot@TiO2 nanosphere was used to sensitize the BiOI substrate, which was combined with a unique tripod DNA walker to develop a new photoelectrochemical (PEC) biosensor for microRNA-21 (miRNA-21) assay. TiO2 has good PEC activity for its narrow band gap, and a large number of ZnIn2S4 quantum dots (QDs) were attached to the TiO2 to form a good heterojunction, realizing double enhancement of PEC performance. Moreover, a tripod DNA walker for target-cycling amplification was synthesized using a simple catalytic hairpin assembly (CHA). After DNA hairpin 5 (HP5) was linked to the BiOI-modified electrode, the prepared three-legged DNA walker opened HP5 DNA, and formed a single-stranded DNA (ssDNA). Then the ZnIn2S4 QDs@TiO2 signal probe was linked to the electrode by specific hybridization of ssDNA with the tripod walker, realizing noticeable amplification of PEC signal for sensitive detection of miRNA-21. This work combined the excellent PEC characteristic, the amplified signal of ZnIn2S4 QDs@TiO2 heterojunction, and an enzyme-free tripod walker amplification technique to achieve sensitive detection of target, which opens a new PEC analysis method for clinical application.

Tunable Competitive Absorption-Induced Signal-On Photoelectrochemical Immunoassay for Cardiac Troponin I Based on Z-Scheme Metal-Organic Framework Heterojunctions.

Recently emerged Z-scheme heterostructure-based immunoassays have presented new opportunities for photoelectrochemical (PEC) biosensing development. Here, we described a tunable signal-on PEC biosensor for the detection of cardiac troponin I (cTnI), which exploited a competitive absorption effect between Cu(II) ions and a Zr metal-organic framework (Zr-MOF) constructed on TiO2 nanorods (Cu2+@Zr-MOF@TiO2 NRs). Water-stable Zr-MOF was coated onto TiO2 NRs on fluorine-doped tin oxide to form a Z-scheme heterostructure substrate (Zr-MOF@TiO2 NRs), which exhibited a high photoelectric response. Cu2+@Zr-MOF@TiO2 NRs, constructed by loading Cu(II) ions onto the architecture of Zr-MOF by electrostatic interaction, demonstrated a low background signal. After sandwich immunorecognition within a 96-well plate, H2S, generated by confined alkaline phosphatase on zeolitic imidazolate framework-8, was directed to react with Cu(II) ions to form CuS. This resulted in an in situ change in the photoelectrode and an enhanced photoelectric signal. The developed PEC biosensing platform exhibited high sensitivity and selectivity for the cTnI immunoassay with a detection limit of 8.6 pg/mL. The Z-scheme-based competition absorption modulation of photoelectrochemistry provides a new strategy for general PEC biosensing development.

A “signal on” photoelectrochemical biosensor for miRNA-21 detection based on layer-by-layer assembled n-n type Bi2S3@CdIn2S4 heterojunction

MicroRNA (miRNA) is an ideal biomarker, and the sensitive monitoring of low-abundance miRNA is of great significance for the treatment of cancer at the onset stage. Herein, a novel Y-shaped DNA-mediated photoelectrochemical (PEC) sensing platform based on the Bi2S3@CdIn2S4 photoanode is proposed for the detection of miRNA-21. First, an n-n type Bi2S3@CdIn2S4 heterojunction with tight interface is formed for the first time through a layer-by-layer assembly strategy due to the matched band structures of Bi2S3 and CdIn2S4. The photocurrent intensity of Bi2S3@CdIn2S4/GCE electrode is 1.7-fold higher than that of Bi2S3/GCE electrode and 2.5-fold higher than that of CdIn2S4/GCE electrode under visible light irradiation. Additionally, miRNA-21-triggered catalytic hairpin assembly facilitates the formation of Y-shaped DNA structure with CdS quantum dots (CdS QDs). As the photosensitizer of Bi2S3@CdIn2S4 heterojunction, CdS QDs accelerate the separation of electron-hole pairs in the sensing system and realizes photocurrent signal enhancement, thus realizing the “signal on” detection of the miRNA-21. The proposed PEC biosensor exhibits a superior sensitivity of 0.18 fM and the recoveries of human serum range from 98.0% to 104% with a relative standard deviation of 5.8–8.9%. Therefore, the constructed PEC biosensor has potential application value in the early diagnosis and treatment of miRNA-related diseases.

Piezotronic Effect-Assisted Photoelectrochemical Exosomal MicroRNA Monitoring Based on an Electron Donor Self-Supplying Strategy

Exosomal microRNAs (miRNAs) as newly emerging reliable and noninvasive biomarkers have demonstrated a significant function in early cancer diagnosis. Photoelectrochemical (PEC) biosensing has attracted unprecedented attention in exosomal miRNA monitoring due to its inherent advantages of both electrochemical and optical techniques; however, the severe charge carrier recombination greatly restricts the PEC assay performance. Herein, a high-sensitive PEC strategy assisted by the piezoelectric effect is designed based on Bi2WO6/Cu2S heterojunctions and implemented for the monitoring of exosomal miRNAs. The introduction of the piezoelectric effect enables promoted electron-hole transfer and separation, thereby improving the analytical sensitivity. In addition, a target reprogramming metal-organic framework-capped CaO2 (MOF@CaO2) hybrids is prepared, in which MOF@CaO2 being responsive to exosomal miRNAs induces exposure of the capped CaO2 to H2O and then triggers self-supplying of H2O2, which effectively suppresses the electron-hole recombination, giving rise to an amplified photocurrent and a decrease in the cost of the reaction. Benefiting from the coupled sensitization strategy, the as-fabricated PEC strategy exhibits high sensitivity, specificity, low cost, and ease of use for real-time analysis of exosomal miRNAs within the effectiveness linear range of 0.1 fM-1 μM. The present work demonstrates promising external field coupling-enhanced PEC bioassay and offers innovative thoughts for applying this strategy in other fields.

Highly Sensitive Photoelectrochemical Biosensor for MicroRNA-21 Based on a Dumbbell-Shaped Heterostructure AuNRs@end-TiO2 Combined with Carbon Dots as Photosensitizers and Duplex-Specific Nuclease-Assisted Signal Amplification.

TiO2 was grown on both ends of gold nanorods (AuNRs) to form a dumbbell-shaped heterostructure (called AuNRs@end-TiO2) first, and then assembled on the fluorine tin oxide (FTO) electrode surface through hydrophobic interactions to construct a concise photoelectrochemical microRNA-21 (miRNA-21, model target) biosensor using carbon dots (CDs) as photosensitizers. Hairpin probes (HPs) were fixed on the AuNRs@end-TiO2-modified FTO electrode surface through the Au-S bond, and CDs-modified complementary DNA (CDs-cDNA) served as photosensitive probes. In the presence of the target, miRNA hybridized with the HP and triggered double-strand-specific nuclease to cleave the complementary part of the HP with miRNA, and miRNA was released, which can trigger another cycle to realize signal amplification. Many HPs were cleaved and the complementary sequence with cDNA was exposed, which can capture the photosensitive probes to the electrode surface and resulted in photocurrent enhancement. The photocurrent intensity system has a linear relationship with the logarithm of the miRNA concentration in the range of 0.1 fM to 100 pM with a low detection limit of 96 aM (S/N = 3). The biosensor has high sensitivity, good selectivity, and good reproducibility and shows satisfactory results in actual sample detection.

Investigation of the enhanced photoactivity of CdS/Bi2MoO6/MoSe2 and its application in antibody-free enzyme-assisted photoelectrochemical strategy for detection of N6-methyladenosine and FTO protein

N6-methyladenosine (m6A) is the most abundant and dynamic reversible modification of mRNA in eukaryotes discovered in the mid-1970s, which is widely involved in various physiological processes. Fat mass and obesity-associated protein (FTO protein) is not only a demethylase for m6A, but also a carcinogenic factor for many human cancers. Therefore, it is very important to build a simple and sensitive platform for simultaneous detection of m6A and FTO protein. To achieve this aim, a novel photoelectrochemical biosensor was constructed with the antibody-free detection strategy of DTT mediated –SH functionalization of m6A triggered by FTO protein catalyzed m6A oxidation. To achieve high detection sensitivity, CdS/Bi2MoO6/MoSe2 system with matched energy gap was employed as photoactive material. To achieve high detection selectivity, the –CH3 of m6A in the captured RNA sequence (m6A RNA) on the electrode surface was oxidized by FTO protein to form hydroxymethyl, followed with the covalent reaction of DTT with hydroxymethyl, making the labeling of m6A with –SH. Finally, a CdS nanoparticle was modified on the electrode through the specific covalent reaction between –SH and Cd, achieving the improvement of the photocurrent with the matched energy band. Under the optimal experimental conditions, the biosensor showed linear range from 0.001 to 50 nM and 0.0005–500 μg/L with the detection limit of 0.37 pM and 0.034 ng/L (S/N = 3) for m6A RNA and FTO protein, respectively. The applicability of the developed method was assessed by investigating the effect of entacapone on FTO protein activity.

Multicomponent Cu@Cu2O@C hybrid-induced photocurrent polarity switching biosensing strategy for the detection of TK1 mRNA

Thymidine kinase 1 messenger RNA (TK1 mRNA) is an attractive biomarker that plays an important role in the cancer diagnosis and prognostic treatment. Herein, an ultrasensitive and selectivity photoelectrochemical (PEC) biosensor is proposed for TK1 mRNA detection based on the multicomponent Cu@Cu2O@C hybrid-induced photocurrent polarity switching of titanium dioxide nanoparticles (TiO2 NPs). The multicomponent Cu@Cu2O@C hybrid with porous structure and specific surface area is successfully synthesized through the carbonization of copper metal organic frameworks (Cu-MOFs) in a nitrogen atmosphere, followed by the spontaneous oxidation of Cu. Through the TK1 mRNA-mediated chain displacement reaction, the Cu@Cu2O@C hybrid is introduced into the TiO2 NPs-modified electrode surface, resulting in the photocurrent polarity switching from anodic to cathodic photocurrents. Originating from high porosity, specific surface area, multicomponent synergistic effect, and efficient photocurrent-polarity-switching capability of the Cu@Cu2O@C hybrid, the constructed PEC biosensor for TK1 mRNA detection shows a wide linear range (1–5000 fM) with a lower detection limit (0.59 fM), and excellent anti-interference ability. Furthermore, the designed multicomponent Cu@Cu2O@C hybrid serves as an excellent photocurrent polarity switcher for constructing a PEC biosensor, and may have great potential in biological analysis and clinical diagnosis.

Precisely controlled CdS/NiO nanomaterials by atomic layer deposition for excellent photoelectrochemical biosensor

It is an effective strategy to enhance the photoelectrochemical (PEC) performance of nano-semiconductor materials by preventing recombination of the photogenerated carriers. Herein, the precisely regulated CdS/xNiO nano-semiconductor materials are successfully synthesized by a facile atomic layer deposition (ALD) technique (x presents the number of ALD cycles). The experimental results showed that the high carrier recombination rate of CdS could be effectively inhibited after 80 ALD cycles with NiO deposited on its surface. Furthermore, the PEC biosensor targeting glucose was regarded as a model to discuss the application of nano-semiconductor materials precisely regulated by ALD in biosensors. Based on the excellent PEC performance of CdS/80NiO and the high specificity and affinity of glucose oxidase, a simple, fast, sensitive and label-free PEC biosensor for glucose detection was successfully developed. In conclusion, the CdS/80NiO-based biosensor has excellent characteristics such as high sensitivity, low detection limit, good anti-interference and good stability, suggesting that nano-semiconductor materials precisely regulated by ALD is a promising nanomaterial for constructing excellent PEC biosensors in clinical applications.

In2O3/CdIn2S4 heterojunction-based photoelectrochemical immunoassay of carcinoembryonic antigen with enzymatic biocatalytic precipitation for signal amplification

This work reported a split-type photoelectrochemical (PEC) immunoassay for the detection of carcinoembryonic antigen (CEA) based on target-induced biocatalytic precipitation (BCP) by using In2O3/CdIn2S4 heterojunctions as the photosensitizers. The synthesized In2O3/CdIn2S4 heterojunctions improved the efficiency of charge separation and shortened the electron convey path to enhance the photocurrent, thus exhibiting high conductivity and low complexation rates of photogenerated electrons and holes. In the presence of CEA, horseradish peroxidase (HRP) catalyzed 4-chloro-1-naphthol (4-CN) to produce benzo-4-chloro-hexadienone (4-CD) through H2O2. Then, 4-CD was deposited onto the surface of In2O3/CdIn2S4 to reduce the photocurrent and realized the signal amplification. The PEC immunoassay revealed an excellent photocurrent toward target CEA within a wide range of 0.01–50 ng mL−1 at a low limit of detection of 2.8 pg mL−1 under the optimum conditions. Multiple switching light excitation tests demonstrated the good reliability and stability of the fabricated PEC biosensor. The accuracy was acceptable in comparison with human CEA enzyme-linked immunosorbent assay (ELISA) kit.