Nanotechnology-based analytical techniques for the detection of contaminants in aquatic products.

Food safety of aquatic products has attracted considerable attention worldwide. Although a series of conventional bioassays and instrumental methods have been developed for the detection of pathogenic bacteria, heavy metal residues, marine toxins, and biogenic amines during the production and storage of fish, shrimp, crabs et al., the nanotechnology-based analyses still have their advantages and are promising since they are cost-efficient, highly sensitive and selective, easy to conduct, facial design, often require no sophisticated instruments but with excellent detection performance. This review aims to summarize the advances of various biosensing strategies for bacteria, metal ions, and small molecule contaminants in aquatic products during the last five years, The review highlights the development in nanotechnologies applied for biorecognition process, signal transduction and amplification methods in each novel approach, the nuclease-mediated DNA amplification, nanomaterials (noble metal nanoparticle, metal-organic frameworks, carbon dots), lateral flow-based biosensor, surface-enhanced Raman scattering, microfluidic chip, and molecular imprinting technologies were especially emphasized. Moreover, this study provides a view of current accomplishments, challenges, and future development directions of nanotechnology in aquatic product safety evaluation.

The effect of adjacent double-strand DNA on the G-triplex-ThT complex fluorescence intensity enhancement and its application in TNOS and Hg2+ detection.

In this paper, we have found that adjacent double-strand DNA (dsDNA) can enhance the fluorescence intensity of the G-triplex (G31)-thioflavin T (ThT) complex. By connecting the newly formed dsDNA with the G31 sequence, terminator nopaline synthase (TNOS) gene and Hg2+ were detected. The intermolecular duplex hybridization (e.g., TNOS gene and its complementary DNA), or the intramolecular mismatched thymine (T)-Hg2+-T pairs induced the formation of dsDNA with planar morphology, which resulted in the increased binding capacity of adjacent G31 to ThT, as well as the enhanced fluorescence intensity of G31-ThT complex. A versatile 'turn-on' fluorescence scaffold was developed for discriminating transgenic and non-transgenic soybeans and detecting Hg2+ in lake water.

Fluorescence method for kanamycin detection based on the conversion of G-triplex and G-quadruplex.

A versatile fluorescence scaffold was constructed by connecting a G-triplex sequence (G31) with G-rich DNA (aptamer of kanamycin) and using thioflavin T (ThT) as the fluorescent molecule. With the assistance of an aptamer, the G-quadruplex DNA structure was fabricated using G31 as three strands and the aptamer as the fourth strand. Due to the parallel planar morphology of the final products, which was favorable for ThT binding and which restricted the rotation of the aromatic rings of ThT, the fluorescence signal intensity of ThT was significantly enhanced. Because of the specific interaction of aptamer and kanamycin, in addition to the greater ability for kanamycin to bind with G-triplex than ThT, the conformation of G-quadruplex DNA was changed; in addition, ThT was dissociated from the aptamer-G31, and therefore a 'turn-on' to 'turn-off' detection principle was applied for kanamycin detection, which yielded reasonable sensitivity and selectivity. The detection range was 50-2000 nM, with a limit of detection of 1.05 nM. Our proposed method was thus successfully applied for kanamycin determination in pork, chicken, and beef samples, and satisfactory results were obtained.

Amyloid-ß oligomer targeted theranostic probes for in vivo NIR imaging and inhibition of self-aggregation and amyloid-ß induced ROS generation.

To enable the early detection and intervention of Alzheimer's disease (AD), it is highly desirable to develop novel theranostic agents for simultaneous detection of toxic and pathogenic amyloid-ß (Aß) oligomers in vivo and attenuation of Aß-induced toxicity. Herein, we report a new series of oligomeric Aß targeted near infrared (NIR) emissive dibutylnaphthylamine-based cyanine probes for in vivo and ex vivo imaging of Aß in AD mouse model. These new fluorophores exhibited strong solvatochromism and a large bathochromic shift of the emission spectrum upon binding with Aß species, giving rise to advantageous NIR emission. Besides, they showed an intriguingly stronger fluorescence enhancement upon interacting with Aß oligomers and monomers, and binding affinity toward Aß oligomers and monomers than Aß fibrils, suggesting they were selective to Aß oligomers and monomers. In addition to low toxicity, one of the fluorophores, DBAN-SLM, showed remarkably effective inhibitory effect on Aß aggregation, significant neuroprotection effect against the Aß-induced toxicities, and suppression on Aß-induced reactive oxygen species (ROS) generation. Because of excellent blood-brain barrier (BBB) permeability, good biocompatibility and stability, high specificity towards Aß oligomers as well as strong turn-on fluorescence upon Aß binding, DBAN-SLM was successfully applied for in vivo and ex vivo imaging of Aß in AD mouse model, signifying its great promise as a useful theranostic agent for the early diagnosis and therapy of AD. Our results also demonstrated for the first time that the dibutyl-2-naphthylamine moiety is a useful and effective structural building block to promote the targeting capability of oligomeric Aß.

Exonuclease I-assisted fluorescent method for ochratoxin A detection using iron-doped porous carbon, nitrogen-doped graphene quantum dots, and double magnetic separation.

In this paper, a fluorescent method was developed for ochratoxin A (OTA) detection that uses iron-doped porous carbon (MPC) and aptamer-functionalized nitrogen-doped graphene quantum dots (NGQDs-Apt) as probes. In this method, the adsorbance of the NGQDs-Apt on the MPC due to a π-π interaction between the aptamer and the MPC results in the quenching of the fluorescence of the NGQDs-Apt. However, since OTA interacts strongly with the aptamer, the presence of OTA leads to the detachment of the NGQDs-Apt from the MPC, resulting in the resumption of fluorescence from the NGQDs-Apt. When exonuclease I (Exo I) is also added to the solution, this exonuclease specifically digests the aptamer, leading to the release of the OTA back into the solution. This free OTA then interacts with another MPC-NGQDs-Apt system, inducing the release of more NGQDs into the solution, which enhances the fluorescent intensity compared to that of the system with no Exo I. Utilizing this behavior of OTA in the presence of NGQDs-Apt, it was possible to detect concentrations of OTA ranging from 10 to 5000 nM, with a limit of detection of 2.28 nM. Our method was tested by applying it to the detection of OTA in wheat and corn samples. This method has four advantages: (1) the magnetic porous carbon is easy to prepare, its porosity enhances its loading capacity for NGQDs, it highly efficiently quenches the fluorescence of the NGQDs, and its magnetic properties facilitate the separation of the MPC from other species in solution; (2) applying double magnetic separation decreases the background signal; (3) Exo I digests the free aptamer effectively, which allows the resulting free OTA to induce the release of more NGQDs-Apt, ultimately enhancing the fluorescent signal; and (4) the proposed method presented high sensitivity and a wide linear detection range. This method may prove helpful in food safety analysis and new biosensor development (achieved by using different aptamer sequences to that used in the present work). Graphical abstract Exonuclease I (Exo I)-assisted fluorescent method for ochratoxin A (OTA) detection using magnetic porous carbon (MPC), nitrogen-doped graphene quantum dots (NGQDs), and double magnetic separation.

Colorimetric method for glucose detection with enhanced signal intensity using ZnFe2O4-carbon nanotube-glucose oxidase composite material.

In this paper, a composite material comprised of ZnFe2O4 nanomaterial, carbon nanotubes (CNT) and glucose oxidase (GOD) was synthesized and used for glucose detection. ZnFe2O4-CNT was formed by a one-step solvothermal approach using acid-treated CNT as precursor, then GOD was linked to it by coupling reaction between -NH2 and -COOH. After addition of glucose, which is oxidized by GOD, the intermediate product (H2O2) further oxidizes the 3,3',5,5'-tetramethylbenzidine (TMB) substrate and forms a blue product. This process was accelerated in the presence of peroxidase-mimic ZnFe2O4 nanomaterial and the detected signal intensity was correspondingly enhanced. The linear detection range of glucose was 0.8 to 250 µM, with a limit of detection of 0.58 µM. This may originate from (1) the limited diffusion of intermediate species, which resulted in enhanced local concentrations of reaction compounds; (2) enhanced electron transmission among CNT, GOD and ZnFe2O4; (3) the synergistic enhancement of catalytic activity of ZnFe2O4 compared with other metal oxides; (4) the high loading capacity of ZnFe2O4-CNT for GOD molecules, because of its high surface-to-volume ratio. Meanwhile, this method has reasonable selectivity, stability and reusability and can be used for real serum detection, which may be useful for the development of sensitive biosensors.

One-step synthesized flower-like materials used for sensitively detecting amyloid precursor protein.

In this paper, we developed a new method to detect Alzheimer's disease (AD)-related amyloid precursor protein (APP). A composite material containing horseradish peroxidase (HRP), APP antibody, and Cu3(PO4)2 was synthesized as the biosensor by co-precipitation method. In this competitive immunoassay, APP was first conjugated onto the microplate surface with the help of poly-L-lysine as the coating reagent; the composite materials were then attached onto the microplate through the interaction of APP and antibody; the HRP can catalyze the oxidation of 3,3',5,5'-tetramethylbenzidine (TMB) and formed colored species. Therefore, the more APP in the detection solution (free form), the less composite material was combined with the immobilized APP on the microplate, resulting in the production of less colored TMB species. A series of detection parameters were studied, such as the composite material synthesis process, the concentration, and reaction time of different compounds. Our method has higher sensitivity compared with the similar immunoassay without using composite materials (the limits of detection are 0.3 and 3 ng/mL, respectively), and can be used for real samples (human serum) detection. The detection results using our method are consistent with the ELISA results, which is useful for the AD detection. Graphical abstract ᅟ.

Preparation of enzyme-functionalized carbon nanotubes and their application in glucose and Fe2+ detection through "turn on" and "turn off" approaches.

A versatile enzyme-functionalized carbon nanotube (CNT) platform was fabricated by covalently conjugating glucose oxidase (GOD) and/or horseradish peroxidase (HRP) on carboxyl-group-functionalized CNTs. The GOD and HRP co-conjugated CNTs were used for the detection of glucose through the chain reaction between glucose, GOD and HRP. The locally formed H2O2 originating from the oxidization of glucose by GOD is able to further oxidize the 3,3',5,5'-tetramethylbenzidine (TMB) substrate, resulting in the production of colorimetric products. The reaction between H2O2 and Fe2+ can deplete the amount of H2O2 in solution, which in turn decreases the oxidization extent of TMB and decreases the absorbance of the solution in the presence of HRP-conjugated CNTs. The hybrid materials can increase the number of active sites, thus increasing the amount of immobilized enzyme molecules on the surface. Electron transmission between different species is also accelerated and the co-conjugated enzymes can decrease the diffusion of intermediate products, further increasing the local concentrations of reactants. By utilizing these hybrid materials, glucose and Fe2+ were successfully detected. The linear dynamic range of glucose and Fe2+ was 1-100 µM, and the limits of detection for glucose and Fe2+ were 0.3 and 0.22 µM, respectively. The selectivity of glucose and Fe2+ was also studied by adding different kinds of interferents (e.g., sugars, metallic ions and biomolecules), and satisfactory results were obtained. In particular, Fe2+ can be distinguished from Fe3+. Meanwhile, the performance of these biosensors was also validated in biological samples (human serum and human serum albumin) using standard addition methods, and good recoveries were obtained.

Fluorescence method for quickly detecting ochratoxin A in flour and beer using nitrogen doped carbon dots and silver nanoparticles.

In this paper, a FRET (Forster resonance energy transfer) based fluorescence method was developed for the quickly detection of ochratoxin A (OTA) in agricultural products (e.g., flour and beer). A highly fluorescent nitrogen doped carbon dots (CD) were served as energy donor, the DNA and MCH (6-mercapto-1-hexanol) modified Ag nanoparticles were served as energy acceptor in the FRET system. OTA can be detected in a concentration range between 10 and 5000 nM, the limit of detection is 8.7 nM. This method has three advantages: (1) an enhanced fluorescent intensity can be acquired by utilizing the nitrogen doped CD synthesized by one-step approach without sophisticated modification of nanoparticles; (2) OTA detection was accomplished quickly (less than 30 min) by using MCH as assistant molecule; (3) an extended OTA detection linear range was acquired, which may facilitate the OTA detection in real agricultural samples, and is helpful for solving food safety problems.

Resonance light scattering method for detecting kanamycin in milk with enhanced sensitivity.

In this paper, a resonance light scattering (RLS) method was developed for detecting kanamycin with high sensitivity and selectivity. Here, aptamer specific to kanamycin was utilized for recognizing and competitively binding with kanamycin, and gold nanoparticles (GNPs) were used as probes. After adding kanamycin into solutions containing aptamer and GNPs, the GNPs would aggregate in the presence of NaCl, which resulted in the RLS signal intensities enhanced dramatically. Based on this phenomenon, kanamycin can be detected in the range of 10 to 600 nM with a limit of detection as 1 nM, which is more sensitive than many other instrumental methods, especially the commonly used UV-visible spectroscopic method. Furthermore, we demonstrated that this method can be used for detecting kanamycin in milk samples with satisfactory results, which is meaningful for solving food safety problems.

Kanamycin detection based on the catalytic ability enhancement of gold nanoparticles.

In this paper, we demonstrated that kanamycin could enhance the peroxidase-like activity of citrate-capped gold nanoparticles (AuNPs) through two steps: the attachment of kanamycin onto AuNPs through -NH2 (on kanamycin) and -COOH (on AuNPs) interactions; and the specifically interaction between glucoside on kanamycin and AuNPs which changes the surface property of AuNPs, and produced •OH radicals and Au3+ in the solution, and catalyzed the chromogenic reactions between 3, 3', 5, 5'-tetramethylbenzidine (TMB) and H2O2. Based on this principle, a novel method for kanamycin detection has been developed. This method exhibited high sensitivity and selectivity, as low as 0.1nM kanamycin could be detected with a linear range from 0.1nM to 20nM and 20nM to 300nM, respectively. This method was also successfully applied for the detection of kanamycin content in milk and meat samples.

A homogeneous assay for highly sensitive detection of CaMV35S promoter in transgenic soybean by förster resonance energy transfer between nitrogen-doped graphene quantum dots and Ag nanoparticles.

In this work, a novel homogeneous assay for DNA quantitative analysis based on förster resonance energy transfer (FRET) was developed for cauliflwer mosaic virus 35s (CaMV35S) promoter of transgenic soybean detection. The homogenous FRET of fluorescence signal was fabricated by DNA hybridization with probe modified nitrogen-doped graphene quantum dots (NGQDs) and silver nanoparticles (AgNPs), which acted the donor-acceptor pairs for the first time. The highly efficient FRET and unique properties of the NGQDs made the proposed FRET system as a functionalized detection platform for labelling of DNA. Upon the recognition of specific target DNA (tDNA), the FRET between NGQDs and AgNPs was triggered to produce fluorescence quenching, which could be used for tDNA detection. The fabricated homogeneous FRET assay displayed a wide linear range of 0.1-500.0 nM and a low limit of detection 0.03 nM for the detection of CaMV35S (S/N = 3). This proposed biosensor revealed high specificity to detect tDNA, with acceptable intra-assay precision and excellent stability. This method was successfully applied to identify the real sample of 0.5% containing transgenic soybean, which achieved the most of national law regulations. This assay was further validated by polymerase chain reaction as the genetically modified organisms, suggesting that the proposed FRET system is a feasible tool for the further daily genetically modified organism detection.

Aptamer-based Resonance Light Scattering for Sensitive Detection of Acetamiprid.

In this work, an aptasensor-based resonance light-scattering (RLS) method was developed for the sensitive and selective detection of acetamiprid. The ABA (acetamiprid binding aptamer)-stabilized gold nanoparticles (ABA-AuNPs) were used as a probe. Highly specific single-strand DNA (ssDNA, i.e, aptamers) that bind to acetamiprid with high affinity were employed to discriminate other pesticides, such as edifenphos, kanamycin, metribuzin et. al. The sensing approach is based on a specific interaction between acetamiprid and ABA. Aggregation of AuNPs was specifically induced by the desorption of the ABA from the surface of AuNPs, which caused the RLS signal intensity to be enhanced at 700 nm. The alteration of AuNPs' aggregation has been successfully optimized by controlling several conditions. Under the optimal conditions, the RLS intensity changes (I/I0) of AuNPs were linearly correlated with the acetamiprid concentration in the range of 0 - 100 nM. The detection limit is 1.2 nM (3σ). This method had also been used for acetamiprid detection in lake water samples.

Colorimetric aptasensing of ochratoxin A using Au@Fe3O4 nanoparticles as signal indicator and magnetic separator.

Gold nanoparticles (Au NPs) doped Fe3O4 (Au@Fe3O4) NPs have been synthesized by a facile one-step solvothermal method. The peroxidase-like activity of Au@Fe3O4 NPs was effectively enhanced due to the synergistic effect between the Fe3O4 NPs and Au NPs. On this basis, an efficient colorimetric aptasensor has been developed using the intrinsic dual functionality of the Au@Fe3O4 NPs as signal indicator and magnetic separator. Initially, the amino-modified aptamer specific for a typical mycotoxin, ochratoxin A (OTA), was surface confined on the amino-terminated glass beads surafce using glutaraldehyde as a linker. Subsequently, the amino-modified capture DNA (cDNA) was labeled with the amino-functionalized Au@Fe3O4 NPs and the aptasensor was thus fabricated through the hybridization reaction between cDNA and the aptamers. While upon OTA addition, aptamers preferred to form the OTA-aptamer complex and the Au@Fe3O4 NPs linked on the cDNA were released into the bulk solution. Through a simple magnetic separation, the collected Au@Fe3O4 NPs can produce a blue colored solution in the presence of 3,3',5,5'-tetramethylbenzidine and H2O2. When the reaction was terminated by addition of H(+) ions, the blue product could be changed into a yellow one with higher absorption intensity. This colorimetric aptasensor can detect as low as 30 pgmL(-1) OTA with high specificity. To the best of our knowledge, the present colorimetric aptasensor is the first attempt to use the peroxidase-like activity of nanomaterial for OTA detection, which may provide an acttractive path toward routine quality control of food safety.

Studying the relationship between cell cycle and Alzheimer's disease by gold nanoparticle probes.

In this study, a simple gold nanoparticle (GNP)-based colorimetric assay has been developed for studying the relationship between cell cycle and ß-amyloid peptide (Aß, the biomarker of Alzheimer's disease [AD]) expression level. It was found that Aß expression of neuronal cells (e.g., SHG-44 cell line) is strongly dependent on cell cycle phases; that is, the Aß expression level was highest when cells were arrested in the G1/S phase by thymidine and was lowest when they were arrested in the G2/M phase by nocodazole. This finding may improve the understanding of AD pathology and provide a new tool for anti-dementia drug development.

Label-free colorimetric aptasensor for sensitive detection of ochratoxin A utilizing hybridization chain reaction.

The combination of high selectivity of aptamer with the peroxidase-mimicking property of DNAzyme has presented considerable opportunities for designing colorimetric aptasensor for detection of ochratoxin A (OTA). The activities of both aptamer (as biorecognition element) and DNAzyme (as signal amplification element) are blocked via base pairing in the hairpin structure. Hybridization chain reaction (HCR) between two hairpin DNAs was employed to further improve the sensitivity of this method. The presence of OTA triggers the opening of the hairpin structure and the beginning of HCR, which results in the release of many DNAzyme, and generates enhanced colorimetric signals, which is correlated to the amounts of OTA with linear range between 0.01 to 0.32 nM, and the limit of detection is 0.01 nM under optimal conditions. OTA in yellow rice wine and wheat flour samples was also detected using this method. We demonstrate that a new colorimetric method for the detection of OTA has been established, which is simple, easy to conduct, label-free, sensitive, high throughput, and cost-saving.

Magnetic-fluorescent-targeting multifunctional aptasensorfor highly sensitive and one-step rapid detection of ochratoxin A.

A multifunctional aptasensor for highly sensitive and one-step rapid detection of ochratoxin A (OTA), has been developed using aptamer-conjugated magnetic beads (MBs) as the recognition and concentration element and a heavy CdTe quantum dots (QDs) as the label. Initially, the thiolated aptamer was conjugated on the Fe3O4@Au MBs through Au-S covalent binding. Subsequently, multiple CdTe QDs were loaded both in and on a versatile SiO2 nanocarrier to produce a large amplification factor of hybrid fluorescent nanoparticles (HFNPs) labeled complementary DNA (cDNA). The magnetic-fluorescent-targeting multifunctional aptasensor was thus fabricated by immobilizing the HFNPs onto MBs' surface through the hybrid reaction between the aptamer and cDNA. This aptasensor can be produced at large scale in a single run, and then can be conveniently used for rapid detection of OTA through a one-step incubation procedure. The presence of OTA would trigger aptamer-OTA binding, resulting in the partial release of the HFNPs into bulk solution. After a simple magnetic separation, the supernatant liquid of the above solution contained a great number of CdTe QDs produced an intense fluorescence emission. Under the optimal conditions, the fluorescence intensity of the released HFNPs was proportional to the concentration of OTA in a wide range of 15 pg mL(-1) -100 ng mL(-1) with a detection limit of 5.4 pg mL(-1) (S/N=3). This multifunctional aptasensor represents a promising path toward routine quality control of food safety, and also creates the opportunity to develop aptasensors for other targets using this strategy.

Development of gold nanoparticle based colorimetric method for quantitatively studying the inhibitors of Cu(2+)/Zn(2+) induced ß-amyloid peptide assembly.

In this paper, a kind of gold nanoparticle (GNP)-based colorimetric assay has been developed for studying the reversible interaction of ß-amyloid peptide (Aß) with Cu(2+) and Zn(2+), and quantitatively analyzing four inhibitors (i.e., EDTA, EGTA, histidine and clioquinol) of Cu(2+)/Zn(2+) induced Aß assembly. The inhibition efficiencies (e.g., half maximal inhibitory concentration, IC50 value) of these inhibitors could be measured in this work. As far as we know, these IC50 values were reported at the first time. In this assay, the streptavidin conjugated GNPs (SA-GNPs) were employed as indicators to monitor the Cu(2+)/Zn(2+) induced aggregating/disaggregating behaviors of biotin modified ß-amyloid 1-16 peptides (Aß1-16(biotin)). Because of high affinity of streptavidin (SA) with biotin, the aggregating/disaggregating of Aß1-16(biotin) results in the significant color change of SA-GNPs. Furthermore, we demonstrate that the assay can be used as an effective tool for designing anti-dementia drugs through quantitative analysis of the interactions of four representative inhibitors with Cu(2+)/Zn(2+) induced Aß assembly.

Effects of transplantation of olfactory ensheathing cells in chronic spinal cord injury: a systematic review and meta-analysis.

PURPOSE: The debate on the effects and outcome of olfactory ensheathing cell (OEC) transplantation for the treatment of spinal cord injury (SCI) has remained unresolved for nearly 20 years. This study aimed to evaluate the safety and efficacy of OEC transplantation in chronic SCI patients. METHOD: Electronic databases, including PubMed, the Cochrane Library, EMBASE, and MEDLINE, were searched to identify clinical therapeutic trials studying the use of OEC transplantation for SCI in humans. Each trial was analyzed in accordance with the criteria of the Cochrane Handbook 5.1.0 and MOOSE. Data were analyzed with Review Manager 5.2 and Meta-Analyst Beta 3.13 software. RESULTS: Eleven articles concerning 10 studies of 1,193 patients with chronic SCI treated with OEC transplantation were selected for review. All the articles had low methodological quality. Studies reported their outcomes using the American Spinal Injury Association (ASIA) Impairment Scale; the AISA motor, light touch, pinprick score; the Functional Independence Measure and (or) other measure methods. According to the available relevant data, the incidences of total adverse events and mortality were 7.68% (n = 742) and 0.35% (n = 566), respectively. The most frequently reported adverse events were fever, mild anemia, and syringomyelia; however, the statistical adverse events occurring in different studies were cerebrospinal fluid leakage (7.00%, n = 586, 2 trials), sensory deterioration (0.70%, n = 573, 2 trials), and both motor and sensory deterioration (0.68%, n = 586, 2 trials). CONCLUSIONS: Given the results from our study, we conclude that OEC transplantation appears to be safe, although the evidence for efficacy is modest and requires the support of prospective, randomized trials in larger cohorts of patients. Further randomized controlled trials utilizing strict therapy programs and implanted cell selections are needed to confirm these findings.

A visible light photoelectrochemical biosensor coupling enzyme-inhibition for organophosphates monitoring based on a dual-functional Cd(0.5)Zn(0.5)S-reduced graphene oxide nanocomposite.

A novel visible light photoelectrochemical (PEC) platform coupled with enzyme-inhibition for rapid and sensitive determination of organophosphates (OPs) was constructed based on a dual-functional Cd0.5Zn0.5S-reduced graphene oxide (Cd0.5Zn0.5S-rGO) nanocomposite. Due to the inherent biocompatibility of the Cd0.5Zn0.5S-rGO nanocomposite, acetylcholinesterase (AChE) immobilized on the Cd0.5Zn0.5S-rGO modified electrode can hydrolyze acetylthiocholine chloride into thiocholine, which could increase the photocurrent of the enzyme electrode, and the further inhibition of OPs on the enzyme electrode could decrease the photocurrent response. Based on the notable change in the PEC response of the AChE-Cd0.5Zn0.5S-rGO modified electrode and using Dursban as a model, a simple and effective way for PEC monitoring of OPs is proposed, which showed a wide linear range of 0.001-1 µg mL(-1) with a low detection limit of 0.3 ng mL(-1) (S/N = 3). Moreover, the biosensor was successfully challenged with water samples, demonstrating a new method for rapid and sensitive screening/evaluating exposure to organophosphorus pesticides and other hazardous substances.