Application Of Immunosensor Research Articles

Label-free impedimetric immunosensor based on arginine-functionalized gold nanoparticles for detection of DHEAS, a biomarker of pediatric adrenocortical carcinoma

Pediatric adrenocortical carcinoma (pACC) is a rare and aggressive malignancy of high occurrence in Southern Brazil. pACC is characterized by the usual overproduction of dehydroepiandrosterone sulfate (DHEAS), whose detection in serum or plasma can be effective to the early diagnosis of the disease. Therefore, the present paper reports, for the first time, the construction and application of a label-free impedimetric immunosensor to detect DHEAS, which was based on the modification of an oxidized glassy carbon electrode with arginine-functionalized gold nanoparticles (AuNPs-ARG) and anti-DHEA IgM antibodies (ox-GCE/AuNPs-ARG/IgM). AuNPs-ARG was synthesized by a green route, and characterized by UV–VIS spectroscopy, FTIR, TEM, DLS, and XRD. The construction of ox-GCE/AuNPs-ARG/IgM was optimized through factorial design and response surface methodology. Cyclic voltammetry and electrochemical impedance spectroscopy measurements were employed to characterize the optimized immunosensor. The DHEAS detection principle was based on the variation of charge transfer resistance (∆Rct) relative to the Fe(CN)64−/3− electrochemical probe after immunoassays in the presence of the biomarker. A linear relationship between ∆Rct and DHEAS concentration was verified in the range from 10.0 to 110.0 µg dL−1, with a LOD of 7.4 µg dL−1. Besides the good sensitivity, the immunosensor displayed accuracy, stability, and specificity to detect DHEAS. The promising analytical performance of ox-GCE/AuNPs-ARG/IgM was confirmed by quantifying DHEAS in real patient plasma samples, with results that were comparable to the reference chemiluminescence assay. Our results suggest that the presented immunosensor can find clinical applications in the early diagnosis of pACC and to monitor DHEAS levels in other adrenal pathologies.

Trends and Perspectives in Immunosensors for Determination of Currently-Used Pesticides: The Case of Glyphosate, Organophosphates, and Neonicotinoids.

Pesticides, due to their intensive use and their peculiar chemical features, can persist in the environment and enter the trophic chain, thus representing an environmental risk for the ecosystems and human health. Although there are several robust and reliable standard analytical techniques for their monitoring, the high frequency of contamination caused by pesticides requires methods for massive monitoring campaigns that are capable of rapidly detecting these compounds in many samples of different origin. Immunosensors represent a potential tool for simple, rapid, and sensitive monitoring of pesticides. Antibodies coupled to electrochemical or optical transducers have resulted in effective detection devices. In this review, the new trends in immunosensor development and the application of immunosensors for the detection of pesticides of environmental concern—such as glyphosate, organophosphates, and neonicotinoids—are described.

A highly sensitive label-free electrochemical immunosensor based on AuNPs-PtNPs-MOFs for nuclear matrix protein 22 analysis in urine sample

A reliable and non-invasive electrochemical immunosensor for nuclear matrix protein 22 (NMP22) was presented based on reduced graphene oxide-tetraethylenepentamine (rGO-TEPA) and gold nanoparticles‑platinum nanoparticles-metal organic frameworks (AuNPs-PtNPs-MOFs) nanomaterial. rGO-TEPA is a promising template to enhance the loading ability of electrode for its large specific surface area and abundance in amino groups. AuNPs-PtNPs-MOFs nanomaterial was synthesized by NaBH4 reduction method and applied to immobilize biomolecules due to their good biocompatibility, well conductivity, and excellent H2O2 electrocatalytic ability. The electrochemical response signal was primarily originated from the obstruction of immobilized NMP22 antigen towards electrocatalytic reduction of H2O2 and the signal was recorded by differential pulse voltammetry. Under optimum conditions, the immunosensor showed a sensitive response towards NMP22 at a broad concentration range from 0.005ng·mL−1 to 20ng·mL−1. Two strong linear ranges could be observed at 0.005ng·mL−1 to 0.5ng·mL−1 (R2=0.9833), and 0.5ng·mL−1 to 20ng·mL−1 (R2=0.9909), with a low LOD of 1.7pg·mL−1 (S/N=3). Satisfactory reproducibility, stability and selectivity were obtained for NMP22 detection in real urine samples compared with standard ELISA assay, demonstrating the good analytical performance and potential non-invasive clinical application of this label-free electrochemical immunosensor.

Development and application of a novel electrochemical immunosensor for tetracycline screening in honey using a fully integrated electrochemical Bio-MEMS

Tetracycline (TC) is a veterinary drug, wildly prescribed for prophylactic and therapeutic purposes. Consequently, its remaining residues in food products have to be regularized. We report in this paper about the development of a novel immunosensor based on an integrated bio micro-electromechanical system (Bio-MEMS) containing eight gold microelectrodes (µWEs), an integrated silver and platinum reference and counter electrodes, respectively. TC immobilization on the µWEs surface was conducted using three methods. The first through functionalization with 4-aminophenylacetic acid (CMA), the second by functionalization with CMA followed by preconcentration of a new structure of magnetic nanoparticles (MNPs) coated with poly (pyrrole-co-pyrrole-2-carboxylic acid) (Py/Py-COOH/MNPs) cross-linked with Ab-TC, and the last one directly through the functionalization with Py/Py-COOH/MNPs. The analyte was quantified by competitive detection with TC immobilized on the µWEs surface toward specific polyclonal antibody (Ab-TC), using a mixture of a fixed concentration of Ab-TC and decreasing levels of TC one from 0.1 pg mL−1 to 1000 pg mL−1. Microcontact printing, followed by fluorescence microscopy characterization were performed during the functionalization of the immunosensor surface to certify that the corresponding immune detection process is taking place. This immunosensor was found to be highly sensitive with a limit of detection of 1.2 pg mL−1 and specific in the presence of interferents. The standard addition method was exploited to detect TC in honey samples. The present immunosensor platform is up-and-coming for TC detection which can dramatically decrease the time of analysis providing a new pathway for advanced immunoassays development in industrial food control.

Morphological characteristics of polymeric nylon‐6 film as biological recognition interface for electrochemical immunosensor application

ABSTRACTThe present study elucidates the morphology characteristic of nylon‐6 as protein immobilization film and their influences in biological recognition interface for a single‐use electrochemical immunosensor. A basic requirement of this polymer platform is to allow the testing analyte [conductive polyaniline‐Fe2O3‐glutaraldehyde‐conjugated‐N‐hydroxysuccinimidobiotin (PANI‐Fe2O3‐GA‐b‐NHS)] to access to the immobilized capture reagent [bovine serum albumin (BSA)] on a surface of the nylon‐6 film. As an immunoassay, the biochemical reaction between PANI‐Fe2O3‐GA‐b‐NHS and BSA takes place on a surface of the nylon‐6 support film, which then translated into measurable resistance signal through pulse‐mode measurement. The in‐house developed nylon‐6 film, N‐16B, with 16 wt % nylon polymer and methanol as nonsolvent had demonstrated the fastest lateral wicking speed (1.07 mm s−1) and excellent protein immobilization capacity (1650 ± 85.84 μg cm−3), leading to the higher electrical current signal with a minimal resistance of electrochemical responses (0.57 ± 0.04 MΩ). This work reflects the importance of the physical characteristics of the nylon‐6 film that determines the sensitivity and effectiveness of an immunosensor. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018, 135, 46741.

Ultrasensitive immunoassay of carcinoma antigen 125 in untreated human plasma samples using gold nanoparticles with flower like morphology: A new platform in early stage diagnosis of ovarian cancer and efficient management

Ovarian cancer, as one of the most life-threatening malignancies among women worldwide, is usually diagnosed at the late stage despite up regulation of molecular markers such as carcinoma antigen 125 (CA 125) at the early stages of the malignancy. CA 125 is the only tumor marker recommended for clinical use in the diagnosis and management of ovarian cancer. The potential role of CA-125 for the early detection of ovarian cancer is controversial and has not yet been adopted for widespread screening efforts in asymptomatic women. Therefore, early detection of CA 125 in human biofluids is highly demanded. In the present study, a novel method was proposed for the fabrication of electrochemical immunosensor based reduced graphene oxide (RGO). Cysteamine capped gold nanoparticle (Cys-AuNPs) were deposited over the surface of ERGO probe using electrophoretic deposition method. These Cys-AuNPs/ERGO probes provide the favorable sites to attach the monoclonal antibody specific to CA 125 antigen. Cyclic voltammetry (CV), and square wave voltammetry (SWV) were applied for the electrochemical recognition of the biolayer. The represented signals demonstrates excellent figure of merits and good capability of the engineered immunosensor towards sensitive detection of CA 125. Quantitative measurements of CA 125 in human plasma samples have been demonstrated, showing the potential of the practical application of this novel immunosensor for the analysis of this biomarker in blood serum samples. This immunosensor has the ability of direct electron transfer as compared to earlier reported electrochemical immunosensors based electrochemical methods. Further, this immunosensor provides a very suitable and convenient alternative to replace the expensive commercially available methods such as immunohistochemistry. The following regression equation between the electrochemical current response and the CA 125 concentration range from 0.1 to 400 U/mL was found. The low limit of quantification for this immunosensor was 0.1 U/mL. To the best of our knowledge, this is the first reported on the direct immobilization of antibody on the surface of Cys-AuNPs/ERGO for fabrication of immunosensors.

Nanostructured electrochemical immunosensor for detection of serological alkaline phosphatase

Alkaline phosphatase (ALP) is an enzyme that plays an important role in bone mineralization and skeletal growth. Variations in physiological levels of ALP have been correlated to diseases such as osteomalacia, Paget's disease and arterial calcifications. In this context, the integration of carbon nanotubes (CNT) within osteointegration implants has shown to increase ALP's mineralization activity in virtue of their surface chemistry and their morphological resemblance to collagen nanofibers. In this study we present the development and analytical application of an impedimetric immunosensor based in gold nanoparticle-decorated CNT, which characteristics are desirable in implantable biosensors. The device effectively detects ALP within blood serum, a complex biological fluid where most expressed proteins can be found. Robustness and high sensitivity were attained by immobilizing covalently anti-ALP antibody as a specific probe towards ALP. Cyclic voltammetry, electrochemical impedance spectroscopy and atomic force microscopy were used to characterize the sensor system throughout mounting steps and real sample testing. Impedimetric responses were adjusted to a theoretical electrical circuit and charge transfer resistance showed to be an adequate parameter to evaluate the biorecognition process of the analyte. Additionally, amperometrical current variation and changes in topography found over the surface after positive samples evidenced biorecognition. The final biosensor showed excellent performance with two linear ranges from 0.5 to 50 IU.L-1 and from 100 to 600 IU.L-1; limits of detection were calculated as 0.25 and 84.6 IU.L-1 respectively with a relative standard deviation lower than 5%. The device was found to be selective, avoiding protein c, a potential interferer occurring during inflammatory processes. The proposed strategy is promising for osteogenic applications where it can improve osteointegration implants by monitoring ALP activity.

Enhanced peroxidase-like properties of Au@Pt DNs/NG/Cu2+ and application of sandwich-type electrochemical immunosensor for highly sensitive detection of CEA

Effective treatment of cancer depends upon the early detection of the tumor marker. Here, we report on the development of a new immunosensor for early detection of carcinoembryonic antigen (CEA). Cubic Au@Pt dendritic nanomaterials functionalized nitrogen-doped graphene loaded with copper ion (Au@Pt DNs/NG/Cu2+) with enhanced peroxidase-like properties was synthesized as labels to effectively capture and immobilize secondary anti-CEA. The Au@Pt DNs with more active surface area could efficiently enhance electrocatalysis for reduction of hydrogen peroxide (H2O2). Meanwhile, with good conductivity and large specific surface area, NG can immobilize a large amount of Au@Pt DNs. Furthermore, after adsorbed Cu2+ can further promote the redox of H2O2 and amplify the signal of the immunosensor. For the immobilization of primary antibodies, Au nanoparticles functionalized polydopamine (Au@PDA) were used as transducing materials to modify glassy carbon electrodes and enhance the electron transfer efficiently. Under optimal conditions, the immunosensor exhibited a satisfactory response to CEA with a limit detection of 0.167 pg/mL and linear detection range from 0.5 pg/mL to 50 ng/mL. Based on the high sensitivity and specificity of the immunosensor, we propose this multiple amplified biosensor for early detection of CEA.

Optical Immunosensors for the Efficient Detection of Target Biomolecules

Recently, immunosensors have attracted attention because they are widely applied for the detection of various pathogens. Among the commonly used immunosensors, the optical immunosensor features prominently as an effective tool for the quantification of the amount of antibodies, antigens, or haptens in complex samples with high sensitivity and specificity. However, very few studies provide comprehensive overviews of optical immunosensors. In this review, we present various methods and applications of optical immunosensors in pathogen detection. We introduced a concise definition of optical immunosensors and the principle of using them for detection. We subsequently discuss the main categories of optical immunosensors and their application to the detection of pathogens, as well as their advantages and limitations. Recent publications from 2006 to 2015 on variously designed optical immunosensors have also been updated. We conclude the review with a brief summary and discuss future directions of optical immunosensors.

Electrochemical detection of C-reactive protein using Copper nanoparticles and hybridization chain reaction amplifying signal

In this study, a sandwich-type electrochemical immunosensor for the detection of C-reactive protein (CRP) is described. In design, Copper nanoparticles (Cu NPs) were used for signal tag and hybridization chain reaction (HCR)amplified output signal. The immunosensor fabrication involved three steps: (i) primary antibodies (Ab1) were immobilized on the surface of gold nanoparticles (Au NPs); (ii) the sandwich-type structure formation contained “primary antibodies-antigen-secondary antibodies conjugated with primer (Ab2-S0)”; and (iii) long DNA concatemers intercalating amounts of Cu NPs was linked to the sandwich-type structure via hybridization reaction. Differential pulse voltammetry (DPV) was used to record the response signal of the immunosensor in phosphate-buffered saline (PBS). Under optimal conditions, the anodic peak currents of Cu NPs at the peak potential of about 0.08V(VS.SCE) were linear with the logarithm of CRP concentration in the range of 1.0 fg mL−1 to 100 ng mL−1 with a detection limit of 0.33 fg mL−1 (at signal/noise [S/N] = 3). In addition, the practical application of immunosensor was evaluated by analyzing CRP in real human serum samples, the recoveries obtained were within 95.3%–103.8%, indicating the immunosensor possessed potential application ability for practical disease diagnosis.

An amplified comparative fluorescence resonance energy transfer immunosensing of CA125 tumor marker and ovarian cancer cells using green and economic carbon dots for bio-applications in labeling, imaging and sensing

CA125, is a marker in the clinical diagnosis of several cancers and currently is the best serum-based tumor marker for ovarian cancer. Here, we developed an ultrasensitive antibody-ssDNA aptamer sandwich-type fluorescence immunosensor for CA125 detection. Based on a novel signal amplification strategy the carbon dots (CDs) functionalized with aptamer (CD-aptamer) used as detection probe and PAMAM-Dendrimers/AuNPs was used for covalent attachment of CA125-antibody and completing the sandwich assay method. By measuring of fluorescence resonance energy transfer (FRET) signals between CDs and AuNPs as nanoquenchers, the fluorescence signal quenched during sandwich complex formed between anti-CA125, CA125 and CDs-Aptamer and decreasing of fluorescence response signal is related to CA125 concentrations. Under optimal conditions, the immunosensor exhibited an extremely low calculated detection limit of 0.5fg/mL with wide linear range 1.0fg/mL to 1.0ng/mL of CA 125. The application of the immunosensor for CA125 detection in serum samples and measuring of ovarian-cancer cells was also investigated. The immunosensor revealed good sensitivity and specificity with ovarian cell concentrations from 2.5×103 to 2×104cells/mL with correlation coefficient of 0.9937 and detection limit of 400cells/mL (4 cell in 10μL), indicating potential application of immunosensor in clinical monitoring of tumor biomarkers. Furthermore, the cell viability was not changed upon treatment with CDs probe during 24h, showing the low cytotoxicity of the probe. More importantly, CDs-antibody hybrid was achieved in selective imaging of the cancer cells over the OVCAR-3 line cells, implying its potential applications in biosensing, as well as in cancer diagnosis.

Hydrophilic Polyelectrolyte Multilayers Improve the ELISA System: Antibody Enrichment and Blocking Free.

In this study, polyelectrolyte multilayers were fabricated on a polystyrene (PS) plate using a Layer-by-Layer (LbL) self-assembly technique. The resulting functional platform showed improved performance compared with conventional enzyme-linked immunosorbent assay (ELISA) systems. Poly(diallyldimethylammonium chloride) (PDDA) and poly(acrylic acid) (PAA) were used as cationic and anionic polyelectrolytes. On the negatively-charged (PDDA/PAA)3 polyelectrolyte multilayers the hydrophilic PAA surface could efficiently decrease the magnitude of the noise signal, by inhibiting nonspecific adsorption even without blocking reagent adsorption. Moreover, the (PDDA/PAA)3 substrate covalently immobilized the primary antibody, greatly increasing the amount of primary antibody adsorption and enhancing the specific detection signal compared with a conventional PS plate. The calibration curve of the (PDDA/PAA)3 substrate showed a wide linear range, for concentrations from 0.033 to 33 nM, a large specific signal change, and a detection limit of 33 pM, even though the conventional blocking reagent adsorption step was omitted. The (PDDA/PAA)3 substrate provided a high-performance ELISA system with a simple fabrication process and high sensitivity; the system presented here shows potential for a variety of immunosensor applications.

Electrochemiluminescence behavior of AgNCs and its application in immunosensors based on PANI/PPy-Ag dendrite-modified electrode.

In this study, hyperbranched polyethyleneimine-protected silver nanoclusters (hPEI-AgNCs) with excellent electrochemiluminescence (ECL) emission in the presence of coreactant K2S2O8 were prepared by chemical reduction of silver ions (silver nitrate) coordinated with dendrigraft polymer, and successfully used for the construction of an ECL immunosensor. Polyaniline (PANI)/polypyrrole (PPy)-silver (Ag) dendrites with good electrical conductivity and biocompatibility were electropolymerized on the surface of indium tin oxide (ITO) electrode as carriers. Porous ZnO sphere-loaded hPEI-AgNCs-induced signal amplification strategies were integrated exquisitely and applied sufficiently. Taking carcinoembryonic antigen (CEA) as an example, under optimal conditions, the CEA concentration was determined to be in the range of 10-3 ng mL-1-100 ng mL-1 and with a detection limit of 0.4 pg mL-1 using this method; it exhibited excellent selectivity, high stability, and acceptable fabrication reproducibility. It was anticipated that hPEI-AgNCs would have promising applications in green, selective, and sensitive detection of target analytes in the future.

Amino acid functionalized ZrO2 nanoparticles decorated reduced graphene oxide based immunosensor.

Here, a study is reported on a simple, one-step method for the synthesis of a zirconium dioxide-reduced graphene oxide (ZrO2-RGO) nanocomposite involving the reduction of graphene oxide (GO) and in situ growth of ZrO2 NPs using hydrazine as a reducer. This ZrO2-RGO nanocomposite was functionalized with l-methionine (Meth) for immunosensor application. Morphological and structural studies clearly indicated that ZrO2 NPs (6 nm) were decorated onto the RGO sheets, and enhanced exfoliation, thereby preventing the restacking of the RGO sheets. RGO improved the electrochemical properties of the ZrO2-RGO nanocomposite and minimized the aggregation of ZrO2 NPs. FTIR studies confirmed the functionalization of the ZrO2-RGO nanocomposite with Meth and biomolecules (anti-OTA and BSA). The Meth functionalized ZrO2-RGO nanocomposite had enhanced biocompatibility and wettability as confirmed by MTT assay and contact angle studies, respectively. Furthermore, a uniform thin film of the Meth/ZrO2-RGO nanocomposite was electrophoretically deposited onto an indium tin oxide (ITO) coated glass substrate and utilized for covalent immobilization of monoclonal antibodies specific to ochratoxin A (anti-OTA) for the detection of ochratoxin A (OTA). The fabricated BSA/anti-OTA/Meth/ZrO2-RGO/ITO immunoelectrode exhibited a wide linear detection range of 1-20 ng mL-1 with a sensitivity of 4.8 μA ng-1 mL cm-2 and a detection limit of 0.079 ng mL-1 for OTA detection.

Analytical Application of Flow Immunosensor in Detection of Thyroxine and Triiodothyronine in Serum.

In this study, an immunosensor based on kinetic exclusion analysis (KinExA) was used for thyroxine (T4) and triiodothyronine (T3) estimation. A KinExA™ 3200 instrument was used for this analysis, which is an automated flow fluorimeter designed to separate free unbound antibody binding sites in reaction mixtures of antibody, antigen, and antibody-antigen complex. A T3-BSA- and T4-BSA-coated polymethyl methacrylate (PMMA) bead microcolumn is generated inside the flow cell of the instrument. A sample mixture containing T3 and T4 with their respective monoclonal antibodies and their complexes are drawn past the microbead column. The unbound T3 or T4 monoclonal antibody binding sites are captured by their respective T3 and T4 antigens coated on the PMMA beads as bovine serum albumin conjugates. Fluorescently labeled secondary antibodies bind to the T3 or T4 antigen-antibody complex to generate fluorescence intensity for analysis. The limit of detection for the T3 and T4 assays was found to be 0.06 and 1.9 ng mL-1 with acceptable precision values. The convenience of the automated KinExA format may be valuable in medical diagnostic laboratories.

Facile synthesis of cuprous oxide nanowires decorated graphene oxide nanosheets nanocomposites and its application in label-free electrochemical immunosensor

In this work, the assembly between one-dimensional (1D) nanomaterials and two-dimensional (2D) nanomaterials was achieved by a simple method. Cuprous oxide nanowires decorated graphene oxide nanosheets (Cu2O@GO) nanocomposites were synthesized for the first time by a simple electrostatic self-assembly process. The nanostructure was well confirmed by scanning electron microscope (SEM) and transmission electron microscope (TEM) images. Taking advantages of good electrocatalytic activity and high specific surface area of Cu2O@GO nanocomposites, a label-free electrochemical immunosensor was developed by employing Cu2O@GO as signal amplification platform for the quantitative detection of alpha fetoprotein (AFP). In addition, toluidine blue (TB) was used as the electron transfer mediator to provide the electrochemical signal, which was adsorbed on graphene oxide nanosheets (GO NSs) by electrostatic attraction. The detection mechanism was based on the monitoring of the electrochemical current response change of TB by the square wave voltammetry (SWV) when immunoreaction occurred on the surface of electrode. Under optimal conditions, the proposed immunosensor displayed a high sensitivity and a low detection limit. This designed method may provide an effective method in the clinical diagnosis of AFP and other tumor markers.

ChemInform Abstract: An Overview of Recent Electrochemical Immunosensing Strategies for Mycotoxins Detection

AbstractReview: [97 refs.

Application of Electrochemical Immuno-sensor Based on Ketamine Hydrochloride for the Detection of Sports Illicit Drugs

With the development of modern technology, the developed electrochemical immuno-sensor becomes a new kind of micro measurement technology. The electrochemical immuno-sensor based on ketamine hydrochloride was prepared in this study. Sufficient anti-bodies are combined with the electrode through adsorption of 3-mercaptopropionic acid and gold electrode. The results showed that the electrode had a specific response to antigens. Cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS) and atomic force microscope (AFM) were used for the electrode characterization. Results indicated that, the prepared electrode had good stability and re-producibility. The prepared electrochemical immuno-sensor based on ketamine hydrochloride in this study was applied to the detection of morphine content in sports illicit drugs, and we found that, such kind of sensor was appropriate for detection of illicit drugs. Moreover, it had high sensitivity and was hopeful to be made into a miniature instrument. Thus, the electrochemical immuno-sensor based on ketamine hydrochloride plays an important role in the detection of illicit drugs on the competition site of sports events.

An Overview of Recent Electrochemical Immunosensing Strategies for Mycotoxins Detection

AbstractElectrochemical immunosensors are affinity ligand based biosesnors based on solid state devices in which immunochemical reactions are coupled to a transducer surface to generate the output electrochemical signal. The concept of immunosensor methodology is similar to conventional ELISA based immunoassays; however, in contrast to immunoassays, modern transducer technology permits the highly sensitive quantification of the immune complex in divers ways. Mycotoxins are naturally occurring toxic secondary metabolites produced by fungi contaminating food and feed and are responsible for mycotoxicosis with symptoms of intoxication causing substantial effects on animal and human health. Based on the adverse effect, it has been very crucial to develop ultrasensitive sensing methodologies to ensure food safety and prevent risks in agro‐food and environmental sector. For these purposes, many electrochemical immunosensors based on different analyzing techniques have been reported for mycotoxins monitoring. In this review paper, we provided a general overview on the practical aspects of electrochemical imunosensor designs such as assay format, choice of the transducer surface, immobilization methodologies, signal generating probe and type of output electrochemical signal. In doing so, we also reviewed the recent development in electrochemical immunosensor applications for mycotoxin analysis.

Simple synthesis of silver nanoparticles functionalized cuprous oxide nanowires nanocomposites and its application in electrochemical immunosensor

In this work, silver nanoparticles functionalized cuprous oxide nanowires (Ag@Cu2O) nanocomposites were synthesized by a simple method. The nanostructure of it could be well confirmed by a scanning electron microscope (SEM) image. Due to the good synergistic effect between silver nanoparticles (Ag NPs) and cuprous oxide nanowires (Cu2O NWs), Ag@Cu2O nanocomposites displayed a good electrocatalytic performance towards the reduction of hydrogen peroxide (H2O2). Cyclic voltammograms (CVs) were employed to investigate electrocatalytic mechanism of it. Using Ag@Cu2O nanocomposites as the labels, a novel and ultrasensitive sandwich-type electrochemical immunosensor was developed for the quantitative detection of carcinoembryonic antigen (CEA). Due to the special electrochemical performance of Ag@Cu2O nanocomposites, the facile and sensitive fabrication of the designed immunosensor was achieved. Under optimal conditions, the designed immunosensor exhibited a wide linear range with a low detection limit. It also displayed an electrochemical performance with good reproducibility, selectivity and stability, which would provide potential applications in the clinical diagnosis of other tumor markers.