Study on Piezoelectric Immunosensor for the Detection of H9-subtype Avian Influenza Virus

[Objective] The aim is to develop the piezoelectric immunosensor to detect H9-subtype avian influenza virus（AIV）.[Method] The immunosensor chip was constructed by self-assembling mercaptopmpionic acid（MPA） to be monolayer on the silver-coated electrode of quartz crystal and coupling the monoclonal antibody to H9 subtype AIV with N-ethy-N＇-（3-dimethyl aminopropyl）carbodiimide hydrochloride（EDC） and N-hydroxysuccinimide（NHS）.The immunosensor to detect H9 subtype AIV was established.[Result] The results showed that the immunosensor displayed better specificity to H9 AIV and had no response to H5AIV and NDV when it was used for detection.The sensitivity test indicated the detection sensitivity for the H9 subtype AIV could reach 20-100 EID50.[Conclusion] The research provided a foundation for further research on the immunosensor for detecting AIV and it could be a new approach to detect other related viruses.

A novel impedance immunosensor based on O-phenylenediamine modified gold electrode to analyze abscisic acid

An impedance immunosensor based on O-phenylenediamine modified gold electrode for the determination of phytohormone abscisic acid(ABA) was proposed.The operating pH,absorption time,absorption temperature and concentration of anti-ABA antibody were investigated to optimize the analytical performance.The calibration curve for the determination of ABA was obtained from this impedance immunosensor under optimal conditions.The results showed that the detection limit at about 1 ng/mL in the range of 10-5000 ng/mL...

A Novel Immunosensor Based on Au Nanoparticles and Polyaniline/Multiwall Carbon Nanotubes/Chitosan Nanocomposite Film Functionalized Interface

A novel multilayer film based on Au nanoparticles(AuNPs) and polyaniline/carboxylated multiwall carbon nanotubes-chitosan nanocomposite(PANI/MWCNTs/CS) was exploited to fabricate a highly sensitive immunosensor for detecting chlorpyrifos. PANI-coated MWCNTs were prepared by in situ chemical polymerization and carboxylated MWCNTs played an important role in obtaining the thin and uniform coating of PANI resulting in the improved immunosensor response. Au NPs were used as a linker to immobilize chlorpyrifos antibody. The performance of the immunosensor was characterized by means of cyclic voltammetry(CV), electrochemical impedance spectroscopy(EIS) and scanning electron microscopy(SEM), respectively. All variables involved in the preparation process and analytical performance of the immunosensor were optimized.Under optimal conditions(antibody concentration: 5 μg/mL, working buffer pH: 6.5, incubation time: 40 min,incubation temperature: 25℃), the immunosensor exhibited a wide linear range from 0.1 to 40× 10^(-6)mg/mL and from 40 × 10^(-6)mg/mL to 500 × 10^(-6)mg/mL, and with a detection limit of 0.06 × 10^(-6)mg/mL, which provided a valuable tool for the chlorpyrifos detection in real samples.

A Micro Amperometric Immunosensor Based on MEMS

A micro amperometric immunosensor with the sensitive area of only 1mm^2 was fabricated on silicon using the technique of Micro-Electro-Mechanical Systems (MEMS).A double exposure of SU-8 photoresist process was developed to create both the sensitive pool and reaction pool.Antibody was immobilized via cross-linking with glutaraldehyde on the sensitive area of the electrode surface,which was electropolymerized with polypyrrole previously.The immunosensor was characterized by detection of human immunoglobulin G (HIgG).The immunosensor displayed a good linear response to HIgG concentrations between 5ng/ml and 255ng/ml and demonstrated a fast response time of 3 minutes.

A MXene-functionalized paper-based electrochemical immunosensor for label-free detection of cardiac troponin I

Convenient,rapid,and accurate detection of cardiac troponin I(cTnI)is crucial in early diagnosis of acute myocardial infarction(AMI).A paper-based electrochemical immunosensor is a promising choice in this field,because of the flexibility,porosity,and cost-efficacy of the paper.However,paper is poor in electronic conductivity and surface functionality.Herein,we report a paper-based electrochemical immunosensor for the label-free detection of cTnI with the working electrode modified by MXene(Ti_(3)C_(2))nanosheets.In order to immobilize the bio-receptor(anti-cTnI)on the MXene-modified working electrode,the MXene nanosheets were functionalized by aminosilane,and the functionalized MXene was immobilized onto the surface of the working electrode through Nafion.The large surface area of the MXene nanosheets facilitates the immobilization of antibodies,and the excellent conductivity facilitates the electron transfer between the electrochemical species and the underlying electrode surface.As a result,the paper-based immunosensor could detect cTnI within a wide range of 5-100 ng/mL with a detection limit of 0.58 ng/mL.The immunosensor also shows outstanding selectivity and good repeatability.Our MXene-modified paper-based electrochemical immunosensor enables fast and sensitive detection of cTnI,which may be used in real-time and cost-efficient monitoring of AMI diseases in clinics.

Diagnostic tests for hepatitis C: Recent trends in electrochemical immunosensor and genosensor analysis

Hepatitis C is a liver disease that is transmitted through contact with the blood of an infected person. An estimated 150 million individuals worldwide have been chronically infected with the hepatitis C virus(HCV). Hepatitis C shows significant genetic variation in the global population, due to the high rate of viral RNA mutation. There are six variants of the virus(HCV genotypes 1, 2, 3, 4, 5, and 6), with 15 recorded subtypes that vary in prevalence across different regions of the world. A variety of devices are used to diagnose hepatitis C, including HCV antibody test, HCV viral load test, HCV genotype test and liver biopsy. Rapid, inexpensive, sensitive, and robust analytical devices are therefore essential for effective diagnosis and monitoring of disease treatment. This review provides an overview of current electrochemical immunosensor and genosensortechnologies employed in HCV detection.There are a limited number of publications showing electrochemical biosensors being used for the detection of HCV.Due to their simplicity,specificity,and reliability,electrochemical biosensor devices have potential clinical applications in several viral infections.

Sensing Escherichia coli O157:H7 via frequency shift through a self-assembled monolayer based QCM immunosensor

By means of the specific immuno-recognition and ultra-sensitive mass detection, a quartz crystal microbalance (QCM) biosensor for Escherichia coli O157:H7 detection was developed in this work. As a suitable surfactant, 16-mercaptohexadecanoic acid (MHDA) was introduced onto the Au surface of QCM, and then self-assembled with N-hydroxysuccinimide (NHS) raster as a reactive intermediate to provide an active interface for the specific antibody immobilization. The binding of target bacteria with the immobilized antibodies decreased the sensor’s resonant frequency, and the frequency shift was correlated to the bacterial concentration. The stepwise assembly of the immunosensor was characterized by means of the electrochemical techniques. Using the immersion-dry-immersion procedure, this QCM biosensor could detect 2.0×102 colony forming units (CFU)/ml E. coli O157:H7. In order to reduce the fabrication time, a polyelectrolyte layer-by-layer self-assembly (LBL-SA) method was adopted for fast construction. Finally, the reproducibility of this biosensor was discussed.

Immunosensor Based on Surface Plasmon Resonance for Antigen Recognition

A novel immunosensor based on surface plasmon resonance（SPR） has been developed for the recognition of antigen. The sensor was designed on the basis of the fixed angle of incidence and measuring the reflected intensities in a wavelength range of 430--750 nm in real-time. An ultra-bright white light-emitting diode（LED） was used as the light source. Molecular self-assembling in solution was used to form the sensing membrane on gold substrate. It has been seen that the sensitivity of the SPR sensor with 3-mercaptopropionic acid（MPA）/protein A（SPA） sensing membrane is considerably higher than that with MPA or SPA modified sensing membrane. The kinetic processes on the sensing membrane were studied. The human B factor（Bf）, an activator of complement 3（C3）, was recognized among the other antigens. This sensor can also be used for other antigen/antibody or adaptor/receptor recognition. Under optimized experimental conditions, the sensor has good selectivity, repeatability, and reversibility.

A MEMS Based Amperometric Immunosensor with Self-assembled Monolayers Immobilization Technique

Based on MEMS technology,immunosensor with an'Au,Pt,Pt'three-microelectrode system enclosed in a SU-8 micro pool was fabricated.Employing SAMs technique,the Au electrode was modified by cysteamine(Cys)to assemble gold nanopanicles(nanogold)layer,subsequently,a layer of protein G(PG)was immobilized on nanogold layer to further capture antibody orientedly.Compared with the immunosensors using bulky gold electrode and direct PG binding to electrode immobilization technique for antibody,it has attractive advantages,such as miniaturization,good compatibility,broad linear range for human immunoglobulin(HIgG)and easy to be designed into array.

Experimental Study of A Novel Piezoelectric Tumor Marker Micro-array Immunosensor

A novel 2×5 model of insert-plug piezoelectric quartz crystal tumor marker micro-array immunosensor constructed with screw clamp apparatus has been developed for quantitative detection of the tumor markers such as alpha-fetoprotein (AFP),carcino-embryonic antigen (CEA),prostate specific antigen (PSA),and human chorionic gonadotropin (hCG) in serum,in which every crystal unit can oscillate independently with the stability of±1 hertz (Hz) in air and±2 Hz in liquid.These response characteristics of Pz tumor marker micro-array immunosensor such as temperature, time-cost,reproducibility and specificity etc were also investigated.The detection ranges for AFP,CEA,PSA,and hCG obtained by Pz micro-array immunosensor were 20 ng/ml～640 ng/ml,1.56 ng/ml～50 ng/ml,1.25 ng/ml～50 ng/ml,and 2.5 mIU/ml～250 mlU/mi respectively with the coefficient of variance (CV) less than 5%.No cross-reactivates with other tumor markers in serum were observed.The results of AFP,CEA,PSA,and hCG obtained by this method from 68 serum samples were in good agreement with those given by chemiluminescence immunoassay with the correlation coefficients of 0.92,0.90,0.91,and 0.94 respectively.The Pz immunosensor regenerated by urea solution could be reused for five times without appreciable loss of response activity.Therefore,the proposed insert-plug immunosensor provides a rapid, sensitive,specific,reusable,convenient and reliable alternative for the detection of tumor markers in clinical laboratory.

Monitoring Domoic Acid in Marine Phytoplankton by Disposable Immunosensors

Advances in sensor technology have allowed the significant progress in the monitoring of noxious compounds in the sea, providing real-time detection so as to prevent risks associated with the diffusion and dispersion of toxic substances in the environment. An important element in the overall picture is the harmful algal blooms which pose serious threats to marine ecosystems through the production of toxins that accumulate in filter-feeders and ultimately impact both human health and fisheries. Domoic acid is a neurotoxic amino acid produced by marine planktonic diatoms of the genus Pseudo-nitzschia. Here we monitored domoic acid production by natural Pseudo-nitzschia populations in phytoplankton samples collected along the Middle Tyrrhenian coast, over the course of one year, using selective immunosensors based on screenprinted electrodes, using differential pulse voltammetry as the electrochemical technique, to yield quantitative outputs. In this work, disposable devices have been applied for monitoring the production of domoic acid on algal extracts and the results have been validated by conventional high pressure liquid chromatography-ultraviolet detection methods. The data obtained revealed the presence of domoic acid in Italian phytoplankton, especially in coastal impacted areas, highlighting the potential risk of toxin entering into marine food webs and the environment. Immunosensors based on screen-printed electrodes prove to be effective tools for annual monitoring of domoic acid in seawater samples, thus providing a reliable early warning system relative to health and economic impact of algal toxins.

Simulation of perforated rectangular cantilever immunosensor for estimation of bacterial pathogens

Micro fabricated and multilayered perforated cantilever beam immunosensor was modeled using CoventorWare for the estimation of bacterial antigens of Bacillus Anthrax, Pseudomonas aeruginosa, Coryne Bacterium Diptheria and Treponema pallidum. A rectangular cantilever beam with perforations was simulated with dimensions as length-200 μm, width-10 μm and thickness-0.5 μm. Each perforation is rectangular with length-10 μm, width-5 μm and thickness-0.5 μm. The theoretical and FEM simulations were carried out with five immunoglobulin antibodies, IgA, IgD, IgE, IgG and IgM for the estimation of bacterial antigens. The effect of perforation in cantilever beam and molecular size of antibody and antigen on the performance of the sensor has been studied. The cantilever beam without perforation showed a deflection of 1.8 e + 02 μm whereas the cantilever beam with perforation showed an increase deflection of 1.9 e + 02 μm. With IgG, the difference between analytical and simulation values is positive and low especially with low molecular weight antigens Pseudomonas aeruginosa and Treponema pallidum. The low molecular weight IgG influences the antigen-antibody interaction more fvourably. The simulated perforated rectangular cantilever beam with IgG antibody is a more promising model for the fabrication of a sensor for the estimation of highly motile Pseudomonas aeruginosa and Treponema pallidum.

A Portable Evanescent Wave Optic Fiber Immunosensor for Sensitive and Rapid Detection of 2,4-D in Water Samples

A portable evanescent wave optic ?ber immunosensor was developed for detection of 2,4-dichlorophenoxyacetic acid(2,4-D) using a indirect competitive immunoassay. In this paper, hapten conjugates 2,4-D-OVA were immobilized with covalent binding methods. After pre-reacting, 2,4-D-antibody-Cy5.5 in sample specifically recognized the 2,4-D antigens binding sites on surface of the optical fiber probe. Under optimum conditions, 2,4-D could be detected in less than 18 min for each assay cycle. The regeneration of the optic ?ber surface allowed more than 200 times without losing performance. The limits of detection of 0.039 ug/L and the quantitative detection range of 0.47 - 81.02 ug/L were obtained when the concentration of 2,4-D was 1 mg/L. This immunosensor shows great potential in rapid simultaneous detection of 2,4-D in waters samples.

A Surface Plasmon Resonance-based Immunosensors for Sensitive Detection of Heroin

A simple technique for sensitive detection of heroine based on surface- plasmonresonance has been theoretically and experimentally investigated. The experiment was realized by using an anti-MO monoclonal antibody and a morphine (MO)-bovine serum albumin (MOBSA) conjugate (antigen). The reason for using MO-BSA in the detection of heroine was also discussed. MO-BSA was immobilized on a gold thin film of SPR sensor chip by physical adsorption. The configuration of the device is allowed to be further miniaturized, which is required for the construction of a portable SPR device in the application of in-situ analysis.

Electrochemical Immunosensors for the Diagnosis of Celiac Disease

Celiac disease is a permanent intolerance to gluten proteins of wheat, rye, barley, and oats in genetically susceptible individuals. The clinical picture is characterized by inflammation and damage of the small intestinal mucosa and malabsorption of essential nutrients. Therapeutically, a lifelong strict gluten-free diet is necessary. The diagnosis of celiac disease is complex and includes symptomatology, serology, small intestinal histology, and genetic status. Serological testing plays a central role within the diagnostic procedure and is based on the measurement of disease-specific antibodies against gluten proteins (antigen) and tissue transglutaminase (autoantigen). Immunofluorescence detection and enzyme-linked immunosorbent assays are currently most often applied for antibody testing. However, these tests are expensive and time-consuming. Therefore, simple and rapid alternative methods have been developed during the last years, and electro-chemical immunosensors seem to be the most promising analytical tools. The architecture of these sensors may comprise the following elements: working and reference electrodes, covalent or noncovalent binding of the antigen to the surface of the working electrode by means of a functional monolayer, and blocking of unreacted binding sites. The analytical procedure is initiated by adding the analyte (serum antibodies) and an analyte-specific second antibody, which is usually labeled with an enzyme. The special reaction of the enzyme with an appropriate substrate results in a product that initiates a current that can be measured by different electrical methods. A number of different electrochemical immunosensors variable in different electrodes, binding systems, secondary antibodies, and current measurements have been developed. Most of them have been tested with real human serum samples of celiac patients and healthy individuals, and some of them reached disease sensitivity and specificity comparable with traditional analytical systems. Thus, electrochemical immunosensors can be promising alternatives to existing diagnostic tests in the future. They are simple, reliable, robust, user-friendly, and cost-effective tools with short operation times.

Adjunction of Avidin to a Cysteamine Self-Assembled Monolayer for Impedimetric Immunosensor

In this work an impedimetric immunosensor based on affinity immobilization method of a biotin labelled anti-human IgG antibody, used as a model system, was reported. The experimental procedure involves the growth of a self-assembled monolayer of a thiol (cysteamine) carrying terminal amine groups on gold electrodes. Glutarardehyde, a homobifunctional cross-linker, was used as a coupling reagent for the covalent linking of avidin to the amine groups of cysteamine. The attachment of the biotin labeled antibodies (anti-Human IgG) to the subsequent modified gold electrode was achieved by affinity interactions tacking advantage of the strong avidin-biotin bridge. The stepwise assembly process of the electrode was interrogated by means of cyclic voltammetry, electrochemical impedance spectroscopy and contact angle measurements. The response of the antibody modified electrode to their target antigens was investigated in the presence of BSA (bovin serum albumin) in order to alleviate non-specific adsorption problems. A proposed electrical model was used to analyse the experimental data. The resulting immunosensor has a linear dynamic range of 100 - 900 ng?ml–1 of antigen and a detection limit of 100 ng?ml–1.

Design of nano-piezoelectric immunosensor array to detect bone sialoprotein

Objective With the unique properties of Au nano-particles,a nano-piezoelectric immunosensor microarray was designed using AT-cut 10 Hz quartz crystal to detect blood sialoprotein (BSP) expression from clinical serum.Methods

Mesoporous SiO_(2) Sphere-Based Electrochemical Impedance Immunosensor for Ultrasensitive Detection of Bovine Interferon-γ

Interferon-γis a kind of protein with a wide range of biological activities,which can regulate the immune function of the body,and can be used as an important marker to detect and treat bovine tuberculosis diseases.Here,a picogram-level bovine interferon-γ(BoIFN-γ)electrochemical impedance immunosensor was constructed for the first time using mesoporous silica nanospheres(MS Ns)to immobilize specific monoclonal BoIFN-y antibodies.The MS Ns and BoIFN-γimmuno sensors were characterized using scanning electron microscopy,transmission electron microscope,nitrogen adsorption experiment,X-ray photoelectron spectra,and contact angle measurements.MSNs possess a substantial specific surface area and significant hydrophilicity,and can immobilize many antibody molecules,thereby improving detection sensitivity.The immunosensor has a linear detection range from 0.001 to 10.0 ng/mL with an exceptionally low detection limit of 0.62 pg/mL.Compared to the traditional BoIFN-γanalysis method,BoIFN-γimmunosensor presents superiorities in sensitivity,wide linear range as well as short processing time.More importantly,the BoIFN-γsensor exhibits high selectivity,reliable repeatability as well as stability,providing a promising application prospect for the early diagnosis of Mycobacterium bovis infection.