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BACKGROUND American tegumentary leishmaniasis (ATL) is an endemic neglected tropical disease (NTD), its conventional treatment is toxic, slow, and invasive. Rapid diagnosis is crucial for the clinical management of suspected patients, so the development and use of low-cost, miniaturised and portable devices could be the key. OBJECTIVES This work aimed to develop a simple paper-based electrochemical platform for the serological detection of ATL. METHODS Platform was fabricated in Whatman N°1 paper, contains a hydrophobic zone generated by wax printing, two pencil graphite electrodes, and uses specific crude extracts (CA) antigens for ATL immuno-determination. The platform performance was analysed by measuring the relative impedance change for different antigen-antibody combinations. Then, 10 serum human samples previously diagnosed by the gold standard (five positive ATL cases and five non-ATL cases) were evaluated. FINDINGS The platform presented a linear response for the charge transfer resistance (ΔRct) and the interface reactance (ΔXc). Also, optimal working conditions were established (1/60 serum dilution and 180 µg/mL CA concentration). Then, the platform permits to distinguish between ATL and non-ATL (p < 0.05) human serum samples. MAIN CONCLUSIONS Our platform could allow the diagnosis, management, and monitoring of leishmaniasis while being an extremely simple and environmentally friendly technology.
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BACKGROUND Malaria is a disease that affects many tropical and subtropical countries, including Brazil. The use of tests for malaria detection is one of the fundamental strategies recommended by the World Health Organization for the control and eradication of the disease. The lack of diagnostic tests leads to an increase in transmission and non-reporting cases. OBJECTIVES This work described an electrochemical immunosensor for detecting Plasmodium vivax lactate dehydrogenase antigen (Ag-PvLDH). METHODS The device has developed by immobilising egg yolk IgY antibodies (Ab-PvLDH) on a gold electrode surface using cysteamine as linker. The immunosensor fabrication was followed by differential pulse voltammetry, and contact angle measurements were performed to characterise the modified gold electrode surface. FINDINGS The results for Ag-PvLDH determination exhibit a linear response at 10-50 µg mL-1 concentration range, with a limit of detection of 455 ng mL-1. The excellent selectivity of the device was confirmed. MAIN CONCLUSIONS The developed immunosensor showed a good performance, therefore, it can be considered an alternative test to detect malaria caused by P. vivax.
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Antibiotics are a category of chemical compounds used to treat bacterial infections and are widely applied in cultivation,animal husbandry,aquaculture,and pharmacy.Currently,residual antibiotics and their metabolites pose a potential risk of allergic reactions,bacterial resistance,and increased cancer incidence.Residual antibiotics and the resulting bacterial antibiotic resistance have been recognized as a global challenge that has attracted increasing attention.Therefore,monitoring antibiotics is a critical way to limit the ecological risks from antibiotic pollution.Accordingly,it is desirable to devise new analytical platforms to achieve efficient antibiotic detection with excellent sensitivity and specificity.Quantum dots(QDs)are regarded as an ideal material for use in the development of antibiotic detection biosensors.In this review,we characterize different types of QDs,such as silicon,chalcogenide,carbon,and other doped QDs,and summarize the trends in QD-based antibiotic detection.QD-based sensing applications are classified according to their recognition strategies,including molecularly imprinted polymers(MIPs),aptamers,and immunosensors.We discuss the advantages of QD-derived antibiotic sensors,including low cost,good sensitivity,excellent stability,and fast response,and illustrate the current challenges in this field.
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@#Coronavirus is an important pathogen of humans and animals. Among them, the novel coronavirus disease (COVID-19) breaking out in 2019 has brought a fatal threat to human health. The host"s innate immune response is the host"s first line of defense against pathogen invasion, but an excessive immune response can also aggravate viral infection and pathological damage. The immune escape of coronavirus is a critical pathogenic mechanism causing death. This work mainly reviews the pathogenic mechanism of coronavirus immune escape from several aspects such as host immunosensor, interferon, cytokine and coronavirus antagonizing host immune response, which provide a theoretical reference for the development of anti-coronavirus drugs.
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A competitive electrochemical immunosensor based on the nano-composite material immobilization and enzymatic amplification was designed for detection of microcystin-LR. Gold nanoparticles/carboxylated multi-walled carbon nanotubes (AuNPs/c-MWCNTs) composite film, which formed by electrodepositing of AuNPs on the C-MWCNTs modified glassy carbon electrode,was used for the immobilization of the antibody of microcystin-LR (anti-MCLR). Horseradish peroxidase (HRP) was introduced onto the nanocomposite interface by HRP blocked sensing interface and specific capture of antibody with target. It could be employed to catalyze the reduction of H2O2, and to block the possible remaining active sites as well. A competitive immunoreaction between antigen and MCLR-HRP was used for target analysis. In the presence of H2O2and hydroquinone (HQ),MCLR could be indirectly detected with differential pulse voltammetry (DPV) method by determining the reduction current of HQ. Under the optimal conditions, the proposed immunosensor exhibited wide linear ranges in the concentration ranges of 0.1-100.0 μg/L, with a detection limit of 0.038 μg/L (S/N = 3,n=8). The immunosensor showed good specificity, stability and sensitivity. It was used to determine MCLR in real water samples with the recoveries of 72.9%-117.3%.
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The Au-PDA-Fe3O4 decorated graphene oxide electrode was modified with Prussion blue-secondary antibodies for determination of cancer biomarker α-fetoprotein (AFP) with great sensitivity.Scanning electron microscopy (SEM), X-ray diffraction (XRD) and ultraviolet-visible absorption spectrometry were used to characterize the structure of the material.Greatly enhanced sensitivity for the cancer biomarker is based on a dual signal amplification strategy.First, Fe3O4-PDA-Au used for the biosensor platform increased the surface area to capture a large amount of primary antibodies (Ab1), which resulted in amplification of the detection response.Second, graphene oxide allowed several binding events of PB-Ab2.Enhanced sensitivity was also achieved by introducing the multibioconjugates of Ab2-PB-GO onto the electrode surface through sandwich immunoreactions.The test result shows that there are linear relationships between current and AFP concentrations ranging from 0.005 ng/mL to 1 ng/mL and 1 ng/mL to 20 ng/mL, with the low detection limit (LOD) of 1.0 pg/mL.This immunosensor is simple, low-cost and sensitive and shows a great potential in biomedicine, clinical diagnosis and health examination.
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Objective To construct an immunosensor for detecting CD4+ T lymphocytes without labeling .Methods The staphy-lococcus protein A(SPA) method was adopted to conduct the oriented immobilization of CD4 monoclonal antibodies on the gold in-terdigitated microelectrode surface for capturing CD4+ T lymphocytes .Then cyclic voltammetry(CV) method was used to conduct the representation of modification situation on the gold interdigitated microelectrode surface .Finally the electrochemical impedance spectroscopy(EIS) was used to detect the impedance of CD4+ T lymphocytes captured by the immunosensor .The standard curve was drawn by the impedance values change obtained by the equivalent electric circuit fitting .Results The linear range of this im-munosensor for detecting CD4+ T lymphocytes was (5 × 103 -5 .0 × 106 )/mL ,with lower detection limit of 5 .0 × 102/mL .Conclu-sion The constructed immunosensor has accurate and reliable detection results uhidn is simple to operate accurate ,convenient and cheap ,which might be expected to be used in the real-time detection system ,and offers help for realizing rapid ,accurate and inex-pensive CD4+ T lymphocyte count .
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Objective Todesign a novel impedimetric immunosensor basedon AgI mimic enzyme nanomaterial for detecting carcinoembryonic antigen (CEA) in serum with high sensitivity. Methods A novil chitosan modified AgI (CS-AgI) nanomaterial was synthesized and was characterized by transmission electron microscope (TEM) and Fourier transform infrared spectroscopy (FTIR). Then by utilizing CS-AgI labeled CEA antibody as tags, we prepared a novel impedimetric immunosensor on the gold electrode using the sandwich-type immunoassay. The electrochemical propertiesof the prepared impedimetric immunosensor were observed by electrochemical workstation and the concentration of CEA in sample was quantitatively analyzed. Results The synthesized CS-AgI nanoparticles were spherical in shape, with the particle size being 100 nm; the particles were employed to construct immunosensor as signal markers. The immunosensor had an excellent electrochemical performance in detection of CEA under PBS base solution of pH = 7, and its AC impedance response increased with the increase of the logarithm of CEA concentration, exhibiting a good linear relationship in the range of 0. 1ng/mL to 80ng/mL (r = 0.996), with a detection limkof 0. 05 ng/mL. Conclusion Based on AgI mimic enzyme nanomaterial, the impedance immunosensor prepared in this study shows a high sensitivity in detecting CEA; meanwhile, t has acceptable selectivity, repeatability and stability, providing an experimental evidence for early diagnosis and treatment of cancer.
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Objective To construct an electrochemical immunosensor for ultrasensitive determination of myeloperoxidase (MPO) .Methods The electrochemical immunosensor for M PO was prepared by modifying the electrode using Au-graphitized me-soporous carbon nanoparticles(AuNPs@ GMCs) hybrid and immobilizing MPO antibodies onto the glass carbon electrode surface . The effect of experimental parameters on the immunosensor and results comparison with ELISA were investigated .Results The immunosensor was sensitive to M PO with a linear relationship between 2 .000 and 300 .000 ng/mL and a correlation coefficient of 0 .999 ;the detection limit was 0 .5 ng/mL .The correlation coefficient of two methods was 0 .983 .Conclusion The immunosensor can be used for ultrasensitive detection of MPO .
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Objective To develop a new type of electrochemical immunosensor for the detection of ochratoxin A (OTA ) . Methods Double layers of self‐assembly immunosensor for the detection of OTA were constructed based on the composite single‐walled carbon nanotubes(SWNTs)/chitosan(CS) membrane immobilized on glassy carbon electrode(GC) .Scanning electron mi‐croscopy(SEM) ,square wave voltammetry and cyclic voltammetry were used to analyze the characterization of the sensor ,then its specificity for detection was studied .Results SWNTs/CS composit membrane could increase the sensitivity of OTA detection sig‐nificantly ,and effectively distinguish the different types of mycotoxins .Conclusion The electrochemical immunosensor developed in the study is easy to operate and could detect OTA rapidly with good specificity and low detection limit .
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@#An ultrasensitive electrochemical immunosensor modified with graphene and dienestrol(DE)was developed for the detection of dienestrol through indirect competition with K3Fe(CN)6 acting as the redox probes. The results revealed that under optimized conditions a calibration for DE was obtained with a linear range of 500-5 000 ng/mL and the detection limit was up to 0. 2 ng/mL, showing that the proposed electrochemical immunosensor had excellent sensitivity and wide detection range. The immunosensor was examined in real samples for the analysis of DE. A good recovery in the range of 83. 8%-97. 7% was obtained in pork samples.
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Carbon nanotubes/Au nanoparticles ( CNT/AuNP ) composite film was fabricated on glassy carbon electrode ( GCE) by first dropping CNTs on the electrode surface and then electrodeposition of AuNPs by multi-potential step. The antibody of microcystin-( leucine-arginine ) ( anti-MCLR ) was immobilized on the modified electrode surface through adsorption on AuNPs. Subsequently, bovine serum albumin ( BSA) was used to block the non-specific adsorption to obtain the immunosensor for MCLR assay. The immunosensor could effectively capture MCLR by the specific immunoreaction between the electrode surface-confined antibody and MCLR, followed by the attachment of the anti-MCLR HRP-labeled to form a sandwich-type system. The analysis of MCLR was performed based on the catalytic reaction of HRP toward the oxidation of hydroquinone ( QH2 ) by H2 O2 . Under the optimal experimental conditions, the peak current response increased linearly with the concentration of MCLR in the range of 0 . 50-12 μg/L with a detection limit of 0. 30 μg/L (S/N=3). The developed immunosensor was used to determine MCLR in real water samples, and the recoveries of standard addition experiments were in the range of 93 . 0%-108 . 5%, with the relative standard deviation of 3 . 8%-5 . 0%.
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A label-free electrochemical immunosensor using hollow structure nanomaterials based on its ordered porous and big surface area was designed. Au nanocage, with good conductivity, catalysis, and biocompatibility, was prepared and modified on the surface of glassy carbon electrode with graphene to immobilize antibody of microcystin directly. In the absence of microcystin, biosensor can obtain high current response signal of electrochemical probe ( [ Fe( CN) 6 ] 3-/4-. When microcystin was combined with its antibody specifically, the charge density and mass transfer resistance on the surface of electrode increased, resulting in a decrease of the corresponding peak current of [ Fe ( CN ) 6 ] 3-/4-. This change was in proportion to the concentration of microcystin indirectly. Experiment conditions such as cultivation time of antigen and concentration of antibody were optimized. The results showed wide linear range of 0. 05 μg/L-1. 0 mg/L and the detection limit of 0. 017 ng/mL. This sensor has good stability and simple production procedure. This sensor provides a new and simple means for the ultrasensitive determination of microcystins in real water samples.
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Objective To expand the application of electrochemical immunosensor during deleting aflatoxin B1 in foods and feeds through analyzing impacts of the time of antibody incubation and sample preparation .Methods T he double self-assembly immu-nosensor combined with aflatoxin B1 and carboxylated single-walled carbon nanotubes (SWNTs) was characterized by cyclic volta-mmetry and impacts of the time of antibody incubation and sample preparation methods were investigated .Results The signal in-creased gradually following the increasing time of antibody incubation and reached a plateau at 90 min and sample preparation meth-ods showed a comparatively large impact on results .Additionally ,the crude extractions purified through removing interfering com-pounds by immunoaffinity column could effectively eliminate the interference effects of sample matrix .Conclusion Deleting aflatox-in B1 by electrochemical immunosensor is characterized by various features ,such as fast ,simple and low detection limits .The pres-ent study shows that stability of the electrochemical immunosensor is affected by the time of antibody incubation and sample prepa-ration .
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Objective:To improve the sensitivity and the linear range of electrochemical immunosensor to detect Schistosoma japonicum (S.japonicum) antibody.Methods:Carbon inks and silver/silver chloride inks were printed on a polyethylene terephthalate (PET) board to make a two-electrode test strip,where carbon was the working electrode and S.japonicum soluble egg antigen (SEA) was fixed at one end of working electrode by different methods; silver/silver chloride electrode was used as control.We tested the valency of the antibody by cyclic voltammetry (CV) and differential pulse voltammetry (DPV) in an electrochemistry workstation,and conducted comparison with the results of ELISA.Two new immunosensing electrodes have been developed,based on glutaraldehyde cross-linked (GA) or chitosan-glutaraldehyde cross-linked (Chit-GA) transducer fixing S.japonicum antigen.We tested the titer of the antibody by means of CV and DPV.Results:Our experimental S.japonicum antigen (50 μg/L) is the optimal test concentration for the GA sensor,and 10 μg/L for Chit-GA sensors.The immune reaction time of both electrodes is all essentially complete in 1 minute.The linear range for S.japonicura antibody in human positive serum sample detection by the glutaraldehyde cross-linked immunosensor is 1∶1000 to 1∶400,and by the chitosan-glutaraldehyde cross-linked immunosensor is 1∶1000 to 1∶500.As the concentration of dilution ratio of S.japonicum antibody in human positive serum sample increased,the test value of DPV increased proportionally.Conclusion:GA sensor and Chit-GA cross-linked S.japonicum sensors have high sensitivity and broad linear range response,and both exhibited a good linear relationship between the DPV signal and the test antibody titer.
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A novel and highly sensitive voltammetric enzyme-linked immunosensor was developed based on tyramine) oxidation deposition. It was shown that gold nano-particles(colloid Au) could be used as a platform to immobilize antibodies by adsorption. By a sandwich immunossary format with goat-anti-human IgG labled Horseradish peroxidase(HRP) as the second antibody and catalytic amplification by biotin-tyramine, the immunosensor′s) catalytic ability to hydrogen peroxide increased nearly 20 times), the sensor exhibitd a linear response to human IgG in the concentration range from 1.5 μg/L-22 mg/L, and the detection limit was 0.1 μg/L), the regression equation could be expressed as Δi_p(μA) =2.8859c(mg/L)+17.152 with a correlation) coefficient of 0.9872. The immunosensor can be used to quantitatively determine hIgG in the sample) of human serum).
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A new type of amperometric immunosensor for the determination of naphthalene based on self-assemble) layer-by-layer technique was reported. The preparation procedure of such a sensor was characterized and the operation conditions, such as the pH value of supporting solution, incubated temperature and time were studied by cyclic voltammetry. Under the optimized working conditions, the current response of the immunosensor) was proportional to the concentration of naphthalene in the range of 0.5-100 μg/L with a detection) limit of 0.08 μg/L(r=0.9986). This method was applied to the naphthalene detection in river) water) samples and the recovery was ranging in 94.3%-107.0%. The reported immunosensor exhibited high sensitivity and long-term stability for naphthalene detection, and was easy to be prepared and regenerated.
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Objective To develope a new kind of piezoelectric immunosensor which could detect anti-HCV antibody in short time.Methods The corresponding sensitive material was fixed on the piezoelectric immunosensor by polyethylenimine adhesion and glutaraldehyde cross-linking method.The assembly condition and response characters were investigated and the piezoimmunosensor could be used in detection of clinical blood specimen.Results The respond of the positive serum was 4 times higher than that of negative serum.HBsAg had little interference to the detection of anti-HCV antibody.Conclusion The piezoelectric immunosensor prepared in this study is highly selective,easy to be operated for effective detection of anti-HCV antibody.
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With the development of immunoassay and sensing technologies and the solid waste compost technologies being paid more and more attention,the method of immunosensor can’t be interfered by some interference factors of the commonly used analytical methods,it is of great significance to apply the immunosensor technologies in monitoring,and real-time,online measurement during compost process. The working mechanism and classification of immunosensor are briefly introduced,and the components of the complex compost system are divided into solid phase,liquid phase and gas phase. The development and application of immunosensor in compost is introduced. The latest progress in immunosensor for determination of trace toxicants is reviewed. The application of immunosensor in environmental monitoring and its future development are also discussed.
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OBJECTIVE To develop new 2?5 type of piezoelectric immunoglobulin microarray immunosensor for determination of immunoglobulin.The energy converters are 10MHz AT-cut quartz crystals with gold-coated(electrodes).The monoclonal antibodies of immunoglobulin are immobilized onto the surfaces of crystals gold(electrodes) by staphylococcal protein A(SPA).METHODS The standard substance and serum were detected to find the detection time,temperature and specificity of the immunosensor.RESULTS The piezoelectric quartz(crystal) immunoglobulin microarray immunosensor could complete the detection in 15 min without nonspecific(response).Under the optimized conditions,the experimental results showed that the piezoelectric immunosensor had good(response) to immunoglobulin whose frequency shifts were linearly dependent on immunoglobulin (concentration) in different range.The piezoelectric microarray immunosensor had been used to detect(immunoglobulin) in serum,the analytical results given by this method were in satisfactory agreement with those given by traditional (immunoassay),with correlation coefficient of 0.94,0.94,0.94,0.92 and 0.91.(CONCLUSIONS) Piezoelectric microarray immunosensor for the determination of immunoglobulin is of high(sensitivity),high specificity,high analysis speed,unnecessary labelling,simple operation,real-time detection,(repeated) use,etc.It is suitable for (detecting) of immunoglobulin and should be used for clinical detection.