• KSBB Journal
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• v.13 no.4
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• pp.337-342
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• 1998

Immunosensor for the determination of LDL(Low-Density Lipoprotein), a good indicator for the diagnosis of atherosclerosis and hypercholesterolemia, was developed by using quartz crystal microbalance(QCM). The immunosensor consists of flow-through cell, oscillating circuit, oscilloscope, and frequency counter. FIA(Flow Injection Analysis) was applied to the QCM system for the measurement of LDL in liquid phase. Antibody showing binding affinity against LDL was immobilized on the gold electrode of a quartz crystal by covalent coupling via polyethylenimine / glutaredehyde. LDL was injected and bound to the antibody immobilized on the QCM immunosensor. The response of the immunosensor (F0 - F1) was found to be proportional to the LDL concentration from 200 $\mu\textrm{g}$/ml to 800 $\mu\textrm{g}$/ml. Operational conditions for the operation of immunosensor were also investigated in terms of sensitivity and non-specific binding.

• Bulletin of the Korean Chemical Society
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• v.31 no.11
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• pp.3259-3264
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• 2010

A label-free amperometric immunosensor has been proposed for the detection of myeloperoxidase (MPO) in human serum. To fabricate such an immunosensor, a composite film consisting of N,N-dimethylformamide (DMF), multiwall carbon nanotubes (MWCNTs) and 1-ethyl-3-methyl imidazolium tetrafluoroborate ($EMIMBF_4$) suspension was initially formed on a glassy carbon electrode (GCE). Then cerium dioxide ($CeO_2$) dispersed by chitosan was coated on the GCE. After that, MPO antibodies (anti-MPO) were attached onto the nano$CeO_2$ surface. With a noncompetitive immunoassay format, the antibody-antigen complex formed between the immobilized anti-MPO and MPO in sample solution. The immunosensor was characterized by cyclic voltammetry, transmission electron microscopy (TEM) and scanning electron microscopy (SEM). The factors influencing the performance of the immunosensor were studied in detail. Under optimal conditions, the current change before and after the immunoreaction was proportional to MPO concentration in the range of 5 to $300\;ng\;mL^{-1}$ with a detection limit of $0.2\;ng\;mL^{-1}$.

• Journal of Sensor Science and Technology
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• v.23 no.4
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• pp.278-283
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• 2014

In this study, we propose an immunosensor using zinc oxide nanorods (NRs) inside PDMS channel for detecting the influenza A virus subtype H7N9. ZnO with high isoelectric point (IEP, ~9.5) makes it suitable for immobilizing proteins with low IEP. In this proposed H7N9 immunosensor structure ZnO NRs were grown on the PDMS channel inner surface to immobilize H7N9 capture antibody. A sandwich enzyme-linked immunosorbent assay (ELISA) method with was used 3,3',5,5' tetramethylbenzidine (TMB) for detecting H7N9 influenza virus. The immunosensor was evaluated by amperometry at various H7N9 influenza antigen concentrations (1 pg/ml - 1 ng/ml). The redox peak voltage and current were measured by amperometry with ZnO NWs and without ZnO NWs inside PDMS channel. The measurement results of the H7N9 immunosensor showed that oxidation peak current of TMB at 0.25 V logarithmically increased from 2.3 to 3.8 uA as the H7N9 influenza antigen concentration changed from 1 pg/ml to 1 ng/ml. And then we demonstrated that ZnO NRs inside PDMS channel can improve the sensitivity of immunosensor to compare non-ZnO NRs inside PDMS channel.

• Journal of Microbiology and Biotechnology
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• v.17 no.9
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• pp.1445-1451
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• 2007

A sensitive optical waveguide lightmode spectroscopy-based immunosensor was developed to detect vitellogenin in seawater flatfish (Paralichthys olivaceus). For this purpose, anion-exchange column chromatography with DE-52 resin was used to purify flatfish vitellogenin from flatfish serum containing vitellogenin that had been induced using an intraperitoneal $17{\beta}$-estradiol injection. The anti-flatfish vitellogenin antibody used as the biological component of the above immunosensor was prepared using the purified flatfish vitellogenin. The change in the incoupling angle according to the complexation between the flatfish vitellogenin and its antibody, immobilized over an optical grating coupler sensor chip, was measured to calculate the sensor response. The immunosensor was quite specific to flatfish vitellogenin binding, based on no sensor response in the case of bovine serum albumin immobilization. When plotted using double-logarithmic scales, the sensor responses increased linearly in flatfish vitellogenin concentrations of 0.00675-67.5 nM, with a detection limit of 0.0675 nM. The reusability during seven repetitive measurements was reasonably fair for the preliminary screening of flatfish vitellogenin.

• Journal of Microbiology and Biotechnology
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• v.22 no.6
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• pp.849-855
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• 2012

Plant growth-promoting rhizobacteria (PGPR) pseudomonads have a large number of lipopolysaccharides on the cell surface, which induces immune responses. Cd-resistant PGPR prevalent at the Cd-affected sites under biophytostabilization was monitored. Transmissiom electron microscopy was used to the study the behavior of tolerance of PGPR to cadmium level and its effect on pseudomonad strains (Z9, S2, KNP2, CRPF, and NBRI). An immunosensor was developed by immobilizing antibody (anti-Z9 or anti-S2) against selected PGPR on a piezoelectric quartz crystal microbalance (QCM). Immunosensors were found to supplement the inherent specificity of antigen-antibody reactions with the high sensitivity of a physical transducer. On comparison of the efficiency of detection with ELISA, the spectrophotometric technique, the developed immunosensor was found to be more sensitive, fast, and reliable even after regeneration for several times. Thus, the immunosensor may be used for future detection of PGPR strains after automation of the screening process.

• Bulletin of the Korean Chemical Society
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• v.30 no.4
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• pp.955-958
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• 2009

• Biotechnology and Bioprocess Engineering:BBE
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• v.8 no.2
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• pp.112-116
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• 2003

An immunosensor based on surface plasmon resonance (SPR) onto a protein G layer by Self-assembly technique was developed for detection of Legionella pneumophila. The protein G layer by self-assembly technique was fabricated on a gold (Au) surface by adsorbing the 11-mercaptoundecanoic acid (MUA) and an activation process for the chemical binding of the free amino (-NH$_2$) of protein G and 11-(MUA) using 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride (EDAC) in series. The formation of the protein G layer by self-assembly technique on the Au Substrate and the binding of the antibody and antigen in series were confirmed by SPR spectroscopy. The Surface topographies of the fabricated thin films on an Au substrate were also analyzed by using an atomic force microscope (AFM). Consequently, an immunosensor for the detection of L. pneumophila using SPR was developed with a detection limit of up to 10$^2$CFU per mL.

• Journal of Microbiology and Biotechnology
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• v.18 no.10
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• pp.1695-1700
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• 2008

An immunosensor based on surface plasmon resonance (SPR) with enhanced performance was developed through a mixed self-assembled monolayer. A mixture of 16-mercaptohexadecanic acid (16-MHA) and 1-undecanethiol with various molar ratios was self-assembled on gold (Au) surface and the carboxylic acid groups of 16-MHA were then coordinated to Zn ions by exposing the substrate to an ethanolic solution of $Zn(NO_3)_2\cdot 6H_2O$. The antibody was immobilized on the SPR surface by exposing the functionalized substrate to the desired solution of antibody in phosphate-buffered saline (PBS) molecules. The film formation in series was confirmed by SPR and atomic force microscopy (AFM). The functionalized surface was applied to develop an SPR immunosensor for detecting human serum albumin (HSA) and the estimated detection limit (DL) was 4.27 nM. The limit value concentration can be well measured between ill and healthy conditions.

• Journal of Microbiology and Biotechnology
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• v.16 no.8
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• pp.1169-1173
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• 2006

Imaging ellipsometry (IE) for detection of binding of Escherichia coli O157:H7 (E. coli O157:H7) to an immunosensor is reported. A protein G layer, chemically bound to a self-assembled layer of 11-mercaptoundecanoic acid (11-MUA), was adopted for immobilization of monoclonal antibody against E. coli O157:H7 (Mab). The immobilization of antibody was investigated using surface plasmon resonance. To fabricate antibody spots on a gold surface, protein G solution was spotted onto the gold surface modified with an 11-MUA layer, followed by immobilizing Mab on the protein G spot. Ellipsometric images of the protein G spot, the Mab spot, and Mab spots with binding of E. coli O157:H7 in various concentrations were acquired using the IE system. The change of mean optical intensity of the Mab spots in the ellipsometric images indicated that the lowest detection limit was $10^3$CFU/ml for E. coli O157:H7. Thus, IE can be applied to an immunosensor for detection of E. coli O157:H7 as a detection method with the advantages of allowing label-free detection, high sensitivity, and operational simplicity.

• Asian Pacific Journal of Cancer Prevention
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• v.15 no.21
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• pp.9375-9378
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• 2014

Background: A piezoelectric immunosensor for early cervical cancer detection was developed involving short analyis time and less invasive technique for $p16^{INK4a}$, a protein that has been linked to cervical cancer. Materials and Methods: $5{\mu}L$ of 5.0 mg/mL $p16^{INK4a}$ antibody and then supernatant from different clinical samples from West China Second University Hospital (Sichuan, China) were dripped on the center of the AT-cut crystal through a micro-injector. Absorption of the $p16^{INK4a}$ by antibody caused a shift in the resonant frequency of the immunosensor, and the resonant frequency was correlated to the amount of the $p16^{INK4a}$ in the supernatant. Results: The greater severity of lesion grading, the greater the expression level of $p16^{INK4a}$. Conclusion: Degree of cervical cancer lesion development could be determined by detected amount of $p16^{INK4a}$ in different clinical samples.