“…The response of the sensor increased with increasing hCG concentration (cathodic current = 3.2 ± 5.8 (nA mL mIU -1 )[hCG concentration (mIU mL -1 )] + 71.5 ± 343.8 (nA), where the errors here represent the 95% confidence intervals; correlation coefficient, 0.92, N = 3), with the response only reaching a plateau when the hCG concentration approached 500 mIU mL -1 . This represents a useful concentration range of hCG nearly 7 times wider than that reported by several previous workers. − In addition, the detection limit of the immunosensor has been determined to be approximately 10 mIU mL -1 (defined as twice the standard deviation of the blank solution), which also compares favorably with previous work. − 6 Calibration plot showing the electrochemical immunosensor response to increasing levels of hCG. 7 Calibration plot showing the electrochemical immunosensor response to increasing levels of hCG present in a human serum sample.…”
Section: Resultssupporting
confidence: 72%
“…However, the response curve of the biosensor showed a saturation point at a relatively low hCG concentration of 75 mIU mL -1 . In an alternative design, Robinson et al attempted to coimmobilize both glucose oxidase and the hCG antibody onto a glassy carbon electrode. The binding of hCG to the antibody was used to modulate the electrochemical current arising from the catalytic activity of the enzyme, in the presence of (dimethylaminomethyl)ferrocene and glucose.…”
The development of an amperometric immunosensor for the detection of human chorionic gonadotrophin (hCG) is described. In this immunosensor, Nafion was used to immobilize an anti-hCG monoclonal antibody onto a glassy carbon electrode. A systematic study on the effects of experimental parameters such as the quantity of ethanol present in the Nafion solution, the percentage composition of Nafion, the pH of the immobilization buffer, and the concentration of antibody used for entrapment experiments on the binding between the immobilized antibody and 125I-labeled hCG has been carried out. Two immobilization methods, coimmobilization and adsorption immobilization, have then been attempted. A binding of approximately 3% was obtained in the former method, while 5.5% binding was achieved in the latter. On the basis of these results, adsorption immobilization was employed to entrap antibody on the electrode surface. A sandwich assay was then developed for hCG in which the enzyme horseradish peroxidase was conjugated to a second anti-hCG monoclonal antibody. The activity of the enzyme was determined electrochemically by the reduction of benzoquinone to hydroquinone. Binding of hCG to immobilized antibody determines the quantity of enzyme-conjugated antibody at the electrode surface, permitting the quantification of hCG. By a standard additions calibration method of hCG performed in blank human serum samples, the immunosensor exhibits a limit of linearity at 200 mIU mL-1 and a detection limit of 11.2 mIU mL-1 (based on twice the standard deviation of the blank solution).
“…The response of the sensor increased with increasing hCG concentration (cathodic current = 3.2 ± 5.8 (nA mL mIU -1 )[hCG concentration (mIU mL -1 )] + 71.5 ± 343.8 (nA), where the errors here represent the 95% confidence intervals; correlation coefficient, 0.92, N = 3), with the response only reaching a plateau when the hCG concentration approached 500 mIU mL -1 . This represents a useful concentration range of hCG nearly 7 times wider than that reported by several previous workers. − In addition, the detection limit of the immunosensor has been determined to be approximately 10 mIU mL -1 (defined as twice the standard deviation of the blank solution), which also compares favorably with previous work. − 6 Calibration plot showing the electrochemical immunosensor response to increasing levels of hCG. 7 Calibration plot showing the electrochemical immunosensor response to increasing levels of hCG present in a human serum sample.…”
Section: Resultssupporting
confidence: 72%
“…However, the response curve of the biosensor showed a saturation point at a relatively low hCG concentration of 75 mIU mL -1 . In an alternative design, Robinson et al attempted to coimmobilize both glucose oxidase and the hCG antibody onto a glassy carbon electrode. The binding of hCG to the antibody was used to modulate the electrochemical current arising from the catalytic activity of the enzyme, in the presence of (dimethylaminomethyl)ferrocene and glucose.…”
The development of an amperometric immunosensor for the detection of human chorionic gonadotrophin (hCG) is described. In this immunosensor, Nafion was used to immobilize an anti-hCG monoclonal antibody onto a glassy carbon electrode. A systematic study on the effects of experimental parameters such as the quantity of ethanol present in the Nafion solution, the percentage composition of Nafion, the pH of the immobilization buffer, and the concentration of antibody used for entrapment experiments on the binding between the immobilized antibody and 125I-labeled hCG has been carried out. Two immobilization methods, coimmobilization and adsorption immobilization, have then been attempted. A binding of approximately 3% was obtained in the former method, while 5.5% binding was achieved in the latter. On the basis of these results, adsorption immobilization was employed to entrap antibody on the electrode surface. A sandwich assay was then developed for hCG in which the enzyme horseradish peroxidase was conjugated to a second anti-hCG monoclonal antibody. The activity of the enzyme was determined electrochemically by the reduction of benzoquinone to hydroquinone. Binding of hCG to immobilized antibody determines the quantity of enzyme-conjugated antibody at the electrode surface, permitting the quantification of hCG. By a standard additions calibration method of hCG performed in blank human serum samples, the immunosensor exhibits a limit of linearity at 200 mIU mL-1 and a detection limit of 11.2 mIU mL-1 (based on twice the standard deviation of the blank solution).
“…Data from Figure show a linear range up to 600 mIU/mL and slightly lose linearity at higher concentrations, following a second degree polynomial equation. This linear range is several times wider than those reported previously. – …”
The aim of this study was the fabrication and characterization of biomembranes by the phase inversion (PI) method followed by their subsequent casting onto screen-printed electrodes (SPE) for biomedical applications. The combination of multiwalled carbon nanotubes (MWCNT) as a transducer with polysulfone (PSf) polymer enables easy incorporation of biological moieties (hormones or antibodies), providing a 3D composite with high electrochemical response to corresponding analytes. Antibody/MWCNT/PSf biosensors were characterized by confocal scanning laser microscopy (CSLM), scanning electron microscopy (SEM), and electrochemical methods. For biomedical purposes, human chorionic gonadotropin (hCG) hormone was tested by competitive immunoassay. The detection limit was determined to be 14.6 mIU/mL with a linear range up to 600 mIU/mL. We concluded that the easy and fast incorporation of biomolecules by the PI method, as well as their stability and distribution throughout the 3D polysulfone composite, are testament to the utility for the versatile fabrication of biosensors for clinical diagnosis.
“…This method showed a good relationship for determination of the histamine concentration in the range from 200 to 2000 ng mL -1 . Antibodies conjugated with different enzymes such as glucose-6-phosphate dehydrogenase, glucose oxidase, catalase, and peroxidase − has been applied for electrochemical immunoassay. However, the enzyme-conjugated antibody system required the addition of external reagents and incubation procedures.…”
mentioning
confidence: 99%
“…6 This method showed a good relationship for determination of the histamine concentration in the range from 200 to 2000 ng mL -1 . Antibodies conjugated with different enzymes such as glucose-6-phosphate dehydrogenase, 7 glucose oxidase, 8 catalase, 9 and peroxidase [10][11][12] has been applied for electrochemical immunoassay. However, the enzyme-conjugated In this paper, a new approach for electrochemical immunoassays based on the utilization of encapsulated electrochemical signal-generating microcrystals (e.g., redox-active microcrystals) is described.…”
A new approach to perform electrochemical immunoassay based on the utilization of encapsulated microcrystal was developed. The microcrystal labels create a "supernova effect" upon exposure to a desired releasing agent. The microcrystal cores dissolve, and large amounts of signal-generating molecules diffuse across the capsule wall into the outer environment. Layer-by-Layer (LbL) technology was employed for the encapsulation of electrochemical signal-generating microcrystals (ferrocene microcrystals). The encapsulated microcrystals were conjugated with antibody molecules through the adsorption process. The biofunctionalized microcrystals were utilized as a probe for immunoassays. The microcrystal-based label system provided a high-signal molecule to antibody (S/P) ratio of 10(4)-10(5). Microcrystal biolabels with different antibody surface coverage (1.60-5.05 mg m(-2)) were subjected to a solid-phase immunoassay for the detection of mouse immunoglobulin G (M-IgG) molecules. The microcrystal-based immunoassay for the detection of M-IgG performed with microcrystals having antibody surface coverage of 5.05 mg m(-2) showed a sensitivity of 3.93 nA microg(-1) L(-1) with a detection limit of 2.82 microg L(-1).
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