Enhanced conductometric immunoassay for hepatitis B surface antigen using double-codified nanogold particles as labels
ABSTRACT A new conductometric immunoassay for hepatitis B surface antigen (HBsAg) was developed based bioelectrocatalytic reaction on a microcomb-type electrode by using double-codified nanogold particles as labels. This microcomb-type electrode was fabricated on an interdigitated transducer covered with a well-ordered anti-HBs/protein A/nanogold architecture. The double-codified nanogold particles were prepared by using nanogold-labeled anti-HBs antibodies conjugated with horseradish peroxidase (HRP). Sandwich-type immunoassay protocol was successfully introduced for the detection of HBsAg. The formation of the immunocomplex changed the direct electrical communication between the carried HRP and the electrode, and thus local conductivity variations could be assayed based on the bioelectrocatalytic reaction of the carried HRP in 0.01 M PBS (pH 7.0) containing 60 μM H2O2, 0.08 M KI and 0.1 M NaCl. Under optimized conditions, the linear range obtained by using HRP-conjugated anti-HBs as secondary antibodies was 1.5–450 ng/mL HBsAg, while the assay sensitivity by using double-codified nanogold particles could be further increased to 0.01 ng/mL with the linear range from 0.1 to 600 ng/mL HBsAg. The developed immunoassay method showed good precision, high sensitivity, acceptable stability and reproducibility, and could be used for the detection of real sample with consistent results in comparison with those obtained by the ELISA method.
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ABSTRACT: Nanostructured materials are promising compounds that offer new opportunities as sensing platforms for the detection of biomolecules. Having micrometer-scale length and nanometer-scale diameters, nanomaterials can be manipulated with current nanofabrication methods, as well as self-assembly techniques, to fabricate nanoscale bio-sensing devices. Nanostructured materials possess extraordinary physical, mechanical, electrical, thermal and multifunctional properties. Such unique properties advocate their use as biomimetic membranes to immobilize and modify biomolecules on the surface of nanoparticles. Alignment, uniform dispersion, selective growth and diameter control are general parameters which play critical roles in the successful integration of nanostructures for the fabrication of bioelectronic sensing devices. In this review, we focus on different types and aspects of nanomaterials, including their synthesis, properties, conjugation with biomolecules and their application in the construction of immunosensing devices. Some key results from each cited article are summarized by relating the concept and mechanism behind each sensor, experimental conditions and the behavior of the sensor under different conditions, etc. The variety of nanomaterial-based bioelectronic devices exhibiting novel functions proves the unique properties of nanomaterials in such sensing devices, which will surely continue to expand in the future. Such nanomaterial based devices are expected to have a major impact in clinical immunodiagnostics, environmental monitoring, security surveillance and for ensuring food safety.Sensors 01/2010; 10(7):6535-81. · 1.74 Impact Factor