Gold Nanoparticles Doped Three‐Dimensional Sol‐gel Matrix for Amperometric Human Chorionic Gonadotrophin Immunosensor

Abstract

A novel electrochemical immunosensor for human chorionic gonadotrophin (hCG) was proposed by immobilization of hCG in gold nanoparticles doped three-dimensional (3D) sol-gel matrix and an interfacial competitive immunoreaction. The 3D organized composite structure was prepared by assemble of gold nanoparticles into a hydrolyzed (3-mercaptopropyl)-trimethoxysilane sol-gel matrix, which showed good biocompatibility. After the interfacial competitive immunoreaction the formed HRP-labeled immunoconjugate showed good enzymatic activity for the oxidation of o-phenylenediamine by H 2 O 2 . With a competitive format, a method comprising of ophenylenediamine-H 2 O 2 -immobilized HRP labeled hCG immunoconjugate system for immunoassay of hCG from 5.0 to 30.0 mIU mL À1 was developed. The immunosensor showed good precision, high sensitivity, acceptable stability and reproducibility and could be used for detection of hCG in human serum with the consistent results in comparison with those obtained by a commercial analyzer.

Selective determination of dopamine using quantum-sized gold nanoparticles protected with charge selective ligands

“…The GS-Au 25 modified electrode was prepared by a two-step process 37 in which a three-dimensional sol-gel matrix is first formed, followed by immobilization of GS-Au 25 into the sol-gel matrix. In a typical procedure, the sol-gel stock solution was prepared by mixing 0.36 mL of MPTMOS with 0.1 mL of water, 0.05 mL of ethanol and 0.017 mL of 0.1 M HCl, followed by sonication for 30 min until a clear solution was obtained.…”

Control of Tumor Markers Using Nanotechnology

“…Thus, several electrochemical methods have been reported for hCG [84], CEA [85] and CA 125 [86] determination in serum using HRP-antibody conjugated as tracer. These assays are based on the immobilization of the antigen in AuNPs coated on the surface of a glassy carbon [84,86] or an indium-tin oxide [85] electrode, using trimethoxysilane [84], chitosan [85] or cellulose acetate [86] to stabilize the AuNPs in the corresponding electrode. After the interfacial competitive immunoreaction, the tracer showed enzymatic activity for the oxidation of o-phenylenediamine by hydrogen peroxide.…”

“…In some instances, these NPs are only used as nanoscaffolds to improve the immobilization of the antibodies [19,20,84], although other methods involve the measurement of a property of the AuNPs, which is correlated with the analyte concentration, such as SPR [63], light scattering [48,49] and color intensity image [64][65][66]. The lowest LOD reported corresponds to a sandwich assay using this last detection system [65].…”

“…The direct assay only requires the measurement of the change in electrode potential upon binding of the antigen to the antibody. The other [66] [84] microfluidic device, described for the determination of PSA, AFP and CEA [92], involves the use of a microchip-based multiplex electro-immunosensing system, AuNPs and silver enhancer. The method uses a sandwich format in which capture antibodies were immobilized onto polystyrene microbeads and the secondary antibodies were conjugated to AuNPs.…”

Raspberry-Like Bismuth Oxychloride on Mesoporous Siliceous Support for Sensitive Electrochemical Stripping Analysis of Cadmium

“…However, these methods heavily rely on professional instrumentations that may not be suitable for the field and on-spot applications. Electrochemical methods that possess qualities of portability, ultra-sensitivity, readiness and low cost [ 10 , 11 ] are useful and efficient methods for the trace determination of heavy metals [ 12 ]. In particular, anodic stripping voltammetry (ASV), which involves an effective preconcentration step in addition to sensitive electroanalysis generating a high signal-to-noise ratio, has been employed for such a purpose during the last decade [ 13 , 14 , 15 , 16 , 17 , 18 , 19 , 20 , 21 ].…”