Electrochemical Immunoassay of Human Chorionic Gonadotrophin Based on Its Immobilization in Gold Nanoparticles‐Chitosan Membrane

Abstract

A human chorionic gonadotrophin (hCG) doped gold nanoparticles -chitosan membrane was prepared for forming an immunoconjugate of horseradish peroxidase labeled hCG antibody and hCG on glassy carbon electrode. The nanoparticles provided a congenial environment of the adsorbed proteins. Thus, the immobilized HRP-labeled immunoconjugate showed good enzymatic activity for the oxidation of o-phenylenediamine by H 2 O 2 . With a competitive mechanism, an amperometric method for immunoassay of hCG up to 30 mIU mL À1 with a relatively low detection limit of 0.26 mIU mL À1 at 3s was developed. The hCG immunosensor showed good precision, high sensitivity, acceptable stability and reproducibility.

Electrochemical Immunosensor for Carcinoembryonic Antigen Based on Antigen Immobilization in Gold Nanoparticles Modified Chitosan Membrane

“…This prepared CEA immunosenor is more economic due to the low-cost ITO film electrode obtained from industrial mass production compared to the method usng a glassy-carbon electrode. 37 It possesses acceptable detection and storage stability for fabrication in batch.…”

“…36 It has been extensively used for immunoassay due to the presence of reactive amino and hydroxyl functional groups. 37,38 Since the gold surface permits an easy absorption of protein molecules, colloidal gold nanoparticles have been used as the matrix for the immobilization of antibodies or antigens [39][40][41] in order to retain the bioactivity of macromolecules. It was reported that 3-mercaptopropyl trimethoxysilane has been used to firmly adsorb gold colloids onto functionalized ITO surfaces in the previous studies.…”

“…44 It was said that this absorption could provide an assembly of gold nanoparticle multilayers and a suitable microenvironment similar to the native environment of bioconjugates in electrochemical immunoassay. 37 Thus, herein we chose this colloidal gold nanoparticles modified chitosan membrane (Au-chitosan) to immobilize CEA antigen. Although some studies using Au-chitosan to immobilize antigens on glassy carbon electrode and carbon-paste electrode have been reported, 37,45 an optically transparent and conducting ITO electrode has never been used for the immobilization of antigen to fabricate an electrochemical immunosensor.…”

“…37 Thus, herein we chose this colloidal gold nanoparticles modified chitosan membrane (Au-chitosan) to immobilize CEA antigen. Although some studies using Au-chitosan to immobilize antigens on glassy carbon electrode and carbon-paste electrode have been reported, 37,45 an optically transparent and conducting ITO electrode has never been used for the immobilization of antigen to fabricate an electrochemical immunosensor. In our work, a disposable electrochemical immunosensor for the determination of CEA has been proposed based on the antigens immobilized on a Au-chitosan modified ITO electrode surface with the competitive immunoassay format.…”

Amperometric Immunosensor for Prostate Specific Antigen Based on Co‐adsorption of Labeled Antibody and Mediator in Nano‐Au Modified Chitosan Membrane

“…It was reported that the adsorption of colloidal gold nanoparticles in a chitosan membrane (Au-chitosan) could provide a suitable microenvironment similar to the natural environment of bio-conjugates or cells in electrochemical immunoassay. [15][16][17][18][19] Although some studies using Au-chitosan to immobilize antigens on a glassy carbon electrode and carbon-paste electrode have been reported, 13,16,20 an optically transparent and conducting indium-tin oxide (ITO) electrode has never been used for the immobilization of antigen on this membrane to fabricate an electrochemical immunosensor. It was reported that simultaneous immobilization of the mediator and labeled antibody on the electrode surface has been widely used to develop the biosensors.…”