Gold Nanoparticle‐Based Redox Signal Enhancement for Sensitive Detection of Human Chorionic Gonadotropin Hormone

Abstract

A sensitive immunosensor for the detection of pregnancy marker, human chorionic gonadotropin hormone (hCG), was developed using the direct electrical detection of Au nanoparticles. We utilized disposable screen-printed carbon strips (SPCSs) for the development of our immunosensor, which provided cost-effective tests with the required antigen sample volume as small as 2 mL. After the recognition reaction between the surface-immobilized primary antibody and hCG, the captured antigen was sandwiched with a secondary antibody that was labeled with Au nanoparticles. Au nanoparticles were exposed to a preoxidation process at 1.2 V for 40 s, which was subsequently followed with a reduction scan on the same surface using differential pulse voltammetry (DPV). We could observe Au nanoparticle-labeled antigen-antibody complexes immobilized on the surface of SPCS using scanning electron microscopy (SEM). Additionally, the number of Au nanoparticles on the immunosensor was determined using SEM images, and showed a linear relationship with the current intensity obtained from the DPV measurements with a detection limit of 36 pg/mL hCG (612 fM, 3.6 Â 10 À4 IU/mL). Our immunosensor system, a combination of the screenprinting technology with Au nanoparticles provides a promising biosensor for various applications in life sciences.

Gold nanoparticle as an electrochemical label for inherently crosstalk-free multiplexed immunoassay on a disposable chip

“…Capture antibodies could be immobilized onto rough carbon electrode surfaces by passive adsorption [21,23,31]. 0.5 L of MaH and RaG at 0.2 mg mL −1 in PBS were dropped on two working electrodes respectively.…”

“…This method requires a preoxidization process with highly toxic Br 2 for a relatively long time. As the improvement, an electrooxidization method of AuNPs in HCl to produce electroactive AuCl 4 − has been demonstrated, which has been applied to monitor protein interactions [21][22][23] and DNA hybridization [24]. This work * Corresponding authors.…”

Gold nanoparticles based dipstick immunoassay for the rapid detection of dichlorodiphenyltrichloroethane: An organochlorine pesticide

“…By modifying the nanoparticle's (GNPs) outer layer a large variety of chemical, molecular, and biological entities can be effectively bound to it. Gold nanoparticle based immunoassay has been developed and applied increasingly in various research fields such as for the detection of hormones (pregnancy, fertility), and bacteria (Streptococcus A) (Huang, 2006;Idegami et al, 2008).…”

New Micro‐ and Nanotechnologies for Electrochemical Biosensor Development

“…Chu et al [155] were able to detect a concentration of 1 ng ml − 1 of human IgG using the method based on the precipitation of silver on colloidal gold labels. Direct electrical detection of gold was instead employed by Idegami et al [156] for the design of an immunosensor for the detection of a pregnancy marker (human chorionic gonadotropin hormone). Primary antibody was immobilized on screen -printed carbon strips and the captured antigen was sandwiched with Au -NP -labeled secondary antibody.…”