Electrochemically Assembled Gold Nanostructures Platform: Electrochemistry, Kinetic Analysis, and Biomedical Application

A novel one-step electrochemical method for controlled synthesis of electroactive gold nanoparticles (Au NPs) in an organic medium using an organometallic precursor Au(PPh 3 )Cl [Ph = phenyl] has been proposed. The hierarchical assembly of Au nanostructures has been tuned on indium tin oxide (ITO) surface during electrochemical reduction of Au(PPh 3 )Cl using cysteamine. The Au NPs act as building blocks to form secondary structures of Au that has been confirmed using transmission electron microscopic studies. The presence of triphenylphosphine in Au film enhances the electrocatalytic activity, resulting in higher charge transfer kinetics. The cholesterol oxidase (ChOx) as a model enzyme has been immobilized on various fabricated nanostructured Au films. Direct electron transfer properties of nanostructured Au films result in third-generation cholesterol biosensor. We have investigated the biosensing performance of different Au nanostructures toward cholesterol estimation at low operating potential (+0.3 V). The high sensitivity of 4.22 AM –1 cm –2 and low detection limit of 5.49 μM of this biosensor (ChOx-Glu/Cys-Au/ITO) is due to higher current resulting from monodisperse Au NPs. In addition, this bioelectrode shows charge transfer rate constant as 247.27 s –1 and low K m app value as 0.57 mM. The biosensor shows good reproducibility, stability, and selectivity and thus can be utilized for health care diagnostics application.