Use of silver nanoparticles as an electron transfer facilitator in electrochemical ligand-binding of haemoglobin

Abstract

Silver nanoparticles have an activity for high intensity electron transfer. They can facilitate the electron transfer from the redox centre of a protein, as a high volume molecule, to the electrode surface. In this study, silver nanoparticles were deposited on the surface of a graphite carbon electrode in the 1 V potential region. Deposition of silver nanoparticles, with a diameter between 70 and 150 nm, was observed on the graphite electrode by transmission electron microscopy (TEM). The results demonstrated that the fine redox waves of haemoglobin could be achieved after modification of the graphite electrode by silver nanoparticles. The cathodic and anodic peaks of haemoglobin were at −135 and +375 mV vs. Ag/AgCl, respectively. The effect of guanosine 3′,5′-triphosphate (GTP), guanosine diphosphate (GDP) and guanosine monophosphate (GMP) on the structure of haemoglobin was investigated. It was observed that GTP shifts the cathodic and anodic peaks positively, indicating the transfer of the haem group to the surface of protein as a reflex of easier oxidation and reduction, while GDP and GMP do not show this behaviour. GTP binds with haemoglobin, while GDP and GMP do not.