Construction of Hemoglobin-Platinum Nanoparticle Hybrid System for Studying of Longe-Range Interfacial Electron Transfer by Electrochemical Techniques

A hybrid of the hemoglobin (Hem) and a ۴-۵ nm platinum nanoparticle (PtNP) on Au electrode (AuE) was prepared. In the hybrid system, PtNPs was attached to the AuE via ۱,۶ hexandithiol (۱,۶ HDT) monolayer and capped with captopril (capt) molecule then electrostatically conjugated with Hem. The AuE/PtNP/Hem hybrid system was characterized by cyclic voltammetry (CV) and scanning electrochemical microscopy (SECM). CV shows a very closely ideal protein voltammetric response with low peak separation in both low and very high scan rates.It is suggested that on curved nanoscopic PtNPs, the density of immobilized Hem smaller than PtNP free monolayer and resultant low electrostatic repulsion between Hem molecules during reduction or oxidation. Moreover, enhancement of the interfacial electron transfer (ET) rate of AuE/PtNP/Hem system compared with capt/Hem was observed. SECM approach curves were recorded at different Hem coverages and at different substrate potentials to measure both the kinetics of the bimolecular ET between a Fe(CN)۶-۴ as a redox mediator and immobilized Hem and the tunneling ET between Hem and the AuE. These studies gave fast rate constants, ۲×۱۰۹ cm۳mol-۱s-۱ for bimolecular and ۵۰.۵ s-۱ for tunneling ET rate constants.

کلیدواژه ها:

Hemoglobin ، Platinum nanoparticle ، Captopril ، Self Assembled Monlayer ، Interfacial electron transfer.