Gold nanoparticles impregnated mesoporous silica spheres for simultaneous and selective determination of uric acid and ascorbic acid

Abstract

This work reports the individual as well as simultaneous determination of ascorbic acid (AA) and uric acid (UA) by glassy carbon electrode (GCE) modified with a nanocomposite film of gold nanoparticles (Au NPs) inclusively adhered to MCM-41 type mesoporous silica spheres (Au-MSS). The impregnation of Au NPs into mesoporous silica spheres (MSS) is well established by surface characterization and electrochemical techniques. The Au-MSS modified GCE (GCE/Au-MSS) exhibits stable redox peaks, characteristics of Au NPs. Further, GCE/Au-MSS shows effective electrocatalytic oxidation of both AA and UA diminishing the overpotentials by 580 and 405mV, respectively, than at bare GCE. Similarly, GCE/Au-MSS diminishes the oxidation overpotentials of AA and UA by 200 and 210mV, respectively, relative to GCE/MSS. Differential pulse voltammetry technique is employed for the simultaneous determination of AA and UA in the presence of one another. The limit of detection is found to be 1.65μM and 2.14μM for AA and UA, respectively. The kinetic parameters like diffusion coefficient and the catalytic rate constant for the AA and UA electro-oxidations have been computed using chronoamperometric techniques. High sensitivity is displayed by the modified electrode and has been successfully employed for the analysis of UA in human blood serum.