Thiolated DAB Dendrimer-Gold Nanoparticles Self-Assembled Monolayer as Covalent Support for Direct Electrochemistry of HRP and Sensing Applications

M Pilar García Armada

doi:10.26717/bjstr.2019.13.002442

Abstract

A thiolated DAB dendrimer has been employed to bond gold nanoparticles of several sizes in order to obtain an electrocatalytic framework for the covalent immobilization and direct electrochemistry of horseradish peroxidase (HRP). This biosensor must represent the basis for developing a lot of oxidase-peroxidase bienzymatic biosensors and heavy metals biosensors based on the HRP inhibition. The kinetic study of the modified electrodes showed that the 5 nm and 16 nm gold nanoparticles are the most efficient to contact with the HRP active centre and the optimized biosensor allow to measure hydrogen peroxide at -0.3 V applied potential in linear ranges of 1-5000 and 1-140 or 140-5000 respectively with high sensitivities of 418.6 and 266.3 u A mM-1 cm-2 respectively too with low detection limits of 5 and 9 nM and fast response. The obtained apparent Michaelis-Menten constants, were 0.16 and 0.84 mM respectively. Both are significantly lower than the intrinsic K´M revealing the very high enzymatic efficiency of the developed devices.

Highlights

horseradish peroxidase (HRP) is widely used in hydrogen peroxide amperometric biosensors of 2nd and 3rd [1,2,3,4,5] generations because the possibility of stablish direct electrochemistry with the electrode material
This biosensor must represent the basis for developing a lot of oxidase-peroxidase bienzymatic biosensors and heavy metals biosensors based on the HRP inhibition
The kinetic study of the modified electrodes showed that the 5 nm and 16 nm gold nanoparticles are the most efficient to contact with the HRP active centre and the optimized biosensor allow to measure hydrogen peroxide at -0.3 V applied potential in linear ranges of 1-5000 and 1-140 or 140-5000 respectively with high sensitivities of 418.6 and 266.3 A mM-1 cm-2 respectively too with low detection limits of 5 and 9 nM and fast response

Summary

Introduction

HRP is widely used in hydrogen peroxide amperometric biosensors of 2nd and 3rd [1,2,3,4,5] generations because the possibility of stablish direct electrochemistry with the electrode material. In order to develop 3rd generations biosensors, three-dimensional nanoparticle materials as gold nanoparticles (AuNPs), constitutes a favourable surface for the immobilization of biomolecules because maintain their biological activity and favouring longer stability and higher reproducibility [8] by their ability to form S-Au bonds with the thiol and amine groups. Due to their nanometric size, AuNPs confine the enzymes in the proper orientation onto the electrode surface, acting as nanoelectrodes.On the other hand, The dendrimers combine the physical and chemical desired properties with tuneable solubility and surface reactivity. We present the kinetic and analytical characterization of a new sensitive DAB-SAuNPs-HRP peroxide biosensor with the intention of develop the basis of different bienzymatic oxidase-peroxidase or inhibition biosensors

Methods

Results

Conclusion