Vertically aligned Pt nanowire array/Au nanoparticle hybrid structure as highly sensitive amperometric biosensors

Abstract

In recent years, vertically aligned nanowires have been investigated in a range of sensor development for high sensitivity and selectivity detection. In this research, a novel 3D hybrid structure based on vertically aligned Pt nanowire array (PtNWA) coated with Au nanoparticles has been developed as highly sensitive electrochemical biosensors. The vertical Pt nanowire array has been prepared by an electrodeposition method within anodic aluminum oxide (AAO) membranes; then a controllable electroless plating procedure was applied to deposit Au nanoparticles uniformly onto the surface of the Pt nanowires. Finally, glucose oxidase (GOD) enzyme was immobilized on the surface of Au nanoparticles with two widely used enzyme immobilization methods (1-Ethyl-3-(3-dimethylaminopropyl) carbodiimide/N-hydroxysuccinimide (EDC/NHS) crosslinking and glutaraldehyde crosslinking). This nanowire/nanoparticle hybrid structure resulted in higher density of Au nanoparticles than traditional 2D planar electrode modification method. The high density of Au nanoparticles could significantly increase the density of glucose oxidase enzyme immobilized, resulting in better sensing ability. The electron transfer could be enhanced by the 3D vertically aligned Pt nanowire array, leading to higher signal to noise ratio. The electrochemical performances under two different enzyme immobilization methods were studied. The results showed that the PtNWA/AuNPs/GOD sensor exhibited a sensitivity of 184μAmM−1cm−2, a limit of detection of 15μM, and high selectivity toward the detection of glucose, by using the EDC/NHS immobilization method. The storability and real sample tests have also been investigated. This novel nanowire array/nanoparticle hybrid structure, with appropriate enzyme immobilization, can be used as a platform for quantitative measurements of a variety of biomolecules.