Hydroxyapatite/Graphene oxide composite for electrochemical detection of L-Tryptophan

Abstract

In this work, hydroxyapatite/graphene oxide modified screen-printed electrode (SP-HAp/GO) were investigated for L-tryptophan (Trp) detection using linear sweep voltammetry (LSV) technique. HAp/GO composite was prepared by growth of HAp on GO in the simulated body fluid. Surface wettability, surface morphology and chemical functional group of the modified electrodes were determined by contact angle measurement, scanning electron microscope and Fourier transform infrared spectrometer, respectively. Contact angle of the electrode modified with HAp/GO composite is about two- and three-times larger than those of GO-modified electrode (SP-GO) and bare electrode (SP), respectively. SP-HAp/GO and SP show rough surface with cracks and pore-like structures, whereas SP-GO forms dense and smooth surface. After electrochemical determination of Trp, the linear range (7–1,000 µM) and limit of detection (LOD ∼ 5.5 µM) obtained from HAp/GO-modified electrode are better than those of bare (25–1000 µM, LOD ∼ 17.5 µM) and GO-modified (10–1000 µM, LOD ∼ 7.0 µM) electrodes. The information from this study may be useful for rapid Trp determination and for development of electrode materials used in bio-molecule sensors.