Selective Detection of Acetylcholine Using Enzyme-Protected Quantum Dot-Attached Graphene Oxide

Abstract

Neurotransmitters are chemical messengers that have the unique function of sending signals from one nerve cell to another. Acetylcholine (ACh) is one of the major neurotransmitter that performs a vital role in regulating the peripheral nervous system and modulating the central nervous system. Several studies have been performed to detect ACh by using electrochemical analysis methods. In this study, we developed an enzyme-protected quantum dot (QD)-attached graphene Oxide (GO) (GO-QDs@Enzyme hybrid) as a biosensor for the detection of ACh. Chymotrypsin, an enzyme that belongs to the serine protease family, was immobilized on the surface of GO-attached QDs using 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide/N-hydroxysuccinimide (EDC/NHS) sulfo coupling reaction. The as-synthesized GO-QDs@Enzyme hybrids were characterized using several analytical tools such as scanning electron microscopy, Fourier transform infrared spectroscopy, Raman spectroscopy, and photoluminescence (PL) spectroscopy. The fluorescence of GO-QDs@Enzyme hybrids was quenched by ACh, and the limit of detection was calculated to be as low as 36 nM. The PL intensity of GO-QDs@Enzyme hybrids strongly depends on the various concentrations of ACh.