Preparation of boronic acid functionalized carbon dots for glucose detection via enzymatic reaction of glucose oxidase

Abstract

In this study, novel BCDs materials were synthesized by one step hydrothermal carbonization using three isomers (ortho-, meta- and para-) of aminophenylboronic acid as a precursor for preparing the carbon dots, namely, o-BCDs, m-BCDs and p-BCDs. The morphology and structural properties of these BCDs were investigated by FT-IR, AFM, TEM, XPS techniques and 11B-NMR spectroscopy. From TEM and AFM image, the BCDs are single layer of graphene sheet and the fairly uniform of spherical quasi circular sheet. From XPS techniques and 11B-NMR spectroscopy, o-BCDs and p-BCDs have the similar component structures which is different from m-BCDs. The different structure leaded to the different emission bands of o-, m- and p-BCDs at 345 nm, 375 nm and 343 nm with quantum yield of 3.02%, 17.26% and 3.30%, respectively. Each BCDs material was applied as a fluorescent probe for H₂O₂ and glucose sensing application. For enzymatic glucose biosensor, the fluorescence quenching of BCDs depended on the concentration of H₂O₂ which was generated from enzymatic reaction by glucose and GOx. Interestingly, the m-BCDs served as an excellent fluorescent probe for glucose detection via enzymatic reaction with LOD of 0.857 mM and LOQ of 2.858 mM whereas o-BCDs and p-BCDs can detect only added H₂O₂ but H₂O₂ generated from enzymatic reaction by glucose and GOx cannot be determined.