Glucose biosensor using fluorescence quenching with chitosan-modified graphene oxide

A novel graphene oxide (GO) nanomaterial, which was rapidly and simply synthesised and conjugated with low-molecular-weight chitosan (CS), was used to develop a simple, sensitive GO biosensor system for glucose detection by fluorescence resonance energy transfer. The GO-CS was used to detect low concentrations of glucose based on competitive binding with maltose-binding protein (MBP). The α-subunit of recombinant phycocyanin (rPC), which emits far-red fluorescence, was used to label MBP (MBP-rPC). The rPC emission was quenched by binding between GO-CS and MBP. However, in the presence of glucose, GO-CS was out-competed for binding to MBP, leading to rPC fluorescence. Glucose was sensitively and selectively detected with this biosensor, with a linear detection range of 0.1-1 mg glucose/ml. The limit of detection for glucose was ~0.05 mg/ml.