High sensitivity detection of glucose with negatively charged gold nanoparticles functionalized the gate of AlGaN/GaN High Electron Mobility Transistor

Abstract

A high sensitivity glucose sensor using AlGaN/GaN based high electron mobility transistor (HEMT) was fabricated. The 3-aminopropyltriethoxysilane (APTES) was aligned to the GaN surface by forming the covalent linkage between them. The negatively charged gold nanoparticles (AuNPs) can be effectively self-assembled on the positively charged APTES surface. The morphology of the immobilized AuNPs was observed by the field emission scanning electron microscope (FE-SEM). The chemical groups after APTES/AuNPs functionalization were confirmed by X-ray photoelectron spectroscopy (XPS). Glucose oxidase (GOx) was immobilized on the APTES/AuNPs functionalized the gate surface through electrostatic attraction. From the analysis of the current signals, our glucose sensor exhibited wide detection range from 0.001 to 9 mM with higher sensitivity of above 1 × 106 μA mM-1 cm-2. It showed a quick response time of less than 8 s and a detection limit of 1 nM. Furthermore, it was found that the performance of detection after AuNPs attachment can be increased by 15 % as compared to the HEMT sensor without AuNPs. The apparent Michaelis-Menten constant KMαpp was calculated about 0.06 mM, indicating high affinity of GOx to glucose. Consequently, proposed strategy for the AuNPs-gated AlGaN/GaN HEMT could be an efficient immobilization platform for biosensing of the different bio-analytes.