Performance characteristic studies of glucose biosensors modified by (3-mercaptopropyl)trimethoxysilane sol–gel and non-conducting polyaniline

The materials (3-mercaptopropyl)trimethoxysilane (MPTMS) sol–gel and non-conducting polyaniline (PAn) were prepared for coating on two different amperometric biosensors fabricated by the immobilization of glucose oxidase (GOx) in conducting polyaniline (PA) as permselective membranes. A few performance characteristics of the MPTMS and the PAn-modified glucose sensors are comparable. In detecting 1 mM glucose, the biosensors’ response times were 11 and 12 s, respectively, and results from the repeating measurements (N = 10) showed that R.S.D. = 2.09 and 1.70%, respectively. The detection linearity of the two biosensors was up to 12.5 mM with R = 0.9989 and 0.9969. When they were used to detect 0.5 mM of ascorbic acid (AA), uric acid (UA), and acetaminophen at an anodic potential of 0.4 V, current signals were either insignificant or invisible. The PAn-coated glucose sensor exhibited superior sensitivity at 18.91 μA/(mM cm²), and a maximum current density of 3.70 mA/cm². GOx in the MPTMS-modified biosensor presented a stronger affinity to glucose with K_m = 48.87. More importantly, the stability of this biosensor is superior to that of the PAn-modified biosensor and has lasted for almost 5 months.