Use of the ionic liquid, l-butyl-3-methylimidazolium tetrafluoroborate in the optimization of the performance of amperometric biosensors

摘要

Cholesterol and Glucose biosensors were prepared by deposition of cholesterol oxidase and glucose oxidase respectively entrapped within a U.V. crosslinked poly (2-hydroxyetbyl methacrylate), [p(HEMA)] hydrogel containing tetraethyleneglycol diacrylate onto a platinum electrode. The performance characteristics for the Pt/p(HEMA)/ChOx biosensor were as follows: Response time of 50 seconds at all cholesterol concentrations investigated, detection limit of 3.0 x 10~(-6) M, liner range of 3 x 10~(-5) -1.6 x 10~(-2) M of cholesterol, sensitivity of 56510 μA/M, working potential of+450mV with a regression value of 0.986 for the calibration curve (y = 5.651x). The Pt/ p(HEMA)/GOx optimized sensor parameters were: an enzyme loading of 1365 units GOx/cm~2;aHEMA:TEGDAratio of 2.75:1% vol.; a film thickness of 0.2mm; a stirring speed of 450 r.p.m, and a temperature optimum of 50°C, a linear response over a glucose concentration range of 1 x 10~(-5) to 1 x 10~(-3) mM (r=0.994), with a detection limit of 6.0 x 10~(-6) M, with a response time of 45 seconds at all glucose concentrations investigated. These biosensors retained an average of 90% of initial enzyme activity when stored in the ionic liquid, [bmim] [BF4], at 4 °C after six months.