Preparation and application of immobilized C60-glucose oxidase enzyme in fullerene C60-coated piezoelectric quartz crystal glucose sensor

Immobilized fullerene C60-glucose oxidase enzyme was prepared and applied in a C60-coated piezoelectric (PZ) quartz crystal glucose sensor. The activity of the immobilized C60-glucose oxidase enzyme was investigated with an oxygen electrode detector. An optimum pH at 7.0 and optimum temperature at 30°C for activity of the insoluble immobilized enzyme were found. The useful life of the immobilized C60-glucose oxidase enzyme was sufficient with an activity of 88% after 93 days. The fullerene C60-coated PZ quartz crystal membrane glucose sensor based on immobilized C60-glucose oxidase enzyme with a home-made computer interface for signal acquisition and data processing was prepared. The fullerene C60-coated crystal sensor was employed to detect gluconic acid, a product of glucose oxidation by immobilized C60-glucose oxidase coated on porous silica plates in glucose aqueous solutions. The oscillating frequency of the quartz crystal decreased due to the adsorption of gluconic acid on fullerene C60. The immobilized enzyme PZ glucose sensor exhibited a linear frequency response to the log concentration of glucose with a slope of 5.9×102 Hz per decade (ΔHz/Δlog M) and a good lower limit of linearity (LLL) of approximately 3.9×10−5 M for glucose in aqueous solutions. The interference of various common species in the human blood, e.g. urea, creatine, galactose, cysteine, tyrosine, ascorbic acid and metal ions, to the PZ glucose sensor was also investigated. These species showed nearly no interference with the PZ glucose sensor. Effects of coating load of C60 and amount of immobilized enzyme on the frequency response of the C60-coated PZ glucose immobilized enzyme sensor were also studied and discussed.