Potentiometric Biosensing of Glucose by Fullerene-Based Silver Selective Electrodes

A novel methanofullerene containing pyridine pendants has been synthesized and used to fabricate a silver selective electrode. The selectivity coefficient was found to be 6.9 x10-5 and 6.2 x 10-5, respectively, for Cu2+ and Hg2+, while for other cations it was less than 10-5. It has a Nernstian behavior over a wide concentration range of Ag+ ion (5 x 10-7 to 1 x 10-1 mol L-1). The slope and linear range from the calibration graph was found to be 58.8 mV decade-1 and 5.0 x 10-7 to 1.0 x 10-1 mol L-1, respectively. The limit of detection was found to be 1 x 10-7 mol L-1. The fabricated electrodes can be used in a wide pH range (pH 4-7.5) with a response time less than 10 s. The fabricated electrodes were used for bioanalysis of glucose with silver nanoparticle as the potential redox marker. The working linear range for glucose detection was found to be 1 x 10-5 to 1 x 10-3 in phosphate buffer (pH 6.6). Parameters affecting the reaction rate such as pH and the amount of GOx and AgNPs were analyzed. The lower detection limit was 1.0 x 10-6 M. The sensors exhibited very good repeatability with %R.S.D. 6 and high sensor-to-sensor reproducibility. Application in analysis of glucose in real life sample (blood plasma) has also been demonstrated.