Cholesterol-LDL Biosensor Based on P450scc-Functionalized Electrodes and Stand-Alone Driver Electronics

Bezerra Correia Tercio, Enrico Stura and Claudio Nicolini

Nanoworld Institute, University of Genoa, Corso Europa 30, 16132 Genoa, Italy




Cytochrome P450scc has been used as sensing molecule for the detection of LDL-Cholesterol levels in acqueous solution, as preliminary study for blood analysis. Since the electron transfer response of the biological system is very low in statical conditions (below the normal sensitivity of common electronic equipments), a cyclic voltammetry experiment must be carried out, sweeping the voltage across a range of potential where the oxidation of Cholesterol occurs. The reaction is detected measuring the current during the process. This operation is normally performed by means of controlled potentiostatic/galvanostatic laboratory instruments. To obtain a stand-alone portable device, a triangular wave function generator has been realized using operational amplifiers networks, controlling the period, the amplitude and the offset of the generated wave, while the current is constantly measured and its maximum value is kept as output value. This parameter is recorded by means of a "sample and hold" system. Preliminary results of acqueous solutions of LDL-Cholesterol revealed a sensitivity of 50 uM/cm2.