Development of an electrochemical biosensor based on mesoporous silicon containing carbon nanotubes obtained by a sol-gel process. Electrochemical determination of pesticides.

Abstract

In this project the objective is related to the development of a biosensor based in the immobilization of acetilcholinesterase biomolecule in a mesoporous silicon matrix contaning carbon nanotubes, which will be used in the electrochemical determination of pesticides in foodstuffs. In the firs part of this project the non-ordered silica matrizes containing different amounts of nanotubes (10, 20 and 30%) will be synthesized by a Sol-Gel process using HF as the acid catalyst. In a second step, this silica matrixes will be used as substrate for the biomolecule immobilization. To that, the electrode will be immersed in a Britton-Robinson buffer solution containing the enzyme acetylcholinesterase allowing its adsorption by the modified surface. Changes in the structural properties of the surfaces will be studied. To do so, BET will be used to evaluate the surface area, transmission electronic microscopy will furnish the surface morphology, together with atomic force microscopy and scanning electron microscopy. Elemental analysis of C, H and N will determine the adsorption of enzyme on the modified surface. The electrochemical properties of the biosensor will be evaluated by electrochemical techniques such as cyclic voltammetry, pulses voltammetry, chronoamperometry, etc. The efficiency of the biosensor will be analysed by the inhibition caused by the carbamates and organophosphorous pesaticides in the acetylcholinesterase activity by hydrolises the neurotransmitter acetylthiocholine. The percentage of inhibition will be evaluated as a function of pesticide concentration and the analytical curve will be used to monitoring the pesticides concentrations in samples of cabbage, tomato, strawberry, etc.