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Using tetraethoxysilane and 3-aminopropyltriethoxysilane as the silica sources, amino-functionalized mesoporous silica thin films with 3-dimensional cubic structure have been deposited on conducting ITO substrate in the presence of surfactant F127 templates under acid conditions. The acetylcholinesterase (AchE) and cytochrome c (Cyt c) were incorporated into the pores of mesoporous thin films, and an amperometric biosensor was obtained. After adsorption of AchE and Cyt c, the ordered cubic structure of mesoporous silica and the bioactivities and electrochemical activities of the immobilized protein and enzyme molecules were retained. The sensor properties of the biosensor were investigated by using acetylthiocholine iodide as the substrate and Cyt c as the electron transfer mediator. The inhibition versus the logarithm of concentration was found to be linear to organophosphorus pesticide dichlorvos over the concentration ranges of 1.0×10-8 mol/L to 1.0×10-3 mol/L with the detection limit of 3.1×10-9 mol/L. [ABSTRACT FROM AUTHOR]