Porous Silicon applications in biotechnology

Biotechnology is a field in great expansion and the continuous boost for obtaining smaller and more efficient devices stimulates the increase of interest from the research community. Nanostructured materials, and among them porous silicon (PS), appear to be good candidates for coupling with biological molecules because of their peculiar characteristics. In the case of porous silicon, the most noticeable are the very large specific area, which allows the loading of large amounts of biological material in a very small volume, and the possibility to easily tailor the pore size and morphology as function of the kind of molecules to be introduced. Besides, the proven biocompatibility and non toxicity of PS allow the development of electronic devices to be directly implanted into living organisms without risk of rejection. In this thesis we mainly focus our attention on the fabrication and characterization of a porous silicon-based potentiometric biosensor for triglycerides analysis, made of a lipase immobilized on a mesoporous Si matrix. Prototypes, realized on 1 x 1 cm n+-type silicon wafers, show a very high enzymatic activity. Moreover the properties of these biosensors have been shown to be stable in a several months time interval, clearly showing their advantages with respect to traditional triglycerides detection systems. The Michaelis Menten curve is obtained to demonstrate the absence of diffusion problems. Potentiometric measurements are also shown.