Covalent immobilization of Pseudomonas cepacia lipase on semiconducting materials

Lipase from Pseudomonas cepacia was covalently immobilized on crystalline silicon, porous silicon and silicon nitride surfaces. The various stages of immobilization were characterized using FTIR (Fourier transform infrared) spectroscopy. The surface topography of the enzyme immobilized surfaces was investigated using scanning electron microscopy (SEM). The quantity of the immobilized active enzyme was estimated by the para-nitrophenyl palmitate (pNPP) assay. The immobilized lipase was used for triglyceride hydrolysis and the acid produced was detected by a pH sensitive silicon nitride surface as a shift in the C–V (capacitance–voltage) characteristics of an electrolyte–insulator–semiconductor capacitor (EISCAP) thus validating the immobilization method for use as a biosensor.