Estudo da interação da peroxidase de raiz forte em interfaces nanoestruturadas

Abstract

SCHMIDT, T. F. Study of horseradish peroxidase interaction in nanostructured interfaces. 2008. 150 f. Dissertation (Master degree) – Instituto de Fisica de Sao Carlos, Universidade de Sao Paulo, Sao Carlos, 2008. A study has been performed on the interaction of the enzyme horseradish peroxidase (HRP) in nanostructured interfaces and their possible application in biosensors for hydrogen peroxide. The nanostructured films were obtained with the Langmuir, Langmuir-Blodgett (LB) and layer-bylayer (LbL) methods. The interaction between HRP and species at interfaces was investigated using materials that served as matrix for immobilization, viz. chitosan (Ch) and the phospholipid 1,2-dipalmytoil-sn-glycero-3-[phosphatidyl-rac-(1-glycerol)] (sodium salt) (DPPG). The Langmuir films were characterized with surface pressure, surface potential, elasticity measurements and polarization-modulation reflection and absorption infrared spectroscopy (PMIRRAS). For LB and LbL films, use was made of fluorescence, absorption in the UV-vis. and infrared spectroscopy. HRP displayed strong interaction with DPPG, which was confirmed in Langmuir films with measurements of surface pressure, dynamic elasticity and PM-IRRAS. The mass of HRP transferred onto a solid support in a mixed LB film with DPPG was 200 ng, according to data from a quartz crystal microbalance. The HRP activity was preserved in the mixed LB film, with a catalytic activity that was even higher than in solution or in LbL films of HRP/Ch. The catalytic activity measurements did not affect the morphology of the LB films, studied with atomic force microscopy (AFM), in contrast to the LbL films. The main conclusion is that HRP immobilization is more efficient in an LB film with a phospholipid matrix, with good prospects for developing biosensors for hydrogen peroxide.