Construção e caracterização de sensores SPR: influência da camada metálica e do substrato dielétrico.

Abstract

A sensor based on surface plasmon resonance (SPR) was developed, exploring di erent materials to built the substrate/metal/sample multilayer arrangement type. The multilayer arrangement de nition of a SPR sensor is crucial because it determines the conditions for sensor construction by setting its functional blocks, besides being responsible for the molecular interaction transduction to be detected, and de nes the incidence angle and wavelength of the light used for plasmons excitation at the metal and analyte interface. The quality of surface plasmons exitation in thin metal lms was investigated by changing the materials of substrate/metal pairs of the multilayer arrangement with Kretschmann structure. The sensor response characterization was performed using the optical prism PPBIO due it's trapezoid structure that facilitates instrumentation, avoiding mobile and/or rotational parts. Prisms with PC, PMMA and TOPAS polymers and glass BK7 were manufactured. The metals gold (Au), silver (Ag), copper (Cu) and aluminum (Al) were deposited on the top surfaces of the prisms. The prisms manufacture aspects, the metal layer deposition, the assembly of components in the experimental set-up and details about the software which processes the sensor response are presented. Experiments with reversible and irreversible linkage in both angular and wavelength interrogation mode were performed. The results show that the arrangement composed of PC/Al pair does not possess good response. Arrangements with Ag and Cu easily form oxide layers. Protein adsorption is more pronounced in Au lms, moderate in Ag lms and weak/absent in Cu and Al lm. Moreover the results attest the feasibility of the surface plasmons excitation in PPBIO based SPR sensors, with 1 10􀀀�6 RIU on the order of refractive index limit of detection.