Obtenção de sensores plasmônicos baseados em nanopartículas de prata

Abstract

With the development of technology and nanoscience it has been observed a considerable rise in studies and usage of silver nanoparticles (AgNPs) in the construction of biosensors. AgNPs show interesting improvements related to its use in sensorial devices, such as: easy manipulation, low cost of acquisition, characteristic light absorption in the ultraviolet-visible region, relative high optical sensitivity to stimuli, among others aspects. The most common biosensors based in AgNPs, exploiting the Localized Surface Plasmon Resonance (LSPR) phenomenon. The maximum wavelength of absorption depends highly on the refractive index in nanoparticles’ surroundings, which makes them particularly useful in biosensors’ construction to monitor reactions that occur on its surface. Therefore, the objective of this research is to study the optimization of AgNPs’ synthesis, for the production of multilayer content platforms of AgNPs. The AgNPs will be produced through the reduction by the silver ion precursor (AgNO3) in solution using sodium borohydride (NaBH4). For the synthesis was employed different quantities of AgNO3. In addition, the temporal stability of the suspensions produced and their stabilities under different storage conditions were studied. The solution was synthesized in the optimum (more stable) condition to prepare plasmid substrates from activated glass with 3-aminopropyltriethoxysilane. The best synthesis condition was the one that used 14 mL of AgNO3 solution to 50 mL of NaBH4 solution, both 1x10-3 mol/L. The storage under light and refrigerating, provided greater maintenance of the properties of the colloidal suppression throughout the days. Optical sensitivity studies of substrates obtained with AgNPs in the best condition were obtained by obtaining light absorption spectra of substrates containing five layers of AgNPs immersed in solutions with different refractive, in which the sensitivity obtained was 160.3 nm / UIR. This value is considered high when compared to other substrates in the literature. Therefore, the plasmid substrate can be used to detect biomolecules as a plasmid sensor.