Adsorções de proteínas em superfícies nanoestruturadas de prata caracterizadas por espectroscopia SERS

Abstract

Proteins are macromolecules that perform several vital functions in organisms, being made up of chains of amino acids. Using Surface Enhanced Raman Scattering (SERS) spectroscopy, it was possible to investigate mechanisms of interaction between the amino acid L-Methionine (MET), the dipeptide L-Carnosine (CAR), the protein of Bovine Serum Albumin (BSA) and Anti-Bovine Serum Albumin antibody (Anti-BSA) and Anti-folate receptor antibody (Anti-FOL) antibodies with the surface of nanostructured containing silver nanoparticles (AgNPs). Through UV-VIS-NIR spectroscopy, the localized surface plasmon resonance (LSPR) of the synthesized nanoparticles was monitored before and after centrifugation/resuspension in aqueous medium, in order to have an initial estimate of the size distribution, which was obtained by Dynamic Light Scattering (DLS), which resulted in an average value around 21 nm before and at 25 nm after centrifugation/resuspension. The surface charge of -43,1 mV before and 5,94 mV after centrifugation/resuspension was measured, indicating colloidal stability. The nanostructured silver surfaces (AgNS) were built on a glass plate, and in the case of protein samples, the metallic surface was modified with 2- Mercaptoethanol (ME). In the surfaces with the presence of this surface modifier generator of hydrogen bonds, the proteins were adsorbed preserving a unique spectral pattern SERS. In the absence of ME, the proteins showed different adsorption therefore, different SERS spectral patterns indicating that ME anchors macromolecules on the silver surface. Through vibrational assignment it was proposed tyrosine is involved in the formation of hydrogen bonds with ME, working as anchorage points for the adsorption of three proteins.