Design of nanocomposites with applications in sers-based biodetection

Resum

Surface Enhanced Raman Scattering (SERS) is a spectroscopic technique that records greatly enhanced Raman scattering from molecules on or in close proximity of metal nanostructures that support localized surface plasmon resonances (LSPRs). Enhancement factors can be as high as 1014-15, which in some cases are sufficient to allow even single molecule detection. SERS combines the molecular specificity of vibrational Raman spectroscopy with high sensitivity due to plasmon-assisted scattering. These features render SERS a highly versatile technique with potential application in very diverse fields and particularly interesting toward the study of biomolecules and biologically relevant analytes. However, the direct detection of analytes in real complex biological media remains a challenge. Usually, SERS analysis of biological media results in a very complicated vibrational spectrum due to the presence of a huge amount of different moieties. Thus, it is clear that the advancement in direct SERS biodetection is linked to the clever design of new nanostructured materials that can avoid the direct contact of the plasmonic nanoparticles with the biological media. In this context, hybrid materials that combine metal nanoparticles with mesoporous thin films appear to be an interesting nanocomposite for direct SERS-based biodetection. Study of biomolecules by SERS spectroscopy is an emerging tool due to the high potential of SERS to be performed under physiological conditions. The direct detection of proteins and the study of their interaction with different ligands can provide information toward understanding biological processes. Within this thesis, we designed hybrid materials with potential application in SERS selective biodetection in complex matrices. We additionally introduced the use of SERS for analysis of the Quorum Sensing communication mechanism in bacteria colonies. The main goal of this thesis is thus the label-free and in situ detection of analytes by SERS spectroscopy for biological applications.