Functionalisation of SERS substrates for ex vivo detection of inflammatory state

only in englishThe detection of disease-specific biomarkers can be costly, not available to many patients, and sometimes impossible at early stages using traditional clinical methods. SERS is a fast, sensitive, and nondestructive analytical technique that can identify trace amounts of disease biomarkers. SERS nanosensors can be combined with immunochemical reactions to identify disease markers. In this work, we designed SERS materials for a selective and sensitive ex vivo detection of markers of inflammatory state in atherosclerotic aorta tissue and in blood plasma. We used specific antigen-antibody reaction to track our target of interest. As a result, nanosensors with different SERS design labels that can identify specific target binding were identified. iSERS (immuno SERS) was employed to detect smooth muscle cells (SMCs) in mice brachiocephalic artery (BCA) with established atherosclerosis. For that, we employed a SERS label comprising of Au/Au core/satellite nanoparticles covered by a Raman reporter conjugated with an antibody directed against the α-actin of SMCs. They were identified by the SERS signal of a Raman reporter using spectroscopic imaging for direct and indirect method. Classic immunohistochemistry (IHC) imaging (reference technique) and iSERS show a very similar SMCs distribution in the atherosclerotic plaques and wall of the aorta for the direct method. We designed a sandwich type SERS nanosensor to detect interleukin-6 (IL-6) in the blood plasma. A chemical functionalization of selected SERS platforms was developed and their capability on every step of the functionalization was tested. The antibody functionalization of SERS gold and silver substrates were also tested. As a linker between substrate and antibody, we used 4-mercaptobenzoic acid (4-MBA), which has COOH groups necessary for bioconjugation with the antibody (anti-IL-6) and a strong Raman signal. Gold nanoparticles synthesis using 4-NTP as the Raman Reporter was also performed with a respective antibody incubation (anti-IL-6), antigen incubation, and SERS probe immobilization