Adosorción y detección ultrasensible de sustancias de dopaje deportivo sobre nanopartículas plasmódicas

Abstract

Surface-enhanced Raman spectroscopy (SERS) is an extremely sensitive analytical technique based mainly on the giant electromagnetic enhancement induced by metal nanoparticles (NPs)[6, 7, 37, 39, 40]. This enhancement is attributed to the localized surface plasmon resonance (LSPR) phenomenon that takes place when light at the characteristic plasma frequency of the LSP interacts with the NP surface[20, 41]. Briefly, when situated within the proximity of a nanostructured plasmonic surface, a molecule will undergo a huge increase in the cross section of various optical spectroscopies; especially for Raman, which enlarges highly the sensitivity of this technique. The most commonly employed SERS substrates are metal NPs in suspension (colloids) or immobilized and distributed on a solid surface[36]. Although the main interest in SERS remains in the fields of single molecule or few molecules detection[8, 10, 68, 219, 220], there is a general acceptance that SERS can be sufficiently reliable and low cost to compete with established analytical techniques across a broad range of applications and sample types[86, 221, 222]. We have developed in this Thesis several strategies to increase the applicability of SERS technique in the sensitive and selective detection of sport doping drugs (SDD). In a first approach, we have investigated the effect of the type of metal, interface composition, nanoparticle morphology and pH on the SERS response of molecules with affinity to plasmonic surfaces, in order to optimize the measurement conditions in a quantitative analysis. In a second approach, we have functionalised the nanoparticle surface with host molecules so as to allow the approximation of molecules with no affinity to it.