This proposal aims at the development of novel nanostructured materials based on crystalline assemblies of anisotropic plasmonic (gold/silver) nanoparticles, to be used for the surface enhanced Raman scattering (SERS) detection of quorum sensing (QS) signaling molecules, and to the demonstration of applications of such materials to monitor population kinetics in bacterial colonies and the determination of the interaction mechanisms between mixed colonies and their manipulation through external parameters. This will involve a first stage related to the careful design of the most appropriate nanoparticle morphology and composition, as well as an understanding of their specific assembly processes (both on substrates and in solution), so that the collective plasmonic response will be optimized towards the enhancement of the Raman signal of the probe molecular codes. Coating of the nanoparticle supercrystals with a mesoporous layer will be required to protect them against contact with bacteria and cells, while permitting contact with the QS signalling molecules.
Ultimately, when the sensing system has been optimized and its performance demonstrated for monitoring of QS signals and colony growth, two final and important goals will be pursued. First, the interaction between mixed colonies (bacteria-bacteria and bacteria-eukaryotic cell) will be monitored in order to get information about synergic or antagonist (toxicity) QS mechanisms during the growth and proliferation of different bacteria and interspecies. This goal will permit the design of in vitro experiments where a bacterial strain may be manipulated by means of external introduction of the appropriate QS signalling molecules. Finally, the major challenge will be the practical demonstration of the ability of these new materials in this particular configuration for understanding and manipulating the growth and communication of different types of prokaryotic and peukaryotic cells.