Ag-COATED GOLD NANOSTARS SYNTHESIS FOR SPECIFIC AND ULTRASENSITIVE SERS/SERRS DETECTION OF BIOANALYTES IN COMPLEX MATRICES

LEANDRO BENAVIDES; MARIA ANA CASTRO; DANIEL H. MURGIDA

Simposio; Frontiers in Physical Sciences; 2016

The current work is aimed at the development of analytical techniques which allow for fast, specific and ultrasensitive detection of multiple analytes in complex matrices based upon Surface Enhanced Resonant Raman Spectroscopy (SERRS). With this objective in mind, we set upon designing nanostructures so that de nanometal?s plasmon resonance condition is concomitantly satisfied with the electronic resonance of the dispersive molecule, thereby allowing the same laser to activate simultaneously both resonant Raman (RR) and surface enhanced Raman spectroscopy (SERS) enhancement mechanisms. Therefore, SERRS?s superior selectivity and sensitivity are achieved.Several kinds of metal nanostructures were synthesized and characterized seeking the optimal condition to maximize enhancement. Gold nanostars were chosen as the best candidate for the task at hand1, but to allow for easier coupling of both enhancement mechanisms an Ag-coating was added to the nanostars, effectively blue-shifting the plasmon band2. UV-Vis spectroscopy for these structures shows a well-defined plasmon band which is finely tunable by synthesis conditions. These nanoparticles were also characterized by electron miscroscopy (TEM and SEM). The resulting structures were loaded with cyanine dyes and the Raman enhancement for this molecule was studied. The best behaving nanostructures in regards to enhancement will be selected to be encapsulated in an inert matrix for a later conjugation to specific recognition elements (i.e. monoclonal antibodies, aptamers) to develop specific sensors that allow for multiplex detection