Laser-Fabricated Plasmonic Nanostructures for Surface-Enhanced Raman Spectroscopy of Bacteria Quorum Sensing Molecules

A laser deposition technique, based on the photo-reduction of silver ions from an aqueous solution, was used to fabricate silver nanostructure surfaces on glass cover slips. The resulting silver nanostructures exhibited plasmonic properties, which show promise in applications towards surface enhanced Raman spectroscopy (SERS). Using the standard thiophenol, the enhancement factor calculated for the deposits was approximately ~106, which is comparable to other SERS-active plasmonic nanostructures fabricated through more complex techniques, such as electron beam lithography. The silver nanostructures were then employed in the enhancement of Raman signals from N-butyryl-L-homoserine lactone, a signaling molecule relevant to bacteria quorum sensing. In particular, the work presented herein shows that the laser-deposited plasmonic nanostructures are promising candidates for monitoring concentrations of signaling molecules within biofilms containing quorum sensing bacteria.