Nanoplasmonics within a biofilm.

Biofilm templated gold nanonetwork provide a platform to study the transition of local plasmon to a surface plasmon. The switch from localized surface plasmon resonance (LSPR) to surface plasmon resonance (SPR) is induced by the percolation of metal atoms between gold nano-islands. Formed nano-composites showed a transition in metal percolation state (non-percolating to percolating state), as evident from electrical properties. The optical component of the study followed a previously tested method by our group, in which photonic coherences are induced by biofilms. Peaks were obtained in enhancement spectra that were found to correspond with plasmonic peaks, which in turn depended on Au precursor concentration that had been added.