Over the last decade Metal-Enhanced Fluorescence (MEF) has emerged as the next generation of fluorescence spectroscopy. MEF is a consequence of the near-field interactions of fluorophores with the metallic surface plasmons, which leads to enhanced fluorescence signatures. Metal-Enhanced Bioluminescence (MEB) is bioluminescence signal enhancement via proximity to deposited metallic nanoparticles. This approach employs a whole cell bioreporter harboring a plasmid-borne fusion of a specific promoter incorporated with a bioluminescencet reporter gene. The use of silver deposition enables a doubling of the bioluminescent signal amplitude by the bacterial bioreporter when compared to an untouched non-silver deposited microtiter plate surface. This can be carried out in the less optimal but necessary far-field distance. SEM micrographs provide a visualization of the proximity of the bioreporter to the silver nanoparticles. The electromagnetic field distributions around the nanoparticles were simulated using Finite Difference Time Domain, further suggesting a re-excitation of non-chemically excited bioluminescence in addition to metal-enhanced bioluminescence. The possibility of an antiseptic silver effect caused by such a close proximity was eliminated due to the dynamic growth curves of the bioreporter strains. As a highly attractive biotechnology tool, this silver deposition technique, coupled with whole cell sensing, enables increased bioluminescence sensitivity, making it especially useful for cases in which reporter luminescence signals are very weak.
