Single molecule surface-enhanced Raman (SERS) using liposome-gold conjugates

W. Lum, L. Sagle
University of Cincinnati,
United States

Keywords: SERS, SM-SERS, single molecule, liposome, fluorescence, surface-enhanced, Raman


Probing single molecules with Surface-Enhanced Raman Spectroscopy (SERS) has traditionally required the formation of nanogap junctions between noble metals, but often results in the interaction of probe molecules and the nanogap material1-4. While the advancement of more sensitive SERS substrates continues, our group recently reported a novel liposome-based SERS substrate5. In our substrate, the liposome encapsulates a probe molecule that shields interactions between the desired probe and metal. Secondly, the liposome acts as a scaffold for conjugation to a nanoparticle and the noble metal surface. Additionally, the separation of the probe from the metal surface allows the substrate to also enhance fluorescence. Herein, we report increases in the substrate’s signal enhancement that allow for single molecule SERS detection of crystal violet. Proof of single molecule measurements are confirmed through the isotopologue SERS method and fluorescence. Simulations with finite-difference-time domain are included to model the substrate.