Nanosphere templated optical fiber for In-Vivo SERS sensing applications

We report a new class of Surface Enhanced Raman Scattering (SERS)-optical fiber sensing platform with hexagonally packed polystyrene (PS) nanospheres coated with silver at the distal end of the fiber with signal collected in a back scattering geometry. As a proof of concept, we fabricated the SERS-active substrates at the end of a 1000μm core multimode fiber using different PS beads having diameter 50nm, 100 nm and 400 nm. SERS enhancement and signal collection of the fiber was optimized by varying the concentration of beads and hence their packing density. SERS performance of such PS coated fibers were evaluated by studying the signal intensity measured from a monolayer of one of the common Raman active molecules, 2-naphthalenethiol, which can covalently adsorb onto the active end of the fiber. Efficacy of the fiber for real time remote sensing of liquid sample was demonstrated and direction for developing an in vivo biosensing platform is discussed.