Towards development of fiber-optic surface enhanced Raman spectroscopy probes using 2-photon polymerization for rapid detection of bacteria

摘要

In this study, a variety of direct laser written surface-enhanced Raman spectroscopy (SERS) micro-structures, designedfor bacteria detection, are presented. Various SERS micro-structures were designed to achieve both a high density ofplasmonic hot spots and a strong probability of interaction between the hot spots and the target bacterial cells. Twophotonpolymerization was used for initial fabrication of the polymeric skeletons of the SERS micro-structures, whichwere then coated with a 50 nm-thick gold layer via e-beam evaporation. The micro-structures were fabricated on glasscoverslips and were assessed using a confocal Raman microscope. To this end, Rhodamine 6G was used as an analyteunder 785 nm laser illumination. The optimal SERS micro-structures showed approximately 2×10~3 enhancement inRaman signal (analytical enhancement factor, AEF) at a wavenumber of 600 cm~（-1）. Real-time detection of E. coli insolution was demonstrated using the fabricated SERS platform with low laser powers and a short acquisition time (785nm, 5 mW, 50 ms).