Engineered lab on fiber sers probes by self-assembly on fiber technique

We report on the engineering of repeatable surface enhanced Raman scattering (SERS) probes realized through nanosphere lithography. The Lab-on-Fiber SERS probes consist of polystyrene nanospheres in close-packed arrays (CPA), covered by a thin film of gold, on the optical fiber tip. We systematically studied the SERS performances of the CPA samples by comparing different patterns featured by different nanosphere diameters and gold thicknesses. The analysis allowed us to identify the most promising CPA SERS platform, exhibiting an Enhancement Factor (EF) of 4 × 105 and a SERS measurements variability lower than 10%. We addressed also the limitations related to the use of the same optical fiber for both illumination and light collection by selecting a commercial optical fiber exhibiting a good trade-off in terms of high excitation/collection efficiency and low silica background. Overall, the obtained results represent a step forward towards the realization of repeatable Lab on Fiber SERS optrodes for in vivo clinical studies.