Tailoring Surface-Enhanced Raman Scattering Effect Using Microfluidics

Surface-enhanced Raman scattering (SERS)-based microfluidic platforms are investigated to optimize the detection of biomolecules using silver nanoparticles. The method is established using pefloxacin (an antibacterial agent) as a probe. We first monitor the continuous SERS signal of a 10(-5) M pefloxacin solution diffusing continuously into a silver nanoparticle stream across the shared interface separating the two-phase, segmented microfluidic laminar flow system. Diffusion of the pefloxacin adsorbate begins immediately after the two streams merge, generating silver aggregates and producing a huge enhancement of the Raman bands of pefloxacin. We show that the evolution of the SERS signal presents a diffusion-like behavior, whose dynamics can be easily monitored as the signal measured in the flow-wise direction is proportional to the reaction time. Finally, we demonstrate that it is possible to optimize SERS intensity spectra by adding a controlled amounts of chloride ions through a side channel to control silver particles aggregation and further enhance Raman scattering.