Label-free, in situ SERS monitoring of individual DNA hybridization in microfluidics

We present label-free, in situ monitoring of individual DNA hybridization in microfluidics. By immobilizing molecular sentinel probes on nanoporous gold disks, we demonstrate sensitivity approaching the single-molecule limit via surface-enhanced Raman scattering which provides robust signals without photobleaching for more than an hour. We further demonstrate that a target concentration as low as 20 pM can be detected within 10 min under diffusion-limited transport.