Ultrasensitive surface-enhanced Raman scattering detection of urea by highly ordered Au/Cu hybrid nanostructure arrays.

We report a simple approach to fabricate cost-effective and highly sensitive surface-enhanced Raman scattering substrates based on Au/Cu hybrid nanostructure arrays for the detection of urea, an important molecule in biological and medical fields. By effectively adjusting the gap size between neighbouring nanorods into the sub-10 nm regime, a high density of hot-spots was generated, enabling the substrates to detect urea signals at a concentration as low as 1 mM with great reproducibility.