Rapid and reproducible analysis of thiocyanate in real human serum and saliva using a droplet SERS-microfluidic chip.

As thiocyanate (SCN − ) acts as an important biomarker in human health assessment, there remains an urgent need to realize rapid and reproducible analysis of SCN − in body fluids. Here, a droplet microfluidic device has been designed and fabricated for SCN − detection in real human serum and saliva using the surface enhanced Raman scattering (SERS) technique. Only a few minutes are needed for the whole detection process which simply cost a few microliters of real sample. Gold@silver core–shell nanorods (Au@Ag NRs) with a large SERS enhancement factor were selected to capture SCN − ions in body fluids. The intensity of SERS peak at around 2100   cm −1 , which originates from the –C≡N stretching mode, was used to indicate the concentrations of SCN − ions. Importantly, by generating a droplet environment for mixing reagents and acquiring signals, this microfluidic platform possesses the advantages of an improved reproducibility and reduced time consumption. For practical applications, the SERS-microfluidic system is capable to achieve rapid analysis of SCN − in the presence of human serum, which is very important for realizing the detection in real biological samples. Additionally, SCN − in saliva samples was detected in the SERS-microfluidic chip and the results provide useful information for distinguishing between smokers and nonsmokers.