Fast and straightforward in-situ synthesis of gold nanoparticles on a thread-based microfluidic device for application in surface-enhanced Raman scattering detection

Cotton threads forming a microfluidic device were used for the first time to conduct a fast and straightforward Turkevich synthesis of gold nanoparticles (AuNPs) using minute amounts of reagents. Spherical AuNPs were obtained with sizes that varied from 20 to 40 nm, according to the synthesis conditions. The cotton thread also acted as physical support for the synthesized AuNPs during surface-enhanced Raman scattering (SERS) detection of crystal violet and nicotine. A calibration curve for nicotine with acceptable linearity (R-2 = 0.9844) in the concentration range of 2-6 mg L-1 was obtained. The limit of detection for nicotine was 0.18 mg L-1. The proposed substrate was considered cheap, fast, and easy to be fabricated and applied in SERS detection.