Fabrication and effect study of microfluidic SERS chip with integrated surface liquid core optical waveguide modified with nano gold

A novel microfluidic chip with integrated Teflon AF1600 surface liquid core optical waveguide (LCW) modified with nano gold was proposed and fabricated in this article. Physical deposite method was used to integrate Teflon AF1600 LCW into microchannel. After that, the inner surface of Teflon AF1600 LCW was chemically modified at temperature of 40 °C, subsequent nano gold were in situ immobilied on the silanized inner surface of Teflon AF LCW precoated with a thin layer of poly(diallyldimethylammonium chloride) within microchannel by a chemical self-assembly method. Under the optimized conditions, the prepared microfluidic SERS chip exhibited high sensitivity for R6G with detection limit of 10⁻¹¹ mol/L and SERS enhancement factor (EF) of 2.7 × 10⁸. Compared to single nano gold SERS enhancement substrate within a microfluidic chip, the SERS detection sensitivity for R6G was improved 4 orders of magnitude. Apart from high SERS enhancement effect, the as-prepared integrated microstructure had extremely good SERS detection reproducibility and duration stability. Furthermore, it was successfully used to detect the bovine serum albumin (BSA), and exhibited excellent SERS response. The research showed great prospects and technical support for design and fabrication of integrated SERS microfluidic chip and sensitive detection of trace biochemical samples.