Rapid, one-step preparation of SERS substrate in microfluidic channel for detection of molecules and heavy metal ions

• Published in: Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy Vol. 220; p. 117113
• Main Authors: Yan, Sheng, Chu, Fangjia, Zhang, Haiyan, Yuan, Yuan, Huang, Yingzhou, Liu, Anping, Wang, Shuxia, Li, Weihua, Li, Shunbo, Wen, Weijia
• Format: Journal Article
• Language: English
• Published: England Elsevier B.V 05.09.2019
• Subjects: Biosensor; Heavy metal detection; Microfluidics; Nanoparticle synthesis; Surface-enhanced Raman spectroscopy; Heavy metal detection; Biosensor; Microfluidics; Surface-enhanced Raman spectroscopy; Nanoparticle synthesis
• ISSN: 1386-1425; 1873-3557
• DOI: 10.1016/j.saa.2019.05.018

On-chip fabrication of surface-enhanced Raman spectroscopy (SERS)-active materials enables continuous, real-time sensing of targets in the microfluidic chip. However, the current techniques require the time-consuming, complicated process and costly, bulky facilities. In this work, we present a novel method for synthesis of Ag nanostructures in a microfluidic channel via one-step electroless galvanic replacement reaction. The whole reaction could be achieved <10 mins, while the traditional methods take hours. The microfluidic channel has a Cu base, which can reduce Ag ions to Ag nanoparticles in the presence of AgNO3 solution. The new technique enables the label-free sensing of chemical molecules (i.e., methylene blue) and biomolecules (i.e., urea). Two proof-of-concept experiments are performed to verify the utilization of the prepared SERS substrate. First, the microfluidics-assisted SERS sensor is used to detect Hg ions in aqueous solution with high sensitivity and good selectivity. Second, the fabricated SERS-active material can couple with a concentration gradient generator for continuous SERS detection. This simple technique can be used in any laboratory without any bulky equipment and can realize numerous lab-on-a-chip applications with the integration of other microfluidic networks. [Display omitted] •Microfluidic on-chip preparation of SERS substrate with simple and low-cost process.•The microfluidics assisted SERS sensor showed good sensitivity and biocompatibility.•Mercury detection with high sensitivity and good selectivity against other metal ions.•Real-time SERS detection with the integration of the concentration gradient generator.