Light-Induced Dynamic Assembly of Gold Nanoparticles in a Lab-on-Fiber Platform for Surface-Enhanced Raman Scattering Detection

Abstract

As a highly functional platform, lab-on-fiber (LOF) has exhibited amazing potential to be used in ultrasensitive surface-enhanced Raman spectroscopy (SERS) detection. However, the low detection efficiency and high cost of most SERS-based LOF platforms have severely limited their further applications in environmental monitoring, biomedicine, etc. Here, we report a reusable SERS-based LOF platform through a Au-coated optical fiber integrated into a patterned microfluidic chip. With the assistance of laser-induced thermophoresis, we successfully obtained rich “hot spots” on the Au-coated optical fiber by reversible accumulation of gold nanoparticles within 5 min. Experimental results indicate that it has a low detection limitation of 10–10 mol/L (M) for environmental pollutant molecules. Fortunately, with the dynamic and reversible accumulation of gold nanoparticles controlled by laser on/off, the platform shows excellent reversibility and stability under multiple detection–cleaning cycles, which are better than those of the LOF platform based on chemical modification and photochemical deposition. The thermophoresis-based LOF platform with the advantages of easy operation, miniaturization, and high reusability provides a cost-effective approach for SERS detection.