One-pot platform for the collection and detection of nanoparticles: Flexible surface-enhanced Raman scattering (SERS) substrates with nano-pore structure

The potential of using flexible surface-enhanced Raman scattering (SERS) for single polymer nanoparticle detection has been recognized, however, most studies have used SERS substrates consisting of metal nanoparticles (MNPs) on hard materials, which have limited volume analysis and can easily be damaged. To overcome these issues, researchers have conducted recent studies on flexible or 3D-structured SERS substrates. This study used polydimethylsiloxane (PDMS) membranes for flexible substrates, Ag nanowires (AgNWs) to form nano-pores, and PDMS-polyethylene glycol (PEG) block copolymer (BCP) to improve solvent application. The SERS substrates were able to detect rhodamine 6G (R6G) probes with a limit of detection (LOD) of 7.06 × 10⁻¹¹ M, and were mechanically stable under various conditions such as bending, stretching, and torsion. The nano-pores of the SERS substrates could separate polystyrene (PS) particles from the solution, and filtered particles were visually distinguishable from AgNWs using a dark field microscope. The flexibility of the SERS substrates also allows for swab sampling of irregular surfaces. We were able to detect up to 10^–10 M of crystal violet (CV) in the contaminated scallops and collect and detect PS in stainless-steel structures covered with 200 nm PS particles. Overall, the study shows the potential of using flexible SERS substrates for single polymer nanoparticle detection in various fields.