Photonic Crystal Hydrogel Enhanced Plasmonic Staining for Multiplexed Protein Analysis

Plasmonic nanoparticles are commonly used as optical transducers in sensing applications. The optical signals resulting from the interaction of analytes and plamsonic nanoparticles are influenced by surrounding physical structures where the nanoparticles are located. This paper proposes inverse opal photonic crystal hydrogel as 3D structure to improve Raman signals from plasmonic staining. By hybridization of the plasmonic nanoparticles and photonic crystal, surface‐enhanced Raman spectroscopy (SERS) analysis of multiplexed protein is realized. It benefits the Raman analysis by providing high‐density “hot spots” in 3D and extra enhancement of local electromagnetic field at the band edge of PhC with periodic refractive index distribution. The strong interaction of light and the hybrid 3D nanostructure offers new insights into plasmonic nanoparticle applications and biosensor design. By the hybridization of plasmonic nanoparticles and a photonic crystal structure through plasmonic staining of the protein‐modified hydrogel, improved SERS analysis of multiplexed protein is realized. In comparison, the SERS signals from the plasmonic stained inverse opal photonic crystal hydrogel is about five times of those from plamonic stained nonporous hydrogel.