Synthesis and spectroscopic study of dual self-encoded polymer microbeads with Raman scattering and surface-enhanced Raman scattering

Abstract

The unique Raman spectra of various polymers render polymeric microbeads to be attractive in Raman‐based multiplex analysis and simultaneous biomolecular recognition as self‐encoded supports. The combination of polymer Raman signals with highly sensitive surface‐enhanced Raman scattering (SERS) codes will be able to significantly enhance the combinatory library in bioanalysis. However, there is lack of study on the preparation and spectroscopic analysis of self‐encoded microbeads with both Raman and SERS signatures. This study establishes a robust synthesis and spectral analysis protocol of the microbeads with bi‐codes, namely Raman and SERS. As modal examples, surface carboxylic acid functionalized monodisperse microbeads of polystyrene and poly(4‐tert‐butylstyrene) were conjugated with the amine group of 4‐aminothiophenol, followed by the adsorption of gold nanoparticles (AuNP) on microbead surfaces. The thiol group of 4‐aminothiophenol forms self‐assembled monolayers with AuNPs. The resulting microbeads are Raman and SERS dual self‐encoded as evident from their Raman spectroscopic and imaging analysis. The synthesis and spectroscopic analysis of the Raman and SERS dual‐encoded systems suggest the potential expansion of multiplex library in suspension bioassays.