Self-assemble three-dimensional PMMA@Au core-shell film: an ultrasensitive and reproducible SERS substrate

Metallodielectric photonic crystals (MDPCs) have gained interest across various fields due to their unique optical properties, with applications including optoelectronics, biotechnology, solar cells and surface-enhanced Raman scattering (SERS). In this study, homogeneous polymer spheres of polymethyl methacrylate (PMMA) were synthesized and incorporated with gold nanoparticles to form as PMMA@Au core-shell structure. Exploiting a "bottom-up" technique, thin films of PMMA@Au core-shell substrates was fabricated to investigate its performance in SERS applications by using 4-aminothiophenol (4-ATP) as probe molecule. The findings were validated through UV-Visible spectroscopy which reveal distinct surface plasmon resonance (SPR) peaks at 520 nm for the synthesized gold nanoparticles and 522 nm for the PMMA@Au core-shell. The morphology of the fabricated thin films was meticulously examined at each stage of the study, providing valuable insights into the core-shell structure's formation and characteristics. This research underscores the significant potential of PMMA@Au MDPCs SERS substrate in enhancing Raman signals, particularly the influence of substrate layers on the sensitivity and reproducibility of Raman signals. The findings not only contribute to the understanding of MDPCs but also hold promise for advancing SERS-based molecular detection in various applications.