Rapid Label-free SERS Detection of Viruses Using Bistratal Hydrogel Film@Au Nanoparticles Arrays

Background: Due to their unpredictable and variable nature, novel viruses pose a significant threat to human health as well as to the economy and society. Rapid detection plays a crucial role in the surveillance and management of the transmission and emergence of novel viruses. This study aims to establish a rapid, label-free surface-enhanced Raman scattering (SERS) platform for the highly sensitive and specific identification of emerging viruses. Methods: A novel self-assembly strategy based on the synergistic effect of electrostatic adsorption and hydrogel contraction has been developed to construct highly ordered hexagonally close-packed Au nanoparticle arrays on both surfaces of a polyacrylamide composite hydrogel film. The drying and shrinking of the hydrogel film contribute to the reduction of the particle gap, facilitating the formation of “hot spots” that effectively enhance near-field coupling and significantly amplify the local electromagnetic field in its vicinity. The label-free SERS detection of viruses relies on the intrinsic Raman fingerprints of viral structural components, particularly the envelope glycoproteins and lipid membranes that differ distinctly from host cellular materials. Results: The detection of malachite green and crystal violet on the substrate indicates high Raman optical activity. Validation with probe molecules (crystal violet, malachite green) showed low limits of detection (LOD of 10–11 M) and high linearity (R2 > 0.996). Highly linear quantitative sensitivity was observed, with a limit of detection of 1 TU/mL for both severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) Spike pseudovirus and B6R Mpox pseudovirus. Conclusion: The composite material is anticipated to serve as a novel Raman substrate, enabling the rapid identification of novel viruses and facilitating a prompt response to epidemics.