Quantitative Analysis of Virus Adsorption and Co-adsorption Behavior Using BET Modeling and SERS Spectroscopy

Understanding virus-surface interactions is essential for developing effective biosensors, diagnostic tools, and antiviral strategies. In this study, we present a systematic investigation of the adsorption and coadsorption behavior of 12 respiratory viruses, including influenza, RSV, coronaviruses, adenovirus, and metapneumoviruses, using surface-enhanced Raman scattering (SERS) on SiO₂-coated silver nanorod array substrates. Both single viruses (SVs) and binary virus mixtures (2VMs) were analyzed in water and normal human saliva, and spectral data were modeled using a modified Brunauer-Emmett-Teller (BET) adsorption framework. Linear least-squares spectral decomposition enabled the extraction of adsorption coefficients that correlate with virus concentration and surface binding affinity. All viruses exhibited multilayer physisorption consistent with Type II isotherms, with the BET constant q varying substantially across virus types. Notably, 2VMs demonstrated a significantly enhanced adsorption behavior, often with q values 4-25 times greater than in SVs, indicating strong cooperative or competitive effects. Saliva modulated virus-surface interactions in virus-specific ways, emphasizing the complexity of adsorption dynamics in physiological environments. These findings highlight the limitations of single-virus calibration for quantitative detection in mixed-virus samples and underscore the need for mixture-aware analytical models in biosensing applications. This work provides a robust framework for mechanistic insight and quantitative modeling of virus adsorption relevant to real-world diagnostics and environmental monitoring.