Tamm Plasmon Resonance Responsiveness to SARS-CoV-2 Virus-Like Particles

Bioresponsive optical materials that convert nanoscale biointerface events into measurable spectral signals are of growing interest for sensing and antiviral applications. Here, we show that a Tamm plasmon (TP) device, consisting of a SiO²/TiO² distributed Bragg reflector capped with nanostructured silver, responds to SARS-CoV-2 virus-like particles (VLPs) in a concentration-dependent manner without selective functionalization. Upon VLP exposure, the conventional wavelength shift (Δλ) of the TP resonance is small (∼4 nm), whereas the resonance depth decreases systematically, by about 60% at 10 ng/mL VLP. To capture both spectral and amplitude changes, we define a displacement angle, α, from the translation vector of the Tamm dip before and after exposure. α increases monotonically with VLP concentration, from 1.3° ± 2° at 0 ng/mL to 9.7° ± 0.5° at 10 ng/mL. Control experiments with similarly sized polystyrene nanoparticles and heat-denatured VLPs yield negligible changes (0.7° ± 1.9° and -0.7° ± 4°, respectively), indicating sensitivity to the native conformational state of viral surface proteins rather than generic nanoparticle morphology or bulk refractive-index effects. These results establish TP structures as promising label-free platforms for detection and probing structure-dependent virus-material interactions.