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 (Delta lambda) of the TP resonance is small (similar to 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, alpha, from the translation vector of the Tamm dip before and after exposure. alpha increases monotonically with VLP concentration, from 1.3 degrees +/- 2 degrees at 0 ng/mL to 9.7 degrees +/- 0.5 degrees at 10 ng/mL. Control experiments with similarly sized polystyrene nanoparticles and heat-denatured VLPs yield negligible changes (0.7 degrees +/- 1.9 degrees and -0.7 degrees +/- 4 degrees, 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.