Label-Free Pore-Level Virus and Particle Detection with Bioinspired Inverse Opal Photonic Crystals

For most methods of viral imaging, it is necessary to bind bulky fluorescent molecules to the virus in order to visualize its location with optical microscopy. This increases the complexity of sample processing and may change viral behavior. In this research, we instead electrostatically bind viruses or charged particles to the surface of an inverse opal, which is a bioinspired self-assembled ordered porous material, to create a label-free method for imaging the location of a virus with a light microscope. Attached viruses increase the energy barrier to liquid infiltration in the re-entrant pores of the inverse opal, such that they remain dry when a test solution fills the non-occluded pores. Polarized light microscopy can then be used to distinguish the non-wetted pores, revealing location and concentration information about the viruses. This can create a customizable label-free tool to study viral behavior in laboratory or medical settings.