Nanoporous\nPolystyrene Inverse Opal Materials with\nOptical Interference Properties for Label-Free Biosensing

Colloidal\ncrystal nanomaterials have been proven to be valuable\nsubstrates for optical-based biosensing due to their ordered macroporous\nnanostructure and brilliant optical properties. In this work, silica\ncolloidal crystal (SCC) thin films, as well as polystyrene–SCC\ncomposite films and inverse opal (IO) polystyrene films fabricated\nusing SCC as templates, are investigated for their application as\nsubstrate materials in optical interferometric biosensors. The SCC\nfilms formed by the self-assembly of silica colloidal crystals have\nthe most densely packed nano-3D structure, also known as the opal\nstructure. IO films are fabricated by filling the opal pores of SCC\nwith polystyrene and then removing the template, resulting in an interconnected\nnano-3D ordered macroporous structure, as indicated by the name inverse\nopal. The performance of the three materials was compared and discussed\nbased on an ordered porous layer interferometry optical platform,\nfocusing on refractive index response, protein adsorption response,\nand biomolecular interaction response. These results could potentially\noffer innovative material support for the advancement of label-free\noptical biosensors, which can be used for more biological/biochemical/biomolecular\nreaction monitoring studies.