Inverse opal photonic crystals: Recent advances in fabrication methods and biological applications

Inverse opal photonic crystal (IOPC) micro-structures as the optical materials with their periodic and ordered arrays influence the propagation of light, which contribute to unique reflection spectra and structural colors. Colloidal self-assembly of polymer microspheres is one of the most preferred and low-cost approaches to the formation of PCs as an artificial opaline template for the development of IO architectures. This study primarily reviewed the fabrication methods used for the preparation of IOs structures based on the infiltration of filling materials which can be done by several procedures such as sol-gel, atomic layer deposition (ALD), chemical vapor deposition (CVD) and electrode position methods. The filled materials of IOs structures included ZnO, TiO2, silica, hydrogel, carbon, and silk. Subsequently, it presented several attractive biological applications of artificial IO-based structures and natural PC materials with a particular emphasis on the recent use of these three-dimensional (3D) microporous materials in biosensors, drug delivery and tissue engineering. This review could be useful for interdisciplinary researchers in the field of physics, chemistry, and medicine.