Photonic crystal(PC)is composed of two and more mediums with periodic nanostructure.The unique optical property and characteristic nanostructure of the PC provide effective means for biological and chemical analyses.In our group,we developed a series of analytical methods by using self-assembled PC.1)Label-free detection of biomolecule.By utilizing the volume and refractive index change of biomolecules in PC,we realized label-free detection and visual detection of biomolecules.2)Analysis of gas.Mesoporous PC with high specific surface area was developed.By using this kind of material,we realized the analysis of gas molecules with PC.3)Multiplex detection.One of the key techniques of multiple biological analysis is to identify different biological events simultaneously.Biomolecule encoding is the core technique for the multiplex detection.