LSPR-enhanced photonic crystal allows ultrasensitive and label-free detection of hazardous chemicals

Abstract The responsive photonic crystals (PC) are promising sensing materials owning to their response signal self-expression, but how to attach the recognition element efficiently and how to improve the sensitivity are still challenging. Au nanoparticles (Au NPs), which possess high reactive activity and localized surface plasmon resonance (LSPR) effect, provide a strategy. So, Au NPs are introduced to opal PC, in order to not only amplify the optical signal but also facilitate the fixation of recognition element onto PC. Furthermore, the signal enhancement mechanism is investigated and a universal PC sensing material is developed. This PC is easy-prepared and can reach ultrasensitive detection without label. Coupled with the enhancement of Au NPs, the PC can respond to the trace target with the concentration down to 10−12 g/mL. Simultaneously, the detection of hazardous chemicals can be achieved by replacing the recognition element. This design extensively broadens the PC application in clinical assays, food safety, environmental monitoring, etc.