Water-stable perovskite-silica nanocomposites for encoded microbeads construction and multiplexed detection.

All-inorganic lead halide perovskite nanocrystals exhibiting bright luminescence have great potential as fluorescence elements for optical encoding. However, their limited stability in water hinders the application in biosensing. In this study, novel optical encoded microbeads based on CsPbX (X = Cl, Br) nanocrystals are developed and applied in bead-based suspension arrays for the first time. Through the in-situ crystallization of CsPbX nanocrystals within mesoporous silica nano-templates (MSNs), accompanied by mesopores collapse after sintering, CsPbX@MSNs (X3M) nanocomposites with uniform morphology and stable fluorescence intensity in aqueous solutions for up to 50 days are obtained. By assembling X3M with microspheres to form a host-guest structure, an optical encoding microbead (MX3M) library is established by varying the X3M ratio, halide composition, and the size of host microspheres, which can be easily decoded under multi-channel flow cytometer. As a result, MX3M exhibits outstanding capacity for specific target capture and negligible nonspecific absorption performance in the multiplex nucleic acid detection of respiratory viruses, with a low limit of detection (10 copies/rxn). This result highlights the tremendous potential of MX3M encoded microbeads constructed based on CsPbX nanocrystals for multiplexed bioassays.