Halide salt-tuning at interface: Highly water-stable and anion-exchange-active CsPbX3@SiO2 Trimurti nanoparticles for multicolor metabolite assay

•Crystal phase transition rate from Cs4PbX6 to CsPbX3 can be tuned by halide salt.•Monodisperse CsPbX3 nanoparticles with double-side SiO2-coated is synthesized.•Trimurti nanoparticles exhibit high water stability and fast anion exchange activity.•Anion exchange-based multicolor sensing platform for metabolites is proposed.•The uric acid dual-readout result is the same as that of colorimetric assay kit.