Upconversion NaGdF4 nanoparticles for monitoring heat treatment and acid corrosion processes of hair

Lanthanide-based upconversion core-shell NaGdF4 nanocrystals with strong upconversion luminescence and biocompatibility were synthesized by the solvothermal method.The multicolor upconversion emission of these NaGdF4 nanoparticles could be easily obtained by controlling the core-shell compositions.These multicolor core-shell NaGdF4 upconversion nanocrystals could be employed as fluorescent probes for imaging the mouse hair,by which the porous and scalelike structure of the mouse hair were presented clearly.Meanwhile,it was directly shown by fluorescent signals that the mouse hair could resist the corrosion of the strong acid even when the concentration of hydrochloric acid was increased to 36.5%,but could not avoid the carbonization at high temperature of 400 oC.This procedure based on upconversion fluorescent nanoprobes opens a novel route for investigating the basic physical structure and chemical properties of biological tissue and organism.