“…NaYF 4 :Tm, Yb upconversion microparticles (UCMPs) are constituted by NaYF 4 host and a pair of Tm and Yb ions, typically Yb 3+ ions acting as a sensitizer, and Tm 3+ ions playing the role of emitters. This material exhibits outstanding applications such as photodetectors in NIR region, 10 photocatalyst, [11][12][13] biosensors, [14][15][16] and anticounterfeit printing. 3,17 In addition, surface modication with various ligands has been used to improve the dispersibility and colloidal stability of NaYF 4 UCMPs and the conjugation of UCMPs with biomolecules, polymers, etc.…”