Facile thermal decomposition synthesis of sub-5 nm nanodots with long-lived luminescence for autofluorescence-free bioimaging

Persistent nanophosphors can remain luminescent after the removal of the excitation.Persistent nanophosphors exhibit great advantages in biomedical fields,particularly in autofluorescence-free bioimaging and in-siteexcitation-free photo-theranostics.Despite the great promise of persistent nanophosphors in biomedicine,studies on the controlled synthesis of persistent nanophosphors are limited.Herein,a metal acetylacetonate-based thermal decomposition method was developed for the synthesis of ultra-small persistent luminescence nanodots(PLNDs).The PLNDs display uniform size,good dispersibility and strong persistent luminescence.The luminescent properties of the PLNDs can be readily regulated by ion doping.The thermal decomposition method shows excellent versatility in the synthesis of PLNDs including gallate,sulfide and fluoride.Due to their ultra-small size and surface adsorbed hydrophobic ligand,the PLNDs can be easily integrated with liposomes to construct a stable and biocompatible persistent luminescent nanoplatform for biomedical applications.This work puts forwards a versatile method for the controlled synthesis of ultra-small persistent nanophosphors,and it may further contributes to the areas ranging from biosensing to cancer therapy.