Cysteine modified rare-earth up-converting nanoparticles for invitro and invivo bioimaging

摘要

Cysteine, as a small organic molecule and amino acid, is a basic building block for proteins and has special physiological functions invivo. Cysteine has strong affinity for cells, which can be taken advantage for various applications. A new and facile surface modification method has been developed for rare-earth doped upconversion nanoparticles (UCNs) using cysteine. Compared with unmodified samples, the water-solubility and biocompatibility of the cysteine modified NaYF4:Yb,Er and NaYF4:Yb,Tm UCNs (termed as UCN-Er-Cys and UCN-Tm-Cys, respectively) have been significantly improved, while their particle size and emission properties did not change substantially. Due to the low cytotoxicity as revealed by methyl thiazolyl tetrazolium assay, the cysteine modified UCNs were successfully applied to imaging of Hela cells invitro and nude mouse invivo. Most significant is that the method offers the advantages of ease of synthesis and handling as well as potentially low cost for biomedical emerging applications.