Facile Peptides Functionalization of Lanthanide-Based Nanocrystals through Phosphorylation Tethering for Efficient <i>in Vivo</i> NIR-to-NIR Bioimaging

Abstract

Peptide modification of nanoparticles is a challenging task for bioapplications. Here, we show that noncovalent surface engineering based on ligand exchange of peptides for lanthanide based upconversion and downconversion near-infrared (NIR) luminescent nanoparticles can be efficiently realized by modifying the hydroxyl functional group of a side grafted serine of peptides into a phosphate group (phosphorylation). By using the phosphorylated peptide with the arginine-glycine-aspartic acid (RGD) targeting motifs as typical examples, the modification allows improving the selectivity, sensitivity, and signal-to-noise ratio for the cancer targeting and bioimaging and reducing the toxicity derived from nonspecific interactions of nanoparticles with cells. The <i>in vivo</i> NIR bioimaging signal could even be detected at low injection amounts down to 20 μg per animal