In vivo targeting of metabolically labeled cancers with ultra-small silica nanoconjugates

Unnatural sugar-mediated metabolic labeling of cancer cells, coupled with efficient Click chemistry, has shown great potential for in vivo imaging and cancer targeting. Thus far, chemical labeling of cancer cells has been limited to the small-sized azido groups, with the large-sized and highly hydrophobic dibenzocyclooctyne (DBCO) being correspondingly used as the targeting ligand. However, surface modification of nanomedicines with DBCO groups often suffers from low ligand density, difficult functionalization, and impaired physiochemical properties. Here we report the development of DBCO-bearing unnatural sugars that could directly label LS174T colon cancer cells with DBCO groups and subsequently mediate cancer-targeted delivery of azido-modified silica nanoconjugates with easy functionalization and high azido density in vitro and in vivo. This study, for the first time, demonstrates the feasibility of metabolic labeling of cancer cells with large-sized DBCO groups for subsequent, efficient targeting of azido-modified nanomedicines.