Upconversion luminescence tracking of gene delivery via multifunctional nanocapsules

The real-time fluorescence tracking of gene delivery is very important as it helps to figure out how a vector enters a cell and also to follow its fate within the cell interior. Lanthanide-doped upconversion nanoparticles (UCNPs) have shown great potential in biomedical applications in virtue of their unique optical and biological properties. Herein, we report a simple and versatile strategy to fabricate a multifunctional nanocapsule for effective gene delivery and real-time luminescence tracking. The hydrophobic UCNPs were modified by positively charged amphiphilic polymer together with polyethylene glycol-poly(lactic-co-glycolic acid) (PEG-PLGA) polymer, affording biocompatible nanocapsules with high gene loading capacity and good stability. Red UC luminescence of UCNPs are able to track the delivery of nanocapsules in cells without background fluorescence interference, in the meantime, the green fluorescence of green fluorescence protein (GFP) expressed by the pDNA could subtly monitor the gene transfection efficacy. The results demonstrated that our nanocapsule has ideal biocompatibility, satisfactory gene loading capacity and great bioimaging ability, which is promising for imaging guided cell therapy and gene engineering.