Biocompatibility Study of PEI-NaYF4: Yb,Er Upconversion Nanoparticles

Abstract

Near-infrared fluorescent nanoparticles are becoming a promising approach for various biomedical applications. The increased use of nanoparticles has highlighted the importance of studying their potential hazards. Here we report a study investigating the cytotoxicity and biodistribution of novel polyethylenimine-coated upconversion fluorescent nanocrystals, PEI/NaYF4:Yb,Er. We incubated the PEI/NaYF4:Yb,Er nanopaticles with rat skeletal myoblasts and bone marrow-derived stem cells and used MTS and LDH assay to assess the in vitro cytotoxicity The biodistribution of PEI/NaYF4:Yb,Er nanoparticles were studied in healthy rats following tail vein injection and various organs were harvested to assess the amount of nanoparticles present at different time points. Cell viability decreased significantly from 98 ± 5% to 65 ± 7% as the concentration of the nanocrystals increased from 5 to 100 µg/ml. Yttrium determination showed that the highest amount of PEI/NaYF4:Yb,Er nanocrystals were found in the lung at 30 minutes post-injection at 19.9mg/l/g tissue followed by heart, spleen, kidney, liver and blood at 3.3, 2.17, 1.12, 0.22, 0.05 mg/l/g tissue respectively which then reduced significantly at 24 hours post-injection. By day 7 post-injection, the nanocrystals were mostly out of the rat model’s system. Fluorescent PEI/NaYF4:Yb,Er nanocrystals displayed good in vitro and in vivo biocompatibility, demonstrating their potential applications in both cellular and animal imaging systems.