Transferrin-coupled fluorescence nanodiamonds as targeting intracellular transporters: An investigation of the uptake mechanism

Targeted drug delivery has been an important research field in specific therapy. Transferrin-coupled nanoparticles are attractive scopes as a vehicle for specific cellular uptake and targeted drug delivery. This paper reports that fluorescent nanodiamonds (FNDs) with a size of ∼ 140 nm can be covalently linked with transferrin (Tf) for receptor-mediated targeting of cancer cells. The mechanism of Tf-coated FNDs (FND-Tf) entering HeLa cells was investigated using flow cytometry analysis (FCA). It was found that the uptake of nanoparticles by cells can be significantly inhibited in ATP-depleted environments. Cells pretreated with sucrose showed that the nanoparticles transportation is a clathrin-mediated process. The average measurement with flow cytometry indicated that the Tf-coupled FND particles can be internalized by the cells through receptor-mediated endocytosis, as confirmed by competitive inhibition assays. In addition, it showed that uptake half-life of FND-Tf nanoparticles is about 1.26 h at a particle concentration of 25 μg/mL. Our study implicates that FND-Tf has potential applications on biomedication.