Live-cell imaging of octaarginine-modified polymer dots via single particle tracking.

OBJECTIVES: Nanocarriers can greatly enhance the cellular uptake of therapeutic agents to regulate cell proliferation and metabolism. Nevertheless, further application of nanocarriers is often limited by insufficient understanding of the mechanisms of their uptake and intracellular behaviour.

MATERIALS AND METHODS: Fluorescent polymer dots (Pdots) are coated with synthetic octaarginine peptides (R8) and are analysed for cellular uptake and intracellular transportation in HeLa cervical cancer cells via single particle tracking.

RESULTS: Surface modification with the R8 peptide efficiently improves both cellular uptake and endosomal escape of Pdots. With single particle tracking, we capture the dynamic process of internalization and intracellular trafficking of R8-Pdots, providing new insights into the mechanism of R8 in facilitating nanostructure-based cellular delivery. Furthermore, our results reveal R8-Pdots as a novel type of autophagy inducer.

CONCLUSIONS: This study provides new insights into R8-mediated cellular uptake and endosomal escape of nanocarriers. It potentiates biological applications of Pdots in targeted cell imaging, drug delivery and gene regulation.