Phospholipid-based nanodrill technology for enhanced intracellular delivery of nano-sized cargos

Nanosized drug delivery systems typically enter the cell via endocytosis. However, a significant amount of the endocytosed cargo cannot effectively escape from the endosome, resulting in drug degradation. Therefore, there are several ongoing efforts to develop transmembrane delivery systems that could circumvent endocytosis. In this study, phospholipid nanotube nanodrills (LDs) were formed onto the surface of a human serum albumin nanoparticle via self-assembling phospholipids. The nanodrill technology enhanced the intracellular uptake efficiency of nanoparticles via energy-independent direct cell membrane permeation. The length of the nanodrills according to the DSPE-PEG to DSPC ratio was investigated both experimentally and theoretically. Our findings demonstrated that longer nanodrills were formed on the surface of the nanoparticles as the ratio of DSPC (i.e., a strongly hydrophobic lipid) in the two phospholipids increases. Moreover, the intracellular uptake efficiency increased as the length of phospholipid nanodrills increased. In addition to enhancing intracellular delivery, the phospholipid nanodrills could penetrate the extracellular matrix and enable the introduction of nanoparticles, thus highlighting the promising tissue penetration capacity of phospholipid nanodrill technology. The improved cell permeability of LD technology was demonstrated by effectively inhibiting specific genes via siRNA-based therapeutic delivery. Moreover, this approach enhanced the efficacy of chemotherapeutics against chemo-resistant cancer cells. Therefore, LD technology could be used to deliver genetic materials and chemical-based therapeutics both in vitro and in vivo.