SpyTag/SpyCatcher-ligated nanostructured lipid carriers for active mammary cancer targeting

Nanostructured lipid carriers (NLCs) are the second generation of lipid nanoparticles for delivering pharmaceutical drugs. The current study aimed to improve the cellular uptake of NLCs by preparing surface functionalization. In this study, surface-functionalized NLCs were prepared by conjugating affibody molecules targeting HER2 or the cell-penetrating peptide TAT using the SpyTag/SpyCatcher system for enhanced cellular uptake. The cellular uptake and internalization mechanisms of functionalized NLCs were evaluated. NLCs were successfully prepared with nanosized lipid particles (<160 nm) and maintained storage stability, which was assessed by particle size, polydispersity index, and zeta potential values. Functionalized NLCs with HER2 affibody or TAT peptide were endocytosed when taken up by various cell lines, including SK-BR-3, MCF-7, MDA-MB-231, and HeLa, which were evaluated by flow cytometry and confocal microscopy analysis. These results demonstrated that surface functionalization significantly enhanced the cellular uptake and concomitant cytotoxicity of the NLCs. These findings suggest that the SpyTag/SpyCatcher-based strategy is effective for surface functionalization of lipid-based drug carriers.