Membranotropic Peptide-Functionalized Poly(lactide)-graft-poly(ethylene glycol) Brush Copolymers for Intracellular Delivery

A biodegradable delivery scaffold based on poly(lactide)-graft-poly(ethylene glycol) (PLA-g-PEG) is introduced and tested in vitro. The use of a functional ring-opening polymerization initiator (containing a masked aldehyde) on an azido PEG-lactide monomer combines two known methodologies to afford functionalized PLA. The resulting copolymer features two compatible functional groups and decreased hydrophobicity due to the PEG. The functional groups are capable of performing high-yielding orthogonal postpolymerization reactions, namely strain-promoted azide-alkyne click chemistry and reductive amination. PLA-g-PEG was functionalized with a fluorescent dye (7-nitrobenzoxadiazole, NBD) and a cell internalization peptide, gH625. The resulting delivery vehicle was investigated for cell uptake with HeLa cells, showing that the gH625 conjugation exhibited enhanced cellular uptake and localization in close proximity to the nuclei. The presented methodology is a new approach toward targeted delivery.