Cell-Penetrating, Peptide-Based RAFT Agent for Constructing Penetration Enhancers

Peptide-polymer conjugates represent a promising class of compounds that can be used to overcome some of the limitations associated with peptides intended for therapeutic and diagnostic applications. The efficient generation of well-defined peptide/protein-polymer conjugates can promote the development of the design and synthesis of functional drugs and gene delivery platforms. In this research, a sequence defined cell penetrating peptide (i.e., Transportan 10 (TP 10))-based chain transfer agent (TP-CTA) was designed and synthesized in an automated peptide synthesizer. Thereafter, amphiphilic block copolymers poly[oligo(ethylene glycol) methyl ether acrylate]-<i>b</i>-poly(<i>n</i>-butyl acrylate) (TP-POEGA-<i>b</i>-PBA) were synthesized using the TP-CTA via reversible addition-fragmentation chain transfer (RAFT) polymerization. Circular dichroism (CD) spectroscopy confirmed the preservation of α-helix structure of TP 10, which is crucial for its bioactivity. Transmission electron microscopy (TEM) revealed the formation of self-assembled rod-like and vesicle nanostructures in an aqueous environment. Finally, the obtained peptide-conjugated block copolymers were demonstrated to be effective compounds for cell penetration. This method opens up a way for accessing peptide-polymer conjugates with cell-penetrating abilities.