Amphiphilic Graft Copolymer of Polylysine-g-polytetrahydrofuran and Its Biological Properties

The graft copolymer of poly-(N-epsilon-carbobenzyloxy-L- lysine)-g-poly(tetrahydrofuran) (PZLL-g-PTHF) could be successfully synthesized via the nucleophilic substitution reaction of PTHF+ living polymer chains with secondary amine side groups in the PZLL backbone. The amphiphilic graft copolymers of polylysine-g-poly(tetrahydrofuran) (PLL-g-PTHF) could be obtained by complete deprotection of the precursor of PZLL-g-PTHF. The obvious microphase separation was observed in both PLL-g-PTHF and PZLL-g-PTHF because of the incompatibility between the two kinds of segments. Their micro morphology is dependent on the chemical structure of backbones and the grafting number (GN) of branches. PZLL-g-PTHF is a hydrophobic graft copolymer and the water contact angles (WCAs) of copolymer surfaces decreased from 103 to 91 & DEG; with the increase of GN from 5 to 21. Interestingly, PLL-g-PTHF is an amphiphilic graft copolymer and their WCAs increased from 52 to 90 & DEG; with the increase of GN from 5 to 21. Both PZLL-g-PTHF and PLL-g-PTHF copolymers show good biocompatibility and anti-protein adsorption. The resulting PZLL-g-PTHF copolymers carrying a small amount of Ag nanoparticles, in situ generated from coinitiator AgClO4 for the synthesis of PTHF+ living chains, exhibit high killing efficiency (> 95%) for both Escherichia coli and Staphylococcus aureus. PLL-g-PTHF/Ag nanocomposites show extremely high killing efficiency (> 99%) against both S. aureus and E. coli for binary contribution from Ag nanoparticles and PLL. The antifouling and antibacterial graft copolymers would potentially have biological and medical applications.

Automated summary

Through chemical reactions, graft copolymers of PZLL-g-PTHF and PLL-g-PTHF were synthesized, which exhibit different properties and applications, such as protein adsorption inhibition and antibacterial activity, with potential biomedical applications.