Synthesis and characterization of micelles from thermal-responsive amphiphilic triblock polypeptoids as drug carrier

In this study, a thermal-responsive triblock polypeptoid, poly(N-octylglycine)-b-poly(N-allylglycine)-b-poly(N-methylglycine) (PNOG-b-PNAG-b-PNMG), was synthesized via continuous polymerization of octyl-N-carboxyanhydride (Oc-NCA), allyl-N-carboxyanhydride (Al-NCA), and methyl-N-carboxyanhydride (Me-NCA) by using benzylamine as the initiator. Remarkably, triblocks were self-assembled into micelles in an aqueous solution. The poly(N-octyl glycine) PNOG blocks form the core of the micelle, while poly(N-methyl glycine) PNMG blocks form a hydrophilic shell. The PNAG block, located between the PNOG and PNMG blocks, is soluble in water and forms part of the hydrophilic shell at low temperatures but becomes hydrophobic and associates with the micelle core at high temperatures. The micelle size transition temperature can be adjusted by changing the polypeptoid structures within the range of 35–38°C. We also systematically investigated the degree of polymerization of polymers and the effect of concentration on assembly. The antibacterial (ciprofloxacin (Cip) drug, is encapsulated in micelles through hydrophobic interactions and released in stages by adjusting the size of the hydrophobic core through temperature changes.