Biocompatible Polylactide-<i>block</i>-Polypeptide-<i>block</i>-Polylactide Nanocarrier

Abstract

Polypeptides are successfully incorporated into poly­(l-lactide) (PLLA) chains in a ring-opening polymerization (ROP) of l-lactide by using them as initiators. The resulting ABA triblock copolymers possess molecular weights up to 11000 g·mol^–1 and polydispersities as low as 1.13, indicating the living character of the polymerization process. In a nonaqueous emulsion, peptide-initiated polymerization of l-lactide leads to well-defined nanoparticles, consisting of PLLA-<i>block</i>-peptide-<i>block</i>-PLLA copolymer. These nanoparticles are easily loaded by dye-encapsulation and transferred into aqueous media without aggregation (average diameter of 100 nm) or significant dye leakage. Finally, internalization of PLLA-<i>block</i>-peptide-<i>block</i>-PLLA nanoparticles by HeLa cells is demonstrated by a combination of coherent anti-Stokes Raman spectroscopy (CARS) and fluorescence microscopy. This demonstrates the promise of their utilization as cargo delivery vehicles