Novel graft PLLA-based copolymers: potential of their application to particle technology

This study describes the synthesis of novel biodegradable graft copolymers based on a backbone of poly (L-lactic acid) (PLLA) on which short blocks of polyacrylamide (PAcr) were grafted. Preliminary results of their potential in the field of controlled-release technologies also have been reported. The copolymers have been synthesized through the radical polymerization of acrylamide initiated by a peroxide in the presence of PLLA. Two different methodologies of synthesis, namely, in solution and in emulsion, have been tested. The structure of the copolymers was studied by (1)H-NMR and infrared spectroscopy and by differential scanning calorimetry (DSC) and cytotoxicity tests were conducted to assess their biocompatibility. The copolymers were used to prepare particles by the emulsion-solvent evaporation technique. The shapes and dimensions of the particles were dependent on the polymer type and concentration used. The surfaces of the particles were modified by the presence of polyacrylamide residues, as demonstrated by zeta-potential measurements. The release behavior of the particles was assessed by encapsulating rhodamine B as the model compound. The release was faster for the particles prepared by the grafted polymer as a consequence of its increased hydrophilicity. Based on these novel biomaterials, preliminary results suggest a potential of the particles for peroral or parenteral drug delivery.