Investigation on injectable, thermally and physically gelable poly(ethylene glycol)/poly(octadecanedioic anhydride) amphiphilic triblock co-polymer nanoparticles.

A family of injectable, biodegradable and thermosensitive co-polymer nanoparticle (NP) hydrogels based on mPEG-b-POA-b-mPEG, which was synthesized from mono-methoxy poly(ethylene glycol) (mPEG) and poly(octadecanedioic anhydride) (POA), was investigated in this paper. It was found that the aqueous dispersions of these NPs underwent a reversible gel-sol transition upon temperature change. By using paclitaxel and Bovine serum albumin (BSA) as model drugs, we noticed that the in vitro releases of both in situ gel-forming formulations were sustained and no initial burst releases were observed for 7 days. In vitro cytotoxicity tests via MTT assay indicate that mPEG-b-POA-b-mPEG NPs are non-toxic to normal mouse lung fibroblast cells (L929). The in vivo hydrogel formation and in vivo biocompatibility of co-polymer NP hydrogel were also investigated and the results further validate the biocompatible nature of co-polymer NP hydrogel. In conclusion, our mPEG-b-POA-b-mPEG NP hydrogel is able to control the release of incorporated drug for longer duration.

Poly(ester anhydride)/mPEG amphiphilic block co-polymer nanoparticles as delivery devices for paclitaxel.

This work focused on the preparation and characterization of a novel amphiphilic block co-polymer and paclitaxel-loaded co-polymer nanoparticles (NPs) and in vitro evaluation of the release of paclitaxel and cytotoxicity of NPs. mPEG-b-P(OA-DLLA)-b-mPEG was prepared via melt polycondensation of methoxy poly(ethylene glycol) (mPEG), octadecanedioic acid (OA) and D,L-lactic acid (DLLA) and characterized by FT-IR, (1)H-NMR, (13)C-NMR, GPC, DSC and XRD. The paclitaxel-loaded mPEG-b-P(OA-DLLA)-b-mPEG NPs were prepared by nanoprecipitation and then characterized by LPSA, TEM and (1)H-NMR. In vitro release behaviors of the paclitaxel-loaded NPs were investigated by HPLC. In vitro cytotoxicity of NPs was evaluated by MTT assay with normal mouse lung fibroblast cells (L929) as model cells. The composition of mPEG-b-P(OA-DLLA)-b-mPEG is consistent with that of the designed co-polymer. The paclitaxel-loaded NPs are of spherical shape with core/shell structure and size smaller than 300 nm. Paclitaxel can be continuously released from the paclitaxel-loaded NPs and the in vitro release rate of paclitaxel decreases with increasing the content of the P(OA-DLLA) segments in the co-polymer. The mPEG-b-P(OA-DLLA)-b-mPEG NPs are non-toxic to L929. The results suggest that mPEG-b-P(OA-DLLA)-b-mPEG NPs are a potential candidate carrier material for the controlled delivery of paclitaxel and other hydrophobic compounds.