Design and Development of D-alpha-Tocopheryl Polyethylene Glycol Succinate-block-Poly(epsilon-Caprolactone) (TPGS-b-PCL) Nanocarriers for Solubilization and Controlled Release of Paclitaxel

The objective of this study was to synthesize and characterize a set of biodegradable block copolymers based on TPGS-block-poly(epsilon-caprolactone) (TPGS-b-PCL) and to assess their self-assembled structures as a nanodelivery system for paclitaxel (PAX). The conjugation of PCL to TPGS was hypothesized to increase the stability and the drug solubilization characteristics of TPGS micelles. TPGS-b-PCL copolymer with various PCL/TPGS ratios were synthesized via ring opening bulk polymerization of epsilon-caprolactone using TPGS, with different molecular weights of PEG (1-5 kDa), as initiators and stannous octoate as a catalyst. The synthesized copolymers were characterized using H-1 NMR, GPC, FTIR, XRD, and DSC. Assembly of block copolymers was achieved via the cosolvent evaporation method. The self-assembled structures were characterized for their size, polydispersity, and CMC using dynamic light scattering (DLS) technique. The results from the spectroscopic and thermal analyses confirmed the successful synthesis of the copolymers. Only copolymers that consisted of TPGS with PEG molecular weights >= 2000 Da were able to self-assemble and form nanocarriers of