Synthesis and drug-release behavior of porous biodegradable amphiphilic co-polymeric hydrogels

A series of amphiphilic random block co-polymers were synthesized by the condensation of hydrophobic polycaprolactone diol (PCL diol) with hydrophilic dicarboxy poly(ethylene glycol) (PEG-diacid), obtained by reacting poly(ethylene glycol) (PEG) with succinic anhydride. The PEG/PCL random block co-polymers were then acrylated with acryloyl chloride to form PEG/PCL diacrylates (PCEdA), and then characterized by FT-IR, (1)H-NMR and GPC. The porous biodegradable gels were prepared through photo-polymerization of the PCEdA dissolved in DMSO at low temperature. Thermal behavior, swelling ratio and morphological characteristics as well as biodegradability of the presented gels were investigated. Results showed that the swelling ratio of the gel in deionized water increased with an increase of the PEG chain length in the copolymeric gel. DSC thermograms indicated that the melting point of the PCEdA was lower than that of PCL and PEG blocks, but a new crystalline peak of the co-polymeric gel appeared with increasing of the segmental length of the PEG. Thermal stability of PCE gel was higher than that of PCE diol. The pore size of the gel was influenced by the concentration of PCEdA. The drug-release behavior of PCE gels was also investigated.