Chitosan/PEO blend films crosslinked by genipin as potential membranes for controlled drug release and protein separation

This study was conducted in order to develop novel chitosan/poly(ethylene oxide)(PEO) blend films crosslinked by genipin as potential membranes for potential medical applications, such as controlled drug carriers and separation of proteins from eleutherococcuss enticosus (ES). Genipin, a naturally occurring and non-toxic crosslinking reagent, was used to form chitosan and chitosan/PEO blend networks. Genipin is found in traditional Chinese medicine and extracted from Gardenia fruit. Importantly,it overcomes the problem of physiological toxicity inherent in the use of common synthetic chemicals as crosslinking agents. The miscibility and morphology of chitosan /PEO blends were examined by means of differential scanning calorimetry (DSC), Fourier transform infrared spectroscopy (FT-IR) and small angle X-ray scattering (SAXS). The experimental results indicate that the chitosan/PEO blends are miscible over the whole composition range. A phenomenon was observed for chitosan/LPEO (lower molecular weight PEO) blends: when the composition of chitosan was less than 60% by weight, the melting points increased as the composition of chitosan was increased. It is believed that there are strong molecular interactions between chitosan molecules and the molecules in the crystalline phase of LPEO in the chitosan ALPEO blends. FT-IR and UV spectra analysis of the crosslinking reaction of chitosan revealed that the hydroxyl groups (3400 cm-1) and the amide groups (1645 cm-) in chitosan participated actively in the reaction. SAXS results showed that a heterogeneous structure exists in the chitosan/HPEO (or /LPEO) blend networks. Crosslinking by genipin restricts crystallisation and leads to smaller crystals. The mechanical properties, the stability in water, the swelling behaviour and surface properties of the films were also investigated. (Continues...).