Shape memory hydroxypropyl cellulose-g-poly (ε-caprolactone) networks with controlled drug release capabilities

Hydroxypropyl cellulose-g-poly (epsilon-caprolactone) (HPC-g-PCL) derived networks from different lengths of PCL side chains have been prepared by crosslinking HPC-g-PCL, providing (X(HPC-g-PCL)) films with different gel contents, crystallinity, and morphology. Two networks with different epsilon-cCaprolactone (CL) content (95 and 98%) named X(HPC-g-PCL)-95 and X(HPC-g-PCL)-98 were used for further study of thermo-mechanical properties and shape memory behavior. Young's modulus (E), elongation at break (epsilon(b) %) and tensile strength (sigma(m)) were examined at three different temperatures 22, 37 and 65 degrees C. The results revealed that E values significantly were controlled by crystallinity as well as crosslink density depending on the temperatures. Complete shape recovery was observed for both samples once the degree of crosslinking was increased over 95%, while a narrower recovery temperature ranges from 39 to 41 degrees C was found for the X(HPC-g-PCL)-98 sample. The shape fixity results showed a great dependence on the molecular weight of PCL. Therefore, the X (HPC-g-PCL)-98 sample demonstrated an excellent shape fixation. Naproxen-loaded shape memory films prepared using either the in situ (before crosslinking) or swelling (after crosslinking) methods (3 and 10wt%), were also described as a model for controlled drug release device. The chemical composition of drug-loaded networks, drug concentration and the incorporation method greatly affected the crosslink density, morphology and mechanical properties. Importantly, loading via the in situ method resulted possibility to adjust the amount of incorporated drug and fast subsequent release, while drug-loaded films by the swelling method exhibited an initial burst release. Both networks exhibited slow sustained release of naproxen over two months.