Polyethylenimine-functionalized microcryogels for controlled release of diclofenac sodium

Various changes in the environment can occur as drug delivery systems travel to the targeted area. Therefore, it is an important aspect to consider the effects of environmental changes such as pH and temperature on the release in the development of drug delivery systems. Microcryogels having predefined shape and size were fabricated as drug delivery systems and loaded with diclofenac sodium, a non-steroidal anti-inflammatory drug. Physicochemical, structural, and morphological properties of microcryogels were investigated by swelling, pore volume and porosity tests, infrared spectroscopy, and field emission scanning electron microscopy. Effects of medium pH on drug release were examined at release media with the pH 2.0 as simulated gastric juice, pH 7.4 as the simulated intestinal fluid/intravenous solution, pH 6.0 as a simulated medium during a normal wound healing, and pH 9.0 as a simulated medium for infected wounds. Effects of temperature on drug release were also analyzed at 37 °C as normal body temperature and 42 °C as inflammatory temperature. The obtained results showed that drug release was too low in acidic environment than those observed at higher pH values. Moreover, the release rates were higher at inflammatory temperature compared with the ones at normal body temperature.