Synthesis of Organic Biodegradable Aerogels Used in Controlled Drug Release

A number of polymers used in the production of carriers for drug delivery applications, possessing high surface area, appropriate surface chemistry and porosity, chemical stability and low cost have been investigated. One of these promising candidates are natural polysaccharides such as alginic acid sodium salt, guar gum, xanthan gum and chitosan due to their outstanding merits. They are similar to extracellular matrix having high chemical versatility, good biological performance and cell or enzyme-controlled degradability. Alginates were used in the present research for synthesis of organic biodegradable gels by solgel process, which were further easily converted to aerogels by supercritical drying. They are safe for use, stable, nontoxic, and derived from renewable sources. Alginates undergo reversible gelation in aqueous solution through interaction with divalent cations such as Ca 2+ , which create ionic inter-chain bridges. Two fundamental methods of ionic cross-linking were used to prepare alginate hydrogels: the diffusion method and the internal setting method. After producing the hydrogel, alcogels were formed by solvent exchange using 100% ethanol. Ethanol was later replaced by liquid CO2 with supercritical drying (at 7.375 MPa and 304.14 K). Aerogels made from natural polysaccharides combine both biocharacteristics and aerogel characteristics such as very high porosity and specific surface area, which makes them really attractive in drug delivery applications. The aerogels obtained in present research were therefore studied as drug carriers. The effects of the alginate composition and synthesis on model drug nicotinic acid release were investigated.