An emulsification/internal setting technique for the preparation of coated and uncoated hybrid silica/alginate aerogel beads for controlled drug delivery

Coated and uncoated hybrid silica/alginate aerogel beads have been prepared with a new emulsification/intemal setting technique. Hybrid aerogels combine high specific surface area and good mechanical strength of the inorganic component with biodegradability and bioadhesivity of the organic fraction so resulting in promising materials for drug-delivery. The hybrid beads were characterized through laser diffraction, BET and SAXS. Small particles (average diameter = 282 mu m) with high specific surface area (more. than 900 m(2)/g) and quite stable structural properties were obtained. Preliminary tests were performed to investigate how different kinds of coatings (alginate/hydroxypropyl methylcellulose, silica/hydroxypropyl methylcellulose or hydrophobic silica coating) affected the loading and release rate of model-drug ketoprofen. Among all results, uncoated hybrid aerogel beads resulted in burst release with 90% of the initial loaded drug delivered after 3 min while release was prolonged up to 60 min when a hydrophobic silica coating was used.