In vitro release of dexamethasone or bFGF from chitosan/hydroxyapatite scaffolds.

Chitosan scaffolds containing dexamethasone (Dex) or basic fibroblast growth factor (bFGF) were developed to create alternative drug-delivery systems for possible tissue-engineering applications such as periodontal bone regeneration. Chitosan solutions (2% and 3% (w/v) in acetic acid) were prepared from chitosan flakes with high deacetylation degree (>85%), then these solutions were freeze-dried at -80 degrees C to obtain scaffolds with interconnected pore structures. Dex and bFGF were incorporated into scaffolds by embedding method (solvent sorption method). The initial loading amounts were varied as 300, 600 and 900 ng Dex per dry scaffold (average dry weight is 3 mg) and 50 or 100 ng bFGF per dry scaffold to a range of deliverable doses. Release studies which were conducted in Dulbecco's phosphate-buffered saline (DPBS) showed that 900 ng Dex loaded chitosan scaffolds in both compositions released total Dex during a 5-day period at a nearly constant rate after the initial burst. However, bFGF release from all scaffolds with both loading amounts (50 ng or 100 ng) was completed in 10 or 20 h. In order to prolong the release period of bFGF, composite scaffolds were fabricated in the presence of hydroxyapatite (HA) beads with average particle size of 40 mum. Sustained release of bFGF up to 7 days was achieved due to the electrostatic interactions between HA and bFGF molecules. These results suggested that chitosan scaffolds can be suitable for Dex release; however, the presence of HA in the chitosan scaffold is necessary to achieve the desired release period for bFGF.