Composite hydrogels of alginate and brushite cement for biomedical applications as drug release

Among natural hydrogels, alginate has been widely studied due to its biocompatibility, biodegradability, and low cost. For these reasons it found several applications in the biomedical field, in particular in the tissue engineering and in the drug delivery. However, low mechanical properties of the alginate hydrogels and a high water content, connected with large pore size, causes a low efficiency in the drug release, in particular for the water soluble drugs. In order to reduce the release rate, in this work we prepared a composite based on alginate matrix with dispersed brushite crystals synthetized at room temperature in situ, via complexation of Alginate-Phosphate by calcium ions. The brushite acts partially as barrier in the drug dissolution and, differently from other calcium phosphate, is resorbable. The composite hydrogel obtained was characterized mechanically (DMA analysis), by thermal analysis and by SEM. Viability test based on MTT, reveal also that the composites Brushite-alginate were non-toxic and had a higher proliferation rate in comparison with Ca-Alginate.