In situ formation of multilayer biocomposite with anisotropic crystal orientation

• Mineralized hydrogel composites were fabricated by a novel spray coating process.
• Precipitated brushite crystals were anisotropically arranged within the composites.
• Brushite precipitation occurred between superimposed parallel alginate planes.

Hydrogel composites were fabricated through a novel layer by layer spray coating process using wet chemical precursors, which were sprayed alternately onto a substrate. With this simple method the gelification of calcium alginate gel and the anisotropic crystallization of brushite within the biopolymer matrix could be obtained simultaneously. The oriented deposition of brushite crystals was confirmed by SEM and X-ray diffraction analysis, respectively. The latter showed a higher intensity of the (0 4 0) reflection compared with randomly oriented brushite powder, strongly indicating a preferred crystal orientation within the composites. These composites might be used in biomedical applications as barrier materials or possibly for mineralized interfaces like osteochondral tissue.