In situ CaCO3 mineralization controlled by carbonate source within chitosan-based cryogels

Designing of multifunctional hydrogel/CaCO3 composites has received great interest in the modern tissue engineering. Herein, four chitosan-based cryogel samples as monoliths, prepared by ice-segregation technique and which differ by structural porosity, are proposed as possible matrix for CaCO3 crystal growth, aiming the formation of homogeneous composite materials. Also, four types of carbonate sources were applied as modulators for crystal growth: Na2CO3 in an alternate dipping process, dimethyl- or diethyl-carbonate (DMC or DEC) hydrolysis, and ammonium bicarbonate diffusion. The morphology of the composites was investigated by scanning electron microscopy and the polymorphs characteristics by X-ray diffraction and FTIR-ATR spectroscopy. The crystal growth applied methods were effective for composite formation, tuning the inorganic formation in the whole cryogels 3D pattern. Thus, increasing the number of alternate sorption steps, the amount of CaCO3 crystals increased but keeping the pores open for further specific applications. Also, CaCO3 polymorphs formed by DMC or DEC hydrolysis show mainly the formation of calcite rhombohedral crystals arranged in large polycrystals. The ammonium diffusion method generated the most uniform structures, in the whole investigated cryogels samples, MTS test showing samples biocompatibility.

Automated summary

This study investigated the design of multifunctional hydrogel/CaCO3 composites using four chitosan-based cryogel samples with different porosity structures as possible matrix for CaCO3 crystal growth. Four types of carbonate sources were applied to modulate crystal growth, with methods such as Na2CO3 dipping process, DMC or DEC hydrolysis, and ammonium bicarbonate diffusion. The results showed that the crystal growth methods were effective in composite formation and tunable for inorganic formation in the whole cryogels.