Marine organisms are known to fine-tune the physical and chemical properties of gel-like environments within their bodies to guide the precipitation of calcium carbonate and synthesize mineralized tissues with sophisticated microstructures. While the three-dimensional polymer network provides sites for nucleation, the pore solution regulates mass transport to the growing mineral phase and contains soluble additives that can further influence the expressed crystalline morphology. Hydrogels serve as versatile biomimetic models to help shed light on the mechanisms exploited by living organisms to direct biomineralization in such gel-like environments. Therefore, hydrogels remain a subject of intense research due to their potential for tissue engineering applications. In this work, we use a novel combination of spectrophotometry, microscopy, spectroscopy and dynamic mechanical analysis to showcase a mineralization pathway for agarose hydrogels that proceeds through the formation of an amorphous calcium carbonate (ACC), which improves the mechanical response of the composite. While the formation of ACC is highly dependent on the properties of the agarose network, the transformation to a crystalline phase is regulated by the dissolution of ACC only. By introducing an inorganic additive, we exert control over the kinetics of ACC formation, its distribution within the hydrogel, and the resulting crystalline morphology. In-situ mechanical testing during the mineralization step reveals an agarose-calcium carbonate composite with desirable mechanical properties such as increased resilience and lower viscous dissipation. Through this work we share insights into the mechanisms that control the formation of calcium carbonate in hydrogels and how they can open new avenues for designing bioinspired mineralized tissues.

Linking the kinetics of calcium carbonate formation and crystallization to the mechanical response of mineralized hydrogels

2019 Spring National Meeting

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