Rediscovering Hydrogel-Based Double-Diffusion Systems for Studying Biomineralization.

For those seeking to model biomineralization in vitro, hydrogels can serve as excellent models of the extracellular matrix (ECM) microenvironment. A major challenge posed in implementing such systems is the logistics involved, from fundamental engineering to experimental design. For the study of calcium phosphate (e.g., hydroxyapatite) formation, many researchers use hydrogel-based double-diffusion systems (DDSs). The various designs of these DDSs are seemingly as unique as their applications. In this Highlight, we present a survey of four distinct types of double-diffusion systems and evaluate them in the context of fundamental diffusion theory. Based upon this analysis, we present the design and evaluation of an optimized system. The techniques and framework for the evaluation and construction of a DDS presented here can be applied to any DDS that a researcher may want to implement for their particular studies of biomineralization.