Rediscovering hydrogel-based double-diffusion systems for studying biomineralization

Abstract

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.

Transformation of vaterite nanoparticles to hydroxycarbonate apatite in a hydrogel scaffold: relevance to bone formation

“…The crystallinity increases with time. 57 Transformation of vaterite nanoparticles to HCA in PEG-acetal-DMA hydrogel This surface texture implies that the growth of the HCA crystals occurs through particle aggregation.…”

Phosphorylation regulates the secondary structure and function of dentin phosphoprotein peptides

“…In brief, 6-cm-long segments of disposable Kimax tubes (Agilent, Lawrence, KS, USA) containing a total of 3 mL of 10% gelatin gel in 0.05 M, pH 7.4, Tris buffer and 0.01% sodium azide to prevent bacterial growth were mounted on an apparatus that circulated 100 mM calcium chloride and 100 mM ammonium acid phosphate through the tubes under constant nitrogen pressure. Diffusion rates have been characterized previously [31], and in these gels at room temperature and 1 atm pressure, precipitant bands are noted at 3.5 days when the Ca and inorganic phosphate (Pi) product (Ca × Pi) adjacent to the bands is 5.5 mM 2 [30]. Peptides at concentrations of 0, 1, 5, and 20 μg/mL were placed 1.54 mm from the Pi entrance with 0.5 mg/ml HA seeds.…”

“…FTIR, therefore, is one of few techniques that could be used to analyze the interaction of DPP peptides with HA [29]. (iv) Solution measurements using a gel diffusion system that would provide information on the relative extent of HA proliferation in the presence of different DPP peptides and HA seeds [30,31]. …”

Biological Crystallization

“…Very recently, this technique has emerged as a powerful platform for mimicking crystal deposition in biomineralization processes [135][136][137][138][139]. The main motivation behind this approach has been that many processes take place in a gel-like organic matrix, which is an assembly of proteins, polysaccharides, and/or glycoproteins.…”

“…The main motivation behind this approach has been that many processes take place in a gel-like organic matrix, which is an assembly of proteins, polysaccharides, and/or glycoproteins. Among the many different minerals, most noteworthy is the employment of this technique to crystallize calcium phosphates [136,142] and calcium carbonates [138,143,144] along with the study of the effects of inorganic and organic additives on the crystallization processes of these substances [143,144]. Among the many different minerals, most noteworthy is the employment of this technique to crystallize calcium phosphates [136,142] and calcium carbonates [138,143,144] along with the study of the effects of inorganic and organic additives on the crystallization processes of these substances [143,144].…”