Biomimetic promotion of dentin remineralization using L-glutamic acid: inspiration from biomineralization proteins

The amorphous phase precipitates first during biomineralization and acts as the precursor for the subsequent mineralization of hard tissues including dentin. During this process, various biomineralization proteins with different, even opposite functions control the dimensions and phase states of the amorphous precursors that permeate the collagen matrix and then crystallize to form highly sophisticated organic-inorganic biological materials. In this study, a biomimetic strategy containing polyacylic acid and L-glutamic acid (L-Glu) was applied to promote the remineralization of Ca-depleted dentin collagen. Following the structural features of biomineralization-related non-collagenous proteins (NCPs), L-Glu was found to be capable of promoting the crystallization kinetics of the polyacylic acid-stabilized metastable amorphous to hydroxyapatite phase transformation. It is demonstrated that the dentin remineralization could be shortened within two days by using the cooperative effect of polyacrylic acid and L-glutamic acid. Furthermore, the resulting remineralized dentin layer has the same characteristics, including mechanical strength, as the natural ones. This biomimetic strategy highlights the combination of the two opposing factors of biomineralization components as the key to control the phase-transformation-based mineralization reactions with the organic matrix of dental tissues. In summary, a bio-inspired approach was followed to reconstruct collagen-mineralized tissues with biocompatible functions, morphologies, and characteristics.