Polycarboxy/Sulfo Betaine—Calcium Phosphate Hybrid Materials with a Remineralization Potential

Abstract

Biomacromolecules control mineral formation during the biomineralization process, but the effects of the organic components’ functionality on the type of mineral phase is still unclear. The biomimetic precipitation of calcium phosphates in a physiological medium containing either polycarboxybetaine (PCB) or polysulfobetaine (PSB) was investigated in this study. Amorphous calcium phosphate (ACP) or a mixture of octacalcium phosphate (OCP) and dicalcium phosphate dihydrate (DCPD) in different ratios were identified depending on the sequence of initial solution mixing and on the type of the negative functional group of the polymer used. The more acidic character of the sulfo group in PSB than the carboxy one in PCB determines the dominance of the acidic solid phases, namely, an acidic amorphous phase or DCPD. In the presence of PCB, the formation of ACP with acicular particles arranged in bundles with the same orientation was observed. A preliminary study on the remineralization potential of the hybrid material with the participation of PSB and a mixture of OCP and DCPD did not show an increase in enamel density, contrary to the materials based on PCB and ACP. Moreover, the latter showed the creation of a newly formed crystal layer similar to that of the underlying enamel. This defines PCB/ACP as a promising material for enamel remineralization.

New Nano-Crystalline Hydroxyapatite-Polycarboxy/Sulfo Betaine Hybrid Materials: Synthesis and Characterization

“…The microstructure of the materials obtained by the TEM analysis is consistent with our observations in our previous paper [ 47 ], in which the ACP particles obtained in the presence of PCB are thinner and smaller in size than those obtained in the presence of PSB. In addition, and in good agreement with the observations in the previous paragraph, the large morphological difference resolved by the TEM analysis between the materials synthesized without a polymer and with PSB with respect to the PCB hybrid material indicates a greater ability to anchor Ca ions in specific positions of the PCB polymer that could act as a template to nucleate the HA mineral phase.…”

“…We chose this pH to be close to the physiological pH (7.2–7.4) but to avoid the formation of acid calcium phosphates. In our previous study using these polymers and systems [ 47 ], but without maintaining a constant pH, we found the formation of different uncontrolled ratios of dicalcium phosphate dihydrate (DCPD), octacalcium phosphate (OCP) and even amorphous calcium phosphates (ACPs). We also proved in that previous work that the differences in the negatively charged functional groups of the two polymers influenced the calcium phosphate nucleation and the type of the final formed mineral phases, accordingly.…”

“…The synthesis of PCB and PSB by reversible addition–fragmentation chain-transfer (RAFT) polymerization has been described in detail elsewhere [ 47 ]. Briefly, PCB was prepared by dissolution of ten grams of the monomer carboxybetaine and 0.1% of 2,2-azobis (2-methylpropionamide) dihydrochloride in forty-five milliliters of acetate buffer (pH = 5.2).…”

Calcium Orthophosphate (CaPO4) Containing Composites for Biomedical Applications: Formulations, Properties, and Applications

“…The same is true for CaPO 4 /graphene composites [177,178]. Other examples include biomimetic synthesis [177,178,183,184], the use of amino acid-coated gold nanosized particles as scaffolds to grow CDHA [185], and the preparation of nanosized HA/PA biocomposites [186,187]. In some cases, mechanochemical routes [188,189], emulsions [190][191][192][193][194][195], lyophilization [171,196,197] and freeze-thaw techniques [198], and gel templating mineralization [198,199], as well as vat photopolymerization [200], can be applied to produce CaPO 4 -based biocomposites.…”