1.
Surface Stability and Morphology of Calcium Phosphate Tuned by pH Values and Lactic Acid Additives: Theoretical and Experimental Study.
Chen, H, Lv, C, Guo, L, Ma, M, Li, X, Lan, Z, Huo, J, Dong, H, Zhu, X, Zhu, Q, et al
ACS applied materials & interfaces. 2022;(4):4836-4851
Abstract
The ubiquitous mineralization of calcium phosphate (CaP) facilitates biological organisms to produce hierarchically structured minerals. The coordination number and strength of Ca2+ ions with phosphate species, oxygen-containing additives, and solvent molecules played a crucial role in tuning nucleation processes and the surface stability of CaP under the simulated body fluid (SBF) or aqueous solutions upon the addition of oligomeric lactic acid (LACn, n = 1, 8) and changing pH values. As revealed by ab initio molecular dynamics (AIMD), density functional theory (DFT), and molecular dynamics (MD) simulations as well as high-throughput experimentation (HTE), the binding of LAC molecules with Ca2+ ions and phosphate species could stabilize both the pre-nucleation clusters and brushite (DCPD, CaHPO4·2H2O) surface through intermolecular electrostatic and hydrogen bonding interactions. When the concentration of Ca2+ ions ([Ca2+]) is very low, the amount of the formed precipitation decreased with the addition of LAC based on UV-vis spectroscopic analysis due to the reduced chance for the LAC capped Ca2+ ions to coordinate with phosphates and the increased solubility in the acid solution. With the increasing [Ca2+] concentration, the kinetically stable DCPD precipitation was obtained with high Ca2+ coordination number and low surface energy. Morphologies of DCPD precipitation are in plate, needle, or rod, depending on the initial pH values that were tuned by adding NH3·H2O, HCl, or CH3COOH. The prepared samples at pH ≈ 7.4 with different Ca/P ratios exhibited negative zeta potential values, which were correlated with the surface electrostatic potential distributions and potential biological applications.
2.
Study on microstructure, microhardness, bioactivity, and biocompatibility of La2 O3 -containing bioceramic coating doping SiO2 fabricated by laser cladding.
Fu, Q, Liu, Q, Li, L, Li, X, Gu, H, Sheng, B, Yang, B
Journal of biomedical materials research. Part B, Applied biomaterials. 2020;(5):2099-2107
Abstract
To solve the lack of strength of calcium phosphate ceramic coatings in load-bearing applications, gradient Ca-P bioceramic coatings doped with La2 O3 and SiO2 are fabricated by laser cladding on Ti-6Al-4 V. The effect of SiO2 on microstructure, microhardness, bioactivity, and biocompatibility of coatings was investigated. The experimental results illustrate that the coating doped with La2 O3 and SiO2 has excellent metallurgical bonding. The XRD analysis confirms that the amount of hydroxyapatite and tricalcium phosphate in the coating reached maximum when doping amount of SiO2 is 10 wt %. SiO2 -doped coatings show a significantly higher bone-like apatite precipitation after immersion in SBF than that of other coatings. in vitro experiment also shows that coating with 10 wt % SiO2 is more suitable for the attachment and proliferation of MG63 cells, indicating that coating with 10 wt % SiO2 exhibits best bioactivity and biocompatibility. These results suggest that the addition of SiO2 improves the bonding strength, bioactivity, and biocompatibility of coatings.
3.
Effect of doping different Si source on Ca-P bioceramic coating fabricated by laser cladding.
Fu, Q, Liu, Q, Li, L, Li, X, Gu, H, Sheng, B
Journal of applied biomaterials & functional materials. 2020;:2280800020917322
Abstract
The doping of silicon (Si) has been proved to improve the bioactivity of Ca-P ceramics. In light of this thinking, in the present study, Ca-P coatings with La2O3 by addition of 10 wt% SiO2 and 10 wt% diatomaceous earth (DE) were fabricated by laser cladding on Ti6Al4V, respectively. Coating doped without Si was also fabricated as the comparison group for the experiment. The effect of two different Si sources on the surface morphology, microstructure, microhardness, and bioactivity was systematically studied. The experimental results show that the Si-doped coating is of rough surface morphology, and the addition of DE significantly reduces the number of cracks and improves the microhardness. The X-ray diffraction results reveal that the amount of bioactive phase tricalcium-phosphate (TCP) and hydroxyapatite (HA) reaches maximum in the DE-doped coating. After soaking in simulated body fluid (SBF), the precipitate of bone-like apatite in the DE-doped coating is significantly higher than that of the other coatings.
4.
Novel rechargeable calcium phosphate nanoparticle-filled dental cement.
Xie, X, Wang, L, Xing, D, Qi, M, Li, X, Sun, J, Melo, MAS, Weir, MD, Oates, TW, Bai, Y, et al
Dental materials journal. 2019;(1):1-10
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Abstract
The objectives were to develop a novel rechargeable cement containing amorphous calcium-phosphate nanoparticles (nanoACP) to suppress tooth decay. Five cements were made with: (1) 60% glass particles (experimental control); (2) 40% glass+20% nanoACP; (3) 30% glass+30% nanoACP; (4) 20% glass+40% nanoACP; (5) 10% glass+50% nanoACP. Groups 1-4 had enamel bond strengths similar to Transbond XT (3M) and Vitremer (3M) (p>0.1). The nanoACP cement had calcium and phosphate ion release which increased with increasing nanoACP fillers. The recharged cement had substantial ion re-release continuously for 14 days after a single recharge. Ion re-release did not decrease with increasing recharge/re-release cycles. Groups 3-5 maintained a safe pH of medium (>5.5); however, control cements had cariogenic pH of medium (<4.5) due to biofilm acid. Therefore, nanoACP cement (1) had good bond strength to enamel, (2) possessed calcium and phosphate ion recharge/re-release capability, and (3) raised biofilm pH to a safe level to inhibit caries.