J.C. Trombe

Bio: J.C. Trombe is an academic researcher. The author has contributed to research in topics: Enamel paint & Carbonate. The author has an hindex of 1, co-authored 1 publications receiving 9 citations.

MicroRaman Spectral Study of the PO4 and CO3 Vibrational Modes in Synthetic and Biological Apatites

Abstract: The carbonate and phosphate vibrational modes of different synthetic and biological carbonated apatites were investigated by Raman microspectroscopy, and compared with those of hydroxyapatite. The ν1 phosphate band at 960 cm−1 shifts slightly due to carbonate substitution in both A and B sites. The spectrum of type A carbonated apatite exhibits two ν1 PO43− bands at 947 and 957 cm−1. No significant change was observed in the ν2 and ν4 phosphate mode regions in any carbonated samples. The ν3 PO43− region seems to be more affected by carbonation: two main bands were observed, as in the hydroxyapatite spectrum, but at lower wave numbers. The phosphate spectra of all biominerals apatite were consistent with type AB carbonated apatite. In the enamel spectrum, bands were observed at 3513 and at 3573 cm−1 presumably due to two different hydroxyl environments. Two different bands due to the carbonate ν1 mode were identified depending on the carbonate substitution site A or B, at 1107 and 1070 cm−1, respectively. Our results, compared with the infrared data already reported, suggest that even low levels of carbonate substitution induce modifications of the hydroxyapatite spectrum. Increasing substitution ratios, however, do not bring about any further alteration. The spectra of dentine and bone showed a strong similarity at a micrometric level. This study demonstrates the existence of acidic phosphate, observable by Raman microspectrometry, in mature biominerals. The HPO42− and CO32− contents increase from enamel to dentine and bone, however, these two phenomena do not seem to be correlated.

1.111 – Bioactive Ceramics: Physical Chemistry

Abstract: The chapter mainly discusses the physical–chemical properties of calcium phosphates (Ca-P), among the most important and most used bioactive ceramics. The main calcium phosphate compounds are presented with a brief description of their synthesis methods. Their characterization, using different techniques, including chemical analyses, X-ray diffraction, Fourier transform infrared (FTIR), Raman and solid-state nuclear magnetic resonance (NMR) spectrometries, and scanning and transmission electron microscopies (SEM and TEM), is reviewed and the different information obtained are discussed. The thermal stability and the relationships between different Ca-P phases are then described. The biological properties of Ca-P are related to their behavior in solution; their solubility, transformations and hydrolysis, nucleation ability, and surface properties and reactivity (ion exchange, adsorption) are presented especially in the case of apatites. The biological response regarding bioactivity, biodegradation, and simulated body fluid (SBF) testing is discussed from the point of view of the Ca-P physical chemistry. Several examples of applications are then proposed as ceramics, coatings, cements, and composite materials. A brief presentation of other bioactive mineral compounds follows (oxides and hydroxides, calcium carbonate, calcium sulfate).

Characterization of Calcium Phosphates Using Vibrational Spectroscopies

Abstract: Vibrational spectroscopies are extensively used for the characterization of calcium phosphates either as natural biological minerals (bone, teeth, ectopic calcifications) or as biomaterials (bioceramics, coatings, composites). The present review begins with a theoretical description of expected spectra for the main calcium phosphate phases (i.e., brushite, monetite, octacalcium phosphate, tricalcium phosphates, apatites, amorphous calcium phosphate) followed by the analysis of real spectra, line positions and assignments, and observed anomalies. In the second part, the spectra of complex well-crystallized ion-substituted apatites and other calcium phosphates, as well as solid solutions, are investigated, and the information gained regarding the substitution types and ion distributions are derived. Finally, we will examine and interpret the spectra of nanocrystalline apatites considering the ion substitution effects and the existence of a surface hydrated layer. Quantification processes and spectra treatments are briefly presented and discussed. Examples of the use of vibrational spectroscopies for biomaterials and biominerals characterization will be detailed for coating evaluations, including spectroscopic imaging, following up on mineral cement setting reactions, adsorption studies, near infrared investigations of surface water, residual strains determinations in bone, orientation of apatite crystals in biological tissues, and crystallinity and maturity of bone mineral.