Effect of Silane-Coupling Treatment on Thermal Decomposition of Octacalcium Phosphate

Drug Molecular Immobilization and Photofunctionalization of Calcium Phosphates for Exploring Theranostic Functions

Theranostics (bifunction of therapeutics and diagnostics) has attracted increasing attention due to its efficiency that can reduce the physical and financial burden on patients. One of the promising materials for theranostics is calcium phosphate (CP) and it is biocompatible and can be functionalized not only with drug molecules but also with rare earth ions to show photoluminescence that is necessary for the diagnostic purpose. Such the CP-based hybrids are formed in vivo by interacting between functional groups of organic molecules and inorganic ions. It is of great importance to elucidate the interaction of CP with the photofunctional species and the drug molecules to clarify the relationship between the existing state and function. Well-designed photofunctional CPs will contribute to biomedical fields as highly-functional ormultifunctional theranostic materials at the nanoscales. In this review, we describe the hybridization between CPs and heterogeneous species, mainly focusing on europium(III) ion and methylene blue molecule as the representative photofunctional species for theranostics applications.

Effect of ageing and endodontic treatment on the thermal stability of human dentin

BACKGROUND

Human dentin is a highly calcified tissue of mesenchymal origin with a heterogeneous structure. Its morphology is constantly remodelled throughout the life span of the tooth, as well as under the influence of external stimuli.

OBJECTIVE

The aim of the present study was to obtain information about the thermal changes in the crown and root dentin specimens of vital and devitalized teeth.

METHODS

The investigated samples were divided into 6 groups, depending on the patients' age and dentin location (crown, root). An additional group of endodontically treated teeth was created. The methods of choice were were combined thermal analysis (DTA-TG(DTG)-MS and gas chromatography-mass spectrometry.

RESULTS

After heating up to 1200 °C, endo- and exothermal effects were observed. The effects' dynamic was the same for all samples. The differences were in the samples' weight after the experiment, with root dentin showing the greatest mass loss percentage.

CONCLUSIONS

The observed mass loss differences could be attributed to the presence of impurities in the dentin, as well as alterations in the collagen matrix. Ageing and endodontic treatment could catalyse the accumulation of such changes and affect the microstructure of the mineralized tissue.

Calcium phosphates in Ca(2+)-fortified milk: phase identification and quantification by Raman spectroscopy

Calcium phosphate nanoclusters (CPNs) are important for the structure, function, and nutrient density of many dairy products. Phosphorylated amino acids in caseins stabilize calcium phosphate as nanoclusters which are amorphous to X-ray diffraction and exist within casein micelles, and these CPNs play a key role in micelle stability. Addition of calcium to milk results in further calcium phosphate removal from the serum, and there is uncertainty about the nature of the material formed and its stability. In this work we investigate both the solution and colloidal phases in CaCl2 enriched bovine milk to identify, quantify, and determine the solubility of the calcium phosphate material formed in response to calcium addition to milk. The P-O stretching bands are quite distinct in the Raman spectra of the main synthetic calcium phosphate mineral phases, including the amorphous calcium phosphate phase. In response to adding between 5 and 40 mM CaCl2 to milk, the serum phosphate concentration decreased asymptotically from 7.5 ± 0.2 to 0.54 ± 0.05 mM. Using Raman spectroscopy with a combination of internal and external standards, it was possible to show that the calcium phosphate material formed after Ca(2+) addition to milk was the same as amorphous calcium phosphate nanoclusters present in the absence of added calcium. The use of an internal standard allowed a quantitative analysis of the spectra which demonstrated that the amorphous calcium phosphate formed accounted for all of the calcium and phosphate that was removed from solution in response to calcium addition.