Vibrational spectroscopic characterization of the phosphate mineral barbosalite Fe2+Fe3+2(PO4)2(OH)2 : implications for the molecular structure

Natural single-crystal specimens of barbosalite from Brazil, with general formula Fe2+Fe3+ 2 (PO4)2(OH)2 were investigated by Raman and infrared spectroscopy. The mineral occurs as secondary products in granitic pegmatites. The Raman spectrum of barbosalite is characterized by bands at 1020, 1033 and 1044 cm−1 cm−1, assigned to ν1 symmetric stretching mode of the HOPO3- 3 and PO3- 4 units. Raman bands at around 1067, 1083 and 1138 cm−1 are attributed to both the HOP and PO antisymmetric stretching vibrations. The set of Raman bands observed at 575, 589 and 606 cm−1 are assigned to the ν4 out of plane bending modes of the PO4 and H2PO4 units. Raman bands at 439, 461, 475 and 503 cm−1 are attributed to the ν2 PO4 and H2PO4 bending modes. Strong Raman bands observed at 312, 346 cm−1 with shoulder bands at 361, 381 and 398 cm−1 are assigned to FeO stretching vibrations. No bands which are attributable to water vibrations were found. Vibrational spectroscopy enables aspects of the molecular structure of barbosalite to be assessed.

Randomized controlled trial : a randomized controlled clinical trial comparing a remineralizing paste with an antibacterial gel to prevent early childhood caries

PURPOSE: The purpose of this study was to compare twice daily tooth-brushing using 0.304 percent fluoride toothpaste alone with: (1) twice daily tooth-brushing plus once daily 10% casein phosphopeptide-amorphous calcium phosphate (CPP-ACP) paste; and (2) twice daily tooth-brushing plus once daily 0.12% chlorhexidine gel (CHX) for reducing early childhood caries (ECC) and mutans streptococci (MS) colonization. METHODS: Subjects (n=622) recruited at birth were randomized to receive either CPP-ACP or CHX or no product (study control [SC]). All children were examined at 6, 12, and 18 months old in their homes, and at 24 months old in a community dental clinic. RESULTS: At 24 months old, the caries incidence was 1% (2/163) in CPP-ACP, 2% (4/180) in CHX, and 2% (3/188) in SC groups. In children who were previously MS colonized at 12 and 18 months old, 0% (0/11) and 5% (3/63), respectively, of the CPP-ACP group remained MS-positive versus 22% (2/9) and 72% (18/25) in CHX and 16% (4/25) and 50% (7/14) in SC groups (P<.001). CONCLUSIONS: There is insufficient evidence to justify the daily use of casein phosphopeptide-amorphous calcium phosphate or chlorhexidine gel to control early childhood caries.

A randomised, controlled clinical trial comparing chlorhexidine gel and low-dose fluoride toothpaste to prevent early childhood caries

Objectives This randomised, controlled trial compared the effectiveness of 0.12% chlorhexidine (CHX) gel and 304% fluoride toothpaste to prevent early childhood caries (ECC) in a birth cohort by 24 months. Methods The participants were randomised to receive either (i) twice daily toothbrushing with toothpaste and once daily 0.12% CHX gel (n = 110) or (ii) twice daily toothbrushing with toothpaste only (study controls) (n = 89). The primary outcome measured was caries incidence and the secondary outcome was percentage of children with mutans streptococci (MS). All mothers were contacted by telephone at 6, 12, and 18 months. At 24 months, all children were examined at a community dental clinic. Results At 24 months, the caries prevalence was 5% (3/61) in the CHX and 7% (4/58) in the controls (P = 0.7). There were no differences in percentages of MS-positive children between the CHX and control groups (54%vs 53%). Only 20% applied the CHX gel once daily and 80% less than once daily. Conclusions Toothbrushing using 304% fluoride toothpaste with or without the application of chlorhexidine gel (0.12%) reduces ECC from 23% found in the general community to 5–7%. The lack of effect with chlorhexidine is likely to be due to low compliance.

The influence of cellular source on periodontal regeneration using calcium phosphate coated polycaprolactone scaffold supported cell sheets

Cell-based therapy is considered a promising approach to achieving predictable periodontal regeneration. In this study, the regenerative potential of cell sheets derived from different parts of the periodontium (gingival connective tissue, alveolar bone and periodontal ligament) were investigated in an athymic rat periodontal defect model. Periodontal ligament (PDLC), alveolar bone (ABC) and gingival margin-derived cells (GMC) were obtained from human donors. The osteogenic potential of the primary cultures was demonstrated in vitro. Cell sheets supported by a calcium phosphate coated melt electrospun polycaprolactone (CaP-PCL) scaffold were transplanted to denuded root surfaces in surgically created periodontal defects, and allowed to heal for 1 and 4 weeks. The CaP-PCL scaffold alone was able to promote alveolar bone formation within the defect after 4 weeks. The addition of ABC and PDLC sheets resulted in significant periodontal attachment formation. The GMC sheets did not promote periodontal regeneration on the root surface and inhibited bone formation within the CaP-PCL scaffold. In conclusion, the combination of either PDLC or ABC sheets with a CaP-PCL scaffold could promote periodontal regeneration, but ABC sheets were not as effective as PDLC sheets in promoting new attachment formation.

Osteogenic differentiation of bone marrow MSCs by β-tricalcium phosphate stimulating macrophages via BMP2 signalling pathway

Immune reactions play important roles in determining the in vivo fate of bone substitute materials, either in new bone formation or inflammatory fibrous tissue encapsulation. The paradigm for the development of bone substitute materials has been shifted from inert to immunomodulatory materials, emphasizing the importance of immune cells in the material evaluation. Macrophages, the major effector cells in the immune reaction to implants, are indispensable for osteogenesis and their heterogeneity and plasticity render macrophages a primer target for immune system modulation. However, there are very few reports about the effects of macrophages on biomaterial-regulated osteogenesis. In this study, we used b-tricalcium phosphate (b-TCP) as a model biomaterial to investigate the role of macrophages on the material stimulated osteogenesis. The macrophage phenotype switched to M2 extreme in response to b-TCP extracts, which was related to the activation of calcium-sensing receptor (CaSR) pathway. Bone morphogenetic protein 2 (BMP2) was also significantly upregulated by the b-TCP stimulation, indicating that macrophage may participate in the b-TCP stimulated osteogenesis. Interestingly, when macrophageconditioned b-TCP extracts were applied to bone marrow mesenchymal stem cells (BMSCs), the osteogenic differentiation of BMSCs was significantly enhanced, indicating the important role of macrophages in biomaterial-induced osteogenesis. These findings provided valuable insights into the mechanism of material-stimulated osteogenesis, and a strategy to optimize the evaluation system for the in vitro osteogenesis capacity of bone substitute materials.

A randomised, concentration-controlled, comparison of standard (5-day) vs. prolonged (15-day) infusions of etoposide phosphate in small-cell lung cancer

Purpose: This randomised trial was designed to investigate the activity and toxicity of continuous infusion etoposide phosphate (EP), targeting a plasma etoposide concentration of either 3 μg/ml for five days (5d) or 1 μg/ml for 15 days (15d), in previously untreated SCLC patients with extensive disease. Patients and methods: EP was used as a single agent. Plasma etoposide concentration was monitored on days 2 and 4 in patients receiving 5d EP and on days 2, 5, 8 and 11 in patients receiving 15d EP, with infusion modification to ensure target concentrations were achieved. Treatment was repeated every 21 days for up to six cycles, with a 25% reduction in target concentration in patients with toxicity. Results: The study has closed early after entry of 29 patients (14 with 5d EP, 15 with 15d EP). Objective responses were seen in seven of 12 (58%, confidence interval (CI): 27%-85%) evaluable patients after 5d EP, and two of 14 (14%, CI: 4%42%) evaluable patients after 15d EP (P = 0.038). Grade 3 or 4 neutropenia or leucopenia during the first cycle of treatment was observed in six of 12 patients after 5d EP and 0/14 patients after 15d EP (P = 0.004), with median nadir WBC count of 2.6 x 109/1 after 5d and 5.0 x 109/1 after 15d EP (P = 0.017). Only one of 49 cycles of 15d EP was associated with grade 3 or worse haematological toxicity, compared to 14 of 61 cycles of 5d EP. Conclusions: Although the number of patients entered into this trial was small, the low activity seen at 1 μg/ml in the 15d arm suggests that this concentration is below the therapeutic window in this setting. Further concentration- controlled studies with prolonged EP infusions are required.

Vibrational spectroscopic characterization of the phosphate mineral althausite Mg2(PO4)(OH,F,O) – implications for the molecular structure

Natural single-crystal specimens of althausite from Brazil, with general formula Mg2(PO4)(OH,F,O) were investigated by Raman and infrared spectroscopy. The mineral occurs as a secondary product in granitic pegmatites. The Raman spectrum of althausite is characterized by bands at 1020, 1033 and 1044 cm-1, assigned to ν1 symmetric stretching modes of the HOPO33- and PO43- units. Raman bands at around 1067, 1083 and 1138 cm-1 are attributed to both the HOP and PO antisymmetric stretching vibrations. The set of Raman bands observed at 575, 589 and 606 cm-1 are assigned to the ν4 out of plane bending modes of the PO4 and H2PO4 units. Raman bands at 439, 461, 475 and 503 cm-1 are attributed to the ν2 PO4 and H2PO4 bending modes. Strong Raman bands observed at 312, 346 cm-1 with shoulder bands at 361, 381 and 398 cm-1 are assigned to MgO stretching vibrations. No bands which are attributable to water were found. Vibrational spectroscopy enables aspects of the molecular structure of althausite to be assessed.

A study of the phosphate mineral kapundaite NaCa(Fe3+)4(PO4)4(OH)3⋅5(H2O) using SEM/EDX and vibrational spectroscopic methods

Vibrational spectroscopy enables subtle details of the molecular structure of kapundaite to be determined. Single crystals of a pure phase from a Brazilian pegmatite were used. Kapundaite is the Fe3+ member of the wardite group. The infrared and Raman spectroscopy were applied to compare the structure of kapundaite with wardite. The Raman spectrum of kapundaite in the 800–1400 cm−1 spectral range shows two intense bands at 1089 and 1114 cm−1 assigned to the ν1PO43- symmetric stretching vibrations. The observation of two bands provides evidence for the non-equivalence of the phosphate units in the kapundaite structure. The infrared spectrum of kapundaite in the 500–1300 cm−1 shows much greater complexity than the Raman spectrum. Strong infrared bands are found at 966, 1003 and 1036 cm−1 and are attributed to the ν1PO43- symmetric stretching mode and ν3PO43- antisymmetric stretching mode. Raman bands in the ν4 out of plane bending modes of the PO43- unit support the concept of non-equivalent phosphate units in the kapundaite structure. In the 2600–3800 cm−1 spectral range, Raman bands for kapundaite are found at 2905, 3151, 3311, 3449 and 3530 cm−1. These bands are broad and are assigned to OH stretching vibrations. Broad infrared bands are also found at 2904, 3105, 3307, 3453 and 3523 cm−1 and are attributed to water. Raman spectroscopy complimented with infrared spectroscopy has enabled aspects of the structure of kapundaite to be ascertained and compared with that of other phosphate minerals.

A review of the removal of anions and oxyanions of the halogen elements from aqueous solution by layered double hydroxides

The application of layered double hydroxides (LDHs) and thermally activated LDHs for the removal of various fluorine (F-, BF-4), chlorine (Cl-,ClO-4), bromine (Br-, BrO-3) and iodine (I-, IO-3) species from aqueous solutions has been reviewed in this article. LDHs and thermally activated LDHs were able to significantly reduce the concentration of selected anions in laboratory scale experiments. The M2+:M3+ cation ratio of the LDH adsorbent was an important factor which influenced anion uptake. Though LDHs were able to remove some target anion species through anion exchange and surface adsorption thermal activation and reformation generally produced better results. The presence of competing anions including carbonate, phosphate and sulphate had a significant impact on uptake of the target anion as LDHs typically exhibit lower affinity towards monovalent anions compared to anions with multiple charges. The removal of fluoride and perchlorate from aqueous solution by a continuous flow system utilising fixed bed columns packed with LDH adsorbents has also been investigated. The adsorption capacity of the columns at breakpoint was heavily dependent on the flow rate and lower than result reported for the corresponding batch methods. There is still considerable scope for future research on numerous topics summarised in this article.

A vibrational spectroscopic study of the phosphate mineral minyulite KAl2(OH,F)(PO4)2⋅4(H2O) and in comparison with wardite

Vibrational spectroscopy enables subtle details of the molecular structure of minyulite KAl2(OH,F)(PO4)2⋅4(H2O). Single crystals of a pure phase from a Brazilian pegmatite were used. Minyulite belongs to the orthorhombic crystal system. This indicates that it has three axes of unequal length, yet all are perpendicular to each other. The infrared and Raman spectroscopy were applied to compare the structure of minyulite with wardite. The reason for the comparison is that both are Al containing phosphate minerals. The Raman spectrum of minyulite shows an intense band at 1012 cm−1 assigned to the ν1PO43- symmetric stretching vibrations. A series of low intensity Raman bands at 1047, 1077, 1091 and 1105 cm−1 are assigned to the ν3PO43- antisymmetric stretching modes. The Raman bands at 1136, 1155, 1176 and 1190 cm−1 are assigned to AlOH deformation modes. The infrared band at 1014 cm−1 is ascribed to the PO43- ν1 symmetric stretching vibrational mode. The infrared bands at 1049, 1071, 1091 and 1123 cm−1 are attributed to the PO43- ν3 antisymmetric stretching vibrations. The infrared bands at 1123, 1146 and 1157 cm−1 are attributed to AlOH deformation modes. Raman bands at 575, 592, 606 and 628 cm−1 are assigned to the ν4 out of plane bending modes of the PO43- unit. In the 2600–3800 cm−1 spectral range, Raman bands for minyulite are found at 3661, 3669 and 3692 cm−1 are assigned to AlOH/AlF stretching vibrations. Broad infrared bands are also found at 2904, 3105, 3307, 3453 and 3523 cm−1. Raman bands at 3225, 3324 cm−1 are assigned to water stretching vibrations. A comparison is made with the vibrational spectra of wardite. Raman spectroscopy complimented with infrared spectroscopy has enabled aspects of the structure of minyulite to be ascertained and compared with that of other phosphate minerals.

A vibrational spectroscopic study of the phosphate mineral whiteite CaMn++Mg2Al2(PO4)4(OH)2·8(H2O)

Vibrational spectroscopy enables subtle details of the molecular structure of whiteite to be determined. Single crystals of a pure phase from a Brazilian pegmatite were used. The infrared and Raman spectroscopy were applied to compare the molecular structure of whiteite with that of other phosphate minerals. The Raman spectrum of whiteite shows an intense band at 972 cm-1 assigned to the m1 PO3- 4 symmetric stretching vibrations. The low intensity Raman bands at 1076 and 1173 cm-1 are assigned to the m3 PO3- 4 antisymmetric stretching modes. The Raman bands at 1266, 1334 and 1368 cm-1 are assigned to AlOH deformation modes. The infrared band at 967 cm-1 is ascribed to the PO3- 4 m1 symmetric stretching vibrational mode. The infrared bands at 1024, 1072, 1089 and 1126 cm-1 are attributed to the PO3-4 m3 antisymmetric stretching vibrations. Raman bands at 553, 571 and 586 cm-1 are assigned to the m4 out of plane bending modes of the PO3- 4 unit. Raman bands at 432, 457, 479 and 500 cm-1 are attributed to the m2 PO4 and H2PO4 bending modes. In the 2600 to 3800 cm-1 spectral range, Raman bands for whiteite are found 3426, 3496 and 3552 cm-1 are assigned to AlOH stretching vibrations. Broad infrared bands are also found at 3186 cm-1. Raman bands at 2939 and 3220 cm-1 are assigned to water stretching vibrations. Raman spectroscopy complimented with infrared spectroscopy has enabled aspects of the structure of whiteite to be ascertained and compared with that of other phosphate minerals.

Strong and bioactive tri-calcium phosphate scaffolds with tube-like macropores

Calcium phosphate ceramic scaffolds have been widely investigated for bone tissue engineering due to their excellent biocompatibility and biodegradation. Unfortunately, they have the shortcoming of low mechanical properties. In order to provide strong, bioactive, and biodegradable scaffolds, a new approach of infiltrating the macro-tube ABS (acrylontrile butadiene styrene) templates with a hydroxyapatite/bioactive glass mixed slurry was developed to fabricate porous Si-doped TCP (tri-calcium phosphate) scaffolds. The porous Si-doped TCP ceramics with a high porosity (~65%) and with interconnected macrotubes (~0.8mm in diameter) and micropores (5-100 m) had a high compressive strength (up to 14.68+0.2MPa), which was comparable to that of a trabecular bone and was much higher than those of pure TCP scaffolds. Additional cell attachment study and MTT cytotoxicity assay proved the bioactivity and biocompatibility of the new scaffolds. Thus a potential bioceramic material and a new approach to make the potential scaffolds were developed for bone tissue engineering.

A randomized controlled trial of a 10 percent CPP-ACP cream to reduce mutans streptococci colonization

Purpose The purpose of this study was to investigate the effectiveness of a 10 percent casein phosphopeptide-amorphous calcium phosphate (CPP-ACP) cream to reduce mutans streptococci (MS) colonization and prevent early childhood caries. Methods The cohort was randomized at mean age of 11 days old to receive once-daily CPP-ACP cream (n=102) or no product (comparison group; n=89) from the time of first tooth eruption. All mothers were contacted by telephone at six, 12, and 18 months and advised to brush their children's teeth twice daily with low-dose fluoride toothpaste. At 24 months, all children were examined at a community clinic. Results At 24 months old, one out of 65 (2 percent) children in the CPP-ACP group had caries vs. four out of 58 (seven percent) in the comparison group (difference not statistically significant). There were fewer MS-positive children in the CPP-ACP group (26 percent) vs. the comparison group (47 percent; P=.02). A dose-response effect of CPP-ACP usage on MS was observed, where MS was present in eight percent of regular CPP-ACP users, 28 percent of irregular users, and 47 percent of non-users (P<.02). Conclusions CPP-ACP reduced the percentages of mutans streptococci-positive 24-month-old children, although it did not reduce caries prevalence.

Reply to the comments on “A study of the phosphate mineral kapundaite NaCa(Fe3+)4(PO4)4(OH)3·5(H2O) using SEM/EDX and vibrational spectroscopic methods” by Frost et al. (2014)

"The authors agree with the statements made by Mills and Christy on the study of kapundaite [1]. These authors are correct and have removed any confusion about the origin of the sample kapundaite. The authors (Frost et al.) confirm the sample of kapundaite studied in this work is from the Tom‘s quarry, Australia and can be considered a type material. The authors do not accept the statements by Mills and Christy on “type minerals”. The sample of kapundaite from the Australian source is from the collection of the Geology Department of the Federal University of Ouro Preto, Minas Gerais, Brazil with sample code SAC-111. At least if our mineral sample is not a co-type mineral, our sample is from the same origin as the type mineral. Samples..."--publisher website.