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Microwave assisted wet precipitation method was used to synthesize calcium deficient strontium doped β-tricalcium phosphate (Sr-βTCP) with a chemical formula of Ca 2.96-x Sr x (PO 4 ) 2 . Sr-βTCP was reacted with monocalcium phosphate monohydrate [Ca(H 2 PO 4 ) 2 .H 2 O, MCPM] in presence of water to furnish corresponding Sr containing brushite cement (Sr-Brc). The samples were characterized by using X-ray diffractometry (XRD), Fourier transform infrared spectroscopy (FTIR) and field emission scanning electron microscopy (FESEM). Strontium content in the prepared samples was determined by using inductively coupled plasma optical emission spectrometry (ICP-OES). The effect of Sr 2+ ions on the structural, mechanical, setting properties and drug release of the cement is reported. Incorporation of Sr 2+ ions improved the injectability, setting time and mechanical properties of the Brc. The release profiles of antibiotics incorporated in Brc and Sr-Brc confirmed that the Sr incorporation into the Brc results in the efficient release of the antibiotics from the cement. [ABSTRACT FROM AUTHOR]

Natural brushite (nDCPD) obtained from bovine bone was used to remove Cr(III) from aqueous solutions. Cr(III) adsorption was performed, varying adsorbent concentration and contact time in solution. The kinetic study of Cr(III) adsorption was performed with the kinetic models of pseudo-first order and pseudo-second order, Elovich, intraparticle and external diffusions. The experimental data were examined with the Langmuir, Freundlich, Redlich–Peterson (R–P), SIPS and Temkin isothermal models. The surface of the adsorbent was characterized by various techniques. The results show that most of the kinetic adsorption data were well described by the pseudo-first-order model, the equilibrium data were best fitted to the SIPS and Langmuir models, with adsorption capacity of 43.378 and 50.767 mg/g, respectively. The equilibrium time of the system was set at 10 h. A 95% Cr(III) removal rate was achieved. The calculated thermodynamic parameters show that Cr(III) adsorption is carried out spontaneously on the surface of nDCPD, although it is positively charged, indicating that nDCPD can be a low cost and easy to obtain effective adsorbent for the removal of Cr(III) from aqueous solutions. [ABSTRACT FROM AUTHOR]

A blue calcium phosphate cement with optimal self-hardening properties was synthesized by doping whitlockite (β-TCP) with copper ions. The mechanism and the kinetics of the cement solidification process were studied using energy dispersive X-ray diffraction and it was found out that hardening was accompanied by the phase transition from TCP to brushite. Reduced lattice parameters in all crystallographic directions resulting from the rather low (1:180) substitution rate of copper for calcium was consistent with the higher ionic radius of the latter. The lower cationic hydration resulting from the partial Ca → Cu substitution facilitated the release of constitutive hydroxyls and lowered the energy of formation of TCP from the apatite precursor at elevated temperatures. Addition of copper thus effectively inhibited the formation of apatite as the secondary phase. The copper-doped cement exhibited an antibacterial effect, though exclusively against Gram-negative bacteria, including E. coli , P. aeruginosa and S. enteritidis . This antibacterial effect was due to copper ions, as demonstrated by an almost negligible antibacterial effect of the pure, copper-free cement. Also, the antibacterial activity of the copper-containing cement was significantly higher than that of its precursor powder. Since there was no significant difference between the kinetics of the release of copper from the precursor TCP powder and from the final, brushite phase of the hardened cement, this has suggested that the antibacterial effect was not solely due to copper ions, but due to the synergy between cationic copper and a particular phase and aggregation state of calcium phosphate. Though inhibitory to bacteria, the copper-doped cement increased the viability of human glial E297 cells, murine osteoblastic K7M2 cells and especially human primary lung fibroblasts. That this effect was also due to copper ions was evidenced by the null effect on viability increase exhibited by the copper-free cements. The difference in the mechanism of protection of dehydratases in prokaryotes and eukaryotes was used as a rationale for explaining the hereby evidenced selectivity in biological response. It presents the basis for the consideration of copper as a dually effective ion when synergized with calcium phosphates: toxic for bacteria and beneficial for the healthy cells. [ABSTRACT FROM AUTHOR]

Calcium phosphate cements (CPCs) should ideally have mechanical properties similar to those of the bone tissue the material is used to replace or repair. Usually, the compressive strength of the CPCs is reported and, more rarely, the elastic modulus. Conversely, scarce or no data are available on Poisson's ratio and strain-to-crack-initiation. This is unfortunate, as data on the elastic response is key to, e.g. , numerical model accuracy. In this study, the compressive behaviour of brushite, monetite and apatite cements was fully characterised. Measurement of the surface strains was done using a digital image correlation (DIC) technique, and compared to results obtained with the commonly used built-in displacement measurement of the materials testers. The collected data showed that the use of fixed compression platens, as opposed to spherically seated ones, may in some cases underestimate the compressive strength by up to 40%. Also, the built-in measurements may underestimate the elastic modulus by up to 62% as compared to DIC measurements. Using DIC, the brushite cement was found to be much stiffer (24.3 ± 2.3 GPa) than the apatite (13.5 ± 1.6 GPa) and monetite (7.1 ± 1.0 GPa) cements, and elastic moduli were inversely related to the porosity of the materials. Poisson's ratio was determined to be 0.26 ± 0.02 for brushite, 0.21 ± 0.02 for apatite and 0.20 ± 0.03 for monetite. All investigated CPCs showed low strain-to-crack-initiation (0.17–0.19%). In summary, the elastic modulus of CPCs is substantially higher than previously reported and it is concluded that an accurate procedure is a prerequisite in order to properly compare the mechanical properties of different CPC formulations. It is recommended to use spherically seated platens and measuring the strain at a relevant resolution and on the specimen surface. [ABSTRACT FROM AUTHOR]

Calcium phosphate powder was synthesized from calcium formiate Ca(CHO) and ammonium hydrophosphate (NH) HPO with Ca/P ratio in the initial water solutions equal to 1. The phase composition of the powders synthesized from 0.5M solutions was represented by brushite CaHPO · 2HO and octacalcium phosphate Ca(HPO) (PO) · 6HO. After firing at 1100°C the phase composition of the powder was represented by calcium pyrophosphate β-CaPO and tricalcium phosphate β-Ca (PO). The synthesized powder can be used to obtain biocompatible resorbable biphase ceramic materials and composites with a polymer matrix. [ABSTRACT FROM AUTHOR]

Stabilized white mold cheese is a commercially important variant of traditional white mold cheese (sometimes called bloomy rind cheese) that has an extended shelf life compared with the traditional permutation. The objectives of this observational study were to document mineral element movements and the development of a pH gradient in stabilized white mold cheese, and to use novel crystallographic techniques to identify crystals that form in the rind of this cheese. Cheeses from 3 separate batches were collected from a commercial supplier at d 1, 4, 10, 14, and 18 of aging and analyzed in a randomized block design. Samples from the center and rind of each cheese were analyzed for calcium, magnesium, phosphorus, sodium, and moisture content. The effect of location within the cheese wheel was significant for all effects, whereas the effect of aging time was significant for all effects except sodium content. The interaction between location within the cheese and aging time was significant for all effects. Using powder x-ray diffractometry, the crystals that formed in the rind during aging were identified as brushite (CaHPO4 · 2H2O). The accumulation of mineral elements in the rind resulted in a substantial decrease in calcium, magnesium, and phosphorus in the center. After 18 d, calcium, magnesium, and phosphorus in the center had decreased by 26.4, 14.8, and 12.1%, respectively, compared with the first day of aging. The observations in the present study represent the first definitive identification of crystals in the rind of a white mold cheese. The use of novel crystallographic techniques in the present study lays the groundwork for the use of this technology in future investigations of mineral element diffusion phenomena in surface-ripened cheese. [ABSTRACT FROM AUTHOR]

The iron doped brushite (Fe-DCPD) nano particles were synthesized via co-precipitation method with Fe concentrations (0 ≤ x ≤ 1) in steps 0.2. The influence of iron concentration on the crystallinity, particle shape, morphology, optical, magnetic and electrical properties was investigated. The results showed that iron doping content is the crucial factor in the variation of physical properties. The particle shape changed from spheres at x = 0.2 to be fiber network at x = 0.8. The saturation magnetization (M s ) increased from 0.4 (emu/g) at x = 0.2 to 1.6 (emu/g) at x = 0.8 which is considered more than four times with a considerable decrease of coercive field. [ABSTRACT FROM AUTHOR]

A calcium phosphate powder has been synthesized from aqueous 0.25, 0.5, and 1.0 M calcium lactate and ammonium hydrogen phosphate solutions atat a Ca/P = 1, without pH adjusting. According to X-ray diffraction data, the as-synthesized powder consisted of brushite (CaHPO · 2HO) and octacalcium phosphate (Ca(HPO)(PO) · 5HO). After heat treatment in the range 500-700°C, the powders were gray in color because of the destruction of the reaction by-product. The powders heat-treated in the range 500-700°C consisted largely of γ-CaPO. The ceramics prepared from the synthesized powders by firing at 1100°C consisted of β-CaPO and β-Ca(PO). [ABSTRACT FROM AUTHOR]

Calcium phosphate cements are osteoconductive biomaterials that are widely used for bone repair and regeneration applications, including spinal fusion, vertebroplasty, khyphoplasty, cranioplasty and periodontal surgeries. The flow and deformation behavior (rheology) and injectability of the calcium phosphate bone cements to the treatment site are governed by the setting kinetics of the cement during which the initially flowable, viscous cement paste transforms into a rigid elastic solid. Here time-dependent development of the linear viscoelastic properties of a brushite-forming calcium phosphate cement are characterized and linked to the mechanism and kinetics of the setting reaction and to the injectability window available during the surgical applications of the cement. The setting kinetics is shown to be a function of the deformation conditions that are utilized in rheological characterization, emphasizing the intimate relationships between setting kinetics, particle to particle network formation and deformation history. Furthermore, the preshearing of the calcium phosphate cement prior to injection and temperature are shown to alter the kinetics of the setting reaction and thus to provide additional degrees of freedom for the tailoring of the rheological behavior and injectability of the calcium phosphate cement. [ABSTRACT FROM AUTHOR]

Brushite samples doped with Ni(II) in different concentrations, from 5% to 20%, were prepared in aqueous solution at pH = 7 and at two temperatures: 25 and 37 °C. The solid samples were characterized by chemical analysis, infrared spectroscopy (FTIR) and x-ray powder diffraction (XRPD). Chemical analysis has shown Ni(II) almost complete incorporation to the solid phase up to 15%. X-ray diffraction patterns have allowed to identify brushite phase with almost no modification of the line breadth and only small shifts of lines positions with increasing Ni(II) incorporation up to 15%. For larger Ni(II) concentration, in solution, a mixture of phases has been detected. Infrared spectra have supported diffraction results. For Ni(II) 20% and over the characteristic bands of HPO 4 2- anions tend to vanish, and the typical shaped PO 4 3− bands are observed. These results have allowed to establish that the presence of low levels of Ni in the synthetic process not only helps brushite formation; but, also prevents brushite from apatite conversion and, in addition, preserves brushite crystallinity. According to these findings, it is possible to propose that nickel traces present in the urinary system might be a trigger to brushite stone formation and/or growth, rather than the expected brushite conversion to hydroxyapatite. This outcome would explain the recurrent detection of difficult to treat brushite stones, observed in the last three decades. [ABSTRACT FROM AUTHOR]

Blast furnace slag (BF slag) was converted using alkali fusion method into a novel adsorbent to remove phosphate from aqueous solutions. The slag was mixed with NaOH powder (NaOH / Slag = 1.6) and then heated at 600 °C for 6 h to prepare the fused precursor. The precursor was stirred in distilled water at room temperature to synthesize the adsorbent and its ability to remove phosphate from aqueous solution was investigated. Fand PO43- removal efficiencies by the adsorbent were higher than those of raw BF slag, with the removal of PO43- being particularly excellent (99%), while Cl-, SO42-, NO3- and Brwere barely adsorbed. With increasing pH of the solution to around pH 7, phosphate removal of the product increases, and then becomes almost constant. The equilibrium adsorption capacity of the product for PO43- was found to fit the Freundlich isotherm better than the Langmuir isotherm, and the calculated maximum PO43- adsorption capacity of the product was 7.67 mmol/g. Phosphate removal corresponded better to a pseudo second-order kinetic model than a pseudo first-order model. The high affinity of the adsorbent for PO43- in aqueous solution was caused by the formation of hydroxyapatite [Ca5(PO4)3(OH)] and brushite [CaHPO4•2H2O]. [ABSTRACT FROM AUTHOR]

A composite bioceramic with density at least 80% of the theoretical value was obtained from thermolyzed octacalcium phosphate (OCP). The treatment temperatures of OCP were 450, 600, and 700°C. The ceramic was obtained by firing thermolyzed powders at maximum temperature 1000, 1050, and 1100°C with soaking for 3, 6, and 9 h. Samples obtained from OCP treated at 450°C demonstrate the highest strength in bending (up to 125 MPa). [ABSTRACT FROM AUTHOR]

Dicalcium phosphate cements (brushite and monetite) are resorbable biomaterials with osteoconductive potential for bone repair and regeneration that have yet to gain widespread commercial use. Brushite can be converted to monetite by heat treatments additionally resulting in various changes in the physico-chemical properties. However, since conversion is most commonly performed using autoclave sterilisation (wet heating), it is uncertain whether the properties observed for monetite as a result of heating brushite under dry conditions affect resorption and bone formation favourably. This study was designed to produce monetite grafts of differing physical form by autoclaving and dry heating (under vacuum) to be compared with brushite biomaterials in an orthotopic pre-clinical implantation model in rabbit for 12 weeks. It was observed that monetite grafts had higher porosity and specific surface area than their brushite precursors. The autoclaved monetite grafts had compressive strength reduced by 50% when compared with their brushite precursors. However, the dry heat converted monetite grafts had compressive strength comparable with brushite. Results from in vivo experiments revealed that both types of monetite graft materials resorbed faster than brushite and more bone formation was achieved. There was no significant difference in the amount of bone formed between the two types of monetite grafts. The implanted brushite grafts underwent phase transformation to form hydroxyapatite, which ultimately limited bioresorption. However, this was not observed in both types of monetite grafts. In summary, both autoclaving and dry heating the preset brushite cement grafts resulted in monetite biomaterials which were more resorbable with potential to be investigated and optimized for orthopaedic and maxillofacial bone repair and regeneration applications. Statement of Significance We present in this original research article a comparison between dicalcium phosphate cement based grafts (brushite and 2 types of monetite grafts prepared by wet and dry thermal processing) with regards to resorption and bone formation in vivo after orthotopic implantation in rabbit condylar femural region. To the best of our knowledge this is the first in vivo study that reports a comparison resorption and bone formation using brushite and two types of monetite biomaterials. Also, we have included in the manuscript a summary of all the in vivo studies performed on brushite and monetite biomaterials to date. This includes cement composition, physical properties (porosity and surface area), implantation and histomorphometrical details such as animal species, site of implantation, observation period, percentage bone tissue formation and residual graft material. In addition, we calculated the percentage resorption of graft materials based upon various implantation sites and included that into the discussion section. The results of this original research provides greater understanding of the resorption processes of dicalcium phosphate based grafts, allowing preparation of bone substitute materials with more predictable resorption profiles in future. [ABSTRACT FROM AUTHOR]

Due to the relatively lower potential health risks as well as the good affinity for fluoride anion, calcium-based minerals have been widely carried out for the adsorption of fluoride. The improvement of adsorption capacity can be accomplished by regulation of particle size, shape and structure. Thus, here we report the controllable synthesis of petal-like nanosheets of brushite by using chitosan as a regulator. The addition of chitosan polymer in calcium precursor not only could serve ideal nucleation sites but also could play a vital role in confining the calcium phosphate aggregates and thus controlling the size of the brushite flakes. When the concentration of chitosan was 0.01 wt%, the as-synthesized brushite showed nanosheet-structured with the dimensions ranged from 100 to 200 nm and displayed outstanding fluoride adsorption capacity of 231.5 mg/g according to the fitted Langmuir model, which was comparatively higher than that of the previously reported calcium-based adsorbents. Moreover, the pH change and common co-existing anions in solution almost presented less negative effect on the F − adsorption onto petal-like brushite nanosheets. We hope that these petal-like nanosheets based on green nanotechnology can help to achieve the intention of safe drinking water. [ABSTRACT FROM AUTHOR]

The application of biologically active metal ions to stimulate cellular reactions is a promising strategy to accelerate bone defect healing. Brushite-forming calcium phosphate cements were modified with low doses of Cu 2 + , Co 2 + and Cr 3 + . The modified cements released the metal ions in vitro in concentrations which were shown to be non-toxic for cells. The release kinetics correlated with the solubility of the respective metal phosphates: 17–45 wt.-% of Co 2 + and Cu 2 + , but < 1 wt.-% of Cr 3 + were released within 28 days. Moreover, metal ion doping led to alterations in the exchange of calcium and phosphate ions with cell culture medium. In case of cements modified with 50 mmol Cr 3 + /mol β-tricalcium phosphate (β-TCP), XRD and SEM analyses revealed a significant amount of monetite and a changed morphology of the cement matrix. Cell culture experiments with human mesenchymal stromal cells indicated that the observed cell response is not only influenced by the released metal ions but also by changed cement properties. A positive effect of modifications with 50 mmol Cr 3 + or 10 mmol Cu 2 + per mol β-TCP on cell behaviour was observed in indirect and direct culture. Modification with Co 2 + resulted in a clear suppression of cell proliferation and osteogenic differentiation. In conclusion, metal ion doping of the cement influences cellular activities in addition to the effect of released metal ions by changing properties of the ceramic matrix. [ABSTRACT FROM AUTHOR]

The formation of kidney stones is a significant human health problem. Calcium minerals are involved in a majority of these stones. Despite much research, the processes involved in stone formation remain poorly understood and, hence, reliable procedures for preventing their formation have yet to be developed. However, recent advances point to some key steps in mineral formation and transformation involving calcium phosphates, which can help to illuminate these issues. A computer model has been developed to express the current status of literature data succinctly and to illustrate that computer modeling is a powerful tool for calculating mineral solubilities and for providing insight into the processes involved. Determining the nature of the initial solid phase of calcium phosphate formed is evidently important. [ABSTRACT FROM AUTHOR]

In this study, a granular material (GM) developed from building waste was used for phosphate removal from phosphorus-containing wastewater. Batch experiments were executed to investigate the phosphate removal capacity of this material. The mechanism of removal proved to be a chemical precipitation process. The characteristics of the material and resulting precipitates, the kinetics of the precipitation and Ca2+ liberation processes, and the effects of dosage and pH were investigated. The phosphate precipitation and Ca2+ liberation processes were both well described by a pseudosecond-order kinetic model. A maximum precipitation capacity of 0.51±0.06 mg g-1 and a liberation capacity of 6.79±0.77 mg g-1 were measured under the experimental conditions. The processes reached equilibrium in 60 min. The initial solution pH strongly affected phosphate removal under extreme conditions (pH <4 and pH >10). The precipitates comprised hydroxyapatite and brushite. This novel GM can be considered a promising material for phosphate removal from wastewater. [ABSTRACT FROM AUTHOR]

Sodium alginate was successfully utilized to improve cohesion and limit particulate debris of a premixed calcium phosphate cement ( pCPC) that following the exchange of water set to form monetite. Modified pastes using glycerol and 2 wt% alginate exhibited initial and final setting times of 60 ± 9 and 1355 ± 105 minutes, respectively. Despite these setting times being significantly longer than clinically recommended the improved washout resistance of this formulation would allow for wound closure during setting. Set monetite pastes exhibited a maximum compressive strength of 8.6 ± 3.5 MPa with a corresponding porosity of 59% compared to 15.6 ± 5.8 MPa and 25% for the unmodified aqueous brushite cement. Storage of the pCPC paste at 4°C for 14 days was shown to significantly ( P<0.05) increase the compressive strength of the harden matrix (13.2 ± 1.5 MPa), however, subsequent deterioration was observed after 90 days storage. Methylene blue was utilized to visualize perfusion into the matrix during setting, demonstrating that the use of glycerol altered mass transport and ultimately shifted the crystallization kinetics in favor of monetite. Samples >20 mm did not reach full saturation after 10 days of immersion, which for the first time suggests an upper volume limit that will form a homogeneous cement highlighting an important consideration for clinical translation of pCPCs. [ABSTRACT FROM AUTHOR]

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We have studied the formation of octacalcium phosphate (OCP) in various buffer solutions. Brushite hydrolysis in acetate and succinate buffer solutions at 60°C and pH 5.75 ensures rapid synthesis of pure OCP and substituted OCP (sOCP), which allows a rather large amount of this phosphate (at least 10 g in a single synthesis run) to be obtained in 50-60 min. The observed differences in phase composition between the OCP and sOCP thermolysis products make it possible to obtain biphasic ceramic composites of various kinds: β-TCP/β-CPP (Ca/P = 1.33) in the case of OCP and β-TCP/HA (Ca/P = 1.54) in the case of sOCP. Ceramics with a density of 80% of theoretical density and higher produced using the OCP precursors synthesized in this study have a uniform microstructure, possess the desired microporosity, and are potentially attractive for further advances in the field of bioresorbable osteoplastic materials. [ABSTRACT FROM AUTHOR]

There is interest in recovering phosphate (P(V)) from secondary sources, such as waste water streams for potential use as fertilizers reducing the environmental impacts of P(V) discharges and providing alternative phosphorus sources. The goal of this work was to provide an understanding of P(V) removal by fly ash (FA) from coal power plants. Phosphate removal using Ca(II) rich FA was evaluated in terms of i) sorption equilibrium, ii) sorption kinetics under the expected pH values and P(V) concentrations in wastewaters effluents, and iii) P(V) availability of the FAs in agricultural applications. At the pH values (6–9) expected for wastewater effluents, P(V) removal proceeds as a combination of CaO(s) dissolution and brushite (CaHPO 4 (s)) formation on the FA particles. This process avoids the formation of relatively insoluble Ca–phosphates, such as, hydroxyapatite (Hap) with limited fertilizing properties. High P-loadings were achieved (up to 50 mgP-PO 4 /g FA (5% P(V) by weight)) at a pH of 8. The removal kinetics data were well described as a diffusion-based process of phosphate ions (H 2 PO 4 − and HPO 4 2− ) on FA particles, and the CaO(s) dissolution process was discarded as the rate controlling step. The P(V) availability from loaded samples was determined via an agronomical assay with NaHCO 3 solutions with P(V) release ratios of 10–30 mgP-PO 4 /g in FA, confirming the appropriateness of this material as a potential fertilizer, even in calcareous soils. [ABSTRACT FROM AUTHOR]

The crystal growth of monetite (CaHPO 4 , DCPA), the least stable calcium phosphate has been investigated by the seeded growth method from solutions supersaturated exclusively with respect to this phase alone. The kinetics of crystal growth was measured at constant supersaturation at 37° C, pH 6.0. The measurements of the rates of crystal growth of DCPA showed a second order dependence on the relative supersaturation of the solutions with respect to DCPA, suggesting that the rate determining step is surface diffusion of the growth units to the active growth sites of the crystals. The heterogeneous crystallization of brushite (CaHPO 4 ·2H 2 O, DCPD) on DCPA seed crystals in solutions supersaturated with respect to both DCPD and DCPA showed that DCPD nucleation and growth took place selectively by heterogeneous nucleation on the DCPA seed crystals. The same parabolic dependence of the rates on the relative supersaturation of the solutions with respect to DCPD was found, showing that the mechanism was the same as in the case of growth of DCPA on DCPA seed crystals. Seeding of solutions supersaturated with respect to both DCPA and DCPD at pH 6.0, 37 °C with collagen type II in powdered form, resulted to the formation of an apatitic solid. The morphology of the crystals formed on the collagenous matrix suggested that the identified mineral was probably the result of rapid hydrolysis of metastable calcium phosphatephases. The formation of the mineral phase on collagen took place past long induction time periods inversely proportional to the relative supersaturation with respect to DCPD and showed that the collagen substrate did not stabilize calcium phosphate at the same conditions at which DCPA did. [ABSTRACT FROM AUTHOR]

Biocompatible ceramic coatings were fabricated at room temperature by via aerosol deposition (AD), in order to improve the bonding strength between the dental sapphire bracket and the resin. First, the deposition properties of the brushite films coated on the flat sapphire substrate were investigated, confirming their good deposition rate and appropriate adhesive strength. Then, the mesh and check patterns of the coatings were formed on the sapphire brackets in order to obtain a sufficient shear bond strength. The mesh-pattern grown by converging nozzles exhibited a low film thickness (<10 µm) and shear bond strength (<7 MPa) due to the sharp triangular-shaped cross sections. In contrast, the check-pattern showed a high film thickness of ~70 µm at the same deposition time, as well as a high shear bond strength of ~14 MPa, implying that this check-pattern brushite coating formed via the AD process is a promising candidate for application in dental brace brackets. [ABSTRACT FROM AUTHOR]

In this work, two solutions were developed: the first, rich in Ca 2 + , PO 4 3 − ions and the second, rich in Ca 2 + , PO 4 3 − and Mg 2 + , defined as Mg-modified precursor solution. For each Mg-modified precursor solution, the concentrations of Mg 2 + ions were progressively increased by 5%, 10% and 15%wt. The aims of this research were to investigate the influence of magnesium ions substitution in calcium phosphate coatings on titanium surface and to evaluate these coatings by bioactivity assay in McCoy culture medium. The obtained coatings were characterized by X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR) analysis, and the presence of Mg ions was confirmed by the inductively coupled plasma atomic emission spectroscopy (ICP) analysis. In vitro bioactivity assay in McCoy culture medium showed bioactivity after 14 days in incubation for the HA and 10% Mg-monetite coatings. The high chemical stability of Mg-HA coatings was verified by the bioactivity assays, and no bone-like apatite deposition, characteristic of bioactivity, was observed for Mg-HA coatings, for the time period used in this study. [ABSTRACT FROM AUTHOR]

The interaction of aminoacids (Glycine, Proline, Lysine) with brushite based bone cements has been investigated by several techniques (FTIR spectroscopy, Thermogravimetry-TG, Scanning Electron Microscopy-SEM, mechanical properties studies), with the aim to elucidate the properties of the resulting composite materials and the interaction occurring at molecular level between the inorganic matrix and the organic moieties. Brushite phase is predominantly obtained also in the presence of aminoacids added during preparation of the bone cement. Focusing on Glycine incorporation, the presence of a fraction of bulk Glycine, weakly interacting with the inorganic matrix, together with Glycine specifically interacting with adsorption sites can be envisaged, as pointed out by FT IR and thermogravimetric data. In detail, FT-IR data evidenced changes in shape and position of bands associated to stretching modes of the carboxylic groups in Glycine structure, which can be explained by the coordination of these functional groups with the Ca ions in the matrix. Heating this composite at controlled temperature results in the detection of a condensation products, either cyclic condensation product, either dipeptide. Diffuse and not specific H-bonding seems to be the main form of interaction of Proline and Lysine with brushite. Due to the coordination with Ca ions here described, Glycine can act as retardant during brushite preparation, allowing good workability of the resulting composite. [ABSTRACT FROM AUTHOR]

Five variations of the monetite (M) synthesis were evaluated modifying the stirring, the phosphoric acid addition rate, the homogeneity and the drying temperature. Products were assessed by means o f XRD, FTIR, SEM-EDS analysis and chemical assay o f Ca/P (calcium by titration with potassium permanganate and phosphorus by colorimetric assessment o f the molybdenum blue complex). X-ray diffraction, infrared spectroscopy and Ca/P ratio indicate that the synthesized phosphate corresponds to pure monetite. It was found that the most influential factors affecting grain composition, crystal size, shape and structure as well as Ca/P molar ratio of synthesized phosphates were stoichiometry and ballmilling mechanoactivation. [ABSTRACT FROM AUTHOR]

[Display omitted] • Se-load brushite produces photothermal/photodynamic effect under 1060 nm laser. • Se-load brushite significantly inhibits the growth of E. coli and S. aureus in vitro under laser. • Se-load brushite significantly inhibits the growth of E. coli and S. aureus ex vivo under laser. This work proposes a novel antibiotic-free antibacterial strategy for bone scaffolds using white Se-loaded brushite (Se-Bru) under near-infrared light irradiation. The as-prepared Se-Bru exhibited stable photothermal properties and released a low concentration of liner oxygen under a 1060 nm laser irradiation. Moreover, Se-Bru could inhibit the growth of more than 99.9 % of E. coli and 96.6 % of S. aureus in the broth when the bacterial concentration was as high as 5.0 × 108 CFU/mL. Furthermore, Se-Bru significantly inhibited the growth of these bacteria even if the laser light shined on the material through skin and fat. Therefore, Se-Bru has a promising application for treating infected bone defects under near-infrared light irradiation. [ABSTRACT FROM AUTHOR]

Aims The purpose of this multi-phase explorative in vivo animal/surgical and in vitro multi-test experimental study was to (1) create a 3 wt%-nanostrontium hydroxyapatite-enhanced calcium phosphate cement (Sr-HA/CPC) for increasing bone formation and (2) creating a simvastatin-loaded poly(lactic- co -glycolic acid) (SIM-loaded PLGA) microspheres plus CPC composite (SIM-loaded PLGA + nanostrontium-CPC). The third goal was the extensive assessment of multiple in vitro and in vivo characteristics of the above experimental explorative products in vitro and in vivo (animal and surgical studies). Methods and results pertaining to Sr-HA/CPC Physical and chemical properties of the prepared Sr-HA/CPC were evaluated. MTT assay and alkaline phosphatase activities, and radiological and histological examinations of Sr-HA/CPC, CPC and negative control were compared. X-ray diffraction (XRD) indicated that crystallinity of the prepared cement increased by increasing the powder-to-liquid ratio. Incorporation of Sr-HA into CPC increased MTT assay (biocompatibility) and ALP activity (P < 0.05). Histomorphometry showed greater bone formation after 4 weeks, after implantation of Sr-HA/CPC in 10 rats compared to implantations of CPC or empty defects in the same rats (n = 30, ANOVA P < 0.05). Methods and results pertaining to SIM-loaded PLGA microspheres + nanostrontium-CPC composite After SEM assessment, the produced composite of microspheres and enhanced CPC were implanted for 8 weeks in 10 rabbits, along with positive and negative controls, enhanced CPC, and enhanced CPC plus SIM (n = 50). In the control group, only a small amount of bone had been regenerated (localized at the boundary of the defect); whereas, other groups showed new bone formation within and around the materials. A significant difference was found in the osteogenesis induced by the groups sham control (16.96 ± 1.01), bone materials (32.28 ± 4.03), nanostrontium-CPC (24.84 ± 2.6), nanostrontium-CPC-simvastatin (40.12 ± 3.29), and SIM-loaded PLGA + nanostrontium-CPC (44.8 ± 6.45) (ANOVA P < 0.001). All the pairwise comparisons were significant (Tukey P < 0.01), except that of nanostrontium-CPC-simvastatin and SIM-loaded PLGA + nanostrontium-CPC. This confirmed the efficacy of the SIM-loaded PLGA + nanostrontium-CPC composite, and its superiority over all materials except SIM-containing nanostrontium-CPC. [ABSTRACT FROM AUTHOR]