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1.
J Indian Soc Pedod Prev Dent ; 38(2): 132-137, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32611858

RESUMO

Background: Apical plug formation by mineral trioxide aggregate (MTA), Biodentine, and EndoSequence root repair material (RRM) is an excellent alternative technique to the conventional apexification procedure. Several antimicrobial agents have been incorporated in MTA and Biodentine to boost their antimicrobial efficacy. Considering the polymicrobial nature of root canal infection, a combination of potent antimicrobials like triple antibiotic powder (TAP) would be needed to address the diverse flora encountered. Calcium release is the consequential factor in the clinical excellence of these cements. Aim: The aim of the study was to evaluate and compare the calcium released from the apical plugs formed by MTA, Biodentine, and EndoSequence RRM with and without incorporation of 2% TAP. Methods: Ninety single-rooted teeth were divided into (n = 15) Group A: MTA + 2% TAP, Group B: MTA, Group C: Biodentine + 2% TAP, Group D: Biodentine, Group E: EndoSequence RRM + 2% TAP, and Group F: EndoSequence RRM to form the 4 mm apical plugs. Each sample tooth was then immersed in 10 ml of deionized water. Evaluation of calcium release was done on days 7, 15, and 30 using an atomic absorption spectrophotometer. Data were analyzed using one-way analysis of variance, post hoc test, and unpaired t-test. Results: Calcium released was maximum for Group E compared to Group F (P < 0.05), maximum for Group C compared to Group D, and was maximum for Group A compared to Group B (P < 0.05) at days 7, 15 and 30. Conclusion: Incorporation of 2% TAP resulted in increased calcium ions released from MTA, Biodentine, and EndoSequence RRM.


Assuntos
Cálcio , Materiais Restauradores do Canal Radicular , Compostos de Alumínio , Antibacterianos , Compostos de Cálcio , Fosfatos de Cálcio , Combinação de Medicamentos , Óxidos , Silicatos
2.
J Environ Manage ; 270: 110837, 2020 Sep 15.
Artigo em Inglês | MEDLINE | ID: mdl-32507743

RESUMO

The Fukushima Daiichi nuclear disaster and the decommissioning of over a hundred nuclear reactors worldwide led to the increase in the demand for efficient water treatment technologies to remove radionuclides, such as 90Sr. Brushite or dicalcium phosphate dihydrate (DCPD) is a potential adsorbent to remove strontium from water. In this study, composite poly(acrylonitrile) (PAN) nanofiber (NF) adsorbents with DCPD (PAN/DCPD) were prepared, characterized, and investigated for strontium adsorption in water. Material characterization revealed mechanically suitable, hydrophilic, and macroporous composite NF adsorbents with average fiber diameters of <500 nm. As-prepared DCPD powder exhibited a superior strontium uptake capacity of 81.7 mg g-1 at pH â‰… 10 of aqueous Sr2+ solution over its biogenic and synthetic predecessor, hydroxyapatite. Increased DCPD loading resulted in higher adsorption. Maximum Sr2+ uptake of PAN/DCPD NF with 70 wt% DCPD loading (PAN/70DCPD NF) was 146 mg g-1 considering the Sips isotherm model. Kinetic studies revealed that Sr2+ removal by PAN/DCPD NF was a chemisorption process which involved ion exchange and surface complexation. PAN/70DCPD NF as a dead-end membrane filter exhibited superior removal efficiency over pure PAN NF. The overall results of this study revealed the potential application of PAN/DCPD NF adsorbent for 90Sr removal from water.


Assuntos
Nanofibras , Purificação da Água , Resinas Acrílicas , Adsorção , Fosfatos de Cálcio , Cinética , Estrôncio , Água
3.
Int J Nanomedicine ; 15: 3729-3740, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32547025

RESUMO

Background: Duraplasty is one of the most critical issues in neurosurgical procedures because the defect of dura matter will cause many complications. Electrospinning can mimic the 3D structure of the natural extracellular matrix whose structure is similar to that of dura matter. Poly(L-lactic acid) (PLLA) has been used to fabricate dura matter substitutes and showed compatibility to dural tissue. However, the mechanical properties of the PLLA substitute cannot match the mechanical properties of the human dura mater. Methods and Results: We prepared stereocomplex nanofiber membranes based on enantiomeric poly(lactic acid) and poly(D-lactic acid)-grafted tetracalcium phosphate via electrospinning. X-ray diffraction results showed the formation of stereocomplex crystallites (SC) in the composite nanofiber membranes. Scanning electron microscope observation images showed that composites nanofibers with higher SC formation can keep its original morphologies after heat treatment, suggesting the heat resistance of composite nanofiber membranes. Differential scanning calorimeter tests confirmed that the melting temperature of composite nanofiber membranes was approximately 222°C, higher than that of PLLA. Tensile testing indicated that the ultimate tensile strength and the elongation break of the stereocomplex nanofiber membranes were close to human dura matter. In vitro cytotoxicity studies proved that the stereocomplex nanofiber membranes were non-toxic. The neuron-like differentiation of marrow stem cells on the stereocomplex nanofiber membranes indicated its neuron compatibility. Conclusion: The stereocomplex nanofiber membranes have the potential to serve as a dura mater substitute.


Assuntos
Materiais Biomiméticos/química , Dura-Máter/fisiologia , Nanofibras/química , Poliésteres/química , Animais , Fosfatos de Cálcio/química , Varredura Diferencial de Calorimetria , Diferenciação Celular , Linhagem Celular , Cristalização , Humanos , Masculino , Células-Tronco Mesenquimais/citologia , Camundongos , Nanofibras/ultraestrutura , Neurônios/citologia , Ratos Sprague-Dawley , Estereoisomerismo , Temperatura , Difração de Raios X
4.
Int J Nanomedicine ; 15: 3877-3886, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32581535

RESUMO

Introduction: Vaccine formulation with appropriate adjuvants is an attractive approach to develop protective immunity against pathogens. Calcium phosphate nanoparticles (CaPNs) are considered as ideal adjuvants and delivery systems because of their great potential for enhancing immune responses. In the current study, we have designed nanoparticle-based vaccine candidates to induce immune responses and protection against B. melitensis and B. abortus. Materials and Methods: For this purpose, we used three Brucella antigens (FliC, 7α-HSDH, BhuA) and two multi-epitopes (poly B and poly T) absorbed by CaPNs. The efficacy of each formulation was evaluated by measuring humoral, cellular and protective responses in immunized mice. Results: The CaPNs showed an average size of about 90 nm with spherical shape and smooth surface. The CaPNs-adsorbed proteins displayed significant increase in cellular and humoral immune responses compared to the control groups. In addition, our results showed increased ratio of specific IgG2a (associated with Th1) to specific IgG1 (associated with Th2). Also, immunized mice with different vaccine candidate formulations were protected against B. melitensis 16M and B. abortus 544, and showed same levels of protection as commercial vaccines (B. melitensis Rev.1 and B. abortus RB51) except for BhuA-CaPNs. Discussion: Our data support the hypothesis that these antigens absorbed with CaPNs could be effective vaccine candidates against B. melitensis and B. abortus.


Assuntos
Antígenos de Bactérias/química , Vacina contra Brucelose/química , Vacina contra Brucelose/imunologia , Nanopartículas/química , Adjuvantes Imunológicos/administração & dosagem , Adjuvantes Imunológicos/farmacologia , Animais , Proteínas de Bactérias/imunologia , Brucella abortus/imunologia , Brucella melitensis/imunologia , Brucelose/imunologia , Brucelose/prevenção & controle , Fosfatos de Cálcio/química , Sistemas de Liberação de Medicamentos , Feminino , Imunidade Humoral , Imunização , Imunoglobulina G/imunologia , Proteínas de Membrana Transportadoras/imunologia , Camundongos Endogâmicos BALB C
5.
Braz Dent J ; 31(2): 93-102, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32556021

RESUMO

Several studies have aimed to develop alternative therapeutic biomaterials for bone repair. The purpose of this systematic review was to evaluate how statins carried by calcium phosphate affect the formation and regeneration of bone tissue in animal models when compared to other biomaterials or spontaneous healing. This systematic review followed the recommendations of the Cochrane Handbook for Systematic Reviews of Interventions, the PRISMA guidelines, and the Preclinical Systematic Review & Meta-analysis Facility (SyRF). The protocol of this systematic review was registered in PROSPERO (CRD42018091112) and in CAMARADES. In addition, ARRIVE checklists were followed in order to increase the quality and transparency of the search. An electronic search was performed using the MEDLINE/PubMed, Scopus, SciELO, and PROSPERO library databases. The authors used a specific search strategy for each database, and they also conducted a search in the grey literature and cross-references. The eligibility criteria were animal studies, which evaluated bone repair treated with calcium phosphate as a simvastatin carrier. The selection process yielded 8 studies from the 657 retrieved. All manuscripts concluded that locally applied simvastatin carried by calcium phosphate is biocompatible, enhanced bone repair and induced statistically greater bone formation than cloth or calcium phosphate alone. In conclusion, the pertinent pre-clinical studies evidenced the calcium phosphate biocompatibility and its effectiveness in delivering SIM to improve the repair of bone defects. So, clinical trials are encouraged to investigate the impact of SIM associated with calcium phosphate bone graft in repairing bone defect in humans.


Assuntos
Fosfatos de Cálcio , Sinvastatina , Animais , Regeneração Óssea , Transplante Ósseo , Humanos , Osteogênese
6.
Chemosphere ; 256: 126968, 2020 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-32428738

RESUMO

The recycling of nutrients from wastewater and their recovery in the form of valuable products is an effective strategy to accelerate the circular economy concept. Phosphorus recovery from wastewater by struvite crystallization (MgNH4PO4·6H2O) is one of the most applied techniques to compensate for the increasing demand and to slow down the depletion rate of phosphate rocks. Using low-cost magnesium sources, such as seawater, improves the financial sustainability of struvite production. In this study, the potential of seawater for struvite crystallization versus the commonly used magnesium source, MgCl2, was tested by crystal growth and kinetic experiments. The impact of ammonium concentration, magnesium concentration and pH on the growth kinetics of struvite in synthetic and real reject water were studied. The results showed that simultaneous precipitation of calcium phosphate was insignificant when using seawater, while presence of struvite seeds diminished it further. Among the supersaturation regulators, pH had the most significant effect on the struvite growth with both MgCl2 and seawater, while high N:P molar ratios further improved the struvite crystal growth by seawater. The N:P molar ratios higher than 6 and Mg:P molar ratios higher than 0.2 are recommended to improve the crystal growth kinetics. It was concluded that seawater is a promising alternative magnesium source and the control of supersaturation regulators (i.e., Mg:P, N:P and pH) is an effective strategy to control the reaction kinetics and product properties.


Assuntos
Modelos Químicos , Água do Mar/química , Estruvita/química , Fosfatos de Cálcio , Cristalização , Cinética , Magnésio/química , Cloreto de Magnésio/química , Compostos de Magnésio/química , Minerais , Fosfatos/química , Fósforo/química , Reciclagem , Águas Residuárias/química
7.
Med Oral Patol Oral Cir Bucal ; 25(4): e532-e540, 2020 Jul 01.
Artigo em Inglês | MEDLINE | ID: mdl-32388521

RESUMO

BACKGROUND:  The aim of this histomorphometric study was to assess the bone regeneration potential of beta-tricalcium phosphate with fibronectin (ß-TCP-Fn) in critical-sized defects (CSDs) in rats calvarial, to know whether Fn improves the new bone formation in a short time scope. MATERIAL AND METHODS:  CSDs were created in 30 Sprague Dawley rats, and divided into four groups (2 or 6 weeks of healing) and type of filling (ß-TCP-Fn, ß-TCP, empty control). Variables studied were augmented area (AA), gained tissue (GT), mineralized/non mineralized bone matrix (MBM/NMT) and bone substitute (BS). RESULTS:  60 samples at 2 and six weeks were evaluated. AA was higher for treatment groups comparing to controls (p < 0.001) and significant decrease in BS area in the ß-TCP-Fn group from 2 to 6 weeks (p = 0.031). GT was higher in the ß-TCP-Fn group than in the controls expressed in % (p = 0.028) and in mm2 (p = 0.011), specially at two weeks (p=0.056). CONCLUSIONS:  Both ß-TCP biomaterials are effective as compared with bone defects left empty in maintaining the volume. GT in defects regeneration filed with ß-TCP-Fn are significantly better in short healing time when comparing with controls but not for ß-TCP used alone in rats calvarial CSDs.


Assuntos
Fibronectinas , Crânio , Animais , Regeneração Óssea , Fosfatos de Cálcio , Ratos , Ratos Sprague-Dawley
8.
J Evid Based Dent Pract ; 20(1): 101416, 2020 03.
Artigo em Inglês | MEDLINE | ID: mdl-32381413

RESUMO

ARTICLE TITLE AND BIBLIOGRAPHIC INFORMATION: Effectiveness of casein phosphopeptide-amorphous calcium phosphate-containing products in the prevention and treatment of white spot lesions in orthodontic patients: A systematic review. Pithon MM, Baião FS, Sant'Anna LID, Tanaka OM, Cople-Maia L. J Invest Clin Dent 2019;e12391. SOURCE OF FUNDING: No financial support was reported. TYPE OF STUDY/DESIGN: Systematic review.


Assuntos
Cárie Dentária , Braquetes Ortodônticos , Fosfatos de Cálcio , Caseínas , Fluoretos , Humanos , Fosfopeptídeos , Remineralização Dentária
9.
Chemosphere ; 255: 127005, 2020 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-32416395

RESUMO

Recovering phosphorus from livestock wastewater could partly mitigate the global phosphorus resource crisis. Crystallization is a promising method for removing phosphorus from wastewater, but the costs of calcium- and magnesium-containing reagents are increasing. Cheap, available, efficient materials are required to replace conventional calcium and magnesium reagents. Here, we describe a new approach to removing and recovering phosphorus from livestock wastewater of a large pig farm, containing a high phosphorus concentration. The effects of the pH, stirring speed, stirring time, and extract dose (containing calcium and magnesium) on phosphorus removal from livestock wastewater were investigated. The product was characterized by X-ray diffractometry, Fourier-transform infrared spectroscopy, and scanning electron microscopy. Under optimized conditions (pH 9.0, stirring speed 200 r/m, stirring time 600 s, Ca 207.62 mg/L, Mg 122.86 mg/L), 92% of the phosphorus was removed from livestock wastewater. The product was mainly the hydroxyapatite (Ca5(PO4)3OH) precursor amorphous calcium phosphate but also contained 1.65% (by mass) magnesium ammonium phosphate (MgNH4PO4·6H2O) crystals. The cost of dolomite to treat 1 m3 of high-phosphorus wastewater was 0.20 yuan (45.9%, 25.9%, and 75.9% lower than for pure MgCl2, MgSO4, and CaCl2, respectively) in 2019. Using dolomite to provide calcium and magnesium effectively decreases the crystallization process cost and should encourage the use of crystallization to remove phosphorus from wastewater.


Assuntos
Carbonato de Cálcio/química , Magnésio/química , Fósforo/isolamento & purificação , Águas Residuárias/química , Poluentes Químicos da Água/isolamento & purificação , Purificação da Água/métodos , Animais , Fosfatos de Cálcio/isolamento & purificação , Cristalização , Fazendas , Gado/crescimento & desenvolvimento , Estruvita/isolamento & purificação , Suínos
10.
Ann Rheum Dis ; 79(7): 975-984, 2020 07.
Artigo em Inglês | MEDLINE | ID: mdl-32371389

RESUMO

OBJECTIVE: Calcification of cartilage with basic calcium phosphate (BCP) crystals is a common phenomenon during osteoarthritis (OA). It is directly linked to the severity of the disease and known to be associated to hypertrophic differentiation of chondrocytes. One morphogen regulating hypertrophic chondrocyte differentiation is Wnt3a. METHODS: Calcification and sulfation of extracellular matrix of the cartilage was analysed over a time course from 6 to 22 weeks in mice and different OA grades of human cartilage. Wnt3a and ß-catenin was stained in human and murine cartilage. Expression of sulfation modulating enzymes (HS2St1, HS6St1) was analysed using quantitative reverse transcription PCR (RT-PCR). The influence of BCP crystals on the chondrocyte phenotype was investigated using quantitative RT-PCR for the marker genes Axin2, Sox9, Col2, MMP13, ColX and Aggrecan. Using western blot for ß-catenin and pLRP6 we investigated the activation of Wnt signalling. The binding capacity of BCP for Wnt3a was analysed using immunohistochemical staining and western blot. RESULTS: Here, we report that pericellular matrix sulfation is increased in human and murine OA. Wnt3a co-localised with heparan sulfate proteoglycans in the pericellular matrix of chondrocytes in OA cartilage, in which canonical Wnt signalling was activated. In vitro, BCP crystals physically bound to Wnt3a. Interestingly, BCP crystals were sufficient to induce canonical Wnt signalling as assessed by phosphorylation of LRP6 and stabilisation of ß-catenin, and to induce a hypertrophic shift of the chondrocyte phenotype. CONCLUSION: Consequently, our data identify BCP crystals as a concentrating factor for Wnt3a in the pericellular matrix and an inducer of chondrocyte hypertrophy.


Assuntos
Fosfatos de Cálcio/metabolismo , Diferenciação Celular/genética , Condrócitos/patologia , Osteoartrite/genética , Proteína Wnt3A/metabolismo , Animais , Cartilagem Articular/citologia , Condrócitos/metabolismo , Matriz Extracelular/patologia , Humanos , Hipertrofia , Camundongos , Osteoartrite/patologia , Via de Sinalização Wnt/genética
11.
J Contemp Dent Pract ; 21(3): 267-270, 2020 Mar 01.
Artigo em Inglês | MEDLINE | ID: mdl-32434972

RESUMO

AIM: To compare the efficacy of casein phosphopeptide-amorphous calcium phosphate-fluoride (CPP-ACP-F) paste and 0.2% sodium fluoride mouthwash in the prevention of dental erosion using profilometer. MATERIALS AND METHODS: The buccal surfaces of 36 premolar sound teeth were ground and polished to achieve a flat surface with silicone disks. Samples were allocated in three groups randomly. Group I was pretreated for 5 days four times a day with CPP-ACP-F paste. Group II was pretreated for 5 days with 0.2% sodium fluoride mouthwash four times a day. Group III remained as the control group without any pretreatment. In the next step, all the samples were exposed four times a day for 3 days to carbonated beverages. The samples were rinsed with saline after each erosive cycle and stored in artificial saliva. The profilometer was used to determine the surface loss. The data collected were evaluated using one-way analysis of variance (ANOVA) along with post hoc test. RESULTS: The erosion of group I (CPP-ACP-F paste) and group II (0.2% sodium fluoride mouthwash) was significantly less than that of group III (control group). The erosion in group II was significantly lower than in group I. CONCLUSION: Both sodium fluoride mouthwash and CPP-ACP-F paste are effective in the prevention of dental erosion. Sodium fluoride mouthwash shows higher reduction in dental erosion when compared with CPP-ACP-F paste. CLINICAL SIGNIFICANCE: This study contributes to the understanding of the efficacy of CPP-ACP-F paste and 0.2% sodium fluoride mouthwash in the prevention of dental erosion.


Assuntos
Caseínas , Fluoretos , Fosfatos de Cálcio , Esmalte Dentário , Antissépticos Bucais , Fosfopeptídeos , Fluoreto de Sódio , Remineralização Dentária
12.
Arthroscopy ; 36(4): 1009-1010, 2020 04.
Artigo em Inglês | MEDLINE | ID: mdl-32247400

RESUMO

Biomechanical studies with reliable clinical applicability are challenging to carry out. The results can be heavily dependent on the materials being tested (condition and ages of specimens), environmental conditions (temperature, moisture), magnitude and direction of loading, loading characteristics (static, dynamic), loading cycles and frequency, and how one measures and defines failure. The interested reader gains more confidence in the results and recommendations of a biomechanics study if the methodology reasonably models real-world scenarios and multiple studies from different labs all come to the same general conclusion.


Assuntos
Fosfatos de Cálcio , Âncoras de Sutura , Fenômenos Biomecânicos
13.
PLoS One ; 15(4): e0230493, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32255786

RESUMO

Phosphate toxicity is a major threat to cardiovascular health in chronic kidney disease. It is associated with oxidative stress, inflammation and the accumulation of calcium phosphate commonly known as calcification in soft tissues leading to functional disorders of blood vessels. An improved calcification propensity test for the assessment of phosphate toxicity was developed, which measures the velocity of calcium phosphate mineralization from colloidal precursors in vitro. This so called T50 test measures the transformation from a primary into a secondary form of nanosized colloidal plasma protein-calcium phosphate particles known as calciprotein particles. The T50 test in its previous form required a temperature controlled nephelometer and several hours of continuous measurement, which precluded rapid bed side testing. We miniaturized the test using microfluidic polymer chips produced by ultrasonic hot embossing. A cartridge holder contained a laser diode for illumination, light dependent resistor for detection and a Peltier element for thermo control. Increasing the assay temperature from 37°C to 75°C reduced the T50 test time 36-fold from 381 ± 10 min at 37°C to 10.5 ± 0.3 min at 75°C. Incorporating sputtered micro mirrors into the chip design increased the effective light path length, and improved signal-to-noise ratio 9-fold. The speed and reproducibility of the T50 chip-based assay run at 75°C suggest that it may be suitable for rapid measurements, preferably in-line in a dialyser or in a portable microfluidic analytic device with the chip inserted as a disposable cartridge.


Assuntos
Fosfatos de Cálcio/sangue , Microfluídica/métodos , Polímeros/química , Calcinose/sangue , Calcinose/diagnóstico , Humanos , Falência Renal Crônica/patologia , Dispositivos Lab-On-A-Chip , Microfluídica/instrumentação , Diálise Renal , Razão Sinal-Ruído , Temperatura
14.
Dent Mater J ; 39(4): 678-689, 2020 Aug 02.
Artigo em Inglês | MEDLINE | ID: mdl-32295987

RESUMO

Short-term studies on calcium-phosphate (CaP) ion-rechargeable composites were reported. The long-term rechargeability is important but unknown. The objectives of this study were to investigate nanocomposite with strong antibacterial and ion-recharge capabilities containing dimethylaminododecyl methacrylate (DMAHDM) and nanoparticles of amorphous calcium phosphate (NACP), and evaluate long-term ion-recharge by testing for 12 cycles (taking 6 months to complete) for the first time. Three groups were tested: (1) Heliomolar control; (2) Resin+20%NACP+50%glass; (3) Resin+3%DMAHDM+20%NACP+50%glass. Biofilm acid and colony-forming units (CFU) were measured. Ion-recharge was tested for 12 cycles. NACP-DMAHDM composite reduced biofilm acid, and reduced CFU by 4 logs. High levels of ion releases were maintained throughout 12 cycles of recharge, maintaining steady-state releases without reduction in 6 months (p>0.1), representing long-term remineralization potential. Bioactive nanocomposite demonstrated long-term ion-rechargeability for the first time, showed remineralization and potent anti-biofilm functions, with promise for tooth restorations to combat caries.


Assuntos
Cárie Dentária , Nanocompostos , Antibacterianos , Biofilmes , Fosfatos de Cálcio , Humanos , Metacrilatos
15.
J Oral Sci ; 62(2): 242-244, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32224576

RESUMO

When the sinus is enlarged, it may be necessary to elevate the floor of the maxillary sinus using the crestal or lateral approach. This report presents a case where sinus floor elevation was performed using tricalcium phosphate (TCP) plates supported by implant bodies, and only the blood clot was present around the implant bodies. Cone-beam computed tomography images, taken one year after the lateral approach, revealed the presence of a TCP-like radio-opacity, which almost disappeared after two years. About seven years after the surgery, the patient's superstructure and occlusion were stable. Furthermore, the grafted TCP was completely absorbed, and the implant body appeared to be in good condition, with no signs of bone resorption around the implant.


Assuntos
Implantes Dentários , Levantamento do Assoalho do Seio Maxilar , Fosfatos de Cálcio , Tomografia Computadorizada de Feixe Cônico , Humanos , Seio Maxilar
16.
Nat Commun ; 11(1): 1546, 2020 03 24.
Artigo em Inglês | MEDLINE | ID: mdl-32210234

RESUMO

Calcium orthophosphates (CaPs) are important in geology, biomineralization, animal metabolism and biomedicine, and constitute a structurally and chemically diverse class of minerals. In the case of dicalcium phosphates, ever since brushite (CaHPO4·2H2O, dicalcium phosphate dihydrate, DCPD) and monetite (CaHPO4, dicalcium phosphate, DCP) were first described in 19th century, the form with intermediary chemical formula CaHPO4·H2O (dicalcium phosphate monohydrate, DCPM) has remained elusive. Here, we report the synthesis and crystal structure determination of DCPM. This form of CaP is found to crystallize from amorphous calcium hydrogen phosphate (ACHP) in water-poor environments. The crystal structure of DCPM is determined to show a layered structure with a monoclinic symmetry. DCPM is metastable in water, but can be stabilized by organics, and has a higher alkalinity than DCP and DCPD. This study serves as an inspiration for the future exploration of DCPM's potential role in biomineralization, or biomedical applications.


Assuntos
Biomineralização , Fosfatos de Cálcio/química , Animais , Linhagem Celular , Cristalização , Células-Tronco Mesenquimais , Metanol/química , Simulação de Dinâmica Molecular , Ratos , Solventes/química , Água/química , Difração de Raios X
17.
Chemosphere ; 251: 126335, 2020 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-32145573

RESUMO

Pyrolysis of biomass with phosphate compound is a promising method to improve biochar characteristics. However, how phosphate compound affects the three components of biomass during the biochar formation is still unclear. In this study, a typical phosphate compound, calcium dihydrogen phosphate (Ca(H2PO4)2), was premixed with cellulose, hemicellulose, and lignin reagent, at the ratio of 20% (w/w) for biochar production through pyrolysis, aiming to investigate the effects of Ca(H2PO4)2 addition on biochar formation. Results show that, with Ca(H2PO4)2 additions, carbon retention of biochars from cellulose (MCBC) and hemicellulose (MHBC) increased by 63.4% and 48.3%, respectively, but that of lignin (MLBC) decreased by 6.7% due to the reactions between lignin and Ca(H2PO4)2. Moreover, the stable carbon proportion in the biochar decreased by 10.2% for MCBC, almost unchanged for MHBC, and increased by 6.15% for MLBC based on the potassium dichromate oxidation. During the pyrolysis process, Ca(H2PO4)2 addition fixed more volatile and/or labile carbon in biochar, resulting in greater carbon retention. Declined carbon stability of biochar might be caused by the inhibited formation of aromatic-C, evidenced by the Fourier transform infrared spectroscopy analysis. This study highlights the importance and potential mechanisms of calcium dihydrogen phosphate influencing the carbon retention and stability of biochar derived from three biomass components.


Assuntos
Fosfatos de Cálcio/química , Carvão Vegetal/química , Biomassa , Cálcio , Carbono/química , Sequestro de Carbono , Celulose/química , Lignina/química , Polissacarídeos/química , Espectroscopia de Infravermelho com Transformada de Fourier
18.
PLoS One ; 15(3): e0230533, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32182267

RESUMO

As part of a verification model of antibiotic therapy in cranioplasty, we evaluated the impregnation efficiency of interporous calcium phosphate materials with saline under atmospheric pressure and compared it to the efficiency of using the decompression method established by the Japanese Industrial Standard, under which pressure is reduced by 10 kPa. Five types of material formed in 1 mL cubes were selected as test samples: two consisting of hydroxyapatite (HAp) with 85% and 55% porosity and three of ß-tricalcium phosphate (ß-TCP) with 75%, 67%, and 57% porosity. All test samples showed an impregnation ratio of more than 70%, except for the HAp sample with 55% porosity, which had a ratio of approximately 50%. These high ratios were achieved at only 15 min. The impregnation effects were likely dependent on porosity and were independent of base material, either HAp or ß-TCP. Obtaining sufficient impregnation and antimicrobial efficacy in materials with low porosity, which are commonly used in cranioplasty, would require an increased volume of antibiotics rather than increased duration of impregnation. Our findings will enable the simple preparation of drug-impregnated calcium phosphate materials, even in operating rooms not equipped with a large decompression device.


Assuntos
Antibacterianos/uso terapêutico , Materiais Biocompatíveis/química , Fosfatos de Cálcio/química , Durapatita/química , Pressão Atmosférica , Modelos Teóricos , Porosidade
19.
Minerva Stomatol ; 69(2): 87-94, 2020 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-32181607

RESUMO

BACKGROUND: Calcium ions levels in bone niches have been demonstrated to severely influence new bone formation. Osteoinductive scaffolds containing calcium have been largely studied to control the release of calcium in bone regeneration and tissue engineering purpose. The aim of the present study was, firstly, to synthesize two different resorbable calcium phosphate-based powders, thought to be reservoirs of calcium ions, and secondary, to investigate their effects on human osteoblasts, in order to develop a suitable titanium coating material. METHODS: Tetracalcium phosphate (A450) and biphasic tetracalcium phosphatae/tricalcium phosphate (A850) powders were prepared with an innovative method. The presence of calcium phosphate structures was chemically confirmed with XRD. Furthermore, powders macroscopic aspect was observed with a stereomicroscope. For in-vitro experiments, human osteoblastic cells were cultured in the presence of A450 and A850, and assayed for viability and metabolic activity through Crystal Violet and MTT, respectively. RESULTS: Our synthesis led to the formation of calcium phosphates in both samples, even though A850 presented a higher level of crystallinity and a more powdery aspects than A450. Both the samples enhanced the viability of cultured cells, inhibiting cell metabolic activity in the case of A850, which furthermore showed to be internalized by cells. CONCLUSIONS: We developed two different kind of calcium phosphate-based powders and we tested their effect on human osteoblasts, underlying the possibility of use calcium phosphate-based coatings to enhance cell response on implantable materials.


Assuntos
Fosfatos de Cálcio , Osteoblastos , Humanos , Pós , Difração de Raios X
20.
Dent Mater J ; 39(2): 187-199, 2020 Mar 31.
Artigo em Inglês | MEDLINE | ID: mdl-32161239

RESUMO

Octacalcium phosphate (OCP) is a material that can be converted to hydroxyapatite (HA) under physiological environments and is considered a mineral precursor to bone apatite crystals. The structure of OCP consists of apatite layers stacked alternately with hydrated layers, and closely resembles the structure of HA. The performance of OCP as a bone substitute differs from that of HA materials in terms of their osteoconductivity and biodegradability. OCP manifests a cellular phagocytic response through osteoclast-like cells similar to that exhibited by the biodegradable material ß-tricalcium phosphate (ß-TCP). The use of OCP for human cranial bone defects involves using its granule or composite form with one of the natural polymers, viz., the reconstituted collagen. This review article discusses the differences and similarities in these calcium phosphate (Ca-P)-based materials from the viewpoint of the structure and their material chemistry, and attempts to elucidate why Ca-P materials, particularly OCP, display unique osteoconductive property.


Assuntos
Substitutos Ósseos , Materiais Biocompatíveis , Regeneração Óssea , Fosfatos de Cálcio , Humanos
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