Dicalcium Phosphate Dihydrate Research Articles

High toughness resorbable brushite-gypsum fiber-reinforced cements

The ideal bone substitute material should be mechanically strong, biocompatible with a resorption rate matching the rate of new bone formation. Brushite (dicalcium phosphate dihydrate) cement is a promising bone substitute material but with limited resorbability and mechanical properties. To improve the resorbability and mechanical performance of brushite cements, we incorporated gypsum (calcium sulfate dihydrate) and diazonium-treated polyglactin fibers which are well-known for their biocompatibility and bioresorbability. Here we show that by combining brushite and gypsum, we were able to fabricate biocompatible composite cements with high fracture toughness (0.47 MPa·m1/2) and a resorption rate that matched the rate of new bone formation. Adding functionalized polyglactin fibers to this composite cement further improved the fracture toughness up to 1.00 MPa·m1/2. XPS and SEM revealed that the improvement in fracture toughness is due to the strong interfacial bonding between the functionalized fibers and the cement matrix.This study shows that adding gypsum and functionalized polyglactin fibers to brushite cements results in composite biomaterials that combine high fracture toughness, resorbability, and biocompatibility, and have great potential for bone regeneration.

Preparation of Co-Processed Excipients for Controlled-Release of Drugs Assembled with Solid Lipid Nanoparticles and Direct Compression Materials.

The purpose of the study was to develop a novel, directly compressible, co-processed excipient capable of providing a controlled-release drug system for the pharmaceutical industry. A co-processed powder was formed by adsorption of solid lipid nanoparticles (SLN) as a controlled-release film onto a functional excipient, in this case, dicalcium phosphate dihydrate (DPD), for direct compression (Di-Tab®). The co-processed excipient has advantages: easy to implement; solvent-free; industrial scaling-up; good rheological and compressibility properties; and the capability to form an inert platform. Six different batches of Di-Tab®:SLN weight ratios were prepared (4:0.6, 3:0.6, 2:0.6, 1:0.6, 0.5:0.6, and 0.25:0.6). BCS class III ranitidine hydrochloride was selected as a drug model to evaluate the mixture’s controlled-release capabilities. The co-processed excipients were characterized in terms of powder rheology and dissolution rate. The best Di-Tab®:SLN ratio proved to be 2:0.6, as it showed high functionality with good flow and compressibility properties (Carr Index = 16 ± 1, Hausner Index = 1.19 ± 0.04). This ratio could control release for up to 8 h, so it fits the ideal profile calculated based on biopharmaceutical data. The compressed systems obtained using this powder mixture behave as a matrix platform in which Fickian diffusion governs the release. The Higuchi model can explain their behavior.

Enhanced reactivity of dicalcium phosphate dihydrate with fluoride ions by coating with apatite nanoparticles

ABSTRACT The formation of nanoscale precursors on the surface of dicalcium phosphate dihydrate (DCPD) is an important step in various methods; however, this process requires an unstable solution. Herein, we propose a simple method for the deposition of nanoscale fluorapatite (FAp) particles on the surface of DCPD particles using a weakly acidic, aqueous solution containing only calcium, phosphate, and fluoride ions (C-P-F solution). Repeated immersion in the same solution increases the amount of FAp deposition and almost no delay time is observed. Experimental results indicate that approximately 10 wt.% of FAp on the DCPD surface is optimal to enhance its reactivity with fluoride ions. Our results demonstrate an optimum FAp deposition amount on DCPD particles for improved reactivity with fluoride ions, and we achieved an improved surface of the DCPD particle for fluoride immobilization in wastewater and soil environments.

Ferric iron incorporation promotes brushite hydrolysis and enhances cadmium immobilization.

Dissolution-precipitation processes on the surface of brushite (dicalcium phosphate dihydrate, DCPD) control the migration and transformation of potentially harmful elements (PHEs). The incorporation of impurities could affect the properties of DCPD and its interactions with PHEs. In this study, we synthesized Fe3+-bearing DCPD via coprecipitation and investigated the influence of Fe3+ incorporation on the crystal structure, hydrolysis process, and Cd removal performance. Fe-bearing DCPD had lattice expansion due to the coupled substitution of Fe3+ and NH4+ for Ca2+. Therefore, the Cd removal performance of Fe-DCPD was enhanced, with a maximum Cd uptake capacity of 431.6mg/g, which is 1.77 times that of Fe-free DCPD (244.4mg/g). Furthermore, Fe-DCPD also exhibited a faster hydrolysis rate, which was up to 2.67 times that of Fe-free DCPD and accelerated Cd's transfer to the stable host mineral, hydroxylapatite. Cd was first caught by the DCPD surface in a weakly crystalline form and then incorporated into the hydroxylapatite structure during crystallization. Based on the X-ray photoelectron spectroscopy and thermogravimetric analysis results, we concluded that the decrease in interstitial water due to Fe incorporation was responsible for accelerating hydrolysis and enhancing Cd immobilization. In all, the incorporation of Fe3+ into DCPD could promote its transformation and improve its Cd uptake capacity. Our results suggest that Fe-DCPD could be a promising candidate for environmental remediation.

Effect of platelet-poor plasma additive on the formation of biocompatible calcium phosphates

Biocompatible calcium phosphates were synthesized by mixing calcium- and phosphate-containing solutions in medium with various pH value, which contained up to 6 vol.% of platelet-poor plasma (PPP). Depending on the pH of precipitation medium, the influence of PPP components favored the formation of calcium-deficient hydroxyapatites with varying composition. In neutral medium, dicalcium phosphate dihydrate (DCPD) was the predominant phase but the buffering properties of PPP favored formation up to 24 wt.% of apatitic tricalcium phosphate. In alkaline medium, negatively charged surface of the PPP component macromolecules inhibited Ca2+ diffusion, which in turn lowered the Ca/P molar ratio of the formed hydroxyapatite from 1.67 to 1.62. After soaking in simulated body fluid (SBF), DCPD underwent hydrolysis yielding 29 wt.% of octacalcium phosphate and 19 wt.% of apatitic tricalcium phosphate and hydrolyzed DCPD/PPP sample contained 9 wt.% and 42 wt.% of octacalcium phosphate and apatitic tricalcium phosphate. Calcium-deficient hydroxyapatite in HA/PPP sample consumed the ions of SBF with an increase of its Ca/P molar ratio from 1.62 up to 1.66. In both cases, the Ca/P molar ratio of the calcium phosphates increased, indicating the apatite forming ability of the obtained calcium phosphates. Obtained results seem to be promising in development of new generation of hybrid composites based on calcium phosphates and blood components.

Experimental dentin adhesives containing calcium orthophosphate particles: Effect on dentin bond strength, micro-permeability and collagen degradation

PurposeTo assess the effect of dicalcium phosphate dihydrate (DCPD) or mineral trioxide aggregate (MTA) particles on the microtensile bond strength (μTBS), micro-permeability and enzymatic activity at the adhesive-dentin interface of experimental dental adhesives. Materials and methodsAn experimental ethanol-based, two-step etch-and-rinse adhesive system was prepared. Four experimental groups were tested, based on the type of particle added: (1) DCPD functionalized with diethylene glycol dimethacrylate (DCPD_DEGDMA), (2) citric acid (DCPD_CA), (3) calcium silicate (MTA) and (4) unfilled (control). All particles were added at 10 wt%. Human third molars had their occlusal enamel removed and dentin surface polished. After acid etching, the adhesives were applied on the dentin surfaces and the teeth were restored with a commercial nanofilled resin composite. The μTBS and micro-permeability were tested after 24 h or 2 months of storage in simulated body fluid (SBF) at 37 °C. Bonded interfaces were observed using scanning electron microcopy (SEM). Gelatinolytic activity at the adhesive interfaces was assessed by in situ zymography at 24 h and 2 months in SBF/37 °C. The results were described as relative florescent units (RFU). μTBS data were analyzed by ANOVA/Games–Howell test. Data from micro-permeability and in situ zymography were analyzed by Kruskal–Wallis/Mann–Whitney test (alpha: 5%). ResultsDifferences in μTBS were found among adhesives (control = MTA > DCPD_CA > DCPD_DEGDMA, p < 0.001), but not between storage times. The control group showed the lowest permeability at both observation periods. Except for DCPD_CA, no significant increases in micro-permeability were observed after 2 months. All groups presented significant reductions in RFU values between 24 h and 2 months. DCPD_DEGDMA (at 24 h) and MTA (at 2 months) presented statistically lower RFU than the control (p < 0.01). ConclusionEvidence of reduced MMP activity was observed at adhesive interfaces with the use of experimental adhesives containing calcium-releasing particles. However, after two months, bond strength and micro-permeability results suggest that interfacial stability was not affected by adhesive formulation.

Synthesis and Hydrolysis of Brushite (DCPD): The Role of Ionic Substitution

Brushite (dicalcium phosphate dihydrate, DCPD) is considered one of the possible precursors of the apatitic phase that constitutes the mineral component of bones, and it is often utilized in the pr...

Self-setting β-tricalcium phosphate granular cement at physiological body condition: effect of citric acid concentration as an inhibitor

The aim of this study is to investigate the effect of citric acid (CA) concentration as an inhibitor on the properties of β-tricalcium phosphate (β-TCP) granular cement. In this study, β-TCP granules were exposed to an acidic calcium phosphate solution containing 0.01 mol/L, 0.10 mol/L, and 1.00 mol/L of CA at physiological body conditions for 10 min. These specimens were denoted as 0.01 mol/L CA, 0.10 mol/L CA, and 1.00 mol/L CA, and its properties were characterized throughout the study. Physical appearance results showed that increasing citric acid concentration in an acidic calcium phosphate solution up to 1.00 mol/L reduced the self-setting ability of β-TCP granules. Meanwhile, compositional and morphological analyses showed the amount of dicalcium phosphate dihydrate (DCPD) crystals that precipitated and interlocked between β-TCP granules decreased when the concentration of citric acid increased. The decreasing trend of DCPD formation in set specimens increased its porosity and reduced the compression strength up to 27.4%. Therefore, these findings evinced that by altering the concentration of citric acid in an acidic calcium phosphate solution, the setting reaction of β-TCP granules at physiological body condition was inhibited.

Influence of adding Pluronic F127 in the electrolyte on the morphology, structure and biofilm adhesion of calcium phosphate coatings

In this work, we have investigated the addition of Pluronic F127 (PF127) into the electrolyte solution on the structure, morphology and antibacterial growth of calcium phosphate (CaP) coatings synthesized by an electrochemical method on Ti substrate. Different parameters of the deposition process were investigated, which were temperature, time and PF127 wt%. The coatings were characterized by X-ray diffraction (XRD), gravimetric analysis, Fourier-transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). In vitro antimicrobial assays against S. aureus were performed. XRD analysis confirmed the formation of dicalcium phosphate dihydrate (DCPD) or anhydrous dicalcium phosphate (DCPA) and octacalcium phosphate (OCP). The structure and morphology depended mainly on PF127 wt% and deposition temperature in lower deposition time. Interestingly, structure and morphology were not influenced by adding PF127 at higher deposition time using higher PF127 concentrations. The morphology by SEM changed from plate-like to fiber by varying the PF127 concentration as well as blocks at higher temperatures. Moreover, all coatings were crystalline, uniform and crack-free. Antibacterial assays showed that biofilm formation was prevented when a coating of PF127 is deposited on the surface. Bacterial growth depended on the phase and morphology of washed coatings. Thus, the structure, morphology and consequently bacterial growth resistance can be tailored by the use of PF127 in the electrochemical processing at shorter deposition times.

Efficient adsorptive removal of Cobalt(II) ions from water by dicalcium phosphate dihydrate

Although the radionuclide 60Co is widely used, its presence in various effluents demands its removal to preclude environmental pollution and detrimental effects on human health. This study investigated the batch adsorption performance of a potential cobalt adsorbent, dicalcium phosphate dihydrate (DCPD), in immobilizing Co2+ from water. The influences of solution pH, contact time, initial concentration, and competing cations were examined and discussed. Stable cobalt uptake was observed at pH 4–8. The sorption kinetics showed a multi-stage uptake profile, implying that several mechanisms are involved in the adsorption process. Microscopy and structural analysis revealed that DCPD decomposes to its anhydrous form during adsorption, which explains the multistep curve over the entire adsorption period. However, the non-apatitic transformation is not exclusive to cobalt uptake. Intraparticle diffusion also contributed to the overall removal kinetics of Co2+ from water. Considering the Sips isotherm model, the maximum Co2+ adsorption capacity of DCPD was 441 mg g−1. Cobalt uptake selectivity dropped in the presence of Ca2+ ions, from 1.21 × 104 to 207 mL g−1, indicating DCPD would be more applicable in treating soft 60Co-contaminated waters. Structural analysis, elemental mapping, and qualitative analysis of solid residues confirmed that ion exchange is involved in the removal of cobalt from aqueous solutions.

A slow and sustained release of methotrexate (MTX) from a new polymeric dicalcium phosphate dehydrate cement (P-DCPD)

A novel and injectable polymeric dicalcium phosphate dihydrate (P-DCPD) was developed by the reaction of acidic CPP gel with alkali TTCP that is completely different from classical DCPD. P-DCPD is mechanically strong and has excellent cohesion.

Amorphization of a proposed sorbent of strontium, brushite, CaHPO4•2H2O, studied by X-ray diffraction and Raman spectroscopy

We present a systematic study of the transformation of brushite (dicalcium phosphate dihydrate, CaHPO4•2H2O) under irradiation of electrons of well-defined energy (2.5 MeV) and flux as a function of the irradiation dose. Contrarily to model hydroxides such as portlandite and brucite, which are very resistant to electron radiation damage, the studied brushite decomposes quite easily, even for very low irradiation doses. Irradiated brushite samples were characterized using X-ray diffraction (XRD) and Raman spectroscopy to get complementary information about changes in atomic structure and chemical composition respectively under irradiation. XRD showed that irradiation causes a very limited dilatation of unit cell of crystalline brushite, which becomes progressively amorphous with increasing radiation dose. Raman spectroscopy complemented XRD results and confirmed that the transformation of brushite to the amorphous phase was not abrupt, but rather progressive. Raman spectroscopy allowed for the identification of the amorphous phase as a calcium pyrophosphate. Both techniques showed that the amorphization of brushite was not fully complete at the maximum dose used, 5.5 GGy (4 C). Interestingly, monetite phase, (CaHPO4 dicalcium phosphate), was not detected at any step of the transformation as it is the case when brushite is thermally decomposed. This study reveals the high sensitivity to electron radiation of both hydrogen bonds and protonated phosphate units in brushite, thus facilitating the transformation into pyrophosphate. The damage of brushite by energetic electrons is to be carefully considered for applications related to the use of brushite as ion-exchanger in the decontamination of effluents polluted with strontium-90, an efficient beta ray emitter.

Synthesis and physicochemical characterization of Zn-doped brushite

Dicalcium phosphate dihydrate (DCPD) enriched by different amounts of Zn2+ ions was synthesised in aqueous solution via standard precipitation method. The obtained powders were characterised by powder X-ray diffractometry (PXRD), infrared spectroscopy (FT-IR), solid-state nuclear magnetic resonance (ssNMR), inductively coupled plasma optical emission spectroscopy (ICP-OES) and scanning electron microscopy (SEM). These tests confirmed that all the powders were highly microcrystalline brushite. As the concentration of zinc increased, an additional crystalline phase of α-hopeite appeared, and, simultaneously, the crystallinity of brushite slightly decreased. Moreover, according to the shifts of PXRD, FTIR and 31P ssNMR line positions, it was proved that zinc ions were successfully introduced into the crystal of DCPD. The (Ca + Zn)/P molar ratio calculated from ICP-OES results was ca. 1.0, which is typical for DCPD; only the (Ca + Zn)/P molar ratio of the sample with the highest concentration of Zn slightly differs, which was caused by the presence of α-hopeite. SEM images have shown a high tendency of Zn-containing brushite to agglomerate into the spherical, compact clusters. The preliminary biological tests have shown that the powders are non-toxic, which makes them promising materials for potential use in mineralised tissue engineering.

Kinetic Study of Calcium Phosphate Precipitation in the System H3PO4-Ca(OH)2-H2O at 30°C

The precipitation kinetics of calcium phosphates, namely, hydroxyapatite (HAP), dicalcium phosphate dihydrate (DCPD), dicalcium phosphate anhydrous (DCPA), and monocalcium phosphate monohydrate (MCPM), were studied at 30°C by mixing calcium hydroxide, water, and phosphoric acid. The studied mixture was selected according to the stability domain of different calcium phosphates by referring to the phase diagram of the ternary system of H3PO4-Ca(OH)2-H2O at 30°C. The precipitation reaction has been monitored by following the changes in the conductivity, pH, and calcium concentration. The solid phases formed at different stages of this precipitation were characterized by X-ray diffraction.

Calcium phosphate coatings enhance biocompatibility and degradation resistance of magnesium alloy: Correlating in vitro and in vivo studies

Magnesium (Mg) and its alloys are promising biodegradable materials for orthopedic applications. However, one of the major problems is their rapid degradation rate with quick evolution of hydrogen gas. To overcome this problem, calcium phosphate (CaP) coatings have been used to improve the degradation resistance and the biocompatibility of Mg materials. This study focuses on the comparison and correlation of the in vitro and in vivo degradation and biocompatibility behaviors of these materials. A CaP coating consisting of dicalcium phosphate dihydrate (DCPD) was deposited on an AZ60 Mg alloy by the chemical conversion method. Then, the in vitro degradation testing including electrochemical and immersion tests, and in vivo implantation of the CaP coated Mg alloy were conducted to compare the degradation behaviors. Next, the in vitro cell behavior and in vivo bone tissue response were also compared on both uncoated and CaP-coated Mg samples. Data showed that the CaP coating provided the Mg alloy with significantly better biodegradation behavior and biocompatibility. The in vitro and in vivo biocompatibility tests exhibited good consistency while not the case for biodegradation. Results showed that the in vitro electrochemical test could be a quick screening tool for the biodegradation rate, while the in vitro immersion degradation rate was often 2–4 folds faster than the in vivo degradation rate.

Bio-modulation of scaring Glaucoma Filtration Surgery using a novel application of coated magnesium

Filtration surgery still plays a mainstream role of treatment for glaucoma. Postoperative scarring is the main cause of surgical failure. This study evaluated the biocompatibility and anti-proliferative properties of pure magnesium with three different coatings, which are hydroxyapatite (HA), dicalcium phosphate dihydrate (DCPD) and DCPD + stearic acid (SA), in a primary culture of human tenon's capsule fibroblasts (HTCFs) and in rabbit Glaucoma Filtration Surgery. Titanium and glass were used as controls in vitro , and trabeculectomy was used as control in vivo . The results show the number and shape of HTCFs seeded on different coatings showed less quantity and poor cell morphology. Each type of coated magnesium demonstrated significantly decreased metabolic activity of HTCFs. DCPD + SA showed higher cytotoxicity than the other coatings. Significant inhibition of proliferation was observed with the DCPD + SA coating. The expression of α-SMA was decreased in the cells when seeded on all of the coated magnesium disks. In vivo , no obvious adverse effects were observed after operation. No significant difference existed for any of the different samples regarding different ion concentrations in the aqueous humor. The inflammatory response in the titanium, DCPD and DCPD + SA treated eyes was more intense than in the trabeculectomy alone and HA groups. Western Blot analysis showed that collagen-1 and α-SMA expression was significantly lower in the titanium, HA, DCPD and DCPD+SA groups compared with the control. Different coatings on magnesium were able to affect the corrosive properties, which in turn, influenced the morphology and function of HTCFs. HA coated magnesium may be considered a very promising biodegradable material for the next generation of glaucoma drainage devices.

Behavior of Osteoclast Cells Response on Dicalcium Phosphate Dihydrate Layer-Coated β-Tricalcium Phosphate Granular

The aim of this study is to investigate the behavior of osteoclast cells response on dicalcium phosphate dihydrate (DCPD) layer-coated β-TCP granules. β-TCP granules with 300-600 μm were exposed to acidic calcium phosphate solution for 30 mins in order to get 10 mol% DCPD layer-coated β-TCP granular. DCPD free-coated β-TCP granular had used as control specimen. Both specimens were implant in 9 mm of rat calvarial bone defect for 4 weeks. After 4 weeks, the block section of rat calvarial containing specimen were removed for Tatrate-Resistance Acid Phosphatase (TRAP) analysis. Results of TRAP staining reveal that the number of osteoclast cells attached on 10 mol% layer-coated β-TCP granular is higher than DCPD free-coated β-TCP granular. Since remodeling of new bone formation involved simultaneous osteoclast and osteoblast cells response, therefore, the results obtained in this study indicated that the presence of DCPD layer-coated on β-TCP granular helps to improve osteoclast cells response that contribute in stimulating new bone formation.

Challenges and Solutions for the Additive Manufacturing of Biodegradable Magnesium Implants

Abstract Due to their capability of fabricating geometrically complex structures, additive manufacturing (AM) techniques have provided unprecedented opportunities to produce biodegradable metallic implants—especially using Mg alloys, which exhibit appropriate mechanical properties and outstanding biocompatibility. However, many challenges hinder the fabrication of AM-processed biodegradable Mg-based implants, such as the difficulty of Mg powder preparation, powder splash, and crack formation during the AM process. In the present work, the challenges of AM-processed Mg components are analyzed and solutions to these challenges are proposed. A novel Mg-based alloy (Mg–Nd–Zn–Zr alloy, JDBM) powder with a smooth surface and good roundness was first synthesized successfully, and the AM parameters for Mg-based alloys were optimized. Based on the optimized parameters, porous JDBM scaffolds with three different architectures (biomimetic, diamond, and gyroid) were then fabricated by selective laser melting (SLM), and their mechanical properties and degradation behavior were evaluated. Finally, the gyroid scaffolds with the best performance were selected for dicalcium phosphate dihydrate (DCPD) coating treatment, which greatly suppressed the degradation rate and increased the cytocompatibility, indicating a promising prospect for clinical application as bone tissue engineering scaffolds.

Insights into self-healing behavior and mechanism of dicalcium phosphate dihydrate coating on biomedical Mg

Self-healing coatings have been developed as smart surface coatings for Mg and its alloys to retain local corrosion from the coating damages. In this study, we prepared dicalcium phosphate dihydrate (DCPD) coating on biomedical Mg, and found that the artificial scratches in DCPD coating can be efficiently sealed by anti-corrosive products in both Hank's and normal saline (NS) solutions. Besides, the in-depth study revealed that DCPD was served as not only a physical barrier but also a self-healing agent, demonstrating an autonomous self-healing coating without embedded extra corrosion inhibitors. Moreover, Hank's solution provided foreign-aid film-forming ions to promote self-healing behavior. The findings might offer new opportunities for further studies and applications of efficient self-healing coatings on biodegradable Mg implants.

Deposition of anti-corrosion hybrid film of hexamethylene diaminetetrakis (methylene phosphonic acid)/hydroxyapatite on biodegradable Mg: Influence of deposition procedures

Magnesium and its alloys are promising biodegradable materials because of their light weight and superior mechanical properties. However, the high corrosion susceptibility of magnesium is the main obstacle that hinders the application of Mg in biomedical applications. In this article, two approaches have been employed to fabricate hybrid films of hexamethylene diamine tetrakis (methylene phosphonic acid) (HMDTMPA) and hydroxyapatite (HA) on Mg. The direct dipping method involves an immersion in a single solution containing both calcium, phosphate, and the organic compound. However, it results in poor-quality loose films, due to unstable film of monocalcium phosphate monohydrate (MCPM). The other method involves immersion in two separated solutions: Ca-P solution and HMDTMPA solution. Our results showed that the corrosion resistance was enhanced about 12-times compared with HMDTMPA film due to the formation of a stable hybrid film of dicalcium phosphate dihydrate (DCPD). The mechanism of formation of anti-corrosion DCPD was discussed on the light of SEM, EDS, FTIR, XRD and XPS.