Calcium Phosphate Nanopowders Research Articles

Extrusion-based 3D printing of osteoinductive scaffolds with a spongiosa-inspired structure.

Critical-sized bone defects resulting from trauma, inflammation, and tumor resections are individual in their size and shape. Implants for the treatment of such defects have to consider biomechanical and biomedical factors, as well as the individual conditions within the implantation site. In this context, 3D printing technologies offer new possibilities to design and produce patient-specific implants reflecting the outer shape and internal structure of the replaced bone tissue. The selection or modification of materials used in 3D printing enables the adaption of the implant, by enhancing the osteoinductive or biomechanical properties. In this study, scaffolds with bone spongiosa-inspired structure for extrusion-based 3D printing were generated. The computer aided design process resulted in an up scaled and simplified version of the bone spongiosa. To enhance the osteoinductive properties of the 3D printed construct, polycaprolactone (PCL) was combined with 20% (wt) calcium phosphate nano powder (CaP). The implants were designed in form of a ring structure and revealed an irregular and interconnected porous structure with a calculated porosity of 35.2% and a compression strength within the range of the natural cancellous bone. The implants were assessed in terms of biocompatibility and osteoinductivity using the osteosarcoma cell line MG63 and patient-derived mesenchymal stem cells in selected experiments. Cell growth and differentiation over 14days were monitored using confocal laser scanning microscopy, scanning electron microscopy, deoxyribonucleic acid (DNA) quantification, gene expression analysis, and quantitative assessment of calcification. MG63 cells and human mesenchymal stem cells (hMSC) adhered to the printed implants and revealed a typical elongated morphology as indicated by microscopy. Using DNA quantification, no differences for PCL or PCL-CaP in the initial adhesion of MG63 cells were observed, while the PCL-based scaffolds favored cell proliferation in the early phases of culture up to 7days. In contrast, on PCL-CaP, cell proliferation for MG63 cells was not evident, while data from PCR and the levels of calcification, or alkaline phosphatase activity, indicated osteogenic differentiation within the PCL-CaP constructs over time. For hMSC, the highest levels in the total calcium content were observed for the PCL-CaP constructs, thus underlining the osteoinductive properties.

Color Adsorption Performance of Bone Biocomponent for Textile Dyeing Effluent Treatment in Ethiopia

The continued expansion of industrial growth has contributed significantly to the economic development of many countries. However, untreated discharge from the textile factory significant impacts freshwater and public health. The aim of this study is to explore the economical-local wastewater treatment for local textile industries. The experiment used the waste bones as a source of calcium-phosphate nanopowder (CNP) biocomponent, adsorbent for azo dye effluent treatment. An isolated biocomponent was analyzed using FTIR and UV-VIS, and its adsorption isotherm was also calculated. The FTIR analysis of CNP showed carbonates, amide, and high-intensity phosphate peaks of 1008 cm−1 and 1337 cm−1. The effect of contact time analyzed by UV-VIS absorption spectra revealed that 70% of color removal was achieved within 30 minutes and 60 minutes for disperse red 1 dye (DR1D) and DCT reactive blue 109 dyes (RB109D), respectively. In addition, the effects of the condition parameters on percentage color removal were analyzed using DOE response surface methodology. The maximum color removal performances are 98.65% and 96%, respectively, for DR1D and RB109D at neutral pH. The Langmuir isotherm was observed in the adsorption of RB109D effluent with an R2 value of 0.994 and the Freundlich isotherm in the adsorption of DR1D with an R2 value of 0.993. Finally, the gauge of the effectiveness of treatment was analyzed by COD, BOD, and TSS values before and after treatment. The maximum deduction percentages of COD, BOD, and TSS were 82, 87, and 70% from RB109D; 89, 90, and 89% from DR1D; and 82, 89, and 71% from the industry sample, respectively. Generally, the study showed that the current adsorbent was a good substitute for synthetic adsorbents.

EXTRUSION-BASED PRINTING OF OSTEOINDUCTIVE SCAFFOLDS USING CALCIUM PHOSPHATE

Critical-sized bone defects can result from trauma, inflammation, and tumor resection. Such bone defects, often have irregular shapes, resulting in the need for new technologies to produce suitable implants. Bioprinting is an additive manufacturing method to create complex and individualised bone constructs, which can already include vital cells.In this study, we established an extrusion-based printing technology to produce osteoinductive scaffolds based on polycaprolactone (PCL) combined with calcium phosphate, which is known to induce osteogenic differentiation of stem cells.The model was created in python based on the signed distance functions. The shape of the 3D model is a ring with a diameter of 20 mm and a height of 10 mm with a spongiosa-like structure. The interconnected irregular pores have a diameter of 2 mm +/− 0.2 mm standard deviation.Extrusion-based printing was performed using the BIO X6. To produce the bioink, PCL (80 kDa) was combined with calcium phosphate nanopowder (> 150 nm particle size) under heating. After printing, 5 × 106 hMSC were seeded on the construct using a rotating incubator.We were able to print a highly accurate ring construct with an interconnected pore structure. The PCL combined with calcium phosphate particles resulted in a precise printed construct, which corresponded to the 3D model. The bioink containing calcium phosphate nanoparticles had a higher printing accuracy compared to PCL alone. We found that hMSC cultured on the construct settled in close proximity to the calcium phosphate particles. The hMSC were vital for 22 days on the construct as demonstrated by life/dead staining.The extrusion printing technology enables to print a mechanically stable construct with a spongiosa-like structure. The porous PCL ring could serve as an outer matrix for implants, providing the construct the stability of natural bone. To extend this technology and to improve the implant properties, a biologised inner structure will be integrated into the scaffold in the future.

Green synthesis of amorphous calcium phosphate nanopowders using Aloe Vera plant extract and assessment of their cytotoxicity and antimicrobial activities

Considering the existing various sources that can supply the nano-biomaterials that are related to the Amorphous Calcium Phosphate (ACP) family, Aloe Vera plant has been selected and utilized for the successful fabrication of (ACP) in this work. Synthetic Amorphous Calcium Phosphate (ACP) has proved to be applicable in certain applications, such as the reconstruction of damaged bone or tooth zones, due to containing outstanding biocompatibility and bioactivity qualities. The synthesis of nanoparticles via Aloe Vera extract has been distinguished through the methods of X-ray diffraction (XRD), Zeta potential, Fourier transform infrared (FTIR) spectroscopy, field emission scanning electron microscopy (FESEM), Atomic force microscopy (AFM) and the Nitrogen adsorption–desorption isotherms (BET). The zeta potential has been observed to be −28.7 mV, which is indicative of their particle desorption and stability. In addition, the XRD results have confirmed that the characterized peaks had been indexed as ACP structure, while FTIR spectroscopies have been applied to determine the optical features of the calcined powders. According to the outcomes of FESEM procedure, the studied powder has contained a satisfying crystalline grade and due to being spherically shaped, it can be assumed that they are able to easily penetrate into organisms and pass through the cell membranes. In addition, the cytotoxicity evaluation of ACP nanoparticles, which had been performed by the usage of KB (oral squamous cell carcinoma) cell lines, has interestingly exhibited their superior cell viability. The gathered data on the improved antibacterial and biocompatibility features of these nanoparticles can lead to the evolution of antibacterial agents for fabricating next-generation self-sterile textiles, antibacterial coatings, and useful health care products supporting cell viability.

DEVELOPMENT OF NEW SYNTHESIS ROUTES FOR HYDROXYAPATITE NANOPOWDERS PRODUCTION FROM CHICKEN EGGSHELLS

Hydroxyapatite (HA) nanopowders are attracting interest for surface application to ceramic biomaterials. In this study, we developed innovative and new viable synthesis routes of calcium phosphate nanopowders from the natural calcium carbonate of chicken eggshells. Following the four routes, alternative co-precipitation, vacuum process, brushite, and calcination, we obtained the HA samples, which were then characterized by different methods. The X-ray diffraction /Rietveld method showed the HA phases, monetite and brushite crystallinity with greater symmetry, and nanoscale. Transmission electron microscopy showed the morphology of nanoparticles functionalized nanoparticles smaller than 100 nm in routes A, B and D, and Fourier-transform infrared spectrophotometry and Raman spectroscopy identified the classic chemical groups of calcium phosphates by four routes mainly groups (PO4) 3- and (CO3 -). Scanning electron microscopy analysis revealed a good surface topography to future cell biointeraction in A, B and D routes, and thermogravimetric analysis showed the mass loss profile inherent to each synthesis route with slot at 200 °C. Hence, the eggshell HA and brushite and the specific monetite nanoparticles with different morphology can be prepared from the four new possible and viable routes using different methods.

Mechanism of formation governs the mechanism of release of antibiotics from calcium phosphate nanopowders and cements in a drug-dependent manner.

The kinetics of drug release from hydroxyapatite (HAp) cements could be tuned by controlling the kinetics of crystallization of their HAp precursor powders during synthesis. Here it is shown that this history of formation affects not only the kinetics, but also the mechanism of release. Cements composed of two HAp powders precipitated under different conditions, one (HAp2) taking twice longer to transform from the amorphous to the crystalline state than the other (HAp1), were mixed at different ratios to tune their drug release kinetics and tested for the release mechanism in conjunction with compositional and microstructural analyses. While the cement component converting to the amorphous phase during gelation (HAp2) exhibited a faster, but also more anomalous, non-Fickian mechanism of release of vancomycin, the cement component retaining its crystalline state all throughout gelation, setting and hardening (HAp1) stabilized at the ideal, Fickian diffusion case corresponding to the Korsmeyer-Peppas exponent value of 0.45 ± 0.02. This effect got reversed for the other antibiotic studied as a drug, ciprofloxacin, in which case HAp2 exhibited the ideal, Fickian diffusion with n = 0.45 ± 0.02 and the increase in the content of the cement component retaining its crystallinity during gelation, setting and hardening (HAp1) steadily shifted the mechanism of release to more anomalous, non-Fickian types. This has indicated that the molecular structure of the drug is an essential determinant of the mechanism of release and that the design of a carrier for a universally tunable release of drugs based on the passive transport is likely impossible. Preliminary assays involving the addition of chitosan or gelatin as polymeric components to HAp led to the inclusion of swelling and erosion as additional effects by which the drug escapes the carrier and shifted the release toward less diffusional and more multimodal mechanisms. With regard to the microstructural and compositional effects governing the release mechanism and kinetics, the retention of a finite concentration of slit-like pores of the amorphous precursor in HAp2 and its lower surface energy and lesser drug binding potential in the gelled, amorphous state, but also its possibly less stable and more diffusive particle surface and higher structural water content were elaborated as potential reasons explaining the distinct rates and mechanisms of release from the two HAp powders with different histories of formation.

Phases Obtained by Mechanoactivation in Ceramic Based on Calcium Phosphate Nanopowders with Ca/P = 1.25

Phases Obtained by Mechanoactivation in Ceramic Based on Calcium Phosphate Nanopowders with Ca/P = 1.25

Antibacterial activity evaluation of bioactive glass and biphasic calcium phosphate nanopowders mixtures

The aim of this work was to evaluate the antibacterial activity of bioactive glass (BG) and biphasic calcium phosphate (BCP) nanopowders mixtures for the first time. 37S BG and BCP (50% HA-50% β-TCP) nanopowders were prepared via sol–gel technique. Characterization techniques such as X-ray diffraction, scanning electron microscopy, transition electron microscopy, and X-ray fluorescent. The antibacterial activity was studied using Escherichia coli and Salmonella typhi as gram-negative, and Staphylococcus aureus as gram-positive bacteria. The antibacterial effect of BG, BCP nanopowders, and their mixtures was evaluated at different concentrations. The 37S BG nanopowders showed minimum bactericidal concentration at 25 mg/ml. At broth concentrations below 300 mg/ml, BCP showed no antibacterial activity. BCP and BG nanopowders mixture (M2) with 60/40 ratio of BCP/BG showed noticeable antibacterial effect. It was concluded that BCP and 37S BG nanopowders mixture could be used as a good candidate for dental and orthopedic applications.

Dissolution and storage stability of nanostructured calcium carbonates and phosphates for nutrition

Rapid calcium (Ca) dissolution from nanostructured Ca phosphate and carbonate (CaCO3) powders may allow them to be absorbed in much higher fraction in humans. Nanosized Ca phosphate and CaCO3 made by flame-assisted spray pyrolysis were characterized by nitrogen adsorption, X-ray diffraction (XRD), Raman spectroscopy, and transmission electron microscopy. As-prepared nanopowders contained both CaCO3 and CaO, but storing them under ambient conditions over 130 days resulted in a complete transformation into CaCO3, with an increase in both crystal and particle sizes. The small particle size could be stabilized against such aging by cation (Mg, Zn, Sr) and anion (P) doping, with P and Mg being most effective. Calcium phosphate nanopowders made at Ca:P ≤ 1.5 were XRD amorphous and contained γ-Ca2P2O7 with increasing hydroxyapatite content at higher Ca:P. Aging of powders with Ca:P = 1.0 and 1.5 for over 500 days gradually increased particle size (but less than for CaCO3) without a change in phase composition or crystallinity. In 0.01 M H3PO4 calcium phosphate nanopowders dissolved ≈4 times more Ca than micronsized compounds and about twice more Ca than CaCO3 nanopowders, confirming that nanosizing and/or amorphous structuring sharply increases Ca powder dissolution. Because higher Ca solubility in vitro generally leads to greater absorption in vivo, these novel FASP-made Ca nanostructured compounds may prove useful for nutrition applications, including supplementation and/or food fortification.

Structure and properties of silver-doped calcium phosphate nanopowders

Stable and antimicrobial silver-doped calcium phosphate nanopowders were synthesized using sol–gel route by setting the atomic ratio of Ag/(Ag+Ca) at 3% and (Ca+ Ag)/P at 1.67. Prior to synthesis of nanopowders, influence of time of hydrolyzation on pH and density of precursors were comprehensively studied. Hydrolyzation time was found to have profound influence on pH of constituent precursors. Sufficient hydrolysis resulted in early maturation of sol. Scanning electron microscopy (SEM) showed the heterogeneous and agglomerated state of particles with average size of 3.9± 1.9 μm. Energy dispersive X-ray spectroscopy (EDX) presented uniform distribution of O, Ag, Ca and P elements in nanopowder. Fourier transform infrared spectroscopy (FTIR) confirmed the formation of apatitic structure, whereas X-ray diffraction (XRD) revealed the multiphase constitution of nanopowders primarily composed of β-TCP, Ag and other hybrid phases. Crystallite size and lattice parameters of β-TCP and Ag phases were increased with the rise in calcination temperature. Thermogravimetric analysis (TGA) showed three regions of weight change and indicated the high thermal stability of nanopowders. Disk diffusion method was used to test the antimicrobial resistance of nanopowders against Escherichia coli and Staphylococcus aureus bacterial strains. All nanopowders exhibited antimicrobial resistance against both E. coli and S. aureus bacteria.

Bioinspired Calcium Phosphate Coated Mica Sheets by Vapor Diffusion and Its Effects on Lysozyme Assembly and Crystallization

We propose for the first time the vapor diffusion method to deposit bioinspired calcium phosphate films on mineral substrates, that is, delaminated mica muscovite sheets and to assess the capability of these films to affect the nucleation and growth of lysozyme crystals. Deposited calcium phosphate layers were composed of octacalcium phosphate (OCP) and apatite (Ap) nanocrystals, with increased amount of OCP at higher crystallization times. In the presence of poly(acrylic acid) (PAA) deposited layers were composed of amorphous calcium phosphate (ACP). Results of lysozyme crystallization showed that OCP/Ap-coated mica sheets slowed down the nucleation process without altering significantly the number of nucleated crystals per droplet respect to the uncoated control. ACP-coated mica sheets acted as an inhibitor, thus delaying the nucleation and reducing in addition the number of crystals. These results contrasted with the nucleation induction effect observed when calcium phosphate nanopowders were added to ...

Synthesis of a two-phase nanopowder from prototype human synovial fluid and the use of the nanopowder for the preparation of coatings on titanium plates

Using prototype human synovial fluid, we have synthesized a calcium phosphate nanopowder consisting of two crystalline phases (whitlockite and carbonate-containing hydroxyapatite). The nanopowder was used to produce calcium phosphate (monetite) coatings on titanium substrates by microarc oxidation. It has been shown that, with increasing microarc oxidation voltage (from 200 to 300 V), the mass, thickness, roughness parameter, and Ca : P ratio of the coatings increase linearly. Increasing the voltage to 300 V and the calcium phosphate coating growth time to 10 min allows a single-phase coating up to 100 μm in thickness, consisting of monetite nanocrystals, to be produced on a metallic surface and its adhesion strength to be improved.

Ca3(PO4)2 biomaterial: A non toxic template to prepare highly porous Cr2O3

There is great interest in finding efficient templates. Here we report that Cr2O3 powders with enhanced surface properties were synthesized by a calcination of chromium nitrate salt that used Ca3(PO4)2 calcium phosphate nanopowder as a biotemplate reactant. We used various amounts of template in order to modulate the surface properties of the chromium oxide powder, which was characterized by different techniques. Improved surface properties (SBET=49.59m2/g, Vp=0.18cm3/g) for the Cr2O3 powder were obtained with a Cr2O3/Ca3(PO4)2 weight ratio of 1. This calcium-based biotemplate is clearly an alternative to other conventional templates used for preparing large surface materials. The template is non-toxic and readily removable, which are real advantages.

Physical Properties of Calcium Phosphate-Alumina Bio ceramics as Dental Implants

In order to perform new dental implant, we carried out investigations on α-alumina and calcium phosphate based composites. α-Alumina nano-powder were synthesized using reverse micelle method while calcium phosphate nano-powders with different molar ratio starting from 1.8 to 1.1 were synthesized by precipitation method, using calcium nitrate (Ca(NO3)2.4H2O) and ammonium hydrogen orthophosphate (NH4H2PO4) as precursor materials as source for calcium (Ca²+) and phosphate ((PO4)3-) ions respectively. Samples of respectively 5, 10 and 20% weight of Calcium phosphate powder were mixed with alumina, consolidated and sintered at 1400°C for 4 hours. The synthesized composites, in form of pellets were characterized for bulk density, apparent porosity, hardness and flexural strength properties.

Synthesis, characterisation and antibacterial effects of sol–gel derived biphasic calcium phosphate nanopowders

Hydroxyapatite (HA) and β-tricalcium phosphate (β-TCP) represent the main types of calcium phosphates used for the reconstruction of bone defects in maxillofacial, dental, orthopaedic and drug delivery applications. The bioactivity and bioresorbability of biphasic calcium phosphate (BCP) ceramics can be controlled by varying the HA/β-TCP ratio. In this reported work, BCP nanopowders were prepared by a simple sol-gel method, in which Ca(NO 3 ) 2 · 4H 2 O and P 2 O 5 were used as precursors for calcium and phosphate, respectively. The different phase ratios of HA/β-TCP were obtained by changing the sintering temperature. X-ray diffraction, inductive coupled plasma-atomic emission spectroscopy, scanning electron microscopy, transmission electron microscopy and Fourier transformer infrared spectrophotometer results have shown that increasing the sintering temperature could cause more decomposition of HA into β-TCP. Moreover, the size of the prepared nanoparticles was measured between 10 and 500 nm. Finally, the antibacterial activity was studied using Escherichia coli (ATCC 25922) as the Gram-negative bacteria. The antibacterial effect of the BCP sample with 50% HA-50%β-TCP phase ratio was tested at concentrations of 100, 200 and 300 mg/ml. The results showed bacterial growth reduction at a concentration of 300 mg/ml, which makes it a good candidate for the treatment of bone defects.

Effect of Synthesized Parameters on Biphasic Calcium Phosphate Nanopowders Prepared from Chicken Eggshells

Effect of Synthesized Parameters on Biphasic Calcium Phosphate Nanopowders Prepared from Chicken Eggshells

Synthesis and thermal behavior of Mg-doped calcium phosphate nanopowders via the sol gel method

The aim of this study was to investigate the thermal behavior of Mg-doped calcium phosphate compounds. Nanocrystalline HA and β-TCP mixtures containing different magnesium contents were synthesized via an alkoxide sol gel method. The ratio of (Ca+Mg)/P was kept constant at 1.67, and the Mg content ranged between 0 and 3 mol%. The influence of magnesium on the phase composition, chemical structure, thermal behavior and morphological characteristics of nanopowders was analyzed using X-ray Diffraction (XRD), Fourier Transform Infrared Spectroscopy (FT-IR), Simultaneous Thermogravimetry and Differential Thermal Analysis (STA/DTA), Scanning Electron Microscopy (SEM) and Transmission Electron Microscopy (TEM). Based on the results of this research, the presence of magnesium led to the formation of Mg-doped hydroxyapatite (Mg-HA) and Mg-doped tricalcium phosphate (β-TCMP) phases. The characteristic peaks of apatite structures have been identified in the FTIR spectra. It was found that both the presence of magnesium and low Ca/P ratio caused the formation of a biphasic mixture, even at 470 °C. In addition, the β-TCP to α-TCP transformation temperature increased due to the presence of magnesium ions. Morphological investigations showed that the synthesized powders were composed of nanoparticles, with sizes ranging from 40 to 100 nm.

Effect of low temperature on formation mechanism of calcium phosphate nano powder via precipitation method

Calcium phosphate powders were synthesized with Ca/P molar ratios of initial reagents ranging from 1.660 to 1.667 using wet precipitation method. This work deals with allocating a specific temperature level to each H3PO4 solution and Ca(OH)2 suspension prior to the mixing process, and studying their influences on powder composition. A high pH value of the synthesis medium and the incorporation of numerous carbonate ions into the structure were attained by dropping the temperature of the Ca(OH)2 suspension down to 5°C. X-ray diffractometry and FTIR spectroscopy showed that heating samples that had a medium temperature exceeding 25°C resulted in the dominant HAp phase, regardless of the initial acid solution temperature. By maintaining the medium temperature at 5°C, a sudden formation of the β-TCP phase occurred after thermal treatment at 1300°C, and this trend continued with the concurrent decrease in the temperature of the initial acid solution. An interpretation of the formation mechanism under these low-temperature conditions is proposed in terms of the temperature and pH value of the medium and the state of the phosphate and carbonate ions.

Silver-doped calcium phosphate nanopowders prepared by electrostatic spraying

Silver-doped calcium phosphate nanopowders were successfully prepared by the cost-effective electrostatic spray-pyrolysis process. The properties of the silver-doped nanopowder annealed at 500°C for 30 min were investigated through X-ray diffraction analysis, field emission scanning electron microscope, and Fourier transform infrared spectroscopy. The silver-doped nanopowders with 70–90 nm particle size showed an antibacterial performance against Escherichia coli.

Hydroxyapatite forming ability of electrostatic spray pyrolysis derived calcium phosphate nano powder

A novel fabrication technique, i.e., electrostatic spray pyrolysis (ESP), has been used in this study to prepare calcium phosphate nano powders. Final annealing was done at 400 degrees C for 30 min in air. The hydroxyapatite-forming ability of the annealed powder has been investigated in Eagle's minimum essential medium solution. X-ray diffracton, field emission scanning electron microscope, energy dispersive X-ray spectroscope, and Fourier transform infrared spectroscope were employed to characterize the annealed powders after immersion. The powder with an amorphous structure induced hydroxyapatite formation on their surfaces after immersion for 15 days.