Carbonated Hydroxyapatite Nanoparticles Research Articles

Morphological Properties of Poly (vinyl alcohol)/Gelatin contained Indonesian Carbonated Hydroxyapatite Abalone Nanofibrous Scaffold by Electrospinning

One strategy for dealing with bone defects is replicating and reconstructing artificial bone for bone tissue engineering (BTE) application, known as the scaffold. Bone consists of an extracellular matrix (ECM) which, at the nanoscale, has a fibrous structure that can be replicated in synthetic scaffolds using an electrospinning method. This work describes the analysis of the morphological properties of Poly (vinyl alcohol) (PVA)/Gelatin contained Indonesian carbonated hydroxyapatite (CHA) abalone nanoparticle scaffold by electrospun nanofiber. CHA nanoparticles were produced using a co-precipitation method, and nanofibrous PVA/Gelatin/CHA 5 wt% scaffold was fabricated by electrospinning. The synthesized CHA produced the same condition as B-type CHA, ensured by Fourier Transform Infrared Spectroscopy (FTIR), X-Ray Diffractometer (XRD), and differential scanning calorimetry (DSC), and energy-dispersive X-ray spectroscopy (EDS) tests. The morphological properties of PVA/Gelatin/CHA are analyzed using Scanning Electron Microscopy (SEM). The SEM image indicated that PVA/Gelatin nanofiber tended to have a fine morphology without beads. The agglomeration of the PVA/Gelatin/CHA 5 wt% nanofiber scaffold can be neglected because it is still on the sub-micron scale (1 μm–100 nm). Moreover, adding CHA 5 wt% in the PVA/Gelatin matrix decreased the average fiber diameter. The diameter fiber results are within the fiber diameter range (100–450 nm) in native bone ECM. Therefore, PVA/Gelatin/CHA 5 wt% has the potential to serve as an alternative scaffold material for BTE application.

Energy Efficiency of the Carbonate Hydroxyapatite Nanoparticle Synthesis Using Microwave Heating Treatment and Its Effect on Material Characteristics

This work aimed to study the energy efficiency of the synthesis process of carbonated hydroxyapatite (CHA) nanoparticles using microwave heating treatment and its effect on material characteristics. Microwaves can provide heat quickly, so it is expected to increase the efficiency of CHA synthesis through the heat provided. The CHA nanoparticles were synthesized using precipitation and heated using a microwave oven. The unheated and hydrothermal-heated precipitation methods were also conducted for comparison purposes. The microwave-heated precipitations were done at 270 W for 0.05, 0.10, and 0.15 h, while the hydrothermal-heated precipitations were done at 100 °C for 1, 2, and 3 h. The CHA materials were characterized using an infrared spectrophotometer, X-ray diffractometer, and electron microscope. The X-ray diffractogram and infrared spectra confirmed that the synthesized materials had a hydroxyapatite crystal phase with a CO32− functional group in their spectra. Microscopic images revealed that the materials were nanometer-sized grain aggregates. The heat treatment and duration increased the material characteristics, i.e., crystallinity, crystallite, and grain size. The CHA with microwave heat treatment had the highest crystallinity and crystallite size. The electrical energy calculation revealed microwave heating had better energy efficiency than hydrothermal heating.

A previously unknown way of heme detoxification in the digestive tract of cats

Free heme is a highly toxic molecule for a living organism and its detoxification is a very important process, especially for carnivorous animals. Here we report the discovery of a previously unknown process for neutralizing free heme in the digestive tract of domestic cats. The cornerstone of this process is the encapsulation of heme into carbonated hydroxyapatite nanoparticles, followed by their excretion with faeces. This way of heme neutralization resembles the formation of insoluble heme-containing particles in the digestive tracts of other hematophagous species (for example, the formation of insoluble hemozoin crystals in malaria-causing Plasmodium parasites). Our findings suggest that the encapsulation of heme molecules into a hydroxyapatite matrix occurs during the transition from the acidic gastric juice to the small intestine with neutral conditions. The formation of these particles and their efficiency to include heme depends on the bone content in a cat’s diet. In vitro experiments with heme-hydroxyapatite nanoparticles confirm the proposed scenario.

Biofilm interfacial acidity evaluation by pH-Responsive luminescent nanoparticle films

Biofilms are dense bacterial colonies that may adhere to the surfaces of medical devices and are major contributors to infections. These colonies are characterized by a self-produced matrix of extracellular polymeric substances (EPS). Bacterial biofilms are difficult to treat with the commonly used antibiotics partially because of their poor diffusion through the EPS and therefore require new targeted strategies to effectively fight them. Biofilms may produce an acidic microenvironment which can be exploited to design such targeted treatment strategies. However, there is currently a lack of high-throughput ways to determine the acidity of biofilms at their interface with the medical device. Here, a novel all-inorganic pH responsive system is developed from luminescent carbonated hydroxyapatite nanoparticles doped with Eu3+ ions which can determine the biofilm acidity fluorometrically due to carbonate removal in acidic environments that directly affects the nanoparticle luminescence. The pH responsive nanoparticles are in-situ deposited during their production onto substrates on which a variety of clinically-relevant biofilms are grown. The acidity of their interfacial (micro)environment depends on the bacterial species and strain even when differences in biofilm biomass are considered.

Characterization of nanosized hydroxyapatite prepared by an aqueous precipitation method using eggshells and mulberry leaf extract

Hydroxyapatite (HA) has been vigorously studied for orthopedic and dental applications due to its excellent bioactivity, osteoconductivity, and osteoinductivity. This study aims to present a simple room-temperature aqueous precipitation method for obtaining carbonated HA nanoparticles of high purity from biowaste chicken eggshells. Biowaste chicken eggshells were used for preparing HA through aqueous precipitation method. Moreover, mulberry leaf extract was used as a template to regulate the morphology, size, and crystallinity of HA. All produced nanocrystalline HA powders exhibited rod-like particle agglomerates of a size below 100 nm. The HA particles synthesized with the mulberry leaf extract showed higher crystallinity and slightly decreased crystallite sizes compared to the samples prepared without adding the extract. Carbonate peaks observed for the specimens closely matched those of A- and B-type carbonates, which can contribute to the low crystallinity. Notably, the HA synthesized from the eggshell powders contains several important trace elements such as Mg and Sr, which are beneficial to the overall biological performance as biomaterials. The morphology, size, structure, and composition of the obtained HA products are similar to those of natural bones, and consequently, the products show potential as a material for biomedical applications.

Baicalein-modified hydroxyapatite nanoparticles and coatings with antibacterial and antioxidant properties

Aseptic loosening and bacterial infections are the two main causes of failure for metallic implants used for joint replacement. A coating that is both bioactive and possesses antimicrobial properties may address such shortcomings and improve the performance of the implant. We have sought to study the properties of combining hydroxyapatite-based nanoparticles or coatings with baicalein, a plant-extracted molecule with both antibacterial and antioxidant properties. (B-type) carbonated hydroxyapatite nanoparticles prepared by a chemical wet method could subsequently adsorbed by soaking in a baicalein solution. The amount of adsorbed baicalein was determined to be 63 mg.g−1 by thermogravimetric measurements. In a second approach, baicalein was adsorbed on a biomimetic calcium-deficient hydroxyapatite planar coating (12 μm thick) deposited on Ti6Al4V alloy from an aqueous solution of calcium, phosphate, sodium and magnesium salts. Soaking of the hydroxyapatite coated on titanium alloy in a baicalein solution induced partial dissolution/remodeling of the upper surface of the coating. However, the observed remodeling of the surface was much more pronounced in the presence of a baicalein solution, compared to pure water. The presence of adsorbed baicalein on the HAp layer, although it could not be precisely quantified, was assessed by XPS and fluorescence analysis. Planar coatings exhibited significant antibacterial properties against Staphylococcus epidermidis. Baicalein-modified nanoparticles exhibited significant antioxidant properties. These results illustrate the potential of hydroxyapatite used as a carrier for natural biologically-active molecules and also discuss the challenges associated with their applications as antibacterial agents.

Nanofibrous poly(vinyl alcohol)/chitosan contained carbonated hydroxyapatite nanoparticles scaffold for bone tissue engineering.

A scaffold that mimics the physicochemical structure of bone at the nanoscale level is an attractive alternative to conventional bone grafts, but its development remains a main challenge in bone tissue engineering today. This work describes the fabrication of a nanofibrous poly(vinyl alcohol)/chitosan/carbonated hydroxyapatite (PVA/CS/CHAp) scaffold. CHAp nanoparticles were synthesized using a co-precipitation method, and nanofibrous PVA/CS/CHAp scaffolds were fabricated by electrospinning using CHAp concentrations of 0, 5, 10, 15, and 20 wt%. The physicochemical properties of the scaffolds were evaluated by SEM, XRD, FTIR, and EDS, and the mechanical properties were determined by tensile strength tests. Swelling behavior, protein adsorption onto the scaffold surfaces, surface biomineralization, and cells viability were also evaluated in vitro. The addition of CHAp to the composite decreased the fiber diameter from ∼160 nm at 0 wt% to ∼139 nm at 15 wt% and great agglomerations were evident at 20 wt%. XRD, FTIR, and EDS showed effective incorporation of CHAp into the nanofibrous structure. This CHAp incorporation significantly increased the modulus of the scaffold at PVA/CS/CHAp 15 wt%, with an average 103.86 MPa, but tensile strength was not significantly altered. However, the elongation at break was decreased as the CHAp concentration increased. Swelling capacity of scaffold increases due to CHAp addition. Protein adsorption onto the scaffold increased 2.3fold at 20 wt% when compared to 0 wt%. The PVA/CS/CHAp 15 wt% showed a better bioactivity when compared to PVA/CS/CHAp 0 wt% after immersion of the scaffolds in a simulated body fluid solution for 7 days. Cell viability and cell morphology results reveal that PVA/CS/CHAp able to facilitate osteoblast cells to attach and proliferate. Introducing higher CHAp into the scaffold could increase the cell viability of the scaffold. PVA/CS/CHAp has potential to serve as an alternative scaffold material for bone tissue engineering.

In situ compressibility of carbonated hydroxyapatite in tooth dentine measured under hydrostatic pressure by high energy X-ray diffraction

Tooth dentine and other bone-like materials contain carbonated hydroxyapatite nanoparticles within a network of collagen fibrils. It is widely assumed that the elastic properties of biogenic hydroxyapatites are identical to those of geological apatite. By applying hydrostatic pressure and by in situ measurements of the a- and c- lattice parameters using high energy X-ray diffraction, we characterize the anisotropic deformability of the mineral in the crowns and roots of teeth. The collected data allowed us to calculate the bulk modulus and to derive precise estimates of Young׳s moduli and Poisson׳s ratios of the biogenic mineral particles. The results show that the dentine apatite particles are about 20% less stiff than geological and synthetic apatites and that the mineral has an average bulk modulus K=82.7GPa. A 5% anisotropy is observed in the derived values of Young׳s moduli, with E11≈91GPa and E33≈96GPa, indicating that the nanoparticles are only slightly stiffer along their long axis. Poisson׳s ratio spans ν≈0.30–0.35, as expected. Our findings suggest that the carbonated nanoparticles of biogenic apatite are significantly softer than previously thought and that their elastic properties can be considered to be nearly isotropic.

Study on carbonated hydroxyapatite as a thermoluminescence dosimeter

Abstract In this study, carbonated hydroxyapatite nanoparticles were used for thermoluminescence dosimetry. The nano-structure carbonated hydroxyapatite synthesized via hydrolysis of CaHPO4 and CaCO3. The obtained nano powders were characterized by XRD technique and FTIR spectroscopy system. The carbonated hydroxyapatite samples were irradiated at different doses using 60Co gamma rays, and were subjected to thermoluminescence measurement system, consequently. The TL glow curve exhibited two distinguishable peaks centered at around of 165°C and 310°C. The TL response of carbonated hydroxyapatite samples as a function of absorbed dose was linear in the range of 25–1000 Gy. Other dosimetric features of the carbonated hydroxyapatite nanoparticles including fading and reproducibility were also investigated.

Electrochemical Studies of Carbonated Hydroxyapatite/CHS Nanocomposite

Carbonated hydroxyapatite /CHS nanocomposites of varying composition for biomaterial applications have been synthesized. The Carbonated hydroxyapatite /CHS nanocomposite materials were characterized by XRD, FTIR, FESEM, EDAX, HRTEM and XPS. Carbonated hydroxyapatite (CHAp) nanorod embedded composite was prepared using chitosan (CHS) as a matrix with different weight percentages (wt %). The results indicated that the size and crystallinity of CHAp nano particles decreases with increase in CHS concentration in the composite. FESEM confirms the presence of CHAp nanorod crystals in CHS matrix. Cyclic voltammograms (CVs) were recorded to evaluate the electrocatalytic behaviors of the modified electrode towards the oxidation of 4-NP in the potential range of 0 to +1.0 V. A glassy carbon electrode was modified with carbonated hydroxyapatite nanopowder (CHAp-NP) and characterized in terms of electrochemical oxidation of 4-nitrophenol (4-NP) via cyclic voltammetry. The catalytic reaction facilitates electron transfer between 4-NP and the modified electrode, as a result the electrochemical oxidation of 4-NP becomes easier. The reason for this is that the CHAp-CHS 80 can act as a promoter to increase the rate of electron transfer, lower the overpotential of 4-NP at the bare electrode, and the anodic peak shifts less positive potential. Thus, it is clear that CHAp-CHS 80 modified GCE can be successfully used for the determination of organic pollutant.

Formation of nanosized strontium substituted hydroxyapatites

Incorporation of specific elements into calcium phosphates offers the combination of a bioactive material and a therapeutic effect. This is important for improving the integration of implants as well as treating medical conditions. Strontium is a suitable candidate and displays the ability to stimulate bone growth and reducing bone resorption. This study investigated the formation of strontium carbonated hydroxyapatite nanoparticles from an amorphous phase. Crystallization of carbonated hydroxyapatite occurred at 585 °C, but samples with an intended 25% and 75% replacement of calcium with strontium crystallized at 624 °C. Heat treatment at the crystallization temperature revealed that strontium free apatite does not crystallize in 5 minutes, but an increasing strontium concentration leads to a higher rate of crystallization. X-ray diffraction patterns suggest that it may be difficult to include strontium, but higher strontium concentrations are possibly included with ease in the lattice. This work has produced a nanosized apatite accompanied by an amorphous phase after a short heat-treatment time. This offers a range of features that collectively show great promise for significantly enhancing the release of strontium for improved bone therapeutic effects.

Nanocomposites of Carbonated Hydroxyapatite/Poly (4-vinyl pyridine-co-styrene): Synthesis, Characterization and its Application

nanocarbonated hydroxyapatite/Poly (4-vinyl pyridine-co-styrene) composites of varying composition for biomaterial applications have been synthesized. The nanocarbonated hydroxyapatite/Poly (4-vinyl pyridine-co-styrene) composite materials were characterized by XRD, FTIR, 31P NMR, TGA, DTA and FESEM. Carbonated Hydroxyapatite nanorod embedded composite was prepared using Poly (4-vinyl pyridine-co-styrene) as a matrix with different weight percentages (wt %). The results indicated that the size and crystallinity of Carbonated hydroxyapatite nanoparticles decreases with increase in Poly (4-vinyl pyridine-co-styrene) concentration in the composite. SEM confirms the presence of carbonated hydroxyapatite nanorod crystals in Poly (4-vinyl pyridine-co-styrene) matrix. nanoCarbonated hydroxyapatite/ Poly (4-vinyl pyridine-co-styrene) composites were screened for antimicrobial activity and anti inflammatory activity.

Hydrothermal fabrication of mesoporous carbonated hydroxyapatite microspheres for a drug delivery system

Mesoporous carbonated hydroxyapatite microspheres (MCHMs) with a particle size of ∼5μm have been fabricated hydrothermally by soaking calcium carbonate microspheres (CCMs) in a disodium hydrogen phosphate solution at 140°C. The transformation mechanism is a dissolution–precipitation reaction. After soaking in the disodium hydrogen phosphate solution, the calcium ions released from the CCMs react with phosphate ions in the solution to form carbonated hydroxyapatite nanoparticles. These nanoparticles aggregate to form mesopores with the pore size of 4.0–14.0nm. The MCHMs have been tested as vancomycin delivery systems due to the presence of the OH units in the carbonated hydroxyapatite structure, which provide these carriers of great affinity towards host drug molecules. In addition, in vitro tests into a simulated body fluid (SBF) demonstrate that the MCHMs are bioactive, since an apatite layer deposits on their surfaces after 3days of assay. Such MCHMs could be useful in developing new biomaterials and have potential use in implanting and drug delivery for tissue regeneration.

Electrospinning and Evaluation of PHBV-Based Tissue Engineering Scaffolds with Different Fibre Diameters, Surface Topography and Compositions

While electrospinning is an effective technology for producing poly(hydroxybutyrate-co-hydroxyvalerate) (PHBV) micrometre-scale fibrous scaffolds for tissue regeneration, electrospinning of PHBV fibrous scaffolds composed of sub-micrometre fibres, surface-porous fibres or nanocomposite fibres is rarely explored. In this study, the average PHBV fibre diameter was successfully reduced to the sub-micrometre scale by dissolving a conductivity-enhancing salt in the polymer solution for electrospinning. Surface-porous fibres were made using a mixture of solvents, and carbonated hydroxyapatite (CHA) nanoparticles were incorporated into the fibres with the aid of an ultrasonic power source. Water contact angle measurements demonstrated that both fibre diameter reduction and CHA incorporation enhanced the wettability of the fibrous scaffolds. Tensile properties of the scaffolds were not undermined by the reduction of fibre diameter and the presence of surface pores. In vitro biological evaluation using a human osteoblast-like cell line (SaOS-2) demonstrated that all types of fibrous scaffolds supported cell attachment, spreading and proliferation. Analysis of cell morphology revealed similar projected cell areas on all types of scaffolds. However, cells on sub-micrometre fibres possessed a lower cell aspect ratio than cells on microfibres. The reduction of fibre diameter to the sub-micrometre scale enhanced cell proliferation after 14 days cell culture, while the incorporation of CHA nanoparticles in microfibres significantly enhanced the alkaline phosphatase activity of SaOS-2 cells. The control of fibre diameter, surface topography and composition is important in developing electrospun PHBV-based scaffolds for specific tissue-engineering applications.

Biocompatibility of Carbonated Hydroxyapatite Nanoparticles with Different Crystallinities

Carbonated apatite (CHA) is commonly considered a promising synthetic material for biomedical applications in orthopedic and dental surgery due to its biocompatibility, bioresorption and bioactivity. CHA5, CHA37 and CHA90 powders were synthesized from wet method and the DRX patterns showed that the crystallinity and particle size of CHA samples increased proportionally with the synthesis temperature. Powder extracts medium were obtained from each sample to interact with MC3T3-E1 osteoblastics cells. It was evaluated morphology, citotoxicity, pH and Ca2+ concentration. Citotoxicity assays showed high metabolic activity on all samples when compared to control. The polygonal shaped and the confluent monolayer observed in control cells progressively changed according to the crystallinity increase of samples. Cells under mitosis and spindle-like shaped where the main alterations observed. In addition the cell viability could be sensitive to the acid reactivity and crystallinity of carbonated apatite samples.

Fabrication of mesoporous carbonated hydroxyapatite microspheres by hydrothermal method

Mesoporous carbonated hydroxyapatite microspheres (MCHMs) have been converted from calcium carbonate microspheres (CCMs) by hydrothermal method. After soaking the CCMs in disodium hydrogen phosphate solutions, carbonated hydroxyapatite nanoparticles are formed via a dissolution–precipitation reaction. X-ray diffraction (XRD) and Fourier-transform infrared spectroscopy (FTIR) reveal that the as-obtained samples are calcium deficient hydroxyapatite with B-type CO 3 2− substitution. The transmission electron microscopy (TEM) indicates that the MCHMs are composed of many nanoparticles within the whole microspheres. These nanoparticles aggregate to form mesopores with a pore size of 4.5–14.0 nm among them. The formation mechanism of MHAMs has been discussed.

Fabrication of mesoporous carbonated hydroxyapatite/carbon nanotube composite coatings by microwave irradiation method

Carbonated hydroxyapatite/carbon nanotube composite coatings (MHCs) with mesoporous structures were fabricated by electrophoretic deposition of nacre powders and carbon nanotubes on Ti6Al4V substrates followed by treatment with a phosphate buffer solution (PBS) by microwave irradiation method. The carbon nanotubes are dispersed uniformly on the whole MHCs. The conversion mechanism of the crack-free nacre/carbonate nanotube composite coatings (NCCs) to MHCs is a dissolution-precipitation reaction. After soaking in PBS, calcium ions are released from the nacre powders and react with phosphate ions to form carbonated hydroxyapatite nanoparticles. These nanoparticles aggregate to form mesopores with the pore sizes of ~ 3.9 nm among them. Simulated body fluid (SBF) immersion tests reveal that MHCs have a good in vitro bioactivity.

Sorption of Cadmium Ions on (AB-type) Carbonated Hydroxyapatite Nanoparticles

Sorption of Cadmium Ions on (AB-type) Carbonated Hydroxyapatite Nanoparticles

Electrospinning, characterization and in vitro biological evaluation of nanocomposite fibers containing carbonated hydroxyapatite nanoparticles

Poly(hydroxybutyrate-co-hydroxyvalerate) (PHBV) fibers containing carbonated hydroxyapatite (CHA) nanoparticles with different CHA amounts (5, 10 and 15 wt%) were electrospun with the aid of ultrasonic power for dispersing the nanoparticles. Scanning electron microscopy and energy-dispersive x-ray spectroscopy results showed that the distribution of CHA within the CHA/PHBV nanocomposite fibers was homogeneous when the CHA content was 10 wt%. Slight particle agglomeration occurred when the CHA content was 15 wt%. The diameters of the electrospun CHA/PHBV nanocomposite fibers and PHBV polymer fibers were around 3 µm. Fourier transform infrared spectroscopic analysis further confirmed the presence of CHA in CHA/PHBV nanocomposite fibers. Both PHBV and CHA/PHBV fibrous membranes exhibited similar tensile properties. Compared with PHBV solvent-cast film, the PHBV fibrous membrane was hydrophobic but the incorporation of CHA nanoparticles dramatically enhanced its wettability. In vitro studies revealed that both types of electrospun fibrous membranes (PHBV and CHA/PHBV) supported the proliferation of human osteoblastic cells (SaOS-2). The alkaline phosphatase activity of SaOS-2 cells seeded on the CHA/PHBV fibrous membranes was higher than that of the cells seeded on the PHBV fibrous membranes after 14 days of cell culture. The electrospun CHA/PHBV nanocomposite fibrous membranes show promises for bone tissue engineering applications.

Crystallization kinetics of poly(L‐lactide)/carbonated hydroxyapatite nanocomposite microspheres

AbstractMicrospheres consisting of carbonated hydroxyapatite (CHAp) nanoparticles and poly(L‐lactide) (PLLA) have been fabricated for use in the construction of osetoconductive bone tissue engineering scaffolds by selective laser sintering (SLS). In SLS, PLLA polymer melts and crystallizes. It is therefore necessary to study the crystallization kinetics of PLLA/CHAp nanocomposites. The effects of 10 wt% CHAp nanoparticles on the isothermal and nonisothermal crystallization behavior of PLLA matrix were studied, using neat PLLA for comparisons. The Avrami equation was successfully applied for the analysis of isothermal crystallization kinetics. Using the Lauritzen‐Hoffman theory, the transition temperature from crystallization Regime II to Regime III was found to be around 120°C for both neat PLLA and PLLA/CHAp nanocomposite. The combined Avrami‐Ozawa equation was used to analyze the nonisothermal crystallization process, and it was found that the Ozawa exponent was equal to the Avrami exponent for neat PLLA and PLLA/CHAp nanocomposite, respectively. The effective activation energy as a function of the relative crystallinity and temperature for neat PLLA and PLLA/CHAp nanocomposite under the nonisothermal crystallization condition was obtained by using the Friedman differential isoconversion method. The Lauritzen‐Hoffman parameters were also determined from the nonisothermal crystallization data by using the Vyazovkin‐Sbirrazzuoli equation. CHAp nanoparticles in the composite acted as an efficient nucleating agent, enhancing the nucleation rate but at the same time reducing the spherulite growth rate. This investigation has provided significant insights into the crystallization behavior of PLLA/CHAp nanocomposites, and the results obtained are very useful for making good quality PLLA/CHAp scaffolds through SLS. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009