Journal articles: 'Hydroxyapatite'

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Sokol, K. I., and D. V. Rokhmistrov. "Feature of electric resistance dependence on temperature for hydroxyapatite." Low Temperature Physics 49, no. 4 (April 2023): 453–56. http://dx.doi.org/10.1063/10.0017587.

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Electrical resistance of hydroxyapatites in an interval from room temperature to 1200 °C have been studied. It is shown that the resistance of hydroxyapatite depends sufficiently from the impurities. To identify the impurities, XRD, IR, MS measurements were carried out. It was established that the electrical resistance of hydroxyapatite is related to the water content in the samples, nitrous substances and carbonate ions located inside of hydroxyapatite crystal lattice. Energy activation of electrical conductivity in hydroxyapatite is calculated.

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Eremina, Natalya V., Svetlana V. Makarova, Denis D. Isaev, and Natalya V. Bulina. "Soft mechanochemical synthesis and thermal stability of hydroxyapatites with different types of substitution." Chimica Techno Acta 9, no. 3 (July 26, 2022): 20229305. http://dx.doi.org/10.15826/chimtech.2022.9.3.05.

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The feasibility of soft mechanochemical synthesis was studied here for hydroxyapatite with various types of substitution. It was shown that this method allows obtaining hydroxyapatites substituted with copper or iron cations and hydroxyapatites cosubstituted with zinc cations and silicate groups. Thermal stability of the synthesized samples was evaluated. It was found that to preserve phase homogeneity of the material, the temperature during the preparation of ceramic products and coatings should not exceed 600–800 °C. An exception is the hydroxyapatite where a hydroxyl group is expected to be replaced by a copper cation during the synthesis at a degree of substitution x = 0.5. For this sample, the temperature of the the heat treatment can be increased to 1100–1200 °C because copper cations return to the hydroxyapatite crystal lattice at these temperatures, and the material becomes single-phase.

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Conz, Marcio Baltazar, José Mauro Granjeiro, and Gloria de Almeida Soares. "Physicochemical characterization of six commercial hydroxyapatites for medical-dental applicatons as bone graft." Journal of Applied Oral Science 13, no. 2 (June 2005): 136–40. http://dx.doi.org/10.1590/s1678-77572005000200008.

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The aim of this work was to characterize six hydroxyapatites in granular form for applications in medicine and dentistry as bone graft and to compare with manufacturers' specification. These samples were produced by four different manufacturers, and all of them are easily available in the Brazilian market. Physicochemical characterization was carried out by using electron microscopy (SEM), X-ray diffraction (XRD), infrared spectroscopy (FTIR) and surface area (BET) measurements. The results show that just one hydroxyapatite sample exhibited characterisitics in perfect agreement with the manufacturers' specifications. The studied parameters, namely crystallinity, surface area and composition may be used to estimate hydroxyapatite's biodegradability and as a criterion for quality control.

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Iconaru, Simona, Mikael Motelica-Heino, Régis Guegan, Mihai Predoi, Alina Prodan, and Daniela Predoi. "Removal of Zinc Ions Using Hydroxyapatite and Study of Ultrasound Behavior of Aqueous Media." Materials 11, no. 8 (August 3, 2018): 1350. http://dx.doi.org/10.3390/ma11081350.

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The present study demonstrates the effectiveness of hydroxyapatite nanopowders in the adsorption of zinc in aqueous solutions. The synthesized hydroxyapatites before (HAp) and after the adsorption of zinc (at a concentration of 50 mg/L) in solution (HApD) were characterized using X-ray diffraction (XRD), and scanning and transmission electron microscopy (SEM and TEM, respectively). The effectiveness of hydroxyapatite nanopowders in the adsorption of zinc in aqueous solutions was stressed out through ultrasonic measurements. Both Langmuir and Freundlich models properly fitted on a wide range of concentration the equilibrium adsorption isotherms, allowing us to precisely quantify the affinity of zinc to hydroxyapatite nanopowders and to probe the efficacy of hydroxyapatite in removal of zinc ions from aqueous solutions in ultrasonic conditions.

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Saragih, Agung Shamsuddin, Amin Pamungkas, and Alfian Noviyanto. "Synthesis of Hydroxyapatite from Indonesian Green Mussels (Perna viridis) via Precipitation Methods." Key Engineering Materials 833 (March 2020): 199–203. http://dx.doi.org/10.4028/www.scientific.net/kem.833.199.

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Based on the X-Ray Fluorescence test it was identified that the calcium content in green mussel shells was very high with concentration about 93.83%. The calcium is the main constituent of hydroxyapatite besides phosphorus, so the purpose of this study is to identify a very good potential for synthesized hydroxyapatite from green mussel shells, which is considered the waste of shells that cause environmental pollution. Hydroxyapatite synthesized from green mussels using precipitation method, calcium from green was reacted with phosphate obtained from phosphoric acid. The Fourier transform infrared spectrum show that the functional group in powder is a functional group of hydroxyapatites. The FTIR chart of shellfish hydroxyapatite soaked in acetone and after the precipitation process is heated again to 900°C is the most similar graph to the FTIR commercial HA graph. The results of the X-Ray Diffraction test also prove that the clam shell with this treatment has a diffraction pattern resembling standard hydroxyapatite.

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Byra, Natalia, Sylwester Krukowski, Jaroslaw Sadlo, and Waclaw Kolodziejski. "Composites Containing Nanohydroxyapatites and a Stable TEMPO Radical: Preparation and Characterization Using Spectrophotometry, EPR and 1H MAS NMR." Materials 15, no. 6 (March 10, 2022): 2043. http://dx.doi.org/10.3390/ma15062043.

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Hydroxyapatite is the main constituent of mammalian hard tissues. Basic applications of synthetic hydroxyapatites include bone and dental implantology and drug delivery systems. The study of hydroxyapatite surface properties could give greater insight into the processes of bone mineralization and degradation. Nitroxide radicals are stable radicals that exhibit anticancer and antioxidative properties and are often used as spin probes to study the dynamics of complex biological systems. In this work, we attempted to adsorb the stable 2,2,6,6-tetramethylpiperidine-1-oxyl radical (TEMPO) on two hydroxyapatites (HAs) differing in specific surface area and the degree of hydration. The adsorption was carried out from cyclohexane, 1-chlorobutane and water. The solutions after adsorption were studied spectrophotometrically, while the obtained composites were characterized via NMR and EPR spectroscopy. The results show that it is possible to reproducibly obtain fairly stable composites, where the main factors influencing the adsorbed amount of the radical are solvent polarity and specific surface area of hydroxyapatite. The Langmuir isotherm was determined to be the most suitable adsorption model. The analysis of EPR and NMR spectra allowed us to determine the distribution of the TEMPO molecules on the hydroxyapatite surface, as well as a probable adsorption mechanism. The HA/TEMPO composites could potentially be used to study certain properties of hydroxyapatite surfaces with EPR spectroscopy. They could also be used as fillers after hard tissue surgery, as well as metal-free MRI contrasts.

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Fang, Chih-Hsiang, Yi-Wen Lin, Feng-Huei Lin, Jui-Sheng Sun, Yuan-Hung Chao, Hung-Ying Lin, and Zwei-Chieng Chang. "Biomimetic Synthesis of Nanocrystalline Hydroxyapatite Composites: Therapeutic Potential and Effects on Bone Regeneration." International Journal of Molecular Sciences 20, no. 23 (November 28, 2019): 6002. http://dx.doi.org/10.3390/ijms20236002.

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The development of a novel alloplastic graft with both osteoinductive and osteoconductive properties is still necessary. In this study, we tried to synthesize a biomimetic hydroxyapatite microspheres (gelatin/nano-hydroxyapatite microsphere embedded with stromal cell-derived factor-1: GHM-S) from nanocrystalline hydroxyapatites and to investigate their therapeutic potential and effects on bone regeneration. In this study, hydroxyapatite was synthesized by co-precipitation of calcium hydroxide and orthophosphoric acid to gelatin solution. The microbial transglutaminase was used as the agent to crosslink the microspheres. The morphology, characterization, and thermal gravimetric analysis of microspheres were performed. SDF-1 release profile and in vitro biocompatibility and relative osteogenic gene expression were analyzed, followed by in vivo micro-computed tomography study and histological analysis. The synthesized hydroxyapatite was found to be similar to hydroxyapatite of natural bone tissue. The stromal cell-derived factor-1 was embedded into gelatin/hydroxyapatite microsphere to form the biomimetic hydroxyapatite microsphere. The stromal cell-derived factor-1 protein could be released in a controlled manner from the biomimetic hydroxyapatite microsphere and form a concentration gradient in the culture environment to attract the migration of stem cells. Gene expression and protein expression indicated that stem cells could differentiate or develop into pre-osteoblasts. The effect of bone formation by the biomimetic hydroxyapatite microsphere was assessed by an in vivo rats’ alveolar bone defects model and confirmed by micro-CT imaging and histological examination. Our findings demonstrated that the biomimetic hydroxyapatite microsphere can enhance the alveolar bone regeneration. This design has potential be applied to other bone defects.

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8

Afriani, Fitri, Evi J, Zaitun Zaitun, and Yuant Tiandho. "Improvement of Hardness of Hydroxyapatite by the Addition of Silica from Tin Tailings." Journal of Engineering and Scientific Research 2, no. 2 (December 28, 2020): 85–89. http://dx.doi.org/10.23960/jesr.v2i2.48.

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The application of bone scaffolding in bone therapy is an alternative solution developed in bone tissue engineering technology to avoid bone donors' scarcity. The main requirement for a material that can be used as a scaffold is that it is biocompatible. Hydroxyapatite is a calcium phosphate ceramic that is often used as the primary material for scaffolding because it has good biocompatibility properties. However, like most ceramics, hydroxyapatite has low mechanical properties. In this study, we synthesized hydroxyapatite from cockleshell waste. To improve hydroxyapatite's mechanical properties (hardness), we added silica from tin tailings to hydroxyapatite. Through the analysis of the x-ray diffraction (XRD) pattern, it was found that hydroxyapatite was successfully synthesized from cockleshell using the co-precipitation method. Analysis of the diffraction pattern of tin tailings also shows that most of the crystals comprising tin tailings sand are silica in the ?-quartz phase. The addition of silica to hydroxyapatite followed by compaction and sintering at a temperature of 800 ? did not produce a new crystal phase. The addition still has a diffraction pattern consisting of a combined XRD pattern of hydroxyapatite and silica. Based on the hardness test using the Vickers hardness method, it is known that the addition of silica can increase the hardness of hydroxyapatite.

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9

Troubitsin, M., Viet Hung Hoang, and L. Furda. "INFLUENCE OF THE CRYSTAL-CHEMICAL STRUCTURE IN CALCIUM-PHOSPHATE NANOCOMPOSITE ON THE FORMATION OF ELECTROSURFACE AND ACID-BASIC PROPERTIES." Bulletin of Belgorod State Technological University named after. V. G. Shukhov 6, no. 2 (March 5, 2021): 89–99. http://dx.doi.org/10.34031/2071-7318-2021-6-2-89-99.

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The single-phase modified nanostructured hydroxyapatites and biomimetic calcium-phosphate nanocomposite (BMHAP) doped by silicate and carbonate anions are synthesized by chemical precipitation in aqueous solutions. The chemical composition of the obtained samples is studied by energy dispersive X-ray spectroscopy using a scanning electron microscope. It is shown that the obtained molar ratios are close to the design values in all samples. The influence of different modifying ions in the crystal-chemical structure of hydroxyapatite (HAp) on the electrosurface properties of the synthesized products has been studied. Unmodified hydroxyapatite, silicate-substituted hydroxyapatite, and BMHAP particles are found to carry a negative charge in an aqueous suspension at pH = 7, while carbonate-substituted HAp particles had a positive charge. It is revealed that the introduction of silicate and carbonate anions into the HAp structure is accompanied by an increase in negative values of the zeta-potential from -1.05 to -4.29 mV. The change in the distribution of active centers on the surface of modified nanostructured hydroxyapatites is studied by the adsorption of acid-base indicators method with pKax in the range from -0.3 to +12.8. In contrast to stoichiometric hydroxyapatite, in BMHAP the neutral Bronsted centers prevails, and their concentration is 48.38 mmol-eq/g

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10

Petrovic, Bozana, Maja Krstic, Tihana Mudrinic, Maria Cebela, and Maja Dutour-Sikiric. "Mg and Si substituted hydroxyapatite: Behaviour in simulated body fluid." Serbian Dental Journal 69, no. 2 (2022): 82–88. http://dx.doi.org/10.2298/sgs2202082p.

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Due to its similarity with biological apatite found in vertebrate hard tissues, calcium hydroxyapatite is one of the most investigated materials in bone tissue engineering. As the biological apatite is not stoichiometric, ion substituted hydroxyapatites attract much atention since they more closely mimic the composition of natural bone. Although there are many investigations of the influence of foreign ions on the structure and physico-chemical properties of ion-substituted hydroxyapatites, there is scarse information on their behaviour in different media. In the present study, magnesium (Mg), that plays a key role in bone metabolism and silicon (Si), that is necessary for normal skeletal development, were used as ion substitutes. The behaviour of Mg and Si substituted hydroxyapatite in simulated body fluid was investigated by XRD, FTIR and SEM. Obtained results confirmed great potential of these substituted hydroxyapatites for biomedical applications.

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11

Adekanmi, Daniel Gbenga, Carlos Rodriguez Garcia, and Claudia M. Lopez-Badillo. "Carbonate Hydroxyapatite - A Multifunctional Bioceramics with Non-Medical Applications." Engineering Chemistry 7 (June 26, 2024): 1–24. http://dx.doi.org/10.4028/p-518pjs.

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Carbonate hydroxyapatite is the common derivative of hydroxyapatite found in living systems. It is the building block of most hard tissues, including the teeth and bones. A vast majority of the applications of this versatile material focus on its biomedical applications, which is attributable to its closeness to biological apatites. Hydroxyapatite is a strong precursor to carbonate apatite in nature, and many experiments show that both are similar in a few respects. A significant divergence point is carbonate's obvious impact on its physicochemical properties and concomitant applications. The inclusion of carbonate ions into the lattice of hydroxyapatite results in morphological and physicochemical changes that vary with the method of synthesis and extent of substitution. The unique crystal structure, improved surface area, and porous morphology of carbonate hydroxyapatites also make it useful for catalysis and environmental remediation as adsorbents for heavy metals. This review briefly examines carbonate hydroxyapatite, its synthesis, its modification, and its characterization. It also highlights its biomedical applications while drawing attention to its non-medical potential.

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12

Kurtjak, Mario, Marija Vukomanović, Andraž Krajnc, Lovro Kramer, Boris Turk, and Danilo Suvorov. "Designing Ga(iii)-containing hydroxyapatite with antibacterial activity." RSC Advances 6, no. 114 (2016): 112839–52. http://dx.doi.org/10.1039/c6ra23424k.

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Incorporation of Ga³⁺ ions into hydroxyapatite under different conditions is studied in detail and its influence on ion-release, antibacterial and cytotoxic properties of the resulting Ga(iii)-containing hydroxyapatites is determined.

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13

Youn, Sang Heum, Z. X. Yang, Kyu Hong Hwang, Jong Kook Lee, and H. Kim. "Dissolution of Hydroxyapatite Reinforced Grain Boundary by Glassy Phases." Key Engineering Materials 330-332 (February 2007): 31–34. http://dx.doi.org/10.4028/www.scientific.net/kem.330-332.31.

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Several sintering additives for hydroxyapatite have been tested in order to enhance its sinterability without decomposing the hydroxyapatite(Ca10(PO4)6(OH)2) and without decreasing the bioactivity and/or biocompatibility. In case of sintered pure hydroxyapatites significant dissolution was occurred after immersion in distilled water or in simulated body fluid. At first the dissolution was iniciated at grain boundary creating the nano-size defects such as small pores and grew up to micro scale by increasing the immersion time. This dissolution resulted in grain separation at the surfaces and finally in fracture. And the dissolution was concentrated on those grains adjacent to pores rather than those in the dense region. So glass-reinforced hydroxyapatite(GR-HA) ceramics were prepared to strengthening the grain boundary to prevent dissolution. Several glasses were added at 0 to 10wt.% and sintered at 1200 °C for 2h in air with moisture protection. Glass phase was incorporated into hydroxyapatite to act as the sintering aids followed by crystallization in order to improve the mechanical properties without reducing the biocompatibility. From dissolution test, significant damage was reduced even more than 7days. X-ray diffraction and SEM showed no decomposition of hydroxyapatite to secondary phases and fracture toughness was increased more than pure hydroxyapatite.

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14

Muhamadin, Rilo Chandra, Alviani Hesthi Permata Ningtyas, Ilham Arifin Pahlawan, Rizkyansyah Alif Hidayatullah, Rifky Ismail, Deni Fajar Fitriyana, Nur Fadhilah, and Gilang Taufiqu Rachman. "Characterization and Synthesis Hydroxyapatite from Scallop Mussel Shells Prepared by the Microwave-Assisted Precipitation Methods." Jurnal Sains dan Teknologi Industri 21, no. 1 (December 9, 2023): 175. http://dx.doi.org/10.24014/sitekin.v21i1.26793.

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The need for bone implants is constantly increasing every year as the population of older people, accidents, and bone diseases increase. Various solutions, such as autograft, allograft, and artificial endoprosthesis, have been developed by researchers. Ceramic or bio-ceramic materials become very attractive as bone implants due to their high biocompatibility. One of the most commonly used bio-ceramics today is hydroxyapatite (HAp). Hydroxyapatite is one of the biomaterials that are widely used as biomedical materials, such as bone fillers, bioactive implant coatings, bone tissue repair systems and drug distribution. Kabupaten Gresik is famous for its fisheries, including the scallop mussel shells. The scallop mussel shells (Ruditapes philippinarum) is a species of shells that is widely cultivated in the Kabupaten Gresik. Using scallop mussel shell wastes as hydroxyapatite raw material can reduce shell waste volumes and production costs. Several methods for producing hydroxyapatites include hydrothermal, sol-gel, mechanochemical, wet chemical and microwave methods. Hydroxyapatite synthesis with the microwave method has the advantages of efficient heating, environmentally friendly and economical. This study aims to characterize and synthesize hydroxyapatite using scallop mussel shell waste prepared using microwave-assisted precipitation methods in the Gresik Regency. The research was carried out to convert the scallop mussel shells resulting from calcination with the crystal phase Ca(OH)2 into hydroxyapatite using the microwave method. The synthesis process with the method of microwaves at the power of 450 watts for 2.5 minutes. From the synthesis results, hydroxyapatite was then characterized by XRD and SEM tests. The XRD tests carried out formed 99.1% crystallinity of hydroxyapatite.

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Hmood, Firas, Israa Sabri, and Allaa Najim. "Consolidation and characterization of Cu, Mg substituted hydroxyapatite by cold sintering." Science of Sintering, no. 00 (2024): 6. http://dx.doi.org/10.2298/sos240306006h.

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Cold sintering method is an effective route to consolidate powders at temperatures below 300?C. In this study, pure and (Cu, Mg) substituted hydroxyapatite were sintered at 250?C. Ultrapure and substituted hydroxyapatite powders were synthesized by wet precipitation method. Sintering pressure of 250 MPa was used to compact the powders while they were heated simultaneously. 10% (H3PO4) solution was used as a transsolvent for the ionic-substituted hydroxyapatite while distillated water was supplied to the pure one. The yield geometries were characterized for density, thermal stability, microstructure, and the biodegradation in Tris-HCl buffer. The findings indicate that the pure hydroxyapatite compacts has a density of 2.876 g/cm3 (86% TD). Owing to the low sintering temperature the resulting hydroxyapatites have not experienced thermal decomposition, besides no additional phases have appeared. Biologically, the sintered sample (Cu0.25Mg0.75Ca9(PO4)6(OH)2) showed larger degradability (0.0001 g/mm2) than to others after one day of immersion.

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Hy, Le Ho Khanh, Pham Xuan Ky, Dao Viet Ha, Nguyen Thu Hong, Phan Bao Vy, Doan Thi Thiet, and Nguyen Phuong Anh. "CERTAIN PROPERTIES OF CALCIUM HYDROXYAPATITE FROM SKIPJACK TUNA BONE (Katsuwonus pelamis)." Vietnam Journal of Marine Science and Technology 18, no. 4A (March 14, 2019): 151–63. http://dx.doi.org/10.15625/1859-3097/18/4a/13643.

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This paper is concerned with certain properties of calcium hydroxyapatite from skipjack tuna bone (Katsuwonus pelamis) which are by-products of fish export industry. Hydroxyapatite Ca10(PO4)6(OH)2 and β-tricalcium phosphate Ca3(PO4)2, the high-value compounds, have been successfully extracted from skipjack tuna bones. The bones were heated at different temperatures of 600oC, 900oC, 1200oC. While at 600oC hydroxyapatites were obtained with Ca/P ratio of 1.658, comparable to the value of 1.67 found in human bone; the hydroxyapatite crystals of average size of 0.25 µm were formed with the same size distribution. In case of heated bone samples at 900°C and 1200°C, the calcium formed were biphasic calcium phosphate composed of hydroxyapatite and β-tricalcium phosphate; the Ca/P ratio was between 1.660–1.665; the calcium crystals of more than 1 µm were highly porous and connected to each other in priority orientation of tube direction.

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Kanaya, Tomoko, Kanji Tsuru, Satoshi Hayakawa, Akiyoshi Osaka, Eiji Fujii, Kouji Kawabata, Georgiana Gasqueres, Christian Bonhomme, and Florence Babonneau. "Structure and In Vitro Solubility of Silicon-Substituted Hydroxyapatite." Key Engineering Materials 361-363 (November 2007): 63–66. http://dx.doi.org/10.4028/www.scientific.net/kem.361-363.63.

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Hydroxyapatite (HAp) and Si-containing hydroxyapatite (SiHAp) particles were synthesized by a wet chemical method. Local structures around Si, P and H in the hydroxyapatites were analyzed by solid-state magic-angle spinning nuclear magnetic resonance spectroscopy. In vitro solubility of those SiHAp particles was evaluated by soaking them in acetic acid/acetate buffer solution (pH=4.0) at 36.5°C. As the Si content increased, the in vitro solubility of the SiHAp particles increased, while their crystallite size changed little.

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Chae, M. H., Yong Keun Lee, Kyoung Nam Kim, Jae Hoon Lee, B. J. Choi, H. J. Choi, and K. T. Park. "The Effect of Hydroxyapatite on Bonding Strength in Light Curing Glass Ionomer Dental Cement." Key Engineering Materials 309-311 (May 2006): 881–84. http://dx.doi.org/10.4028/www.scientific.net/kem.309-311.881.

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The mineral phase of bone and teeth is mainly hydroxyapatite. Currently there are numerous researches being conducted on the effect of the addition of hydroxyapatite to dental materials. Among them, several studied were published stating that the addition of hydroxyapatite to composite resin or glass ionomer cement resulted in an improvement in bonding strength and physical properties Therefore, this study will investigate the effect that the addition of hydroxyapatite to light curing glass ionomer cement has on bonding strength. Two different light curing glass ionomer cement products were selected (FujiⅡLC, GC Cor, Japan and Vitremer™ , 3M/ESPE, USA) and hydroxyapatite was mixed into the light curing glass ionomer cement at various concentrations to create hydroxyapatite-light curing glass ionomer cement mixture. In order to confirm that hydroxyapatite-light curing glass ionomer cement met the basic requirements of dental materials, sensitivity to ambient light, depth of cure, and flexural strength were tested. From the results of the above mentioned tests, the hydroxyapatite-light curing glass ionomer cement with the most superior physical properties for each product (15% HA-Fuji Ⅱ LC, 20% HA-Vitremer™)was bonded to the teeth and then immersed in artificial saliva(36.5°C) for four weeks. Finally the sectioned surface was observed under SEM after measuring the bonding strength. As the hydroxyapatite concentration increased, the depth of cure decreased. However flexural strength increased and there was not much change in the sensitivity to ambient light. Bonding strength, which was the main focus of this study, increased with the addition of hydroxyapatie and scanning electron microscope findings show a more cohesive type of fracture in the material with bone like apatite material formation along the tooth-material interface.

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Lytkina, Daria, Anastasiya Gutsalova, Dmitriy Fedorishin, Natalya Korotchenko, Rafik Akhmedzhanov, Vladimir Kozik, and Irina Kurzina. "Synthesis and Properties of Zinc-Modified Hydroxyapatite." Journal of Functional Biomaterials 11, no. 1 (February 20, 2020): 10. http://dx.doi.org/10.3390/jfb11010010.

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Hydroxyapatites modified with metal ions are the main inorganic components of bone tissue and are approved for use as components for biocomposites and coatings for surgical implants. This study examined prototypes of functional materials for bone implants based on hydroxyapatite modified with zinc ions. Zinc-modified hydroxyapatite was composed and synthesized. Using the XRD method, the phase composition was established. Using SEM, EPMA, and low-temperature nitrogen adsorption (BET) methods, surface properties were investigated. Antibacterial activity and biocompatibility have been established. The studied materials have antimicrobial activity; the samples did not cause significant changes in either the internal organs or the general condition of laboratory animals during the entire experiment.

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Mota, Gabriela, José Vitor C. do Carmo, Camila B. Paz, Gilberto D. Saraiva, Adriana Campos, Gian Duarte, Edson C. da Silva Filho, et al. "Influence of the Metal Incorporation into Hydroxyapatites on the Deactivation Behavior of the Solids in the Esterification of Glycerol." Catalysts 12, no. 1 (December 23, 2021): 10. http://dx.doi.org/10.3390/catal12010010.

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The effects of the metal incorporation into hydroxyapatites on the deactivation behavior of the solids were examined in the esterification of glycerol (EG) reaction. The introduction of Cu, Co, or Ni ions by ion exchange in calcium-deficient hydroxyapatites resulted in active catalysts for the EG reaction. The metal contents were varied from 2.0 to 17.0%, providing better performances at rather high metal contents. Part of metal species existed in the hydroxyapatite lattice structure and also as isolated Cu2+, Ni2+, and Co2+ entities on the surface, as shown by XPS and EPR. The effects of the reaction temperature, reaction time, and glycerol to acetic acid molar ratios were deeply investigated. The spent solids used in this study were characterized by XRD, FTIR, SEM-EDS, chemical analyses, EPR, and XPS. The Cu2+–OH acid pairs could promote a superior catalytic performance of Cu-containing hydroxyapatites due to the resistance of these solids against leaching of the active species, which is even better than those of Co and Ni-containing counterparts with high metal contents. Cu into hydroxyapatite had a good reusability and long-term utilization for five consecutive cycles of 24 h under a glycerol to acetic acid molar ratio of 0.25 at 80 °C, and longer reaction times provide triacetin formation. This was due to the fact that Cu was stabilized by interacting with Ca, PO4, and OH sites into the hydroxyapatite lattice, being highly active for the EG reaction. The results also revealed that isolated Cu2+ sites played an important role in enhancing the glycerol conversion, intrinsically due to the Cu-containing hydroxyapatites ability to avoid strong adsorption of glycerol oligomers on the catalytic sites.

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Sugiyama, Shigeru, and Hiromu Hayashi. "Role of Hydroxide Groups in Hydroxyapatite Catalysts for the Oxidative Dehydrogenation of Alkanes." International Journal of Modern Physics B 17, no. 08n09 (April 10, 2003): 1476–81. http://dx.doi.org/10.1142/s0217979203019186.

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The oxidative dehydrogenation of propane on strontium hydroxyapatites (SrHAp) and the hydroxyapatite incorporated with cobalt cation (Co-SrHAp) were tested and related to H-D exchangeability of OH groups in those hydroxyapatites with D2O. With increasing Co2+ contents in those catalysts, the oxidative dehydrogenation of propane and H-D exchangeability of HO groups in those hydroxyapatites with D2O were enhanced. It is suggested that "oxygen-species" derived from the abstraction of hydrogen of OH groups directly contributes to the hydrogen abstraction from propane on those catalysts.

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Silva, Flávia R. O., Nelson B. de Lima, Deiby S. Gouveia, Nildemar A. M. Ferreira, Valter Ussui, Lilia C. Courrol, and Ana Helena A. Bressiani. "Europium-Doped Hydroxyapatite: Influence of Excitation Wavelength on the Eu³⁺ Luminescence in the Hydroxyapatite." Materials Science Forum 820 (June 2015): 335–40. http://dx.doi.org/10.4028/www.scientific.net/msf.820.335.

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Hydroxyapatite (HA) doped with europium (HAEu) offers the advantage of making the hydroxyapatite a fluorescent biomarker, allowing their imaging through emissionin vivoandin vitrotests. Several authors had been based their studies about europium site occupation (CaI and CaII) in hydroxyapatite by the lanthanide ion luminescence, verifying the influence of the method of synthesis and concentration of the dopant ion. In this study HA nanoparticles doped with 1.4 mol% of trivalent europium were synthesized by co-precipitation method and thermal treated at different temperatures (600°C and 1200°C). A careful evaluation of the influence of the excitation wavelength of europium luminescence in the HAEu was performed and it has been verified that both the characteristics transitions of europium, at CaI and CaII sites, and the luminescent intensity are dependent on the excitation wavelength. The non-observance of this fact can lead to erroneous conclusions about the site occupation of europium in hydroxyapatites.

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Suwanprateeb, J., F. Thammarakcharoen, P. Phanphiriya, W. Chokevivat, W. Suvannapruk, and B. Chernchujit. "PREPARATION AND CHARACTERIZATIONS OF ANTIBIOTIC IMPREGNATED MICROPOROUS NANO-HYDROXYAPATITE FOR OSTEOMYELITIS TREATMENT." Biomedical Engineering: Applications, Basis and Communications 26, no. 03 (March 17, 2014): 1450041. http://dx.doi.org/10.4015/s1016237214500410.

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In this study, preparation and characterization of antibiotic-impregnated microporous nano-hydroxyapatite (HA) aiming to function as both antibiotic carrier and bone graft for osteomyelitis treatment were carried out. Microporous nano-hydroxyapatite was prepared by low temperature phosphorization of three-dimensional printed calcium sulfate sample and was impregnated by three types of antibiotics including vancomycin, fosfomycin and gentamicin. Materials properties and antibacterial performance including phase composition, microstructure, degradability, total drug loading, antibacterial activity and shelf life were investigated and reported. Microporous nano-hydroxyapatite having porosity and mean pore size of 63.92% and 0.15 microns was prepared and showed greater resorbability than typical high-temperature sintering samples. Sustained release of antibiotic from the impregnated samples for longer than 29 days was observed, but the difference in the efficiency was related to the difference in the molecular weight, mechanism of action, spectrum of activity of each antibiotic. No deterioration in the antibacterial activity of the prepared antibiotic-impregnated hydroxyapatite was observed after storing for up to 12 months. No cytotoxic potential by MTT assay at all extraction periods was observed for vancomycin-impregnated hydroxyapatite. Gentamicin and fosfomycin impregnated hydroxyapatites showed cytotoxic potential only on day 1 extraction, but no cytotoxic potential was observed on day 2 extraction onward. This could be related to the concentration and characteristics of each released antibiotics.

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Shamray, V. F., V. N. Serebryany, A. S. Kolyanova, V. I. Kalita, V. S. Komlev, S. M. Barinov, D. I. Komlev, and M. V. Barybin. "Quantitative texture analysis of a hydroxyapatite coatings plasma-sprayed on titanium substrates at different temperatures." Industrial laboratory. Diagnostics of materials 86, no. 12 (December 17, 2020): 23–31. http://dx.doi.org/10.26896/1028-6861-2020-86-12-23-31.

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Artificial hydroxyapatite exhibits an excellent biocompatibility with tissues of human body. However, poor mechanical properties of hydroxyapatites and low reliability in wet environments restrict their use. These limitations can be overcome by applying the hydroxyapatite as a coating onto metallic implants. X-ray diffraction analysis (restoration of orientation distribution function from pole figures and the Rietveld method) and scanning electron microscopy have been used to study thick (~330 μm) plasma-sprayed hydroxyapatite coatings. The coatings were deposited onto Ti – 2Al – 1Mn alloy substrates, one of which was held at room temperature (20°C) whereas the other substrate was preheated to 550°C. The texture of the coating deposited on substrate held at room temperature is characterized by the (001)[510] orientation, the volume fraction of which is 0.08, while the coating deposited on preheated substrate has the (001)[410] orientation, the volume fraction of which is 0.10. Results of texture analysis are qualitatively supported by the Rietveld refinement data. The problem of the formation of basal texture in plasma-sprayed hydroxyapatite coatings is discussed in terms of quantitative texture analysis in relation to the differences in the substrate temperature and spraying parameters. It was concluded that the quantitative texture analysis is of importance for deeper understanding the effect of spraying parameters on the formation of hydroxyapatite coatings.

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Tian, Kun, Min Peng, Wei Fei, Chu Hang Liao, and Xiao Hua Ren. "Induced Synthesis of Hydroxyapatite by Chitosan for Enamel Remineralization." Advanced Materials Research 530 (June 2012): 40–45. http://dx.doi.org/10.4028/www.scientific.net/amr.530.40.

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The formation of organized nanocrystals that resemble tooth-like hydroxyapatite is crucial for successful enamel remineralization. Based on the principles of biomineralization , spindle - shaped hydroxyapatites (HA) were synthesized through biomimetic method with chitosan as template under a controllable way in vitro. We observed that hydroxyapatite nanorods can be controlled followed by in situ crosslinking process and triggered by conditions of pH and ionic strength. The dentinal tubule were blocked by neonatal hydroxyapatite layer and this composite a continuous structure of columns crystal with size of 10-40nm. At the same time, XRD showed that the precipitation was calcium fluoride phosphate and Ca:P was 1.6. Furthermore, there were column crystal with parallel direction inside, as same as the crystal array in the top of enamel rod. The results suggest that chitosan monolayer may be useful in the modulation of mineral behavior during in situ dental tissue engineering.

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Murphy, Bríd, Mick A. Morris, and Jhonattan Baez. "Development of Hydroxyapatite Coatings for Orthopaedic Implants from Colloidal Solutions: Part 1—Effect of Solution Concentration and Deposition Kinetics." Nanomaterials 13, no. 18 (September 17, 2023): 2577. http://dx.doi.org/10.3390/nano13182577.

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This study introduces and explores the use of supersaturated solutions of calcium and phosphate ions to generate well-defined hydroxyapatite coatings for orthopaedic implants. The deposition of hydroxyapatite is conducted via several solutions of metastable precursors that precipitate insoluble hydroxyapatite minerals at a substrate–solution interface. Solutions of this nature are intrinsically unstable, but this paper outlines process windows in terms of time, temperature, concentration and pH in which coating deposition is controlled via the stop/go reaction. To understand the kinetics of the deposition process, comparisons based on ionic strength, particle size, electron imaging, elemental analyses and mass of the formed coating for various deposition solutions are carried out. This comprehensive dataset enables the measurement of deposition kinetics and identification of an optimum solution and its reaction mechanism. This study has established stable and reproducible process windows, which are precisely controlled, leading to the successful formation of desired hydroxyapatite films. The data demonstrate that this process is a promising and highly repeatable method for forming hydroxyapatites with desirable thickness, morphology and chemical composition at low temperatures and low capital cost compared to the existing techniques.

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Hadi, Syahiful, Suryajaya Suryajaya, Abdullah Abdullah, and Kissinger Kissinger. "Sintesis Dan Karakterisasi Urea-Hidroksiapatit Dengan Variasi Ca(OH)2 Sebagai Kandidat Pupuk Lepas Lambat." EnviroScienteae 15, no. 1 (April 29, 2019): 112. http://dx.doi.org/10.20527/es.v15i1.6331.

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Urea-hydroxyapatite can be used as fertilizer which was efficient and environmentally friendly. The variation of Ca(OH)2 in the urea-hydroxyapatite’s synthesis and its characterization would provide information for manufacturing slow release fertilizer. The material used were urea (99.5 %); Ca(OH)2; H3PO4 0.67 M and distilled water. The synthesis technique used in this study is bottom-up with Ca(OH)2 variation of 6, 8, 10 and 12 grams. The results of the synthesis with 6 grams of Ca(OH)2 was not able to produce sediment powder. The results of the Scanning Electron Microscopy (SEM) showed that the urea packaging with hydroxyapatite was better for variations of Ca(OH)2 8 grams and 10 grams. The results of the Energy Dispersive X-Ray Spectrometry (EDX) showed more elemental composition in the variation of Ca(OH)2 8 grams and 10 grams which were 35.7 Wt% and 40.4 Wt%. The results of the Fourier Transform Infrared Spectrometer (FTIR) showed that the variation of Ca(OH)2 8 gram has a good bonding of urea and hydroxyapatite. The Particle Size Analyzer (PSA) measurement for all samples of urea-hydroxyapatite yielded the particle size of about 0.5–2.5 mm and 10–15 mm for urea and hydroxyapatite, respectively. As a conclusion, the variation of Ca(OH)2 8 grams could be recommended as a reference in the composition of urea-hydroxyapatite fabrication for slow release fertilizer.

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Meng, Xiang Cai, Xing Yi Li, and Kui Long Lu. "Study of Nano-Hydroxyapatite on the Remineralization of Dismineralized Teeth." Materials Science Forum 475-479 (January 2005): 2423–26. http://dx.doi.org/10.4028/www.scientific.net/msf.475-479.2423.

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The hydroxyapatite (HA) particle with different morphologies were prepared by adding a certain additive into Ca(H2PO4)2·H2O and controlling the bathing and sintering temperature, and the pure needle-like HA sol were obtained when the bathing temperature was 70°C. The experimental results show that the degree of crystallization of HA increase and the particles tend to accumulate with increasing of the drying and sintering temperatures. The particles of HA were spheroid, which diameters were of less than 100nm when they were sintered at the temperature of 700°C. The effect of nano-hydroxyapatite on remineralization of early enamel caries were studied too. The hardness of dismineralized enamel was increased when dismineralized enamel was remineralized by nano-hydroxyapatite. The SEM analysis shows that the interspace of enamel surface were decreased and the many mineral salts were sedimentated, which indicated that the nano-hydroxyapatie could promote remineralization for the dismineralized enamel.

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Nakagiri, Asato, Kazuya Imamura, Kazumichi Yanagisawa, and Ayumu Onda. "The Role of the Surface Acid–Base Nature of Nanocrystalline Hydroxyapatite Catalysts in the 1,6-Hexanediol Conversion." Nanomaterials 11, no. 3 (March 8, 2021): 659. http://dx.doi.org/10.3390/nano11030659.

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Hydroxyapatite is known to have excellent catalytic properties for ethanol conversion and lactic acid conversion, and their properties are influenced by the elemental composition, such as Ca/P ratio and sodium content. However, few reports have been examined for the surface acid–base nature of hydroxyapatites containing sodium ions. We prepared nanocrystalline hydroxyapatite (Ca-HAP) catalysts with various Ca/P ratios and sodium contents by the hydrothermal method. The adsorption and desorption experiments using NH3 and CO2 molecules and the catalytic reactions for 2-propenol conversion revealed that the surface acid–base natures changed continuously with the bulk Ca/P ratios. Furthermore, the new catalytic properties of hydroxyapatite were exhibited for 1,6-hexanediol conversion. The non-stoichiometric Ca-HAP(1.54) catalyst with sodium ions of 2.3 wt% and a Ca/P molar ratio of 1.54 gave a high 5-hexen-1-ol yield of 68%. In contrast, the Ca-HAP(1.72) catalyst, with a Ca/P molar ratio of 1.72, gave a high cyclopentanemethanol yield of 42%. Both yields were the highest ever reported in the relevant literature. It was shown that hydroxyapatite also has excellent catalytic properties for alkanediol conversion because the surface acid–base properties can be continuously controlled by the elemental compositions, such as bulk Ca/P ratios and sodium contents.

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Paucar Álvarez, Carlos, Jeniffer S. Caballero Sarmiento, Sidónio C. Freitas, and Claudia García. "Solvothermal Synthesis of Magnesium Oxide-Substituted Hydroxyapatite Nanoparticles as Antibacterial Nanomaterial for Biomedical Applications." Defect and Diffusion Forum 381 (November 2017): 8–14. http://dx.doi.org/10.4028/www.scientific.net/ddf.381.8.

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In order to generate bactericidal effects in the oral cavity, several alternatives have been studied, including the use of silver nanoparticles but presents problems such as toxicity and low biocompatibility. From human-inspired systems, the antibacterial efficiency of the hydroxyapatite nanoparticles depends strongly on the type of composites and nanoparticles size. Several types of hydroxyapatite nanoparticles and their derivatives have received much attention for their antibacterial potential effect, including magnesium oxide nanoparticles. The purpose of this research was to produce a biocompatible antimicrobial compound of nanoparticles of hydroxyapatite doped with magnesium oxide to generate antibacterial effects in the oral cavity. The solvothermal method was used to produce hydroxyapatite nanoparticles doped with magnesium oxide. Antibacterial activity of as synthesized nanopowders against cariogenicStreptococcus mutanswas tested by the CLSI disk-diffusion method. As result of this research, hydroxyapatite doped with magnesium nanoparticles (nHAMg) were successfully synthetized by the solvothermal method where in structural characterization indicates magnesium substitution and FTIR analysis gives a broader spectrum of the nHAMg when compared to pure nHA and crystallite size of nHA decreased. Furthermore, results of antibacterial assays showed that nHAMg allow to inhibit the grown ofS. mutansby showing a halo of inhibition around the discs. Moreover, this antibacterial activity is enhanced by the addition of silver ion in an amount below to known toxic concentration, showing a synergetic effect that can further potentiate even more these HA nanoparticles. This work demonstrates that solvothermal method is a promising synthesis way for producing antibacterial hydroxyapatites nanoparticles for biomedical applications such as oral tissue regeneration.

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Georgiou, G., J. C. Knowles, and J. E. Barralet. "Dynamic shrinkage behavior of hydroxyapatite and glass-reinforced hydroxyapatites." Journal of Materials Science 39, no. 6 (March 2004): 2205–8. http://dx.doi.org/10.1023/b:jmsc.0000017788.20785.ff.

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Dudek, Agata, and Zygmunt Nitkiewicz. "Structural Analysis of Hydroxyapatite Sinters with Addition of ZrO₂ Phase." Materials Science Forum 638-642 (January 2010): 658–63. http://dx.doi.org/10.4028/www.scientific.net/msf.638-642.658.

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A range of benefits of implants containing hydroxyapatites results, among other things, from their phase composition and degree of porosity. Poor mechanical properties of hydroxyapatite (HA) ceramics considerably limit its wider use. One of the methods for improvement of poor HA properties is addition of solid solution of Y2O3 in ZrO2. [1-8]. The investigations focused on compositions of ceramic powders based on hydroxyapatite with addition of zirconium dioxide (ZrO2 + 8%wt. Y2O3 and ZrO2 + 20%wt. Y2O3). The powders were axially compacted and then sintered at the temperature of 13000C for two hours. After the process of sintering the samples were subjected to analysis of microstructure, phase composition and geometrical measurements in order to determine volume density in each sample.

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&NA;. "Hydroxyapatite." Reactions Weekly &NA;, no. 1345 (April 2011): 19. http://dx.doi.org/10.2165/00128415-201113450-00064.

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Havlik, Robert J. "Hydroxyapatite." Plastic and Reconstructive Surgery 110, no. 4 (September 2002): 1176–79. http://dx.doi.org/10.1097/00006534-200209150-00027.

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Snyderman, Carl H., K. E. N. Scioscia, Ricardo L. Carrau, and Jane L. Weissman. "Hydroxyapatite." Otolaryngologic Clinics of North America 34, no. 1 (February 2001): 179–91. http://dx.doi.org/10.1016/s0030-6665(05)70305-4.

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Havlik, Robert J. "Hydroxyapatite." Plastic and Reconstructive Surgery 110, no. 4 (September 2002): 1176–79. http://dx.doi.org/10.1097/01.prs.0000020998.55126.10.

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Kruger, Emma A., Moises A. Arriaga, Douglas Chen, and Todd Hillman. "S241 – Acoustic Neuroma Surgery: Hydroxyapatite Cement Cranioplasty." Otolaryngology–Head and Neck Surgery 139, no. 2_suppl (August 2008): P156. http://dx.doi.org/10.1016/j.otohns.2008.05.416.

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Objectives To review the outcome of hydroxyapatite cement cranioplasy in acoustic neuroma surgery using trans-labyrinthine and retrosigmoid approaches. Methods Retrospective chart review of the cases of acoustic neuroma resection performed in our institution from January 1, 2007, until November 1, 2007, using 2 separate types of hydroxyapatite cranioplasty in wound closure. Abdominal fat graft in case of translabyrinthine approach and either abdominal fat graft or duragen were covered using Hydrset (Stryker) or Bonesouce (Stryker) hydroxyapatitie cement bone substitute. Translabyrinthine and Retrosigmoid resections were included in the review. The rate of postoperative cerebrospinal fluid leak, lumbar drain use, and early wound complications were recorded. Results There were 33 cases of acoustic neuroma resection over a period of 10 months using hydroxyapatite cranioplasty. Hydroset bone substitue was used in 16 cases and no CSF leak was observed. Bonesource bone substitute was used in 17 cases and 1 case of CSF leak was observed. The leak was managed with lumbar drain placement and resolved without any additional interventions. In the Hydroset group no drains were used, and in the Bonsource group drains were placed at the completeion of a procedure and removed 12 hours postoperatively. There were no wound complications seen at the completeion of the review. No other adverse outcomes were noted. Conclusions Both forms of hydroxyapatite cranioplasty are reliable methods to avoid CSF leak in acoustic neuroma surgery. The handling characteristics and no need for drain with Hydroset may make it preferable as a bone reconstruction technique in acoustic neuroma surgery.

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Nowak, Nicole, and Rafal Jakub Wiglusz. "A Study of Vanadate Group Substitution into Nanosized Hydroxyapatite Doped with Eu3+ Ions as a Potential Tissue Replacement Material." Nanomaterials 12, no. 1 (December 28, 2021): 77. http://dx.doi.org/10.3390/nano12010077.

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In this study, nanosized vanadate-substituted hydroxyapatites doped with 1 mol% and 2 mol% Eu3+ ions were obtained via the precipitation method. To evaluate the structure and morphology of the obtained compounds, the XRPD (X-ray powder diffraction) technique, Rietveld refinement, SEM-EDS (scanning electron microscopy-energy-dispersive spectrometry) and TEM (transmission electron microscopy) techniques as well as FTIR (Fourier transform infrared) spectroscopy were performed. Moreover, the chemical formula was confirmed using the ICP-OES (Inductively coupled plasma optical emission spectroscopy spectroscopy). The calculated average grain size for powders was in the range of 25 to 90 nm. The luminescence properties of vanadium-substituted hydroxyapatite were evaluated by recording emission spectra and excitation spectra as well as luminescence kinetics. The crucial step of this research was the evaluation of the biocompatibility of the synthesized nanomaterials. Therefore, the obtained compounds were tested toward sheep red blood cells and normal human dermal fibroblast to confirm the nontoxicity and biocompatibility of new nanosized Eu3+ ion-doped vanadate-hydroxyapatite. Moreover, the final step of the research allowed us to determine the time dependent ion release to the simulated body fluid environment. The study confirmed cytocompatibility of vanadium hydroxyapatite doped with Eu3+ ions.

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Baskaran, Thivya, Nur Farahiyah Mohammad, Siti Shuhadah Md Saleh, Nashrul Fazli Mohd Nasir, and Farah Diana Mohd Daud. "Synthesis Methods of Doped Hydroxyapatite: A Brief Review." Journal of Physics: Conference Series 2071, no. 1 (October 1, 2021): 012008. http://dx.doi.org/10.1088/1742-6596/2071/1/012008.

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Abstract Hydroxyapatite (HA) has drawn great attention to biomedical applications due to their bone mineral similarity, strong bioactivity, biocompatibility and osteoconductive. Despite the fact that HA has many advantages, several properties are still lacking, emphasising the crucial need for ion doping/substitution. Many attempts have been made to incorporate ions into HA structure to increase their physical, chemical, and biological properties. With such a diverse range of methods available for the synthesis of doped HA, this article discussed the importance of doping for HA and summarizes four common techniques used to prepare doped hydroxyapatites which include precipitation, hydrothermal, sol-gel and mechanochemical method.

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Wei, Mei, D. Vellinga, D. Leavesley, J. H. Evans-Freeman, and Z. Upton. "Cell Attachment and Proliferation on Hydroxyapatite and Ion Substituted Hydroxyapatites." Key Engineering Materials 240-242 (May 2003): 671–74. http://dx.doi.org/10.4028/www.scientific.net/kem.240-242.671.

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Shahabi, Sima, Farhood Najafi, Abbas Majdabadi, Tabassom Hooshmand, Masoumeh Haghbin Nazarpak, Batool Karimi, and Seyyed Mostafa Fatemi. "Effect of Gamma Irradiation on Structural and Biological Properties of a PLGA-PEG-Hydroxyapatite Composite." Scientific World Journal 2014 (2014): 1–9. http://dx.doi.org/10.1155/2014/420616.

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Gamma irradiation is able to affect various structural and biological properties of biomaterials In this study, a composite of Hap/PLGA-PEG and their ingredients were submitted to gamma irradiation doses of 25 and 50 KGy. Various properties such as molecular weight (GPC), thermal behavior (DSC), wettability (contact angle), cell viability (MTT assay), and alkaline phosphatase activity were studied for the composites and each of their ingredients. The results showed a decrease in molecular weight of copolymer with no change in the glass transition and melting temperatures after gamma irradiation. In general gamma irradiation can increase the activation energy ΔHof the composites and their ingredients. While gamma irradiation had no effect on the wettability of copolymer samples, there was a significant decrease in contact angle of hydroxyapatite and composites with increase in gamma irradiation dose. This study showed an increase in biocompatibility of hydroxyapatite with gamma irradiation with no significant effect on cell viability in copolymer and composite samples. In spite of the fact that no change occurred in alkaline phosphatase activity of composite samples, results indicated a decrease in alkaline phosphatase activity in irradiated hydroxyapatites. These effects on the properties of PLGA-PEG-hydroxyapatite can enhance the composite application as a biomaterial.

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Renda, Carmen Greice, Thamara Machado de Oliveira Ruellas, João Otávio Donizette Malafatti, Carla Suellem Sousa Araújo, Gabriela Leite da Silva, Bruno Apolo Miranda Figueira, Simone Quaranta, and Elaine Cristina Paris. "A “Zero-Cost” Adsorbing Hydroxyapatite-Based Material from Amazon Fishery Waste for Water Remediation and Nutrient Release for Agriculture." Physchem 3, no. 1 (January 1, 2023): 34–60. http://dx.doi.org/10.3390/physchem3010004.

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This paper puts forward the use of “low-cost/low-end” hydroxyapatite-based adsorbing materials prepared from Tambaqui fish cleaning residues (i.e., bones) by grinding and/or thermal annealing. The nature of raw materials and treatments practically resulted in a “zero-cost” adsorbent for atrazine pesticide and Co2+ ion remediation in an aqueous solution. Despite the distinctive character of the two contaminants, all adsorptions were found to follow pseudo-second order kinetics and Freundlich isotherm models. Pristine hydroxyapatite proved to be more effective in adsorbing atrazine at low concentrations due to interactions with collagen residues. Conversely, heat-treated materials demonstrated better adsorption performances for cobalt due to the removal of organic residues hindering access to the surface. On the other hand, lower adsorption affinities resulted into a faster and more efficient Co2+ release into water. The different behavior in terms of phosphate and cobalt release shown by the three hydroxyapatite-based absorbents can be exploited for differential liberation of targeted nutrients, with high seed germination rates. Considering circular economic principles, waste-derived hydroxyapatites may be potentially attractive for removing ionic species, minimizing water pollution stemming from heavy industry, and for their subsequent targeted release to edible plants, enhancing agricultural availability of mineral nutrients for soil fertilization.

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Asada, Masayuki, Yoshinari Miura, Akiyoshi Osaka, Katsutoshi Oukami, and Seishiro Nakamura. "Hydroxyapatite crystal growth on calcium hydroxyapatite ceramics." Journal of Materials Science 23, no. 9 (September 1988): 3202–5. http://dx.doi.org/10.1007/bf00551295.

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Pavankumar, K., K. Venkateswarlu, N. Rameshbabu, and V. Muthupandi. "X-Ray Peak Broadening and In Vitro Dissolution Studies of Thermally Stabilized Nanocrystalline Carbonated Hydroxyapatite." Key Engineering Materials 493-494 (October 2011): 739–45. http://dx.doi.org/10.4028/www.scientific.net/kem.493-494.739.

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The present work aims to examine the effect of silicon substitution on thermal and in-vitro dissolution properties of carbonated hydroxyapatite. Hydroxyapatite [Ca10(PO4)6(OH)2, HA], carbonate substituted hydroxyapatite [Ca10(PO4)6-x(CO3)x(OH)2, x=1, 1CHA] and carbonate, silicate co-substituted hydroxyapatite [Ca10(PO4)6-x-y(CO3)x(SiO4)y(OH)2, x=1,y=1, 1C1SiHA] nanoparticles were prepared by microwave synthesis method under identical processing conditions. The XRD results of HA, 1CHA and 1C1SiHA correspond to the standard hexagonal HA (JCPDS 9-432). The crystallite size and lattice strain of the synthesized powder particles were estimated by Williamson-Hall isotropic strain model (W-H ISM) from powder X-ray diffraction data. The dislocation density was calculated by Williamson-Smallman formula. The functional groups present in the as-synthesized powder particles were analyzed by Fourier transform infrared (FT-IR) spectroscopy method. The size and the morphology were examined using a transmission electron microscope (TEM). The in-vitro dissolution behaviour of the synthesized powder particles was studied by ethylenediamine tetra-acetic acid (EDTA) titrimetric method. The W-H ISM results confirm that the prepared powder particles of HA, 1CHA and 1C1SiHA are nanocrystalline with an average crystallite size of 40 nm, 36 nm and 32 nm, respectively. Thus the crystallite size of hydroxyapatite was observed to be decreased gradually with increase in substitutions as indicated by the least size for the 1C1SiHA. In addition, the XRD results of powders annealed at 900 °C for 2 h show the improved thermal stability of 1C1SiHA compared to 1CHA. The TEM results show rod-like shaped morphology for HA, near rod-like with modified edge morphology and increased agglomeration for 1CHA and needle-like shaped morphology for 1C1SiHA powder particles. The in-vitro dissolution study results show a gradual increase in the solubility of HA with carbonate and carbonate-silicate co-substitutions. The calculated microstructural parameters, namely, crystallite size, root mean squared strain and dislocation density were correlated with in-vitro dissolution behaviour of hydroxyapatites.

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UEHARA, Kazumi. "Application of hydroxyapatite implant and bone-hydroxyapatite implant into hydroxyapatite block reconstructed mandibula." Japanese Journal of Oral & Maxillofacial Surgery 37, no. 2 (1991): 499–517. http://dx.doi.org/10.5794/jjoms.37.499.

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Hariani, Poedji Loekitowati, Fahma Riyanti, Fatma Fatma, Addy Rachmat, and Aldi Herbanu. "Removal of Pb(II) using Hydroxyapatite from Golden Snail Shell (Pomacea canaliculata L.) Modified with Silica." Molekul 15, no. 2 (July 27, 2020): 130. http://dx.doi.org/10.20884/1.jm.2020.15.2.641.

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The composites of hydroxyapatite and SiO2 were successfully synthesized. The hydroxyapatite was prepared from golden snail shells (Pomacea canaliculata L). The hydroxyapatite and hydroxyapatite-SiO2 composites were characterized using XRD, FTIR, SEM-EDS. Furthermore, hydroxyapatite and hydroxyapatite-SiO2 composites were used to remove Pb(II) from aqueous solution. Various adsorption parameters such as pH of the solution, contact time, and initial Pb(II) concentration were used to study the adsorption process. The optimum pH of the solution for removal of Pb(II) by hydroxyapatite and hydroxyapatite-SiO2 composite at pH 6 and contact time at 60 minutes. Both adsorbents follow the Langmuir isotherm. The maximum adsorption capacity of the hydroxyapatite-SiO2 composite is greater compare to hydroxyapatite, respectively 135.14 and 123.46 mg/g. The pseudo-second order kinetic model had a correlation coefficient (R2) greater than the pseudo-first order so pseudo-second order kinetic is better to describe adsorption kinetics

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Katayama, Max, Kengo Tamazawa, Ayu Kodaira, and Toru Nonami. "Evaluation of Protein Adsorption Capacity of TiO₂-Supported Spherical Porous Hydroxyapatite." Key Engineering Materials 758 (November 2017): 90–96. http://dx.doi.org/10.4028/www.scientific.net/kem.758.90.

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In this study, a novel titania-supported spherical porous hydroxyapatite (sHAp + TiO2) was prepared by compounding minute, uniquely shaped spherical porous hydroxyapatites (sHAp) with TiO2. Adsorption of the representative protein bovine serum albumin (BSA) was evaluated and simulated body fluid immersion experiments were carried out. Minimal adsorption of BSA to TiO2 was observed, and 33% and 25% adsorption to sHAp + TiO2 and sHAp were observed, respectively. The reduction in BSA concentration observed in the sHAp and sHAp + TiO2 solutions is presumably due to adsorption to HAp. It is highly likely that adsorption of the acidic protein BSA occurred at the sHAp Ca2+ site. In the simulated body fluid immersion experiments, there was greater expression of hydroxyapatite (HAp) on the surface of sHAp than there was on the surface of sHAp + TiO2. In the case of TiO2 alone, no HAp was produced, even after immersion for 3 days. These results suggest a relationship between BSA adsorption and the osteoconductivity of materials.

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Singh, Balraj, Gurpreet Singh, and Buta Singh Sidhu. "Analysis of corrosion behaviour and surface properties of plasma-sprayed composite coating of hydroxyapatite–tantalum on biodegradable Mg alloy ZK60." Journal of Composite Materials 53, no. 19 (March 27, 2019): 2661–73. http://dx.doi.org/10.1177/0021998319839127.

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Magnesium (Mg) and its alloys are promising candidates for biodegradable bio-implants. However, the excessive corrosion in the physiological environment and subsequent decline in the mechanical integrity of Mg and its alloys have limited their utility as biomaterials. In the present study, an attempt has been made to improve the corrosion resistance of Mg alloy ZK60 plasma sprayed with tantalum (Ta)-reinforced hydroxyapatite coating. The experiment was conducted with three varied levels, i.e. 10, 20 and 30 weight percent (wt%) of Ta-content in hydroxyapatite coating. The coatings were characterized and in vitro corrosion behaviour was investigated by electrochemical measurements in Ringer's solution along with the analysis of surface properties. The corrosion resistance of the Mg alloy increased with the incremental increase in Ta reinforcement in hydroxyapatite coating. An increase in the protection efficiency was analysed for the Ta-reinforced hydroxyapatite coatings (∼10%, 18% and 23% for hydroxyapatite-10Ta, hydroxyapatite-20Ta and hydroxyapatite-30Ta, respectively) as compared to the pure hydroxyapatite coating. The hydroxyapatite coating effectively increased the surface hardness of the Mg alloy and Ta reinforcement further enhanced it. Surface roughness decreased with the incremental increase in Ta-content in hydroxyapatite coating. Wettability analysis revealed the hydrophilic nature of pure hydroxyapatite and Ta-reinforced hydroxyapatite coatings. The results of the study suggest that the proposed Ta reinforcement in hydroxyapatite is potentially important for biodegradable Mg bio-implants.

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Fedorishin, Dmitriy, Anastasiya Gutsalova, Daria Lytkina, and Irina Kurzina. "Research of the Influence of Zinc Ions on Synthesis and Properties of Hydroxyapatite." Proceedings 67, no. 1 (November 9, 2020): 25. http://dx.doi.org/10.3390/asec2020-07555.

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Hydroxyapatites modified with metal ions are the main inorganic components of bone tissue that are approved for use as components for biocomposites and coatings for surgical implants. This study examined prototypes of functional materials for bone implants based on hydroxyapatite modified with zinc ions. Antibacterial activity and biocompatibility have been established. The studied materials have antimicrobial activity, the samples did not cause significant changes both in the internal organs and in the general condition of laboratory animals during the entire experiment.

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Bunz, Oskar, Marie-Christine Steegmann, Korbinian Benz, Holger Testrich, Antje Quade, Ella A. Naumova, Wolfgang H. Arnold, Katja Fricke, Andree Piwowarczyk, and Thomas Dittmar. "Human Gingival Fibroblast Adhesion and Proliferation on Hydroxyapatite-Coated Zirconia Abutment Surfaces." Materials 15, no. 10 (May 19, 2022): 3625. http://dx.doi.org/10.3390/ma15103625.

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Abstract:

Applying antibacterial coatings to dental implant materials seems reasonable but can have negative influences on desired cell adhesion and healing. In this study, zirconia abutment specimens interacting with gingival tissue were used. The aim was to compare the influence of machined or coated zirconia surfaces on the adhesion and proliferation of human gingival fibroblasts (HGF-1). Surface modifications were performed using atmospheric plasma coating with hydroxyapatite, zinc, and copper. Zirconia specimens were divided into four groups: hydroxyapatite, hydroxyapatite with zinc oxide (ZnO), hydroxyapatite with copper (Cu), and an untreated machined surface. After the characterization of the surface conditions, the morphology of adhered HGF-1 was determined by fluorescence staining and subjected to statistical evaluation. The visual analysis of cell morphology by SEM showed flat, polygonal, and largely adherent fibroblast cells in the untreated group, while round to partially flat cells were recorded in the groups with hydroxyapatite, hydroxyapatite + ZnO, and hydroxyapatite + Cu. The cell membranes in the hydroxyapatite + ZnO and hydroxyapatite + Cu groups appeared porous. The results show that HGF-1 adhere and proliferate well on machined zirconia, while plasma coating with hydroxyapatite or hydroxyapatite mixtures does not lead to increased adhesion or proliferation.

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Journal articles on the topic 'Hydroxyapatite'

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