• Journal of Powder Materials
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• v.8 no.3
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• pp.192-196
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• 2001

Ag doped Hydroxyapatite powder in nano-scale was successfully synthesized either by co-precipitation or by ion exchange route. The fabricated powder was successfully dispersed through freeze drying due to the prevention of secondary particles. The antimicrobial effects of nano-HAp against E.coli was superior to micron ones not only in its strength but also in duration.

• Korean Journal of Materials Research
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• v.17 no.10
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• pp.544-547
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• 2007

Human teeth were scratched by the abrasive paper, dropping in hydroxyapatite solution during 1, 2, 3, 4 months. We studied teeth surface change with SEM each months. After 1 months treatment the surface appeared the change. Because of the hydroxyapatite ion exchange mechanism. The scratched surface was recovered by the hydroxyapatite. The results of EDS showed that $Ca^{2+}$ ion and $PO_4^{3-}$ ion were removed from hydroxyapatite solution to scratched teeth surface.

• Advances in materials Research
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• v.4 no.4
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• pp.193-205
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• 2015

Contamination by bacterial strands is a major problem after bone replacement surgeries, so there is a great need to develop low cost biocompatible antibacterial bioactive scaffolds to be used in bone tissue engineering. For this purpose, nano-zinc doped hydroxyapatite with different zinc-concentrations (5, 10 and 15 mol%) was successfully prepared by the wet chemical precipitation method. The prepared powders were used to form porous scaffolds containing biodegradable Ca-cross-linked alginate (5%) in order to enhance the properties of alginate scaffolds. The scaffolds were prepared using the freeze-gelation method. The prepared powders were tested by X-ray diffraction; transmission electron microscope and Fourier transform infrared analyses, while the prepared scaffolds were investigated by Fourier transform infrared analyses, thermogravimetric analyses and measurement of the antibacterial properties. Best results were obtained from scaffold containing 15% mol zinc-doped hydroxyapatite powders and 5% alginate concentration with ratio of 70:30.

• Polymer(Korea)
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• v.38 no.2
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• pp.156-163
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• 2014

Hydroxyapatite has osteoconductivity, biocompatibility and noninflammatory, and it has been used clinically as artificial bone. In this study, we prepared hydroxyapatite/poly(lactic-co-glycolic acid) (PLGA) scaffolds using 0, 10, 20, 40 and 60 wt% of hydroxyapatite. We analyzed compressive strength, SEM analysis and FTIR for mechanical property of 3D hydroxyapatite/PLGA scaffolds. For biocompatibility tests, cell proliferation and viability were measured via MTT assay and SEM. We analyzed RT-PCR, FACS, histology (H&E, ED-1) for anti-inflammatory effect. This study showed that hydroxyapatite hybrid scaffolds have low inflammatory reaction compared with the PLGA. This result has a potential for the application of artificial bone graft material.

• Maxillofacial Plastic and Reconstructive Surgery
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• v.33 no.6
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• pp.459-466
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• 2011

Purpose: This study evaluated the capability of bone formation with silk fibroin/nano-hydroxyapatite/corn starch composite scaffold as a bone defect replacement matrix when grafted in a calvarial bone defect of rabbits $in$ $vivo$. Methods: Ten New Zealand white rabbits were used for this study and bilateral round-shaped defects were formed in the parietal bone (diameter: 8.0 mm). The silk fibroin 10% nano-hydroxyapatite/30% corn starch/60% composite scaffold was grafted into the right parietal bone (experimental group). The left side (control group) was grafted with a nano-hydroxyapatite (30%)/corn starch (70%) scaffold. The animals were sacrificed at 4 weeks and 8 weeks. A micro-computerized tomography (${\mu}CT$) of each specimen was taken. Subsequently, the specimens were decalcified and stained with Masson's trichrome for histological and histomorphometric analysis. Results: The average ${\mu}CT$ and histomorphometric measures of bone formation were higher in the control group than in the experimental group at 4 weeks and 8 weeks after surgery though not statistically significant ($P$ >0.05). Conclusion: The rabbit calvarial defect was not successfully repaired by silk fibroin/nano-hydroxyapatite/corn starch composite scaffold and may have been due to an inflammatory reaction caused by silk powder. In the future, the development of composite bone graft material based on various components should be performed with caution.

• Journal of Powder Materials
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• v.20 no.5
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• pp.376-381
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• 2013

Spherical Ti-6Al-4V powders in the size range of 250 and 300 ${\mu}m$ were uniformly doped with nano-sized hydroxyapatite (HAp) powders by Spex milling process. A single pulse of 0.75-2.0 kJ/0.7 g of the Ti-6Al-4V powders doped with HAp from 300 mF capacitor was applied to produce fully porous and porous-surfaced Ti-6Al-4V implant compact by electro-discharge-sintering (EDS). The solid core was automatically formed in the center of the compact after discharge and porous layer consisted of particles connected in three dimensions by necks. The solid core increased with an increase in input energy. The compressive yield strength was in a range of 41 to 215 MPa and significantly depended on input energy. X-ray photoelectron spectroscopy and energy dispersive x-ray spectrometer were used to investigate the surface characteristics of the Ti-6Al-4V compact. Ti and O were the main constituents, with smaller amount of Ca and P. It was thus concluded that the porous-surfaced Ti-6Al-4V implant compacts doped with HAp can be efficiently produced by manipulating the milling and electro-discharge-sintering processes.

• Journal of the Korean Society for Heat Treatment
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• v.28 no.1
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• pp.17-23
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• 2015

Hydroxyapatite coatings were fabricated by a room temperature spray method on zirconia substrates and the influence of heat-treatment on their microstructure was also investigated. Phase composition of coated hydroxyapatite films was similar to the starting powder, but the grain size of hydroxyapatite particles was reduced to the size of nano-scale about 100 nm. Grain size, particle compactness, and adhesiveness to zirconia of hydroxyapatite coatings were increased with heat-treatment temperature, but some of cracks by heat-treatment above $1100^{\circ}C$ were initiated between hydroxyapatite coatings and zirconia substrate. Heat-treated hydroxyapatite layers show the dissolution in SBF solution for 5 days. Hydroxyapatite-coated specimen heat-treated at $1100^{\circ}C$ for 1 h has a good biocompatibility, which specimen induced the nanocrystalline hydroxyapatite precipitates on the coating surface by the immersion in SBF solution for 5 days.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2005.06a
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• pp.757-760
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• 2005

The technology of rapid prototyping (RP) is used for design verification, function test and fabrication of prototype. The current issues in RP are improvement in accuracy and application of various materials. In this paper, a hybrid rapid prototyping system is introduced which can fabricate nano composites using various materials. This hybrid system adopts RP and machining process, so material deposition and removal is performed at the same time in a single station. As examples, micro gears and a composite scaffold were fabricated using photo cured polymer with nano powders such as carbon black and hydroxyapatite. From the micro gear samples the hybrid RP technology showed higher precision than those made by casting or deposition process.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2014.11a
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• pp.185-185
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• 2014

In this study, we investigated surface characteristics of hydroxyapatite coated surface on nano/micro pore structured Ti-35Ta-xNb alloys. This paper was focus on morphology and corrosion resistance of Anodic oxidation. To prepare the samples, Ti-35Ta-xNb (x= 0, 10 wt. %) alloys were manufactured by arc melting and heat-treated for 12 h at $1050^{\circ}C$ in Ar atmosphere at $0^{\circ}C$ water quenching. Micro-pore structured surface was performed using anodization with a DC power supply at 280 V for 3 min, nanotube formed on Ti-35Ta-xNb alloys was performed using DC power supply at 30 V in 60 min at room temperature. Surface morphology and structure were examined by field-emission scanning electron microscopy, energy-dispersive X-ray spectroscopy and X-ray diffraction.

• Journal of the Korean Ceramic Society
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• v.55 no.2
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• pp.145-152
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• 2018

Although many bone graft materials have been developed, powder graft materials are somewhat difficult to use in surgery. To solve this problem, a bone graft material in the form of a viscous paste was prepared. Hydroxyapatite was used as a bone graft material, and methyl cellulose was used to impart viscosity. Three cases of samples were prepared, and freeze-dried block type and sintered specimens were made from the paste. The recrystallization of the graft material in a simulated body fluid and the degree of graft adhesion with a tooth were observed by scanning electron microscopy (SEM). The test for cytotoxicity was carried out and the sample was grafted into the back of a mouse to confirm the presence or absence of side effects in the animal's body. Based on these investigations, composites of this type are expected to be applicable for bone grafts.