Won-Hoon Song

Bio: Won-Hoon Song is an academic researcher from Seoul National University. The author has contributed to research in topics: Apatite & Simulated body fluid. The author has an hindex of 5, co-authored 5 publications receiving 637 citations.

Antibacterial properties of Ag (or Pt)-containing calcium phosphate coatings formed by micro-arc oxidation.

Abstract: Silver (or platinum)-containing calcium phosphate (hydroxyapatite (HA) and tricalcium phosphate (alpha-TCP)) coatings on titanium substrates were formed by micro-arc oxidation (MAO) and their in vitro antibacterial activity and in vitro cytotoxicity were evaluated. MAO was performed in an electrolytic solution containing beta-glycerophosphate disodium salt pentahydrate (beta-GP) and calcium acetate monohydrate (CA), and Ag and Pt were introduced in the form of AgNO(3) (or CH(3)COOAg) and H(2)PtCl(6), respectively. The MG63 and human osteosarcoma (HOS) cell lines were used to investigate the proliferation and differentiation behavior of the cells, respectively, whereas two strains of bacteria, Staphylococcus aureus and Escherichia coli, were used to evaluate the antibacterial activity of the coatings. The phase, morphology, and Ag content of the coatings were strongly dependent on the applied voltage and Ag precursor concentration. HA and alpha-TCP phases were detected in the coatings oxidized above 400 V and the presence of Ag was confirmed by EDS. While the coatings with a high content of Ag were cytotoxic and those obtained in the Pt-containing electrolyte had no apparent antibacterial activity, the calcium phosphate coatings obtained in the low Ag concentration electrolyte exhibited in vitro antibacterial activity but no cytotoxicity. Thus, biocompatible calcium phosphate coatings on Ti implants with antibacterial activity can be achieved by one-step MAO.

Apatite Induction on Ca-Containing Titania Formed by Micro-Arc Oxidation

Abstract: Ca-containing, particularly CaTiO3, titania films were prepared by micro-arc oxidation (MAO) of Ti in an electrolytic solution containing calcium acetate monohydrate (CA), and their apatite-inducing ability was evaluated in a simulated body fluid (SBF). The phase, Ca content, and morphology of the films were found to be strongly dependent on the applied voltage. The CaTiO3-embedded titania was obtained at higher voltages (>300 V). When immersed in SBF, no apatite was induced in all the MAO specimens irrespective of the presence of CaTiO3, which has been claimed to be an apatite inducer. However, after a hydrothermal treatment at 250°C, apatite was formed on the surfaces of the CaTiO3-embedded titania after 28 days, which was closely related to the formation of amorphous Ca(OH)2 and presumably surface Ti–OH groups.

Biomimetic apatite induction of P-containing titania formed by micro-arc oxidation before and after hydrothermal treatment

Abstract: Phosphorous (P)-containing titania films were prepared by micro-arc oxidation (MAO) of titanium (Ti) in an electrolyte containing β-glycerol phosphate disodium salt pentahydrate (β-GP, C 3 H 7 Na 2 O 6 P . 5H 2 O), and their apatite inducing ability in a simulated body fluid (SBF) was investigated. Macro-porous titania films were formed, consisting of only anatase phase, and the P content in the films increased up to 8 at.% with an increasing applied voltage. During hydrothermal treatment, the P in the films was diffused out to the surface and hydrolyzed to form the hydrogen phosphate (HPO 4 2− ) group. When immersed in SBF, no apatite was induced in any of the P-containing MAO specimens for up to 28 days. However, after a hydrothermal treatment at 250 °C, apatite was induced on the titania surfaces as early as 9 h immersion, and the entire exposed surface was covered with the apatite globules after 36 h immersion, which was much faster than the apatite induction on Ca-containing titania. The higher apatite-inducing ability of P-containing titania after hydrothermal treatment was believed to be due to the crystal structure (anatase) and presence of HPO 4 2− group on the surface.

TiO2 nanotubes: Self-organized electrochemical formation, properties and applications

Abstract: The present paper gives an overview and review on self-organized TiO2 nanotube layers and other transition metal oxide tubular structures grown by controlled anodic oxidation of a metal substrate We describe mechanistic aspects of the tube growth and discuss the electrochemical conditions that need to be fulfilled in order to synthesize these layers Key properties of these highly ordered, high aspect ratio tubular layers are discussed In the past few years, a wide range of functional applications of the layers have been explored ranging from photocatalysis, solar energy conversion, electrochromic effects over using the material as a template or catalyst support to applications in the biomedical field A comprehensive view on state of the art is provided

Calcium phosphate coatings for bio-implant applications: Materials, performance factors, and methodologies

Abstract: With an ageing population, war, and sports related injuries there is an ever-expanding requirement for hard tissue replacement such as bone. Engineered artificial scaffold biomaterials with appropriate mechanical properties, surface chemistry and surface topography are in a great demand for enhancing cell attachment, cell growth and tissue formation at such defect sites. Most of these engineering techniques are aimed at mimicking the natural organization of the bone tissues and thereby create a conducive environment for bone regeneration. As the interaction between the cells and tissues with biomaterials at the tissue–implant interface is a surface phenomenon, surface properties play a major role in determining both the biological response to implants and the material response to the physiological condition. Hence surface engineering of biomaterials is aimed at modifying the material and biological responses through changes in surface properties while still maintaining the bulk mechanical properties of the implant. Therefore, there has been a great thrust towards development of Ca–P-based surface coatings on various metallic and nonmetallic substrates for load bearing implant applications such as hip joint prosthesis, knee joint prosthesis and dental implants. Typical coating methodologies like ion beam assisted deposition, plasma spray deposition, pulsed laser physical vapor deposition, magnetron sputtering, sol–gel derived coatings, electrodeposition, micro-arc oxidation and laser deposition are extensively studied at laboratory scale. In the present article, attempts are made to give an overview of the basic principles behind the coating techniques as well as advantageous features such as bioactivity and biocompatibility associated with these coatings. A strong emphasis will be given on laser-induced textured and bioactive coatings obtained by the author's research group [A. Kurella, N.B. Dahotre, Journal of Biomedical Applications 20 (2005) 5–50; A. Kurella, N.B. Dahotre, Acta Biomaterialia 2 (2006) 677–688; A. Kurella, N.B. Dahotre, Journal of Minerals, Metals and Materials Society (JOM) 58 (2006) 64–66; A. Kurella, N.B. Dahotre, Journal of Materials Science: Materials in Medicine 17 (2006) 565–572; P.G. Engleman, A. Kurella, A. Samant, C.A. Blue, N.B. Dahotre, Journal of Minerals, Metals and Materials Society (JOM) 57 (2005) 46–50; R. Singh, A. Kurella, N.B. Dahotre, Journal of Biomaterials Applications 21 (2006) 46–72; S.R. Paital, N.B. Dahotre, Biomedical Materials 2 (2007) 274–281; S.R. Paital, N.B. Dahotre, 2009, Acta Biomaterialia, doi:10.1016/j.actbio.2009.03.004 ; R. Singh, N.B. Dahotre, Journal of Materials Science: Materials in Medicine 18 (2007) 725–751.]. Since cells are sensitive to topographical features ranging from mesoscale to nanoscale, formation of these features by both pulsed and continuous wave Nd:YAG laser system will be highlighted. This can also be regarded as advancement towards third generation biomaterials which are bioinert, bioactive and which once implanted will stimulate cell adhesion, proliferation and growth at the interface. Further, an overview of various bio-implants and bio-devices and materials used for these kinds of devices, performance factors such as mechanical and corrosion behavior and surface science associated with these materials are also explained. As the present article is aimed at describing the multidisciplinary nature of this exciting field it also provides a common platform to understand this subject in a simple way for students, researchers, teachers and engineers in the fields ranging from medicine, dentistry, biology, materials science, biomedicine, biomechanics to physics.

Bacterial adherence and biofilm formation on medical implants: A review

Abstract: Biofilms are a complex group of microbial cells that adhere to the exopolysaccharide matrix present on the surface of medical devices. Biofilm-associated infections in the medical devices pose a serious problem to the public health and adversely affect the function of the device. Medical implants used in oral and orthopedic surgery are fabricated using alloys such as stainless steel and titanium. The biological behavior, such as osseointegration and its antibacterial activity, essentially depends on both the chemical composition and the morphology of the surface of the device. Surface treatment of medical implants by various physical and chemical techniques are attempted in order to improve their surface properties so as to facilitate bio-integration and prevent bacterial adhesion. The potential source of infection of the surrounding tissue and antimicrobial strategies are from bacteria adherent to or in a biofilm on the implant which should prevent both biofilm formation and tissue colonization. This article provides an overview of bacterial biofilm formation and methods adopted for the inhibition of bacterial adhesion on medical implants.