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Deposition of gold nanoparticles on electrospun MgTiO3 ceramic nanofibers.
Aryal, Santosh,Dharmaraj, N,Bhattarai, Shanta Raj,Khil, Myung Seob,Kim, Hak Yong American Scientific Publishers 2006 Journal of Nanoscience and Nanotechnology Vol.6 No.2
<P>A simple method to deposit spherical gold nanoparticles on the surface of MgTiO3 ceramic nanofibers is presented. Electrospun MgTiO3/poly(vinyl acetate) (PVAc) hybrid nanofibers were calcined at 650 degrees C to obtain phase pure ceramic MgTiO3 nanofibers with 100-150 nm diameters. These ceramic nanofibers were immersed in an aqueous solution of HAuCl4 containing poly(vinyl alcohol) (PVA) as capping agent followed by photoreduction at 365 nm to get a novel Au-MgTiO3 nanocomposite. The formation of gold nanoparticles upon irradiation was confirmed by the appearance of a surface plasmon band (SPB) at 590 nm in the UV-visible absorption spectra. The surface morphology and elemental compositions were analyzed by the scanning electron microscope (SEM) equipped with energy dispersive X-ray (EDX), and transmission electron microscope (TEM). X-ray diffraction (XRD) and selected area diffraction (SAED) pattern in TEM revealed the crystallization of gold by exhibiting strong diffractions correspond to Au(111) and Au(200) crystalline planes in addition to the MgTiO3 diffraction.</P>
Carbon nanotubes assisted biomimetic synthesis of hydroxyapatite from simulated body fluid
Aryal, Santosh,Bhattarai, Shanta Raj,K.C., Remant Bahadur,Khil, Myung Seob,Lee, Duck-Rae,Kim, Hak Yong Elsevier 2006 Materials science & engineering. properties, micro Vol.426 No.1
<P><B>Abstract</B></P><P>Synthesis of hydroxyapatite (HA) using carboxylated carbon nanotubes were investigated using simulated body fluid (SBF) similar to physiological condition and products tailored to have chemistry found to mimic natural bone. Composites were synthesized under ambient condition and physiological temperature (37°C). Former results the formation of dense net over carbon nanotubes even after 21 days of reaction, a hierarchy assemblies, whereas later results the formation of large crystals after 7 days of reaction. Physico-chemical characterization of composite material showed that the nucleation of HA initiates through the carboxyl group. Different parameters like temperature and reaction time were found to control the crystallization of HA. After 7 days of reaction, the crystal becames denser and directs towards the single plane; (002), thereby showing its phase purity. The result showed that the carboxylated carbon nanotubes were capable to nucleate HA from SBF, which can be used as a biomaterial for the modification of implant materials.</P>
Aryal, Santosh,Bahadur K. C, Remant,Bhattarai, Shanta Raj,Prabu, P.,Kim, Hak Yong Royal Society of Chemistry 2006 Journal of materials chemistry Vol.16 No.48
<P>The growth of hydroxyapatite (HA) on self-assembled collagen gold nanoparticles is presented for the first time by employing wet chemistry at ambient conditions, and we obtained near-quantitative yields of composite. Transmission electron microscopy reveals that the gold nanoparticles are well dispersed with an average diameter of 4 nm, which was further supported by the strong surface plasmon band (SPB) at 527 nm in the UV-vis spectra. The band broadening, shifting and flattening after the addition of HA precursors suggests the formation of HA aggregates. FT-IR spectroscopy confirms that the characteristic functionalities of collagen are intact even after the conjugation with gold nanoparticles, which renders the formation of randomly aggregated quarter-moon-like HA. Microscopic and crystallographic study at this stage further confirms its crystallographic structure that the HA particles aligned with their crystallographic <I>c</I>-axes preferentially parallel to the orientation of collagen on the gold nanoparticles with an elemental composition resembling that of natural HA. The result showed that gold nanoparticles with collagen form an efficient matrix for the growth of HA and the mineralized collagen can be potentially applied in bone tissue repair and regeneration.</P> <P>Graphic Abstract</P><P>Gold nanoparticles with collagen form an efficient matrix for the growth of hydroxyapatite and the mineralized collagen can be potentially applied in bone tissue repair and regeneration. <IMG SRC='http://pubs.rsc.org/services/images/RSCpubs.ePlatform.Service.FreeContent.ImageService.svc/ImageService/image/GA?id=b608300e'> </P>
Biomimetic hydroxyapatite particulate nanofiber modified silicon: In vitro bioactivity
Aryal, Santosh,Bajgai, Madhab Prasad,Khil, Myung Seob,Kang, Hyung-Sub,Kim, Hak Yong Wiley Subscription Services, Inc., A Wiley Company 2009 Journal of biomedical materials research. Part A Vol.a88 No.2
<P>A novel particulate nanofibrous hydroxyapatite (HA), which mimics the bone matrix, is presented as a surface functional material to modify silicon wafers by the electrospinning method. The HA precursors were treated with viscous polymer solution, and then electrospun under controlled conditions. After successive calcinations, the powder X-ray diffraction patterns of the samples revealed reflection toward the (300) HA plane that is linear with temperature. This prominent reflection suggests the crystallographic purity of the HA. Biocompatibility, cell proliferation, and microstructure were examined using AFM and FE-SEM. Morphology showed cell spreading and penetration instead of cell aggregation. The surface roughness as well as adhesion force was calculated using contact mode AFM. The results show that the composite matrix holds promise for use as a bone implant material. © 2008 Wiley Periodicals, Inc. J Biomed Mater Res 2009</P>
Gaihre, Babita,Aryal, Santosh,Barakat, Nasser A.M.,Kim, Hak Y. Elsevier S.A. 2008 Materials Science and Engineering C Vol. No.
<P><B>Abstract</B></P><P>Inspired by the structural similarity of gelatin (and collagen) linked to a mineral phase based on Ca-phosphates compounds with natural bone and increasing application of magnetic iron oxides in hyperthermia, gelatin coated iron oxide (GIO) was synthesized and hydroxyapatite (HAp) crystal nucleation and growth in the nanoparticles was explored. A series of GIO/HAp nanocomposites with various amount of GIO were synthesized by co-precipitation technique using calcium hydroxide and phosphoric acid as precursor. Various physico-chemical analysis showed that the HAp crystal nucleation and growth occurred at acidic group of gelatin, while magnetic iron oxide nanoparticles (< 8nm) were bound to the amide groups of the gelatin chain. Moreover, the growth of HAp nanocrystals in aq. GIO solution was highly influenced by the GIO contents in the solution. The mineralized composite with magnetic properties could have great scope in biomedical field as a thermoseed to kill the cancerous cell in bone side by side for the bone reinforcement.</P>
Bajgai, Madhab Prasad,Aryal, Santosh,Parajuli, Daman Chandra,Khil, Myung-Seob,Lee, Duck Rae,Kim, Hak Yong Wiley Subscription Services, Inc., A Wiley Company 2009 Journal of applied polymer science Vol.111 No.3
<P>Brush copolymers composed of methoxy poly(ethylene glycol) (MPEG) and poly(ϵ-caprolactone) (PCL) have been synthesized by the ring-opening polymerization of ϵ-caprolactone initiated by hydroxyl function of thermally esterified MPEG-citrate in presence of stannous octoate. Citric acid (CA) acts as spacer between brush-like MPEG and the long chain of PCL. Existence of hydrophobic domains as cores of the micelles were characterized by <SUP>1</SUP>H NMR spectroscopy and further confirmed with fluorescence technique using pyrene as a probe. Critical micelle concentration (CMC) of the synthesized copolymer decreased from 0.019 to 0.0031 mg/mL on increasing the fraction of PCL. Along with the physicochemical study, the brush copolymers were explored for the preparation of nanoparticles by nanoprecipitation technique. The morphology and geometry of micelles were investigated by using DLS, AFM, and TEM. Hydrodyanamic dimensions of micelles were around 118 and 178 nm with the core size of 8–10 nm, which further aggregated to form secondary micelle of 60–90 nm. Such assembled polymeric micelles with its flexible dendritic MPEG corona could hold a promise for the immobilization (encapsulation) of hydrophobic drugs and subsequently promote sustained release so that it can be a good vehicle for anti-cancer drug deliverance. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009</P>