• Title, Summary, Keyword: nanocomposite

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Osteogenic differentiation of bone marrow derived stem cells in gelatin-hydroxyapatite nanocomposite

  • Jeon, Hyun-Jun;Hwang, Young-Sup;Kim, Uk-Kyu;Hwang, Dae-Seok;Lee, Kwang-Ho;Chang, Myung-Cheol
    • Journal of the Korean Association of Oral and Maxillofacial Surgeons
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    • v.35 no.1
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    • pp.7-12
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    • 2009
  • Purpose: Gelatin-hydroxyapatite nanocomposite is similar to inorganic nanostructure of bone. To make a scaffold with osteoinductivity, bone marrow derived stem cells from rabbit femur were impinged into the nanocomposite. This vitro study was to test osteogenic differentiation of the stem cells in the nanocomposite, which was made by authors. Material & Methods: Gel-HA nanocomposite with 10g of HA, 3 g of Gel has been made by co-precipitation process. Bone marrow was obtained from femur of New Zealand White rabbits and osteogenic differentiation was induced by culturing of the BMSCs in an osteogenic medium. The BMSCs were seeded into the Gel-HA nanocomposite scaffold using a stirring seeding method. The scaffolds with the cells were examined by scanning electron microscopy (SEM), colorimetry assay, biochemical assay with alkaline phosphatase (ALP) diagnostic kit, osteocalcin ELISA kit. Results: Gel-HA nanocomposite scaffolds were fabricated with relatively homogenous microscale pores ($20-40{\mu}m$). The BMSCs were obtained from bone marrow of rabbit femurs and confirmed with flow cytometry, Alizarin red staining. Attachment and proliferation of BMSCs in Gel-HA nanocomposite scaffold could be identified by SEM, ALP activity and osteocalcin content of BMSCs. Conclusion: The Gel-HA nanocomposite scaffold with micropores could be fabricated and could support BMSCs seeding, osteogenic differentiation.

Preparation and Characterization of Biopolymer-Based Nanocomposite Films: Chitosan-Based Nanocomposite Films with Antimicrobial Activity

  • Rhim, Jong-Whan
    • 한국포장학회:학술대회논문집
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    • pp.54-73
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    • 2006
  • Four different types of chitosan-based nanocomposite films were prepared using a solvent casting method by incorporating with four types of nanoparticles, i.e., an unmodified montmorillonite (Na-MMT), an organically modified montmorillonite (Cloisite 30B), a Nano-silver, and a Ag-zeolite (Ag-Ion). X-ray diffraction patterns of the nanocomposite films indicated that a certain degree of intercalation was formed in the nanocomposite films, with the highest intercalation in the Na-MMT-incorporated films followed by films with Cloisite 30B and Ag-Ion. SEM micrographs showed that in all the nanocomposite films, except the Nanosilver-incorporated one, nanoparticles were dispersed homogeneously throughout the chitosan polymer matrix. Consequently, mechanical and barrier properties of chitosan films were affected through intercalation of nanoparticles, i.e., tensile strength (TS) increased by 7-16%, while water vapor permeability (WVP) decreased by 25-30% depending on the nanoparticle material tested. In addition, chitosan-based nanocomposite films, especially silver-containing ones, showed a promising range of antimicrobial activity.

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Synthesis of PMMA/Clay Nanocomposite via Emulsion Polymerization (유화중합을 이용한 PMMA/Clay 나노컴포지트의 제조)

  • Kim, Cheol-Woo;Wu, Jong-Pyo
    • Journal of the Korean Applied Science and Technology
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    • v.20 no.3
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    • pp.243-250
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    • 2003
  • Poly(methyl methacrylate)/clay nanocomposite particles with particle size of 275${\sim}$292 nm range were successfully prepared using emulsion polymerization. The content of montmorillonite based on the methyl methacrylate monomer was chosen as 30 wt.%. 2,2-azobis(isobuthylamidine hydrochloride) and n-dodecyltrimethylammonium chloride were used as an initiator and a surfactant in cationic emulsion system. Potassium persulfate and sodium lauryl sulfate were used as an initiator and a surfactant in anionic emulsion system. The evidence of intercalated /exfoliated structure of montmorillonite in the nanocomposite prepared in our experiment was confirmed by wide angle x-ray diffraction patterns of $d_{001}$ plane. Thermal behavior of nanocomposite was traced using DSC and TGA. It was found that the nanocomposite particle prepared by cationic emulsion system showed intercalated structured. We also found that the nanocomposite particle obtained from anionic emulsion system resulted in the fully exfoliated structure.

Effects of Concentration of ZnO Nanoparticles on Mechanical, Optical, Thermal, and Antimicrobial Properties of Gelatin/ZnO Nanocomposite Films

  • Shankar, Shiv;Teng, Xinnan;Rhim, Jong-Whan
    • KOREAN JOURNAL OF PACKAGING SCIENCE & TECHNOLOGY
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    • v.20 no.2
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    • pp.41-49
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    • 2014
  • This study illustrates the synthesis of gelatin based zinc oxide nanoparticle (ZnONPs) incorporated nanocomposite films using different concentrations of ZnONPs. The ZnONPs were oval in shape and the size ranged from 100- 200 nm. The nanocomposite films were characterized by UV-visible, FE-SEM, FT-IR, and XRD. The concentrations of ZnONPs greatly influenced the properties of nanocomposite films. The absorption peaks around 360 nm increased with the increasing concentrations of ZnONPs. The surface color of film did not change while transmittance at 280 nm was greatly reduced with increase in the concentration of ZnONPs. FTIR spectra showed the interaction of ZnONPs with gelatin. XRD data demonstrated the crystalline nature of ZnONPs. The thermostability, char content, water contact angle, water vapor permeability, moisture content, and elongation at break of nanocomposite films increased, whereas, tensile strength and modulus decreased with increase in the concentrations of ZnONPs. The gelatin/ZnONPs nanocomposite films showed profound antibacterial activity against both Gram-positive and Gram-negative food-borne pathogenic bacteria. The gelatin/$ZnONP^{1.5}$ nanocomposite film showed the best UV barrier and antimicrobial properties among the tested-films, which indicated a high potential for use as an active food packaging films with environmentally-friendly nature.

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Fabrication of ZnO and TiO2 Nanocomposite Fibers and Their Photocatalytic Decomposition of Harmful Gases (ZnO와 TiO2 함유 복합나노섬유의 제조와 유해물질분해 성능 평가)

  • Hur, Yoon-Sun;Lee, Seung-Sin
    • Journal of the Korean Society of Clothing and Textiles
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    • v.35 no.11
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    • pp.1297-1308
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    • 2011
  • This research investigates the application of ZnO (zinc oxide) nanoparticles and $TiO_2$ (titanium dioxide) nanoparticles to polypropylene nonwoven fabrics via an electrospinning technique for the development of textile materials that can decompose harmful gases. To fabricate uniform ZnO nanocomposite fibers, two types of ZnO nanoparticles were applied. Colloidal $TiO_2$ nanoparticles were chosen to fabricate $TiO_2$ nano- composite fibers. ZnO/poly(vinyl alcohol) (PVA) and $TiO_2$/PVA nanocomposite fibers were electrospun under a variety of conditions that include various feed rates, electric voltages, and capillary diameters. The morphology of electrospun nanocomposite fibers was examined with a field-emission scanning electron micro- scope and a transmission electron microscope. Decomposition efficiency of gaseous materials (formaldehyde, ammonia, toluene, benzene, nitrogen dioxide, sulfur dioxide) by nanocomposite fiber webs with 3wt% nano-particles (ZnO or $TiO_2$) and 7$g/m^2$ web area density was assessed. This study shows that ZnO nanoparticles in colloid were more suitable for fabricating nanocomposite fibers in which nanoparticles are evenly dispersed than in powder. A heat treatment was applied to water-soluble PVA nanofiber webs in order to stabilize the electrospun nanocomposite fibrous structure against dissolution in water. ZnO/PVA and $TiO_2$/PVA nanofiber webs exhibited a range of degradation efficiency for different types of gases. For nitrogen dioxide, the degradation efficiency was 92.2% for ZnO nanocomposite fiber web and 87% for $TiO_2$ nanocomposite fiber web after 20 hours of UV light irradiation. The results indicate that ZnO/PVA and $TiO_2$/PVA nano- composite fiber webs have possible uses in functional textiles that can decompose harmful gases.

A Study on the Mechanical Properties and Biodegradation of PCL-MMT Nanocomposite (PCL-MMT 나노복합재료의 기계적 성질과 생분해에 관한 연구)

  • Choi, Hyun-Kuk;Lee, Young-Sei;Park, Jae-Kyeung
    • Journal of the Korean Society of Industry Convergence
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    • v.8 no.1
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    • pp.5-10
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    • 2005
  • PCL were intercalated into organically modified MMT (PCL-MMT) at $80^{\circ}C$ for 4hrs to prepare the PCL-MMT nanocomposite. PCL-MMT and PCL were mixed mechanically with two-roll mill at $150^{\circ}C$ for 15mins. From the results of XRD and TEM, it were found that PCL-MMT nanocomposite were prepared. And mechanical properties and biodegradation of nanocomposite have been investigated by tensile meter and biodegradability analysis experiment. Because of MMT dispersed homogeneously in PCL matrix, the Young's modulus of the nanocomposite was found to be excellent. But the tensile strength and elongation were decreased as increase of MMT. And MMT dispersed in PCL matrix was almost not affected on the biodegradation of PCL.

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Thermomechanical Properties of Poly(D, L-actic-co-glycolic acid) and Graphene Oxide Nanocomposite for Scaffolds

  • Sohn, Il-Yung;Yoon, Ok-Ja;Kim, Duck-Jin;Lee, Nae-Eung
    • Proceedings of the Korean Vacuum Society Conference
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    • pp.478-478
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    • 2011
  • The thermomechanical and surface chemical properties of nanocomposite of poly( D, L-actic-co-glycolic acid) (PLGA) were improved significant due to concentration of graphene oxide (GO) nanosheets as nanoscale fillers to PLGA film. Thermomechanical properties of the PLGA/GO (2wt.-%.) nanocomposite were decreased crystallization and melting temperature, weight loss. The storage and loss moduli of the nanocomposite were enhanced by chemical bonding between the oxygenated functional groups of the GO nanosheets and the polymer chains in the PLGA matrix. Enhanced hydrophilicity of nanocomposite caused by embedded GO nanosheets also improved for good biocompatibility. Our findings indicate that thermomechanical properties and biocompatibility of nanocomposite embedded with GO nanosheets are attractive candidates for use in biomedical applications such as scaffolds.

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Flexible and Transparent Reduced Graphene Oxide Nanocomposite Field-Effect Transistor for Temperature Sensing

  • Tran, QuangTrung;Ramasundaram, Subramanian;Hong, Seok Won;Lee, Nae-Eung
    • Proceedings of the Korean Vacuum Society Conference
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    • pp.387.1-387.1
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    • 2014
  • A new class of temperature-sensing materials is demonstrated along with their integration into transparent and flexible field-effect transistor (FET) temperature sensors with high thermal responsivity, stability, and reproducibility. The novelty of this particular type of temperature sensor is the incorporation of an R-GO/P(VDF-TrFE) nanocomposite channel as a sensing layer that is highly responsive to temperature, and is optically transparent and mechanically flexible. Furthermore, the nanocomposite sensing layer is easily coated onto flexible substrates for the fabrication of transparent and flexible FETs using a simple spin-coating method. The transparent and flexible nanocomposite FETs are capable of detecting an extremely small temperature change as small as $0.1^{\circ}C$ and are highly responsive to human body temperature. Temperature responsivity and optical transmittance of transparent nanocomposite FETs were adjustable and tuneable by changing the thickness and R-GO concentration of the nanocomposite.

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Temperature and pH-Responsive Release Behavior of PVA/PAAc/PNIPAAm/MWCNTs Nanocomposite Hydrogels

  • Jung, Gowun;Yun, Jumi;Kim, Hyung-Il
    • Carbon letters
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    • v.13 no.3
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    • pp.173-177
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    • 2012
  • A drug delivery system (DDS) was prepared with a temperature and pH-responsive hydrogel. Poly(vinyl alcohol) (PVA)/poly(acrylic acid) (PAAc)/poly(N-isopropylacrylamide) (PNIPAAm)/multi-walled carbon nanotube (MWCNT) nanocomposites were prepared by radical polymerization for the temperature and pH-responsive hydrogels. MWCNTs were employed to improve both the thermal conductivity and mechanical properties of the PVA/PAAc/PNIPAAm/MWCNT nanocomposite hydrogels. Various amounts of MWCNTs (0, 0.5, 1 and 3 wt%) were added to the nanocomposite hydrogels. PVA/PAAc/PNIPAAm/MWCNT nanocomposite hydrogels were characterized with a scanning electron microscope. The mechanical properties were measured with a universal testing machine. Swelling and releasing properties of nanocomposite hydrogels were investigated at various temperatures and pHs. Temperature and pH-responsive release behavior was found to be dependent on the content of MWCNTs in nanocomposite hydrogels.

Electrical Conduction and Dielectric Properties of Epoxy/Organophilic Clay Nanocomposite

  • Park, Jae-Jun
    • Transactions on Electrical and Electronic Materials
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    • v.14 no.1
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    • pp.43-46
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    • 2013
  • In order to develop electrical insulation material, organically modified layered silicate was incorporated into an epoxy matrix to prepare nanocomposite. Transmission electron microscopy (TEM) observation showed that organophillic clay was in an exfoliated state, while hydrophilic clay was not dispersed into nanolayers within the epoxy matrix. Epoxy/organophilic clay (2.8 wt%) nanocomposite was mixed and cured at $150^{\circ}C$ for 4.5 hr. I-V characteristics, volume resistance and dielectric properties for the cured nanocomposite were estimated. Current density increased with increasing temperature, and volume resistance decreased with increasing temperature, in neat epoxy and epoxy/organophilic clay (2.8 wt%) nanocomposite. As frequency increased, the dielectric loss value decreased in the two systems.