Multi-functional Materials and Structures

Volumes 47-50

doi: 10.4028/

Paper Title Page

Authors: Ting Ting Ding, Jiao Sun, Ping Zhang
Abstract: The study of inflammation is important in understanding the reaction between biomaterials and the immune system. In the current study, human umbilical vein endothelial cells (ECV-304), cultured with PRMI-1640, were detached from cells cultured with the supernatant of macrophages which contained TNF-α and IL-1β because of stimulation by biomaterials. Cells were then put into contact with multiple biomaterials with different biocompatibilities. Levels of monocyte chemoattractant protein-1 (MCP-1) were measured. The results suggested that level of MCP-1 cultured with supernatant of macrophages was higher than PRMI-1640 in the same biomaterials. And, exposure to the positive control, Polytetrafluoroethylene, Poly-Lactic-co-Glycolic acid and American NPG alloy, resulted in high expression of MCP-1 (p< 0.001) following cytokine stimulation. MCP-1 was also significantly expressed in β-Tricalcium Phosphate and Calcium Phosphate Cement samples (p < 0.01). These data suggested that MCP-1 was activated by both cytokines and biomaterials.
Authors: Te Hsing Wu, Ko Shao Chen, Su Chen Chen, Yi Chun Yeh, Lie Hang Shen
Abstract: Expanded polytetrafluoroethylene (ePTFE) is a bioinert material. It has the superior properties of thermal and chemical stabilities, low surface energy and high resistivity, so it was applied in many biomedical fields. In order to improve the ePTFE film biocompatibility, the cold plasma technology was used with acetic acid as monomer to deposit onto ePTFE film and then (N-isopropylacrylamide) was grafted onto the surface by photo-grafting. The characteristics of the material surface were evaluated with X-ray photoelectron spectroscopy (XPS), FTIR and water contact angle. It was found that the contact angle of water on the untreated ePTFE significantly decrease from125° to 72° after ePTFE film being treated with acetic acid plasma deposition procedure. Due to the hydrophilicity of poly(N-isopropylacrylamide), so the contact angle of water on the ePTFE-g-NIPAAm almost approached to 0°. And we obtained the thermal-sensitive ePTFE hydrogels.
Authors: Zhong Hai Yang, Yi Xu, Ping Yang, Yong Xiang Leng, Nan Huang
Abstract: Non-stoichiometric titanium dioxide (TiO2-x) thin films were obtained by unbalanced reactive pulsed magnetron sputtering and subsequently modified by hydrogen plasma. To investigate the influence of hydrogen plasma on the properties of the films, time and temperature were changed during the process with a fixed vacuum pressure of 10 Pa. The film structure, composition, resistance and blood compatibility were studied. The results that the concentration of Ti4+ decreases with the increasing of treated time and substrate temperature, which results in existence of oxygen vacancy and increase of conductivity. It is found that Ti-O film treated in 110°C plasma for 15min represents the lowest thrombosis risks, which could be mainly attributed to its characteristic of n-type semiconductor caused by appropriate oxygen vacancy forming in hydrogen plasma treatment.
Authors: Lertrit Sarinnaphakorn, Patrick Mesquida, Roberto Chiesa, C. Giordano, Michael Fenlon, Lucy DiSilvio
Abstract: Surface treated titanium implants are increasingly being used in dental and orthopaedic applications. This study examined the biological response of primary human alveolar osteoblast (aHOB) cells to a novel silicon based anodic spark deposition treated titanium surfaces. Three different titanium surfaces were investigated: anodic spark deposition (ASD) with silicon based (ASDSi), BioSpark™ (BS), and chemically etched (BioRough™, BR). Commercially pure titanium (cpTi) was the non-treated control surface. Physiological and biological evaluations were conducted on all test and control surfaces. Surface scanning (SEM, EDS, and AFM) confirmed a nano-topography, which was textured for all surfaces; and similar surface chemical composition (Ca and P), of significant was the Si peak on the ASDSi surface. Cell morphological study (SEM) showed good adhere and spreading over the surface, with metabolically active cells having extended filopodia. Biological response was observed with cell proliferation on all test surfaces for the period studied. Proliferation rate was seen to increase with time. This initial favourable cell response will be of benefit in the long term osseointegration of the implant surfaces.
Authors: W. Han, Yue Dan Wang, Y.F. Zheng
Abstract: Nano TiO2 material is an extensively used and adequately studied material and has a close contact with human in various fields, such as dope, dye, ceramic, cosmetic and medicine. Therefore, it’s very important to study the biocompatibility and biosafety of nano TiO2 materials. In the present study, various nano TiO2 materials with different dimension and crystal structures were confected to suspensions with varied concentrations and evaluated in cell model (mouse fibrocyte) after autoclaving sterilization. After 24h, 48h and 72h of cell culture experiments, MTT assay was used to examine the cell proliferation behavior and the flow cytometry was used to examine the cell apoptosis behavior. The present results of cell experiment showed that nano TiO2 materials had no effect on cell proliferation and apoptosis in a certain range of time and concentration. MTT assay indicated the relative cell proliferation rate in all nano TiO2 material groups were above 92% and the toxicity grade were 0 or 1 class.
Authors: K.T. Shek, David C.C. Lam
Abstract: Drug dosage delivered by drug-coated microneedle is dependent on needle insertion behavior. The insertion length and gripping force at varied insertion speeds are determined quantitatively using a precision test frame. The ratio of inserted depth to pressed depth was found to rise asymptotically to a plateau, but decreased rapidly to zero insertion when the needles are pressed less than 1000 microns deep for both silicone rubber and porcine skin. No insertion was observed when the needles are pressed less than 200 microns. The gripping force exerted onto the inserted needle by the skin decreased by 0.1N per mm of needle diameter and insertion depth. The short insertion depth and low force suggest that drug delivery using short 300 micron microneedles would be tenuous. High insertion speeds can help to improve drug delivery, but the improvement is limited to large needles since the results from this study showed that insertions become speedindependent when the needle diameter is less than 130 microns.
Authors: Won Yong Kim, Han Sol Kim
Abstract: Microstructures and pseudoelastic behavior of Ti-Nb-Ge alloys were investigated in order to correlate the pseudoelasticity and microstructure together with martensite transformation. XRD results and transmission electron microscope revealed that stress-induced martensitic transformation takes place during room temperature deformation in the present alloys. Recrystallization heat treatment of the present alloy displayed pseudoelastic behavior to be prominent. It is concluded that the pseudoelastic behavior of a metastable-β Ti-Nb-Ge alloy is correlated to the stress-induced martensite transformation.
Authors: Won Yong Kim, Han Sol Kim
Abstract: The effect of Ge and oxygen content on microstructural formation and mechanical properties of Ti-Nb alloys were investigated in order to design a desirable Ti based alloy through casting process. Three phase mixtures consisting of bcc-structured β phase, orthorhombic structured α" phase and intermediate ω phase were found depending on Nb, Ge, oxygen content in the present alloy system. The volume fraction of α" phase and ω phase decreased with increasing Ge or oxygen content. This microstructural information may indicate that both Ge and oxygen act to increase the stability of β phase rather than α" phase in metastable β-Ti based alloys prepared by water quenching. Elastic modulus values were sensitive to phase stability of constituent phases.
Authors: Jia Chen Kang, Min Wang, Xiao Yan Yuan
Abstract: Electrospinning of poly(L-lactic acid) (PLLA) and gelatin separately to form nonwoven PLLA or gelatin nanofibrous membranes was investigated. Factors that could affect the fiber morphology and fiber diameter were studies for PLLA and gelatin, respectively. The polymer solution concentration was found to play a dominant role in the formation of defected or nondefected ultrafine fibers. Using a specially designed experimental setup with separate syringe pumps for polymer solutions and separate power supplies for high voltages for electrospinning, PLLA-gelatin bicomponent fibrous membranes were formed with PLLA fibers interweaving with gelatin fibers. Multicomponent fibrous scaffolds can be very useful for tissue engineering and/or controlled release applications.
Authors: Biao Fu, Lin Xiao, Long Jiang Yu, Guang Yang
Abstract: A series of biodegradable lactic acid based Polyurethanes modified by castor oil (PLBA-PUs) have been successfully prepared by using a two steps method as follow: Firstly prepolymers with hydroxyl terminated are synthesized by copolymerization of L-lactic acid and 1, 4-butandiol (BD), and then react with castor oil (C.O.) and hexamethylene diisocynate (HDI). The effects of BD/LA monomer ration and C.O./prepolymers mole ratio on the molecular weight and mechanical properties of PLBA-PUs are investigated. The polymers obtained are characterized by gel permeation chromatography, fourier transform infrared spectroscopy, 13C NMR, differential scanning calorimeter (DSC) and tensile testing. Their average molecular weight is over 280,000. They display excellent mechanical properties, such as a tensile strength as high as 31MPa, a tensile modulus as low as 20 MPa, and an elongation at break of 176%. Due to the biocompatibility, these PUs could find applications in biomedical fields, such as soft-tissue engineering.

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