Papers by Keyword: Biomedical Application

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Authors: Meng Lu Pu, Wei Jiang, Yue Qing Shen
Abstract: Magnetite nanoparticles (MNPs) coated with poly (divinylbenzene-co-glycidyl methacrylate) particles (mPDGs) are prepared by co-polymerization of 1,4-divinylbenzene and glycidyl methacrylate monomers via batch emulsion polymerization. The Fe3O4 nanoparticles modified by oleic acid are obtained by chemical precipitation. The chemical composition, morphology, magnetic content, magnetic properties and particle size of the composite particles are investigated using transmission electron microscopy, thermogravimetric analysis, vibrating sample magnetometer, and dynamic light scattering, respectively. The results show that the magnetic nanoparticles have been coated by 1,4-divinylbenzene and glycidyl methacrylate, with the high saturation magnetization being 33.66 emu/g. The mean size of the mPDGs with good dispersion is about 200 nm. Subsequently, the polymer shell with reactive epoxy group is expected to be useful for chemical grafting of any biomolecule containing reactive functional groups (-NH2, -OH, -COOH, etc) or can be chemically modified to desired functional groups. These magnetic nanospheres with multifunctional groups have potential application in biomedical applications.
Authors: Hwang Cherng Chow, Bing Shiun Tang
Abstract: In this paper, a high performance current-mode instrumentation amplifier has been proposed with low noise, low power and high CMRR features. The proposed design can adjust the gain with an external resistor for the processing of various biomedical signals. To reduce the noise of the amplifier, two design methods including PMOS input and lateral pnp BJT input have been implemented to improve the prior arts. To meet the single power supply need, a biomedical voltage level shifter is also proposed for low cost CMOS implementation. Based on the post-layout simulation results, the presented current-mode amplifier achieves high CMRR over 120 dB, power consumption of 61 uW at 1.8-V supply using standard 0.18-um CMOS technology.
Authors: Adele Carradò, Hervé Pelletier, Felix Sima, Carmen Ristoscu, Agnès Fabre, Laurent Barrallier, Ion N. Mihailescu
Abstract: In this article, two original studies of the alumina as porous substrate and PLD (pulsed laser deposition) thin films in view of its biomedical and tribological applications are presented. The first biomedical study aimed to evaluate the role of Al2O3 on thin deposited nanostructures. For this purpose, cerium stabilized zirconia doped hydroxyapatite thin films were deposited by PLD onto high purity, high density alumina substrates with different low porosities. For deposition, an UV KrF* (λ=248 nm, τ ~ 25 ns) excimer laser was used for the multi-pulse irradiation of the targets. The nanostructured surface morphologies of the thin films with micro droplets were evidenced by atomic force microscopy and scanning electron microscopy and the compositions with a Ca/P ratio of 1.7 by energy dispersive spectroscopy. The films were seeded with mesenchymal stem cells for in vitro tests. The cells showed good attachment and spread and covered uniformly the surface of the samples. Different functions of substrate porosities are observed in the efficiency of developing long filopodia and of obtaining the optimal intracellular organization. The second study aimed to understand the influence of micro-structural and mechanical characteristics on the tribological behaviour of stainless steel samples with PLD alumina coatings produced using an UV KrF* (λ=248 nm, τ ~ 20 ns) excimer laser and a sintered alumina target. Various microscopic observation techniques were used in order to connect the tribological response to the amorphous microstructure of the coatings. The results correspond to the determination of the mechanical characteristics by nanoindentation tests, scratch tests, and a tribological behaviour analysis of the treated steel against 100Cr6. The films were stoichiometric, partially crystallized with an amorphous matrix and their surfaces had few particulates deposited on. The obtained values of hardness and elastic modulus of the films were in good agreements with literature data.
Authors: Ludwig J. Gauckler, Kurosch Rezwan
Abstract: Protein adsorption onto metal oxide surfaces is an essential aspect of the cascade of biological reactions taking place at all interfaces between implanted materials and the biological environment. The types and amounts of adsorbed proteins mediate subsequent adhesion, proliferation and differentiation of cells. Protein adsorption to surfaces of metal oxides and their kinetics are important in the formation and growth of seashells, one of the toughest natural ceramics, in modern bio-analytical devices as well as in bone and teeth implant technology. This paper describes results obtained in a feasibility study of how to use metal-oxide particles to obtain biosensors with a high turnover. The most important features of proteins are outlined describing them as purpose-built "polymers" from amino acids with specific conformations. Some key aspects of Metaloxide (MeO) surfaces in water and the influence of electrostatic and hydrophobic interaction on protein adsorption are reported. Results concerning the interaction between different proteins and MeO surfaces in water are discussed in detail. Examples of purely electrostatic interactions of proteins with MeO surfaces as well as the influence of hydrophobic interaction are elucidated. An outlook of the implications of the new insights on natural and synthetic materials will be given concerning bio-compatibility, bio-mineralization and self assembly of materials.
Authors: Mitsuo Niinomi, Masaaki Nakai, Toshikazu Akahori, Harumi Tsutsumi
Abstract: Negative thermal expansion, i.e. a type of shrinkage that occurs during heating, was observed in cold-rolled Ti-29Nb-13Ta-4.6Zr alloy (mass%) (TNTZ). The reduction ratio of cold rolling was systematically changed, and then the thermal expansion rate was measured using a dilatometer. The cyclicity of thermal expansion was also examined for the cold-rolled TNTZ. Further, the effect of oxygen content on the thermal expansion behavior of the cold rolled TNTZ was examined. With an increase in the reduction ratio of cold rolling, the thermal expansion rate of TNTZ cold-rolled parallel to the rolling direction (RD) decreases, but it increases in TNTZ cold-rolled parallel to the transverse direction (TD). The cyclicity of above-mentioned anomalous thermal expansion is observed in a temperature range below 473 K, but it is not observed when the specimen is heated to above 573 K in the first cycle. The oxygen suppresses the negative thermal expansion behavior of TNTZ.
Authors: Huai Xiu Lu, Bin Deng, Long Quan Shao, Yuan Fu Yi, Jie Liu, Wei Wei Zhang, Ning Wen
Abstract: Objective: To evaluate the biological safety of a colored zirconia ceramic in terms of cellular toxicity and a skin sensitivity test. Methods: the cytotoxicity of the ceramic was evaluated by a molecular filtration method and skin irritation activity of the composite was assessed via intradermal injection of a guinea pig test solution, by inducing, enhancing, and stimulating an allergic response after local tissue exposure. Results: cell-coated filter paper in contact with test material showed the appearance of intracellular blue dye at the same staining density as in control samples, leading to a 0 toxicity rating. Guinea pigs showed no obvious erythema or edema from the irritation test, such that the assessment of colored zirconia ceramic skin allergy response in guinea pig was 0%. Conclusion: this colored zirconia ceramic showed low cytotoxicity and elicited no allergic skin inflammation response, indicating good overall biological safety under these conditions.
Authors: Sergey V. Dorozhkin
Abstract: Ceramics used for the repair and reconstruction of diseased or damaged parts of the musculo-skeletal system, termed bioceramics, can be bioinert, bioresorbable and bioactive, as well as porous for tissue ingrowth. This review is devoted to calcium orthophosphates, which belong to the categories of bioresorbable and bioactive bioceramics. There have been a number of major advances made in this field during the past 30 – 40 years. From initial work on development of bioceramics that were tolerated in the physiological environment, emphasis has now shifted towards the use of bioceramics that interact with bone tissue by forming a direct bond. By structural and compositional control, it is now possible to choose whether the bioceramics of calcium orthophosphates are biologically stable once incorporated within the skeletal structure or whether they are resorbed over time. Current biomedical applications of calcium orthophosphate bioceramics include replacements for hips, knees, teeth, tendons and ligaments, as well as repair for periodontal disease, maxillofacial reconstruction, augmentation and stabilization of the jawbone, spinal fusion and bone fillers after tumor surgery.
Authors: Cengiz Kaya, Figen Kaya, Johann Cho, Judith A. Roether, Aldo Roberto Boccaccini
Abstract: Electrophoretic deposition (EPD) has been demonstrated to be a convenient processing technique to fabricate composite ceramic coatings containing ordered arrays of carbon nanotubes. In this investigation, EPD was used to coat Ti6Al4V medical implants with hydroxyapatite (HA) layers reinforced with surface functionalized multi-walled carbon nanotubes (MWCNTs). The functionalization of MWCNTs by treating them with an acid mixture was successfully achieved in order to create functional groups on the MWCNT surfaces enabling them to be homogeneously dispersed in water. The surface treatment was also used to induce the adsorption of HA nanoparticles on MWCNT surfaces. Some critical issues, such as microcracking and peeling of HA layers after EPD, were effectively solved by the use of MWCNTs.
Authors: Toshikazu Akahori, Mitsuo Niinomi, Masaaki Nakai, Michiharu Ogawa
Abstract: The tensile and plain fatigue properties of the β-type titanium alloy, Ti-29Nb-13Ta-4.6Zr alloy (TNTZ), which was subjected to various thermomechanical treatments, and cast TNTZ were investigated in order to judge its potential for biomedical and dental applications. The tensile strengths of TNTZ aged after solution treatment and that aged after cold rolling decrease with an increase in the aging temperature; however, their elongation exhibits an opposite trend. TNTZ composed of the ω phase or the ω and α phases in the β phase exhibits a tensile strength of about 1000 MPa or more. The tensile properties of the cast TNTZ with and without a surface reaction layer is are not significantly different, and are almost identcal to those of as-solutionized TNTZ. The plain fatigue strengths of TNTZ aged after solution treatment and those of TNTZ aged after cold rolling increase with the aging temperature. In particular, TNTZ aged at 723 K after cold rolling exhibits the highest fatigue strength in both the low- and high-cycle fatigue life regions. Further, the plain fatigue limit, which is about 770 MPa, is nearly equal to that of hot-rolled Ti-6Al-4V ELI alloy subjected to aging after solution treatment; Ti-6Al-4V ELI alloy is a representative α+β-type titanium alloy for biomedical applications. The plain fatigue strength of cast TNTZ with a surface reaction layer is considerably less than that of the as-cold-rolled and as-solutionized TNTZ. Consequently, in the low-fatigue life region, the fatigue crack easily occurs at the surface reaction layer, which is brittle, and in the high-fatigue life region, the fatigue crack occurs at the sites of casting defects (shrinkage). The fatigue limits range from 180 MPa to 200 MPa.
Authors: Saran Tantavisut, Boonrat Lohwongwatana, Atchara Khamkongkaeo, Suparat Bootchai, Pairat Tangpornprasert, Aree Tanavalee, Pibul Ittiravivong
Abstract: Ti-based amorphous alloys containing no harmful elements are desired. However, many Ti-based amorphous alloys contain toxic elements such as Al, Ni, V and Be. The presence of toxic elements within amorphous alloys is a concern when they are intended for use as a biomaterial. This problem has steered many researchers toward the development of Ti-based amorphous alloys without toxic elements. Our novel amorphous alloys were developed based on this principle. A series of Ti44Zr10Pd10Cu6+xCo23-xTa7 (x = 0, 4, 8) amorphous alloys were developed for biomedical application. A series of protocol tests were performed to check for biocompatibility and potential use of the novel alloys in humans. First, alloy ingots were alloyed by induction melting and then cast into copper molds. The cast rod was then used as the plasma cathode in a filtered cathodic vacuum arc deposition chamber to coat the 25-nm amorphous alloy thin film on the cover glass slides. These coated cover glass slides were then examined for biocompatibility. Cell proliferation and cell differentiation were investigated using Methylthiazol Tetrazolium assay test and by alkaline phosphatase assay on osteoblast like cells (SaOS-2), respectively. Field emission scanning electron microscopy was performed to evaluate the thin film surface characteristics. The thickness of thin film was analyzed using a Stylus profilometer. An adhesion scratch test was administered to evaluate the thin film adhesive strength and indirect hardness comparison. Electron Dispersive X-ray Spectrometry was performed to study the elemental composition. Lastly, a medical grade Ti-6Al-4V alloy was studied in parallel as a control material. Results indicated that all investigated Ti-based amorphous alloys were non-cytotoxic and were comparable to the Ti-6AL-4V. They also demonstrated an ability to support differentiation of osteoblast like cells. The adhesion and the hardness of the thin films on the substrates were superior to that of Ti-6Al-4V. The results suggested that the novel alloys in this study could be potentially utilized in biomedical applications.
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