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Various Biomedical Applications (various + biomedical_application)
Selected AbstractsMicropatterned Polymer Surfaces and Cellular Response of Dictyostelium,ADVANCED ENGINEERING MATERIALS, Issue 5 2010Magdalena Eder Gecko inspired adhesives are surfaces with many microscale pillars that form Van der Waals forces with other surfaces. They differ from conventional tape in that adhesion is reversible and has the potential for switchability. These properties make gecko adhesives interesting for various biomedical applications. The two objectives of this project were to investigate the formation of biofilms on such surfaces and how the surfaces affect cell development. The developmental stages of the model organism Dictyostelium discoideum were observed by time lapse photography using light and environmental scanning electron microscopy. This study shows that micropatterned surfaces can be used as a biophysical tool to interfere with multicellular tissue formation in multiple ways. [source] Cytotoxicity and Cell Cycle Effects of Bare and Poly(vinyl alcohol)-Coated Iron Oxide Nanoparticles in Mouse FibroblastsADVANCED ENGINEERING MATERIALS, Issue 12 2009Morteza Mahmoudi Super-paramagnetic iron oxide nanoparticles (SPIONs) are recognized as powerful biocompatible materials for use in various biomedical applications, such as drug delivery, magnetic-resonance imaging, cell/protein separation, hyperthermia and transfection. This study investigates the impact of high concentrations of SPIONs on cytotoxicity and cell-cycle effects. The interactions of surface-saturated (via interactions with cell medium) bare SPIONs and those coated with poly(vinyl alcohol) (PVA) with adhesive mouse fibroblast cells (L929) are investigated using an MTT assay. The two SPION formulations are synthesized using a co-precipitation method. The bare and coated magnetic nanoparticles with passivated surfaces both result in changes in cell morphology, possibly due to clustering through their magnetostatic effect. At concentrations ranging up to 80,×,10,3,M, cells exposed to the PVA-coated nanoparticles demonstrate high cell viability without necrosis and apoptosis. In contrast, significant apoptosis is observed in cells exposed to bare SPIONs at a concentration of 80,×,10,3,M. Nanoparticle exposure (20,80,×,10,3,M) leads to variations in both apoptosis and cell cycle, possibly due to irreversible DNA damage and repair of oxidative DNA lesions, respectively. Additionally, the formation of vacuoles within the cells and granular cells indicates autophagy cell death rather than either apoptosis or necrosis. [source] Fabrication of Density Gradients of Biodegradable Polymer Microparticles and Their Use in Guiding Neurite OutgrowthADVANCED FUNCTIONAL MATERIALS, Issue 10 2010Xiaoran Li Abstract A new method for generating both continuous and discrete density gradients in microparticles of biodegradable polymers via an electrospray technique is reported. The gradients are generated by spatially varying the deposition time of electrosprayed microparticles. The substrate coated with a density gradient of microparticles has varying surface roughness, offering a unique system for studying the effect of physical cues on neurite outgrowth from dorsal root ganglia. An optimal surface roughness for promoting neuron adhesion and neurite extension in vitro is obtained. Furthermore, this capability of approach is extended to generate a gradient of fluorescein isothiocyanate labeled bovine serum albumin by encapsulating it in the polymer microparticles in situ during electrospray. Taken together, this new class of substrates with gradients of microparticle density can potentially be used in various biomedical applications such as neural tissue engineering. [source] Biodegradable Polymer Crosslinker: Independent Control of Stiffness, Toughness, and Hydrogel Degradation RateADVANCED FUNCTIONAL MATERIALS, Issue 19 2009Chaenyung Cha Abstract Hydrogels are being increasingly studied for use in various biomedical applications including drug delivery and tissue engineering. The successful use of a hydrogel in these applications greatly relies on a refined control of the mechanical properties including stiffness, toughness, and the degradation rate. However, it is still challenging to control the hydrogel properties in an independent manner due to the interdependency between hydrogel properties. Here it is hypothesized that a biodegradable polymeric crosslinker would allow for decoupling of the dependency between the properties of various hydrogel materials. This hypothesis is examined using oxidized methacrylic alginate (OMA). The OMA is synthesized by partially oxidizing alginate to generate hydrolytically labile units and conjugating methacrylic groups. It is used to crosslink poly(ethylene glycol) methacrylate and poly(N -hydroxymethyl acrylamide) to form three-dimensional hydrogel systems. OMA significantly improves rigidity and toughness of both hydrogels as compared with a small molecule crosslinker, and also controls the degradation rate of hydrogels depending on the oxidation degree, without altering their initial mechanical properties. The protein-release rate from a hydrogel and subsequent angiogenesis in vivo are thus regulated with the chemical structure of OMA. Overall, the results of this study suggests that the use of OMA as a crosslinker will allow the implantation of a hydrogel in tissue subject to an external mechanical loading with a desired protein-release profile. The OMA synthesized in this study will be, therefore, highly useful to independently control the mechanical properties and degradation rate of a wide array of hydrogels. [source] Fluorescent Gold Nanoprobe Sensitive to Intracellular Reactive Oxygen SpeciesADVANCED FUNCTIONAL MATERIALS, Issue 12 2009Hyukjin Lee Abstract Gold nanoprobes immobilized with fluorescein-hyaluronic acid (HA) conjugates are fabricated and utilized for monitoring intracellular reactive oxygen species (ROS) generation in live cells via nanoparticle surface energy transfer. A bio-inspired adhesive molecule, dopamine, is used to robustly end-immobilize HA onto the surface of gold nanoparticles (AuNPs) for securing intracellular stability against glutathione. ROS induces cleavage and fragmentation of the HA chains immobilized on the surface of the AuNPs allows rapid and specific detection of intracellular ROS by emitting strong fluorescence-recovery signals. In particular, fluorescence-quenched gold nanoprobes exhibit selective and dose-dependent fluorescence-recovery signals upon exposure to certain oxygen species such as superoxide anion () and hydroxyl radical (·OH). The fluorescent gold nanoprobe is usefully exploited for real-time intracellular ROS detection and antioxidant screening assay, and has exciting potential for various biomedical applications as a new class of ROS imaging probes. [source] Natural-Synthetic Polyblend Nanofibers for Biomedical ApplicationsADVANCED MATERIALS, Issue 27 2009Narayan Bhattarai The ability to produce well-blended nanofibers from natural and synthetic polymers represents a significant advancement in development of composite materials with desired structures and material properties. The nanofiber presented here exhibits excellent structural stability and mechanical and biological properties favorable for biomedical applications, and offers a new nanofibrous platform for development of matrices for various biomedical applications. [source] Biomedical applications of protein chipsJOURNAL OF CELLULAR AND MOLECULAR MEDICINE, Issue 3 2002Jocelyn H. Ng Abstract The development of microchips involving proteins has accelerated within the past few years. Although DNA chip technologies formed the precedent, many different strategies and technologies have been used because proteins are inherently a more complex type of molecule. This review covers the various biomedical applications of protein chips in diagnostics, drug screening and testing, disease monitoring, drug discovery (proteomics), and medical research. The proteomics and drug discovery section is further subdivided to cover drug discovery tools (on-chip separations, expression profiling, and antibody arrays), molecular interactions and signaling pathways, the identification of protein function, and the identification of novel therapeutic compounds. Although largely focused on protein chips, this review includes chips involving cells and tissues as a logical extension of the type of data that can be generated from these microchips. [source] Synthesis and in vitro degradation of poly(N -vinyl-2-pyrrolidone)-based graft copolymers for biomedical applicationsJOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 21 2002Carl F. Brunius Abstract This work is devoted to the design of a novel family of hydrosoluble biomaterials: poly(N -vinyl-2-pyrrolidone) (PVP)-based graft copolymers. A synthesis route has been elaborated in which ,-functionalized PVP is prepared via chain-transfer radical polymerization, end-group modified, and subsequently grafted onto a polyhydroxylated backbone, typically dextran or poly(vinyl alcohol). The resulting graft copolymer biomaterials are designed for use in various biomedical applications, particularly as materials with a stronger potential for plasma expansion than already existing products have. The graft copolymers are potentially degradable because the PVP grafts are connected to the polyol backbone via a hydrolytically labile carbonate or ester linkage. The degradation of the graft copolymers was performed in vitro over a period of 6 weeks. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 3652,3661, 2002 [source] Synthesis, characterization, in vitro degradation and cytotoxicity of polyphosphazenes containing N -ethoxypyrrolidone side groupsPOLYMER INTERNATIONAL, Issue 2 2010Yunmei Bi Abstract A new biodegradable polyphosphazene (PYRMP) containing N -ethoxypyrrolidone and methoxyethoxyethoxy side groups was synthesized via a route of macromolecular substitution. The synthetic method of poly{bis[2-(2-oxo-1-pyrrolidinyl)ethoxy]phosphazene} (PYRP) was improved. The thermal properties of the polymers were investigated using differential scanning calorimetry. Degradation studies were carried out in vitro with varying pH conditions. The in vitro cytotoxicity of PYRMP and its hydrolysis products was evaluated using the methyl tetrazolium (MTT) cytotoxicity test in HepG2 cell culture. PYRMP and PYRP have low glass transition temperatures of ,68.8 and ,59.6 °C, respectively. The polymers show a higher degradation rate at pH = 5.0 than at both pH = 7.4 and 8.0. The degradation process of PYRMP in different buffer solutions is discussed. The MTT test reveals that PYRMP at concentrations below 800 µg mL,1 and its hydrolysis products are non-toxic to HepG2 cells. Moreover, the hydrolysis products diluted 10 times are able to promote cell proliferation. This study shows that polyphosphazene containing N -ethoxypyrrolidone subsituents provides interesting perspectives for various biomedical applications. Copyright © 2009 Society of Chemical Industry [source] | ||||||||||||||||||||||