Cremmel C.V.M.,Laboratory for Surface Science and Technology |
Kulpa A.,Advanced Materials and Process Engineering Laboratory Advanced Nanofabrication Facility University of British ColumbiaVancouver Canada |
Kappelhoff R.,Center for Blood Research |
Overall C.M.,Center for Blood Research
Journal of Biomedical Materials Research - Part A | Year: 2016
Rough surface topographies on implants attract macrophages but the influence of topography on macrophage fusion to produce multinucleated giant cells (MGC) and foreign body giant cells (FBGC) is unclear. Two rough novel grooved substrata, G1 and G2, fabricated by anisotropic etching of Silicon <110> crystals without the use of photolithographic patterning, and a control smooth surface (Pol) were produced and replicated in epoxy. The surfaces were compared for their effects on RAW264.7 macrophage morphology, gene expression, cyto/chemokine secretion, and fusion for one and five days. Macrophages on grooved surfaces exhibited an elongated morphology similar to M2 macrophages and increased cell alignment with surface directionality, roughness and cell culture time. Up-regulated expression of macrophage chemoattractants at gene and protein level was observed on both grooved surfaces relative to Pol. Grooved surfaces showed time-dependent increase in soluble mediators involved in cell fusion, CCL2 and MMP-9, and an increased proportion of multinucleated cells at Day 5. Collectively, this study demonstrated that a rough surface with surface directionality produced changes in macrophage shape and macrophage attractant chemokines and soluble mediators involved in cell fusion. These in vitro results suggest a possible explanation for the observed accumulation of macrophages and MGCs on rough surfaced implants in vivo. © 2016 Wiley Periodicals, Inc.
Moulzolf S.C.,Laboratory for Surface Science and Technology |
Frankel D.J.,Laboratory for Surface Science and Technology |
Da Cunha M.P.,Laboratory for Surface Science and Technology |
Lad R.J.,Laboratory for Surface Science and Technology |
Lad R.J.,University of Maine, United States
Proceedings of SPIE - The International Society for Optical Engineering | Year: 2013
Nanocomposite films comprised of either Pt-Rh/ZrO2 or Pt-Rh/HfO2 materials were co-deposited using multiple e-beam evaporation sources onto langasite (La3Ga5SiO 14) substrates, both as blanket films and patterned interdigital transducer electrodes for surface acoustic wave (SAW) sensor devices. The films and devices were tested after different thermal treatments in a tube furnace up to 1200°C. X-ray diffraction and electron microscopy results indicate that Pt-Rh/HfO2 films are stabilized by the formation of monoclinic HfO2 precipitates after high temperature exposure, which act as pinning sites to retard grain growth and prevent agglomeration of the conductive cubic Pt-Rh phase. The Pt-Rh/ZrO2 films were found to be slightly less stable, and contain both tetragonal and monoclinic ZrO2 precipitates that also help prevent Pt-Rh agglomeration. Film conductivities were measured versus temperature for Pt-Rh/HfO2 films on a variety of substrates, and it was concluded that La and/or Ga diffusion from the langasite substrate into the nanocomposite films is detrimental to film stability. An Al2O3 diffusion barrier grown on langasite using atomic layer deposition (ALD) was found to be effective in minimizing interdiffusion between the nanocomposite film and the langasite crystal. © 2013 SPIE.
Spratt W.K.,University of Maine, United States |
Vetelino J.F.,Laboratory for Surface Science and Technology |
Lynnworth L.C.,United Road Services
Proceedings - IEEE Ultrasonics Symposium | Year: 2010
The present study continues the torsional guided-wave temperature (T) and liquid level (H) investigation we reported in 2009. For H, the present focus was on sensor shape and other parameters that significantly influence the guided torsional stress reflection coefficient (R), signal to noise ratio (SNR), and the insertion loss (IL) at liquid/vapor and slurry/vapor interfaces. Results showed a diamond cross section has 6 times larger R and 3 times larger S than the rounded rectangle sensors used in 2009. Increasing the area of the transducer contacting a 316 Stainless Steel (SS) sensor increased the SNR 4 dB and reduced the IL by 2 dB. The torsional wave mass loading method was applied to measuring the width of a water column. The width is related to flow rate. Here we used a 100 mm long SS sensor, welded into a shallow v shape from two segments initially of diamond cross section, AR (aspect ratio) 3. The torsional through-transmitted transit time in the sensor increased from 79.4 s in air to 81.4 s when wetted by a water column of N17 mm. Response was nonlinear, attributed partly to the sensor's cross section being non-uniform in the region wet by the water column. © 2010 IEEE.
Broggini N.,University of Bern |
Tosatti S.,Laboratory for Surface Science and Technology |
Ferguson S.J.,University of Bern |
Schuler M.,Laboratory for Surface Science and Technology |
And 5 more authors.
Journal of Biomedical Materials Research - Part A | Year: 2012
Enhancing osseointegration through surface immobilization of multiple short peptide sequences that mimic extracellular matrix (ECM) proteins, such as arginine-glycine-aspartic acid (RGD) and lysine-arginine-serine-arginine (KRSR), has not yet been extensively explored. Additionally, the effect of biofunctionalizing chemically modified sandblasted and acid-etched surfaces (modSLA) is unknown. The present study evaluated modSLA implant surfaces modified with RGD and KRSR for potentially enhanced effects on bone apposition and interfacial shear strength during early stages of bone regeneration. Two sets of experimental implants were placed in the maxillae of eight miniature pigs, known for their rapid wound healing kinetics: bone chamber implants creating two circular bone defects for histomorphometric analysis on one side and standard thread configuration implants for removal torque testing on the other side. Three different biofunctionalized modSLA surfaces using poly-L-lysine-graft-poly(ethylene glycol) (PLL-g-PEG) as a carrier minimizing nonspecific protein adsorption [(i) 20 pmol cm -2 KRSR alone (KRSR); or in combination with RGD in two different concentrations; (ii) 0.05 pmol cm -2 RGD (KRSR/RGD-1); (iii) 1.26 pmol cm -2 RGD (KRSR/RGD-2)] were compared with (iv) control modSLA. Animals were sacrificed at 2 weeks. Removal torque values (701.48-780.28 N mm), bone-to-implant contact (BIC) (35.22%-41.49%), and new bone fill (28.58%-30.62%) demonstrated no significant differences among treatments. It may be concluded that biofunctionalizing modSLA surfaces with KRSR and RGD derivatives of PLL-g-PEG polymer does not increase BIC, bone fill, or interfacial shear strength. Copyright © 2011 Wiley Periodicals, Inc.
Kopf B.S.,Empa - Swiss Federal Laboratories for Materials Science and Technology |
Ruch S.,Institute Straumann AG |
Ruch S.,Laboratory for Surface Science and Technology |
Berner S.,Institute Straumann AG |
And 2 more authors.
Journal of Biomedical Materials Research - Part A | Year: 2015
Protein adsorption and blood coagulation play important roles in the early stages of osseointegration and are strongly influenced by surface properties. We present a systematic investigation of the influence of different surface properties on the adsorption of the blood proteins fibrinogen and fibronectin and the degree of early blood coagulation. Experiments on custom-made and commercially available, microroughened hydrophobic titanium (Ti) surfaces (Ti SLA-Hphob), hydrophilic (Hphil) microroughened Ti surfaces with nanostructures (Ti SLActive-HphilNS), and on bimetallic Ti zirconium alloy (TiZr, Roxolid®) samples were performed, to study the biological response in relation to the surface wettability and the presence of nanostructures (NS). Protein adsorption on the different substrates showed a highly significant effect of surface NS. Hydrophilicity alone did not significantly enhance protein adsorption. Overall, the combination of NS and hydrophilicity led to the highest adsorption levels; independent of whether Ti or TiZr were used. Hydrophilicity induced a strong effect on blood coagulation, whereas the effect of NS alone was weak. The combination of both surface characteristics led to early and most pronounced blood-coagulation. Therefore, nanostructured, hydrophilic Ti and TiZr surfaces may perform better in terms of osseointegration due to continuous protein adsorption and the formation of a layer of blood components on the implant surface. © 2015 Wiley Periodicals, Inc.
Stadler B.,Biosensors |
Stadler B.,University of Melbourne |
Blattler T.M.,Biosensors |
Blattler T.M.,Laboratory for Surface Science and Technology |
Journal of Microscopy | Year: 2010
Myoblast therapy relies on the integration of skeletal muscle stem cells into distinct muscular compartments for the prevention of clinical conditions such as heart failure, or bladder dysfunction. Understanding the fundamentals of myogenesis is hence crucial for the success of these potential medical therapies. In this report, we followed the rearrangement of the surface membrane structure and the actin cytoskeletal organization in C2C12 myoblasts at different stages of myogenesis using atomic force microscopy (AFM) and confocal laser scanning microscopy (CLSM). AFM imaging of living myoblasts undergoing fusion unveiled that within minutes of making cell-cell contact, membrane tubules appear that unite the myoblasts and increase in girth as fusion proceeds. CLSM identified these membrane tubules as built on scaffolds of actin filaments that nucleate at points of contact between fusing myoblasts. In contrast, similarly behaving membrane tubules are absent during cytokinesis. The results from our study in combination with recent findings in literature further expand the understanding of the biochemical and membrane structural rearrangements involved in the two fundamental cellular processes of division and fusion. © 2009 The Royal Microscopical Society.
Isa L.,Laboratory for Surface Science and Technology
Chimia | Year: 2013
Since the seminal work of Pickering and Ramsden more than a century ago, adsorption of solid microand nanoparticles at the interface between two fluids has been recognized as a means to enormously improve emulsion stability against coalescence. Despite their long-standing use in a vast range of practical applications, several key issues regarding the behavior of small objects at liquid interfaces still remain unresolved. In particular, current techniques fail to investigate the properties of individual particles smaller than 500 nm. An exception to this scenario is a technique that we have recently developed, based on freeze-fracture cryo-SEM, which for the first time makes it possible to measure the wetting properties of single nanoscale objects through a metal shadow-casting protocol. In this work we present additional details and results which showcase the potential of this novel tool as the benchmark for in situ characterization of particles at interfaces. © Schweizerische Chemische Gesellschaft.