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Alexander G Shard, Louise Wright, Caterina Minelli
This paper provides an empirical formula to calculate the extinction efficiencies of gold nanoparticles over the size range 1-1000 nm in fluids with refractive indexes which extend from n  = 1 to n  = 1.62. The formula contains a shape factor to account for nonspherical particles and aggregates. The empirical curves are fitted to values calculated from accurate Mie and T-Matrix theory and confirm previous descriptions which are restricted to nearly spherical particles in water of diameter between 5 and 100 nm...
November 13, 2018: Biointerphases
Fang Cheng, Mingyang Li, Xuguang Zhao, Hanqi Wang, Wei He, Xin Hua, Qing Wang, Jingping Qu
Traditional strategies for the functionalization of materials displaying hydroxyl groups either require active esterification reagents or involve the nucleophilic attack of the hydroxyl group toward electrophilic groups. The former tends to hydrolyze in aqueous solutions while the latter occurs under harsh conditions. Herein, the authors reported a new method for the functionalization of hydroxyl groups on the surface via catalytic oxa-Michael addition with vinyl sulfones. Using hydroxyl group terminated self-assembled monolayers as a model surface, a series of organocatalysts were screened and triphenylphosphine stood out for the best catalytic activity...
November 8, 2018: Biointerphases
Katarzyna Janicka, Izabella Jastrzebska, Aneta Dorota Petelska
The purpose of this study was to investigate the interaction between diosgenin analogues [DioA: diosgenin acetate (DAc) and (25 R )-5α,6β-dihydroxyspirostan-3β-ol acetate (DSol)] and cholesterol (Ch) monolayers at the air/water interface. The surface tension of pure and mixed lipid monolayers at 22 °C was measured by using the Langmuir method with a Teflon trough and a Nima 9002 tensiometer. The surface tension values were used to calculate the π-A isotherms and to determine the molecular surface areas...
November 8, 2018: Biointerphases
Shohini Sen-Britain, Wesley L Hicks, Robert Hard, Joseph A Gardella
The development of hydrogels for protein delivery requires protein-hydrogel interactions that cause minimal disruption of the protein's biological activity. Biological activity can be influenced by factors such as orientational accessibility for receptor binding and conformational changes, and these factors can be influenced by the hydrogel surface chemistry. (Hydroxyethyl)methacrylate (HEMA) hydrogels are of interest as drug delivery vehicles for keratinocyte growth factor (KGF) which is known to promote re-epithelialization in wound healing...
October 25, 2018: Biointerphases
Sean Harvey, David Yuen Wah Ng, Jolanta Szelwicka, Lisa Hueske, Lothar Veith, Marco Raabe, Ingo Lieberwirth, George Fytas, Katrin Wunderlich, Tanja Weil
Very small polydopamine (PDA) polyethylene glycol (PEG) crosslinked copolymer (PDA-PEG) nanoparticles have been prepared following a convenient one-step procedure in aqueous solution. Particle sizes and colloidal stabilities have been optimized by varying PEG in view of chain length and end group functionalities. In particular, amine-terminated PEG3000 [PEG3000 (NH2 )2 ] reacted with polydopamine intermediates so that very small, crosslinked PDA-PEG nanoparticles with sizes of less than 50 nm were formed...
October 25, 2018: Biointerphases
Elisa Migliorini, Marianne Weidenhaupt, Catherine Picart
The control over the adsorption or grafting of biomolecules from a liquid to a solid interface is of fundamental importance in different fields, such as drug delivery, pharmaceutics, diagnostics, and tissue engineering. It is thus important to understand and characterize how biomolecules interact with surfaces and to quantitatively measure parameters such as adsorbed amount, kinetics of adsorption and desorption, conformation of the adsorbed biomolecules, orientation, and aggregation state. A better understanding of these interfacial phenomena will help optimize the engineering of biofunctional surfaces, preserving the activity of biomolecules and avoiding unwanted side effects...
October 23, 2018: Biointerphases
Katharina Huttenlochner, Neda Davoudi, Christin Schlegel, Martin Bohley, Christine Müller-Renno, Jan C Aurich, Roland Ulber, Christiane Ziegler
Bacteria in flowing media are exposed to shear forces exerted by the fluid. Before a biofilm can be formed, the bacteria have to attach to a solid surface and have to resist these shear forces. Here, the authors determined dislodgement forces of single Paracoccus seriniphilus bacteria by means of lateral force microscopy. The first measurement set was performed on very flat glass and titanium (both as very hydrophilic samples with water contact angles below 20°) as well as highly oriented pyrolytic graphite (HOPG) and steel surfaces (both as more hydrophobic surfaces in the context of biological interaction with water contact angles above 50°)...
October 18, 2018: Biointerphases
Rory Breathnach, Kevin A McDonnell, Ahmed Chebbi, John J Callanan, Denis P Dowling
Chronic nonhealing wounds, particularly those complicated by multidrug resistant infections, represent a major health and economic challenge. Plasma treatment promotes wound repair due to its antimicrobial, angiogenic, and cell modulating properties. This study investigated the efficacy of the kINPen Med system in promoting healing and assessed if efficacy was enhanced by adding collagen or hyaluronic acid (HA). Two 6 mm diameter punch biopsy wounds were created on the lumbar spine of Sprague Dawley rats...
October 16, 2018: Biointerphases
Hitesh Pingle, Peng-Yuan Wang, Rosalia Cavaliere, Cynthia B Whitchurch, Helmut Thissen, Peter Kingshott
Extracellular deoxyribonucleic acid (eDNA) exists in biological environments such as those around medical implants since prokaryotic or eukaryotic cells can undergo processes such as autolysis, necrosis, and apoptosis. For bacteria, eDNA has been shown to be involved in biofilm formation and gene transfer and acts as a nutrient source. In terms of biofilm formation, eDNA in solution has been shown to be very important in increasing attachment; however, very little is known about the role played by surface immobilized eDNA in initiating bacterial attachment and whether the nature of a DNA layer (physically adsorbed or covalently attached, and molecular weight) influences biofilm formation...
October 16, 2018: Biointerphases
Michelle N Mann, Ellen R Fisher
Silver nanoparticle (AgNP)-loaded polymeric constructs are widely investigated for potential applications as drug delivery systems, wound dressings, and antibiofouling biomaterials. Herein, the authors present several methods for fabricating such materials and evaluate their efficacy against Escherichia coli . H2 O(v) plasma surface modification is employed to enhance material surface wettability (explored by water contact angle goniometry) and nanoparticle incorporation. Compositional analyses reveal that incorporation of AgNPs on the surface and bulk of the materials strongly depends on the fabrication methodology...
September 27, 2018: Biointerphases
Alexandra L Mutch, Lisbeth Grøndahl
The design of current implants produced from biodegradable polyesters is based on strength and rate of degradation and tailored by the choice of polyester used. However, detailed knowledge about the degradation mechanism of surface modified materials with applications in biomaterials science and tissue engineering is currently lacking. This perspective aims to outline the need for a greater focus on analyzing the degradation of modified polyesters to ensure they can fulfil their intended function and that degradation products can effectively be cleared from the body...
September 26, 2018: Biointerphases
Anne-Sophie Mertgen, Gökçe Yazgan, Anne Géraldine Guex, Giuseppino Fortunato, Eike Müller, Lukas Huber, René Schneider, Marzia Brunelli, René M Rossi, Katharina Maniura-Weber, Markus Rottmar
The influence of nano- or micron-sized structures on polymer films as well as the impact of fiber diameter of electrospun membranes on endothelial cell (EC) and blood response has been studied for vascular tissue engineering applications. However, the influence of surface structures on micron-sized fibers on endothelial cells and blood interaction is currently not known. In this work, electrospun membranes with distinct fiber surface structures were designed to study their influence on the endothelial cell viability and thrombogenicity...
September 24, 2018: Biointerphases
Isabela Monteiro A, Tarek Kollmetz, Jenny Malmström
While tremendous leaps in knowledge into cellular signaling and control have been achieved over the last few decades, there is still more to learn in how different signaling pathways act synergistically. A better understanding and control of cells in vitro and in vivo is important to enable more successful and safe applications of tissue engineering and stem cell therapy. This review is focused on two central ways cells sense their surroundings, namely, integrin-mediated mechanotransduction and growth factor signaling...
September 24, 2018: Biointerphases
Victoria le Ching Tan, Angelica Hinchman, Richard Williams, Phong A Tran, Kate Fox
This paper critically reviews the current evidence of research in biomedical applications of selenium nanoparticles (SeNPs) and their effects at cellular and tissue levels. In recent years, interest in SeNPs as a natural trace element nanomaterial for nanomedicine has resulted in a number of studies evaluating their bioactivities, such as anticancer, antimicrobial, and antioxidant properties. Significant data have been generated to demonstrate the effectiveness of SeNPs alone or in combination with other reagents...
September 21, 2018: Biointerphases
Phuong A H Nguyen, Lyndsay Stapleton, Adrian Ledesma-Mendoza, Darnell L Cuylear, Marta A Cooperstein, Heather E Canavan
Poly( N -isopropyl acrylamide) (pNIPAM) is a stimulus-responsive polymer that has been of great interest to the bioengineering community. When the temperature is lowered below its lower critical solution temperature (∼32 °C), pNIPAM rapidly hydrates, and adherent cells detach as intact cell sheets. This cell-releasing behavior in a physiologically relevant temperature range has led to NIPAM's use for engineered tissues and other devices. In a previous study, however, the authors found that although most techniques used to polymerize NIPAM yield biocompatible films, some formulations from commercially-available NIPAM (cpNIPAM) can be cytotoxic...
September 19, 2018: Biointerphases
Eva Bittrich, Flavia Mele, Andreas Janke, Frank Simon, Klaus-Jochen Eichhorn, Brigitte Voit, Dietmar Appelhans
The authors report on highly swellable, stable layers of spherical dendritic glycopolymers, composed of hyperbranched poly(ethylene imine) (PEI) as core and two different maltose shells (A = dense shell and B = open shell). These glycopolymers are cross-linked and attached with poly(ethylene- alt -maleic anhydride) (PEMA) or citric acid on SiOx substrates. The swelling and adsorption of biomolecules were analyzed by spectroscopic ellipsometry and quartz crystal microbalance with dissipation. The swelling degree and complexation with the drug molecule adenosine triphosphate (ATP) were found to be up to 10 times higher for dendritic glycopolymer layers cross-linked with PEMA than for layers cross-linked with citric acid...
September 18, 2018: Biointerphases
Estelle Durantie, Hana Barosova, Barbara Drasler, Laura Rodriguez-Lorenzo, Dominic A Urban, Dimitri Vanhecke, Dedy Septiadi, Liliane Hirschi-Ackermann, Alke Petri-Fink, Barbara Rothen-Rutishauser
Inhalation of combustion-derived ultrafine particles (≤0.1  μ m) has been found to be associated with pulmonary and cardiovascular diseases. However, correlation of the physicochemical properties of carbon-based particles such as surface charge and agglomeration state with adverse health effects has not yet been established, mainly due to limitations related to the detection of carbon particles in biological environments. The authors have therefore applied model particles as mimics of simplified particles derived from incomplete combustion, namely, carbon nanodots (CNDs) with different surface modifications and fluorescent properties...
September 11, 2018: Biointerphases
Yanyi Zang, Ketul C Popat, Melissa M Reynolds
Thrombosis is one of the most critical challenges faced by successful clinical use of blood-contacting medical devices. The formation of blood clots on medical device surfaces is a multistep process that includes protein adsorption, platelet adhesion and activation, and platelet aggregation, resulting in platelet consumption and blockage of blood flow. Without proper treatment, thrombosis will lead to ultimate device failure and create complications in patients. Nitric oxide (NO), a small signaling molecule generated from natural endothelial cells, has been widely shown to reduce platelet adhesion and activation, which occurs in the second step of blood clotting cascade...
September 7, 2018: Biointerphases
Daniel J Graham, Lara J Gamble
The high sputter efficiency and low damage of gas cluster ion beams have enabled depth profiling to greater depths within organic samples using time-of-flight secondary ion mass spectrometry (ToF-SIMS). Due to the typically fixed geometry of the ion sources used in ToF-SIMS, as one digs into a surface, the position sampled by ion beams shifts laterally. This causes a lateral shift in the resulting images that can become quite significant when profiling down more than one micron. Here, three methods to compensate for this image shifting are presented in order to more accurately stack the images to present a 3D representation...
September 5, 2018: Biointerphases
Anas M Sultan, Zak E Hughes, Tiffany R Walsh
How the presence of <mml:math xmlns:mml=""> <mml:msup> <mml:mrow> <mml:mi>Ca</mml:mi> </mml:mrow> <mml:mrow> <mml:mn>2</mml:mn> <mml:mo>+</mml:mo> </mml:mrow> </mml:msup> </mml:math> ions at the aqueous <mml:math xmlns:mml=""> <mml:msub> <mml:mrow> <mml:mi>TiO</mml:mi> </mml:mrow> <mml:mn>2</mml:mn> </mml:msub> </mml:math> interface influences the binding modes of two experimentally identified titania-binding peptides, Ti-1 and Ti-2, is investigated using replica exchange with solute tempering molecular dynamics simulations...
August 31, 2018: Biointerphases
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