AFM investigation of APAC (antiplatelet and anticoagulant heparin proteoglycan)

Antiplatelet and anticoagulant drugs are classified antithrombotic agents with the purpose to reduce blood clot formation. For a successful treatment of many known complex cardiovascular diseases driven by platelet and/or coagulation activity, the need of more than one antithrombotic agent is inevitable. However, combining drugs with different mechanisms of action enhances risk of bleeding. Dual anticoagulant and antiplatelet (APAC), a novel semisynthetic antithrombotic molecule, provides both anticoagulant and antiplatelet properties in preclinical studies. APAC is entering clinical studies with this new exciting approach to manage cardiovascular diseases. For a better understanding of the biological function of APAC, comprehensive knowledge of its structure is essential. In this study, atomic force microscopy (AFM) was used to characterize APAC according to its structure and to investigate the molecular interaction of APAC with von Willebrand factor (VWF), since specific binding of APAC to VWF could reduce platelet accumulation at vascular injury sites. By the optimization of drop-casting experiments, we were able to determine the volume of an individual APAC molecule at around 600 nm(3), and confirm that APAC forms multimers, especially dimers and trimers under the experimental conditions. By studying the drop-casting behavior of APAC and VWF individually, we depictured their interaction by using an indirect approach. Moreover, in vitro and in vivo conducted experiments in pigs supported the AFM results further. Finally, the successful adsorption of APAC to a flat gold surface was confirmed by using photothermal-induced resonance, whereby attenuated total reflection-Fourier transform infrared spectroscopy (ATR-FTIR) served as a reference method.Peer reviewe

Surface and thin film analysis: a compendium of principles, instrumentation, and applications

Surveying and comparing all techniques relevant for practical applications in surface and thin film analysis, this second edition of a bestseller is a vital guide to this hot topic in nano- and surface technology. This new book has been revised and updated and is divided into four parts - electron, ion, and photon detection, as well as scanning probe microscopy. New chapters have been added to cover such techniques as SNOM, FIM, atom probe (AP),and sum frequency generation (SFG). Appendices with a summary and comparison of techniques and a list of equipment suppliers make this book a rapid reference for materials scientists, analytical chemists, and those working in the biotechnological industry. From a Review of the First Edition (edited by Bubert and Jenett) "... a useful resource..." (Journal of the American Chemical Society)

Reversible and Irreversible Binding of Nanoparticles to Polymeric Surfaces

Reversible and irreversible binding of CdSe-nanoparticles and nanorods to polymeric surfaces via a strong, multiple hydrogen bond (= Hamilton-receptor/barbituric acid) is described. Based on ROMP-copolymers, the supramolecular interaction on a thin polymer film is controlled by living polymerization methods, attaching the Hamilton-receptor in various architectures, and concentrations. Strong binding is observed with CdSe-nanoparticles and CdSe-nanorods, whose surfaces are equipped with matching barbituric acid-moieties. Addition of polar solvents, able to break the hydrogen bonds leads to the detachment of the nanoparticles from the polymeric film. Irreversible binding is observed if an azide/alkine-“click”-reaction is conducted after supramolecular recognition of the nanoparticles on the polymeric surface. Thus reversible or irreversible attachment of the nanosized objects can be achieved

La0.6Sr0.4CoO3-δ (LSC) thin film electrodes with very fast oxygen reduction kinetics prepared by a solgel route

La0.6Sr0.4CoO3-δ (LSC) thin film electrodes of about 80 nm thickness were prepared via a sol-gel route on yttria-stabilized zirconia (YSZ) and gadolinium doped ceria (GDC) solid electrolytes. Impedance measurements on microelectrodes fabricated from these films revealed very low polarization resistances for electrochemical oxygen exchange at intermediate temperatures (500–600 ºC). Prerequisite for the very fast oxygen reduction kinetics was a limitation of the preparation (annealing) temperature to 600 ºC. Already after ca. 15 minutes annealing of the sol-gel prepared layer at this temperature, electrodes were electrochemically highly active despite low crystallinity (almost XRD amorphous). LSC electrodes on GDC showed much higher polarization resistances. However, this originated from an additional interfacial resistance rather than from kinetically slow LSC surfaces

Temperature dependence of the thermal boundary conductance in Ag–3Si/diamond composites

The effect of oxygen termination of diamond surfaces on the interface thermal conductance between Ag–3Si and diamonds is investigated in dependence of temperature by measuring thermal conductivity in the temperature range from 4 K up to ambient. Composites for O-terminated diamonds exhibit a marked maximum of 960 W m− 1 K− 1 at roughly 150 K. Calculation of the interface conductance by the differential effective medium (DEM) scheme obtained marked difference between H- and O-terminated diamond surfaces in composites and is supported by AFM force distance measurements on native, H-terminated, and O-terminated diamond single crystal (100) surfaces. O-termination can be easily induced by immersing diamonds in hot aqua regia solution

Advanced portrayal of SMIL coating by allying CZE performance with in-capillary topographic and charge-related surface characterization

International audienc