scholarly journals Adsorption mechanism and valency of catechol-functionalized hyperbranched polyglycerols

2015 ◽  
Vol 11 ◽  
pp. 828-836 ◽  
Author(s):  
Stefanie Krysiak ◽  
Qiang Wei ◽  
Klaus Rischka ◽  
Andreas Hartwig ◽  
Rainer Haag ◽  
...  
Keyword(s):  
Adsorption Mechanism ◽  
Molecular Level ◽  
Model System ◽  
Surface Coatings ◽  
Adhesive Bonds ◽  
Force Microscopy ◽  
Atomic Force ◽  
Aqueous Environments ◽  
End Groups ◽  
Catechol Group

Nature often serves as a model system for developing new adhesives. In aqueous environments, mussel-inspired adhesives are promising candidates. Understanding the mechanism of the extraordinarily strong adhesive bonds of the catechol group will likely aid in the development of adhesives. With this aim, we study the adhesion of catechol-based adhesives to metal oxides on the molecular level using atomic force microscopy (AFM). The comparison of single catechols (dopamine) with multiple catechols on hyperbranched polyglycerols (hPG) at various pH and dwell times allowed us to further increase our understanding. In particular, we were able to elucidate how to achieve strong bonds of different valency. It was concluded that hyperbranched polyglycerols with added catechol end groups are promising candidates for durable surface coatings.

scholarly journals Microbubbles Decorated with Dendronized Magnetic Nanoparticles for Biomedical Imaging. Effective Stabilization via Fluorous Interactions

2019 ◽  
Author(s):  
Da Shi ◽  
Justine Wallyn ◽  
Dinh-Vu Nguyen ◽  
Francis Perton ◽  
Delphine Felder-Flesch ◽  
...  
Keyword(s):  
Molar Ratio ◽  
Aqueous Dispersions ◽  
Force Microscopy ◽  
Atomic Force ◽  
Microscopy Investigation ◽  
End Groups ◽  
Mixed Films ◽  
Effective Stabilization ◽  
Effective Result ◽  
End Group

Dendrons fitted with three oligoethylene glycol (OEG) chains, one of which carrying a fluorinated or hydrogenated end group, and bearing a bisphosphonate polar head (C n X2 n +1OEG8Den, X = F or H; n= 2 or 4) were synthesized and grafted on the surface of iron oxide nanoparticles (IONPs) for microbubble-mediated imaging and therapeutic purposes. The size and stability of the dendronized IONPs (IONP@C n X2 n +1OEG8Den) in aqueous dispersions were monitored by dynamic light scattering. Investigation of the spontaneous adsorption of IONP@C n X2 n +1OEG8Den at the interface between air - or air saturated with perfluorohexane - and an aqueous phase establishes that exposure to the fluorocarbon gas markedly increases the rate of adsorption of the dendronized IONPs to the gas/water interface and decreases the equilibrium interfacial tension. This suggests that fluorous interactions are at play between the supernatant fluorocarbon gas and the fluorinated end groups of the dendrons. Furthermore, small, stable perfluorohexane-stabilized microbubbles (MBs) with a dipalmitoylphosphatidylcholine (DPPC) shell that incorporates IONP@C n X2 n +1OEG8Den (DPPC/Fe molar ratio 28:1) were prepared and characterized using both optical microscopy and an acoustical method of size determination. The dendrons fitted with fluorinated end groups lead to smaller and more stable MBs than those fitted with hydrogenated groups. The most effective result is already obtained with C2F5, for which MBs, ~1.0mm in radius, reach a half-life of ~6.0 h. An atomic force microscopy investigation of spin-coated mixed films of DPPC/IONP@C2X5OEG8Den combinations (molar ratio 28:1) shows that the IONPs grafted with the fluorinated dendrons are located within the phospholipid film, while those grafted with the hydrocarbon dendrons are completely absent from the phospholipid film.

Atomic Force Microscopy (AFM) Imaging and Force Recognition at the Molecular Level in Bacteria

2004 ◽  
Vol 10 (S02) ◽  
pp. 1094-1095
Author(s):  
David P. Allison ◽  
Claretta J. Sullivan ◽  
Jennifer L. Morrell ◽  
Peter R. Hoyt ◽  
Mitchel J. Doktycz
Keyword(s):  
Atomic Force Microscopy ◽  
Molecular Level ◽  
Force Microscopy ◽  
Atomic Force ◽  
Afm Imaging

Extended abstract of a paper presented at Microscopy and Microanalysis 2004 in Savannah, Georgia, USA, August 1–5, 2004.

Formation of assemblies on cell membranes by secreted proteins: molecular studies of free λ light chain aggregates found on the surface of myeloma cells

2013 ◽  
Vol 454 (3) ◽  
pp. 479-489 ◽  
Author(s):  
Andrew T. Hutchinson ◽  
Ansha Malik ◽  
Mark B. Berkahn ◽  
Mark Agostino ◽  
Joyce To ◽  
...  
Keyword(s):  
Light Chain ◽  
Cell Membranes ◽  
Molecular Level ◽  
Myeloma Cells ◽  
Force Microscopy ◽  
Atomic Force ◽  
Zwitterionic Lipids ◽  
Automated Docking ◽  
Chain Aggregates ◽  
Clinical Potential

We have described the presence of cell-membrane-associated κFLCs (free immunoglobulin light chains) on the surface of myeloma cells. Notably, the anti-κFLC mAb (monoclonal antibody) MDX-1097 is being assessed in clinical trials as a therapy for κ light chain isotype multiple myeloma. Despite the clinical potential of anti-FLC mAbs, there have been limited studies on characterizing membrane-associated FLCs at a molecular level. Furthermore, it is not known whether λFLCs can associate with cell membranes of myeloma cells. In the present paper, we describe the presence of λFLCs on the surface of myeloma cells. We found that cell-surface-associated λFLCs are bound directly to the membrane and in an aggregated form. Subsequently, membrane interaction studies revealed that λFLCs interact with saturated zwitterionic lipids such as phosphatidylcholine and phosphatidylethanolamine, and using automated docking, we characterize a potential recognition site for these lipids. Atomic force microscopy confirmed that membrane-associated λFLCs are aggregated. Given the present findings, we propose a model whereby individual FLCs show modest affinity for zwitterionic lipids, with aggregation stabilizing the interaction due to multivalency. Notably, this is the first study to image FLCs bound to phospholipids and provides important insights into the possible mechanisms of membrane association by this unique myeloma surface antigen.

Molecular-Scale Studies of Proteins at Model Biomaterial Surfaces by Atomic Force Microscopy

2001 ◽  
Vol 7 (S2) ◽  
pp. 124-125
Author(s):  
Christopher A. Siedlecki
Keyword(s):  
Atomic Force Microscopy ◽  
Tertiary Structure ◽  
Molecular Level ◽  
Biological Response ◽  
Initial Step ◽  
Protein Layer ◽  
Force Microscopy ◽  
Atomic Force ◽  
Biomaterial Surfaces ◽  
And Function

A widely accepted tenet of biomaterials research is that the initial step following contact of a synthetic material with blood is the rapid adsorption of plasma proteins. The composition of this adsorbed protein layer is dependent on a variety of factors, including the surface properties of the implant material and the nature of the adsorbing proteins, and the composition and function of this protein layer is important in the subsequent biological response and ultimately the success or failure of the implanted material. While a great amount of effort has gone into developing structure/function responses for implanted biomaterials, there is still much about the molecular level interactions to be determined. We utilized atomic force microscopy (AFM) to investigate the molecular-level interactions of proteins with model biomaterial substrates. The AFM is unique in that it offers the opportunity to characterize interfacial environments, determine material properties, measure protein/surface interaction forces, and visualize the tertiary structure of adsorbed proteins.

Kinetics of the Nanohydrogel Flattening at a Hydrophobic Interface

2008 ◽  
Vol 8 (7) ◽  
pp. 3386-3391
Author(s):  
ImShik Lee ◽  
Haiying Sun ◽  
Jingxia Song ◽  
Ying Zhang
Keyword(s):  
Adsorption Mechanism ◽  
Pyrolytic Graphite ◽  
Force Microscopy ◽  
Atomic Force ◽  
Dynamic Observation ◽  
Membrane Mimetic ◽  
Aqueous Conditions ◽  
Unfolding Kinetics ◽  
Kinetics Of ◽  
Hydrophobic Interface

Hydrophobitized polysaccharides were designed to form the self-assembled nanohydrogels (hydrogel nanoparticles) in the aqueous conditions. For improving their biocompatibilities, they were decorated with the biomembrane-mimetic 2-methacryloyloxyethy1 phosphory1choline (MPC) polymers. The interfacial roles of the decorated membrane-mimetic nanohydrogels were investigated by choosing MPC branched choresteryl-bearing pullulan (CHP). Tapping-mode atomic force microscopy was used to study its adsorption mechanism on the hydrophobic highly oriented pyrolytic graphite (HOPG) surface in aqueous conditions. Dynamic observation at the interfaces revealed two distinctive patterns: the immobilized nanohydrogel particles and the flatten layers. The flattening (unfolding) kinetics with and without MPC branched nanohydrogel revealed that the flattening energy was at ∼37 kBT. The flattening rate of the MPC decorated nanohydrogels was ∼1.7 times faster than that without MPC decoration, corresponding to minor reduction of the flattening activation energy.

On the Roughening of Ceramic Surfaces

1995 ◽  
Vol 399 ◽  
Author(s):  
J. R. Heffelfinger ◽  
M. W. Bench ◽  
C. B. Carter
Keyword(s):  
Electron Microscopy ◽  
Model System ◽  
Surface Form ◽  
Local Surface ◽  
Force Microscopy ◽  
Atomic Force ◽  
Transmission Electron ◽  
Ceramic Surfaces ◽  
Surface Disturbances ◽  
Nominal Surface

ABSTRACTThe faceting of single-crystal ceramic surfaces has been investigated by atomic force microscopy, scanning electron microscopy and transmission electron microscopy. Single-crystals of α-Al2O3 (alumina) with different nominal surface orientations were annealed and used as a model system to investigate the faceting of a polished ceramic surfaces. The {1010} orientation of α-alumina, which facets into a hill-and-valley morphology, provides a dramatic representation of the different stages by which a surface facets. This surface starts faceting with the growth of an individual facet. The growth of this facet creates local surface disturbances that promote the nucleation of adjacent facets; thus, domains of faceted surface form on the otherwise smooth surface. Through time, these domains coalesce and the facets coarsen into a hill-and-valley morphology. Surfaces which facet into a terrace-and-step structure, such as (0001) and {1120} surfaces of alumina, are characterized for their progression of surface faceting and are compared with the stages of faceting observed for the {1010} surface.

Pushing, pulling, dragging, and vibrating renal epithelia by using atomic force microscopy

2000 ◽  
Vol 278 (5) ◽  
pp. F689-F701 ◽  
Author(s):  
Robert M. Henderson ◽  
Hans Oberleithner
Keyword(s):  
Atomic Force Microscopy ◽  
Molecular Level ◽  
Molecular Structures ◽  
Biologically Active ◽  
Renal Physiology ◽  
Intact Cells ◽  
Force Microscopy ◽  
Physiological Conditions ◽  
Atomic Force ◽  
Near Future

Renal physiologists focus on events that take place on and around the surfaces of cells. Various techniques have been developed that follow transport functions at the molecular level, but until recently none of these techniques has been capable of making the behavior of molecular structures visible under physiological conditions. This apparent gap may be filled in the future by the application of atomic force microscopy. This technique produces an image not by optical means, but by “feeling” its way across a surface. Atomic force microscopy can, however, be modified in a number of ways, which means that besides producing a high-resolution image, it is possible to obtain several types of data on the interactions between the ultrastructural components of cell membranes (such as proteins) and other biologically active molecules (such as ATP). In this review we describe the recent use of the atomic force microscope in renal physiology, ranging from experiments in intact cells to those in isolated renal transport protein molecules, include examples of these extended applications of the technique, and point to uses that the microscope has recently found in other areas of biology that should prove fruitful in renal physiology in the near future.

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