scholarly journals Ion-Specific and Solvent Effects on PDADMA–PSS Complexation and Multilayer Formation

2021 ◽  
Vol 5 (3) ◽  
pp. 38
Author(s):  
Jasmina Jukić ◽  
Karla Korade ◽  
Ana-Marija Milisav ◽  
Ida Delač Marion ◽  
Davor Kovačević
Keyword(s):  
Mole Fraction ◽  
Solvent Effects ◽  
Polyelectrolyte Multilayers ◽  
Polyelectrolyte Complexes ◽  
Ethanol Mixture ◽  
Force Microscopy ◽  
Atomic Force ◽  
Bromide Ions ◽  
The Difference ◽  
Multilayer Formation

Among various parameters that influence the formation of polyelectrolyte complexes and multilayers, special emphasis should be placed on ion-specific and solvent effects. In our study, we systematically examined the above-mentioned effects on poly(diallyldimethylammonium chloride) (PDADMACl)-sodium poly(4-styrenesulfonate) (NaPSS) complexation in solution and at the surface by means of dynamic light scattering, ellipsometry and atomic force microscopy measurements. As solvents, we used water and water/ethanol mixture. The obtained results confirm the importance of ion-specific and solvent effects on complexes prepared in solution, as well as on multilayers built up on a silica surface. The experiments in mixed solvent solution showed that at a higher ethanol mole fraction, the decrease in monomer titrant to titrand ratio, at which the increase in the size of complexes is observed, takes place. The difference between chloride and bromide ions was more pronounced at a higher mole fraction of ethanol and in the case of positive complex formation, suggesting that the larger amount of bromide ions could be condensed to the polycation chain. These findings are in accordance with the results we obtained for polyelectrolyte multilayers and could be helpful for designing polyelectrolyte multilayers with tuned properties needed for various applications, primarily in the field of biomedicine.

Dynamics and metastable surface structure of double atomic layer of water molecules and ions at the interface between KBr(c) and water

2004 ◽  
Vol 76 (1) ◽  
pp. 115-122 ◽  
Author(s):  
K. Ichikawa ◽  
S. Sato ◽  
N. Shimomura
Keyword(s):  
Surface Structure ◽  
Vertical Motion ◽  
Atomic Layer ◽  
Water Molecules ◽  
Potassium Ions ◽  
Force Microscopy ◽  
Structure And Dynamics ◽  
Atomic Force ◽  
Bromide Ions

The metastable surface structure and dynamics of water molecules, cations, and anions at the interface between KBr(001) and water have been demonstrated from the images in situ observed in atomic resolution using atomic force microscopy. The vertical motion of potassium ions, which means their own transfer from the equilibrium sites to the upper height right on the underlying bromide ions, has been observed at the interface. They are used to be located in some steady state stabilized by their interaction with water molecules in the double atomic layer at the interface. The observed water molecules bridge two bromide ions by hydrogen bond; the water molecules are sandwiched by the potassium ions and vice versa.

scholarly journals Probing surface interactions of underwater oleophobic polyelectrolyte multilayers

2020 ◽  
Author(s):  
Kai Li ◽  
Wei Wang ◽  
Zhi-Peng Yu ◽  
Hang Jin ◽  
Yun-Tong Ge ◽  
...  
Keyword(s):  
Theoretical Calculations ◽  
Interaction Mechanism ◽  
Polyelectrolyte Multilayers ◽  
Layer By Layer ◽  
Surface Wetting ◽  
Force Microscopy ◽  
Atomic Force ◽  
Layer Deposition ◽  
Nacl Concentration ◽  
Force Curves

Abstract In the present work, the interaction mechanism of specific polyelectrolyte multilayers (PEMs), fabricated by layer-by-layer deposition of polydiallyldimethylammonium chloride (PDDA) and poly(sodium 4-styrenesulfonate) (PSS), is studied using atomic force microscopy. The underwater oil-repellency of PSS-capped PEMs was further explored by measuring the interaction forces between tetradecane droplets and PEMs-coated silica substrates under various salinities. The force curves were analyzed following the Stokes–Reynolds–Young–Laplace theoretical model. Desirable consistency was achieved between the experimental and theoretical calculations at low NaCl concentrations (0.1 mM and 1 mM); however, underestimation of the attractive force was found as the NaCl concentration increases to moderate (10 mM) and high (100 mM) levels. Discrepancy analyses and incorporated features toward a reduced surface charge density were considered based on the previous findings of the orientation of anionic benzenesulfonate moieties (Liu et al. in Angew Chem Int Ed 54(16):4851–4856, 2015. https://doi.org/10.1002/anie.201411992). Short-range steric hindrance interactions were further introduced to simulate “brush” effect stemming from nanoscale surface roughness. It is demonstrated in our work that the PSS-capped PEMs remains a stable underwater lipophobicity against high salinity, which renders it potential application in surface wetting modification and anti-fouling.

Growth of Double-Chained Cationic Surfactant Films on Mica

2006 ◽  
Vol 59 (6) ◽  
pp. 381 ◽  
Author(s):  
Annabelle Blom ◽  
Gregory G. Warr ◽  
Erica J. Wanless
Keyword(s):  
Atomic Force Microscopy ◽  
Alkyl Chain ◽  
Effect Of Temperature ◽  
Equilibration Time ◽  
Force Microscopy ◽  
Atomic Force ◽  
The Difference ◽  
Chain Lengths ◽  
Gel Transition

The evolution of adsorbed dialkyl chained quaternary ammonium surfactant films with different alkyl chain lengths has been observed in situ using atomic force microscopy (AFM). Both di-C12DAB and di-C14DAB form a cohesive bilayer immediately, which is observed to strengthen with equilibration time. The slow equilibrium of di-C16DAB allows examination of the film at less than saturated coverage and reveals growth of the bilayer through the nucleation and coalescence of patches. The difference in height between higher and lower regions is insufficient for bilayer and monolayer regions and the postulated structure is that of regions of bilayer with different packing densities. The effect of temperature on film morphologies near the gel transition is also examined.

scholarly journals Mismatch detection in DNA monolayers by atomic force microscopy and electrochemical impedance spectroscopy

2016 ◽  
Vol 7 ◽  
pp. 220-227 ◽  
Author(s):  
Maryse D Nkoua Ngavouka ◽  
Pietro Capaldo ◽  
Elena Ambrosetti ◽  
Giacinto Scoles ◽  
Loredana Casalis ◽  
...  
Keyword(s):  
Atomic Force Microscopy ◽  
Electrochemical Impedance Spectroscopy ◽  
Impedance Spectroscopy ◽  
Electrochemical Impedance ◽  
Complementary Sequence ◽  
Single Base ◽  
Force Microscopy ◽  
Dna Monolayers ◽  
Atomic Force ◽  
The Difference

Background: DNA hybridization is at the basis of most current technologies for genotyping and sequencing, due to the unique properties of DNA base-pairing that guarantee a high grade of selectivity. Nonetheless the presence of single base mismatches or not perfectly matched sequences can affect the response of the devices and the major challenge is, nowadays, to distinguish a mismatch of a single base and, at the same time, unequivocally differentiate devices read-out of fully and partially matching sequences. Results: We present here two platforms based on different sensing strategies, to detect mismatched and/or perfectly matched complementary DNA strands hybridization into ssDNA oligonucleotide monolayers. The first platform exploits atomic force microscopy-based nanolithography to create ssDNA nano-arrays on gold surfaces. AFM topography measurements then monitor the variation of height of the nanostructures upon biorecognition and then follow annealing at different temperatures. This strategy allowed us to clearly detect the presence of mismatches. The second strategy exploits the change in capacitance at the interface between an ssDNA-functionalized gold electrode and the solution due to the hybridization process in a miniaturized electrochemical cell. Through electrochemical impedance spectroscopy measurements on extended ssDNA self-assembled monolayers we followed in real-time the variation of capacitance, being able to distinguish, through the difference in hybridization kinetics, not only the presence of single, double or triple mismatches in the complementary sequence, but also the position of the mismatched base pair with respect to the electrode surface. Conclusion: We demonstrate here two platforms based on different sensing strategies as sensitive and selective tools to discriminate mismatches. Our assays are ready for parallelization and can be used in the detection and quantification of single nucleotide mismatches in microRNAs or in genomic DNA.

AFM Study of Untreated and Treated Fibers of Mongolian Goat Cashmere

2009 ◽  
Vol 610-613 ◽  
pp. 175-178 ◽  
Author(s):  
Namsrai Javkhlantugs ◽  
Enkhbaatar Ankhbayar ◽  
Khishigjargal Tegshjargal ◽  
Damdin Enkhjargal ◽  
Chimed Ganzorig
Keyword(s):  
Surface Roughness ◽  
Atomic Force Microscopy ◽  
Fine Structure ◽  
Ambient Conditions ◽  
Bleaching Process ◽  
Surface Change ◽  
Force Microscopy ◽  
Atomic Force ◽  
Before And After ◽  
The Difference

The morphological surface change of untreated and treated fibers of the Mongolian goat cashmere was investigated by atomic force microscopy (AFM) at ambient conditions. The cuticle scale heights of the Mongolian goat cashmere fibers were measured by the AFM for the fibers before and after treatment. The experimental results showed that the difference between the fine structure of the cuticle and surface roughness of untreated and treated fibers. We found that the surface morphological change of the cashmere fibers was strongly degraded after the bleaching process.

Aromatic polyurethanes: the effect of hard segment and chain structure on their properties

2011 ◽  
Vol 31 (2-3) ◽  
Author(s):  
Abhinay Mishra ◽  
Pralay Maiti
Keyword(s):  
Hard Segment ◽  
Tensile Modulus ◽  
Chain Structure ◽  
X Ray Diffraction ◽  
X Ray ◽  
Force Microscopy ◽  
Atomic Force ◽  
Hard Segment Content ◽  
Microscopic Studies ◽  
The Difference

Abstract Structural variation and its effect on the properties of aromatic polyurethanes (PUs) with different chain structures have been reported. Polarized optical microscopic studies of aromatic PUs demonstrate the development of micro clusters with increasing hard segment content (HSC). Higher crystallinity has also been proven from differential scanning calorimeter (DSC) and X-ray diffraction (XRD) studies. A globular pattern has been observed through atomic force microscopy (AFM) and the pattern depends on the type of diisocyanate used to prepare the PU. The difference in surface morphology is evident for two different PUs. The tensile modulus increases systematically with increasing HSC while toughness decreases, due to the presence of bigger crystallites in higher HSC polymer. Both the modulus and toughness vary on the type of diisocyanate present in PUs.

scholarly journals ГЕОМЕТРИЧЕСКИЕ И ФИЗИКО-МЕХАНИЧЕСКИЕ ПАРАМЕТРЫ ФИБРОБЛАСТОВ И РАКОВЫХ КЛЕТОК ЧЕЛОВЕКА ЛИНИЙ А549 и HEp-2c, ОЦЕНЕННЫЕ С ПОМОЩЬЮ АТОМНО-СИЛОВОЙ МИКРОСКОПИИ

2016 ◽  
pp. 60-66
Author(s):  
M. N. Starodubtseva ◽  
I. E. Starodubtsev ◽  
D. R. Petrenyov ◽  
N. I. Yegorenkov
Keyword(s):  
Cell Surface ◽  
Sliding Friction ◽  
Human Fibroblasts ◽  
Lateral Force ◽  
Geometrical Parameters ◽  
Whole Cells ◽  
Force Microscopy ◽  
Atomic Force ◽  
The Difference ◽  
Cell Contour

Using an atomic force microscopy we studied the physical and mechanical parameters of cell surface layer patches (the parameters of local sliding friction force between atomic force microscope tip and cell surface and the fractal dimension of lateral force maps) and geometrical parameters of whole cells (cell contour, topography, diameter, height and others) for treated with glutaraldehyde (0,5 %) human fibroblasts and cancer epithelial cells lines A549 (lung carcinoma) and HEp-2c (larynx carcinoma). The revealed differences in the studied parameters are indicative of the difference in the cortical cytoskeleton state of the cells.

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