Tuning the Surface Properties of Poly(Allylamine Hydrochloride)-Based Multilayer Films

The layer-by-layer (LbL) method of polyelectrolyte multilayer (PEM) fabrication is extremely versatile. It allows using a pair of any oppositely charged polyelectrolytes. Nevertheless, it may be difficult to ascribe a particular physicochemical property of the resulting PEM to a structural or chemical feature of a single component. A solution to this problem is based on the application of a polycation and a polyanion obtained by proper modification of the same parent polymer. Polyelectrolyte multilayers (PEMs) were prepared using the LbL technique from hydrophilic and amphiphilic derivatives of poly(allylamine hydrochloride) (PAH). PAH derivatives were obtained by the substitution of amine groups in PAH with sulfonate, ammonium, and hydrophobic groups. The PEMs were stable in 1 M NaCl and showed three different modes of thickness growth: exponential, mixed exponential-linear, and linear. Their surfaces ranged from very hydrophilic to hydrophobic. Root mean square (RMS) roughness was very variable and depended on the PEM composition, sample environment (dry, wet), and the polymer constituting the topmost layer. Atomic force microscopy (AFM) imaging of the surfaces showed very different morphologies of PEMs, including very smooth, porous, and structured PEMs with micellar aggregates. Thus, by proper choice of PAH derivatives, surfaces with different physicochemical features (growth type, thickness, charge, wettability, roughness, surface morphology) were obtained.

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Deposition of Functionalised Gold Nanoparticles by the Layer-by-Layer Electrostatic Technique

MRS Proceedings ◽

10.1557/proc-789-n9.12 ◽

2003 ◽

Vol 789 ◽

Author(s):

S. Paul ◽

M. Palumbo ◽

M. C. Petty ◽

N. Cant ◽

S. D. Evans

Keyword(s):

Gold Nanoparticles ◽

Silicon Substrate ◽

Coulomb Blockade ◽

Quantum Mechanical ◽

Layer By Layer ◽

Force Microscopy ◽

Atomic Force ◽

Solid Substrates ◽

Oppositely Charged ◽

Positively Charged

ABSTRACTIntensive research is currently underway to exploit the intriguing optical and electronic behaviour of nano-sized particles. The basis of the unique properties of these particles is the smallness of their size; dimensions on the nanometre scale can result in interesting quantum mechanical phenomena, such as Coulomb blockade. There are currently a number of ways by which the nanoparticles can be deposited onto solid substrates. Here, we report on the use of the layer-by-layer electrostatic method, which has shown much promise in the context of deposition of thin films of certain organic materials. In this technique, layers of oppositely charged materials are generated by dipping an appropriate substrate into solutions of polyelectrolytes. For example, the polybases poly(ethyleneimine) (PEI), when adsorbed on a substrate, produce a positively charged surface. We have deposited carboxylic acid (-COOH) derivatised gold nanoparticles onto a PEI-coated silicon substrate and an amine funtionalised silicon substrate. The distribution of the gold nanoparticles was compared using atomic force microscopy.

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Layer-by-Layer Thin Films of Alginate/Chitosan and Hyaluronic Acid/Chitosan with Tunable Thickness and Surface Roughness

Materials Science Forum ◽

10.4028/www.scientific.net/msf.783-786.1226 ◽

2014 ◽

Vol 783-786 ◽

pp. 1226-1231 ◽

Cited By ~ 5

Author(s):

Thiago Bezerra Taketa ◽

Marisa Masumi Beppu

Keyword(s):

Thin Films ◽

Hyaluronic Acid ◽

Self Assembly ◽

Polymer Chains ◽

Layer By Layer ◽

Natural Polymers ◽

Force Microscopy ◽

Atomic Force ◽

Polyelectrolyte Solutions ◽

Oppositely Charged

Layer-by-layer (LbL) is a bottom-up technique used for construction of films with self-assembly and self-organizing properties. In most cases, the fundamental driving force for the formation of these films is originated from the electrostatic interaction between oppositely charged species. The charged segments of polyelectrolytes behave as small building units and their orientation and position can be designed to target structures of great complexity. Furthermore, the technique enables the use of various materials, including natural polymers. In this work, we chose the cationic biopolymer chitosan (CHI) and the negative polyelectrolytes sodium alginate (ALG) and hyaluronic acid (HA). The aim of this study was to evaluate the effect of ionic strength (0 versus 200 mM) and pH (3 versus 5) on ALG/CHI and HA/CHI nanostructured multilayered thin films properties. From profilometry and atomic force microscopy (AFM) analyses, changes in thickness and roughness of the coatings were monitored. The presence of salt in polyelectrolyte solutions induced the polymer chains to adopt conformations with more loops and tails and this arrangement in solution was transmitted to films, resulting in rougher surfaces. Furthermore, the film thickness can be precisely controlled by adjusting the pH of the polyelectrolyte solution. The variation of these parameters shows that it is possible to molecularly control chemical and structural properties of nanostructured coatings, thus opening up new possibilities of application (e.g. cell adhesion).

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Brittle Behaviour in Aspirin Crystals: Evidence of Spalling Fracture

10.26434/chemrxiv.13238708.v1 ◽

2020 ◽

Author(s):

Benjamin P. A. Gabriele ◽

Craig J. Williams ◽

Douglas Stauffer ◽

Brian Derby ◽

Aurora J. Cruz-Cabeza

Keyword(s):

Surface Roughness ◽

Atomic Force Microscopy ◽

Single Crystals ◽

Spalling Fracture ◽

Force Microscopy ◽

Atomic Force ◽

Afm Imaging

<div> <div> <div> <p>Single crystals of aspirin form I were cleaved and indented on their dominant face. Upon inspection, it was possible to observe strongly anisotropic shallow lateral cracks due to the extreme low surface roughness after cleavage. Atomic Force Microscopy (AFM) imaging showed spalling fractures nucleating from the indent corners, forming terraces with a height of one or two interplanar spacings d100. The formation of such spalling fractures in aspirin was rationalised using basic calculations of attachment energies, showing how (100) layers are poorly bonded when compared to their relatively higher intralayer bonding. An attempt at explaining the preferential propagation of these fractures along the [010] direction is discussed. </p> </div> </div> </div>

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Brittle Behaviour in Aspirin Crystals: Evidence of Spalling Fracture

10.26434/chemrxiv.13238708 ◽

2020 ◽

Author(s):

Benjamin P. A. Gabriele ◽

Craig J. Williams ◽

Douglas Stauffer ◽

Brian Derby ◽

Aurora J. Cruz-Cabeza

Keyword(s):

Surface Roughness ◽

Atomic Force Microscopy ◽

Single Crystals ◽

Spalling Fracture ◽

Force Microscopy ◽

Atomic Force ◽

Afm Imaging

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Atomic force microscopy analysis of native infectious and inactivated SARS-CoV-2 virions

Scientific Reports ◽

10.1038/s41598-021-91371-4 ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

Sébastien Lyonnais ◽

Mathilde Hénaut ◽

Aymeric Neyret ◽

Peggy Merida ◽

Chantal Cazevieille ◽

...

Keyword(s):

Atomic Force Microscopy ◽

Native Conformation ◽

Force Microscopy ◽

Enveloped Virus ◽

Atomic Force ◽

Afm Imaging ◽

Level 3 ◽

Microscopy Analysis ◽

Virus Morphology ◽

Nanoscale Level

AbstractSARS-CoV-2 is an enveloped virus responsible for the Coronavirus Disease 2019 (COVID-19) pandemic. Here, single viruses were analyzed by atomic force microscopy (AFM) operating directly in a level 3 biosafety (BSL3) facility, which appeared as a fast and powerful method to assess at the nanoscale level and in 3D infectious virus morphology in its native conformation, or upon inactivation treatments. AFM imaging reveals structurally intact infectious and inactivated SARS-CoV-2 upon low concentration of formaldehyde treatment. This protocol combining AFM and plaque assays allows the preparation of intact inactivated SARS-CoV-2 particles for safe use of samples out of level 3 laboratory to accelerate researches against the COVID-19 pandemic. Overall, we illustrate how adapted BSL3-AFM is a remarkable toolbox for rapid and direct virus analysis based on nanoscale morphology.

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Atomic force microscopy (AFM) imaging suggests that stromal interaction molecule 1 (STIM1) binds to Orai1 with sixfold symmetry

FEBS Letters ◽

10.1016/j.febslet.2014.06.054 ◽

2014 ◽

Vol 588 (17) ◽

pp. 2874-2880 ◽

Cited By ~ 10

Author(s):

Dilshan Balasuriya ◽

Shyam Srivats ◽

Ruth D. Murrell-Lagnado ◽

J. Michael Edwardson

Keyword(s):

Atomic Force Microscopy ◽

Force Microscopy ◽

Stromal Interaction Molecule 1 ◽

Atomic Force ◽

Afm Imaging ◽

Sixfold Symmetry

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Imaging of Xenopus laevis Oocyte Plasma Membrane in Physiological-Like Conditions by Atomic Force Microscopy

Microscopy and Microanalysis ◽

10.1017/s1431927613001682 ◽

2013 ◽

Vol 19 (5) ◽

pp. 1358-1363 ◽

Cited By ~ 3

Author(s):

Massimo Santacroce ◽

Federica Daniele ◽

Andrea Cremona ◽

Diletta Scaccabarozzi ◽

Michela Castagna ◽

...

Keyword(s):

Atomic Force Microscopy ◽

Plasma Membrane ◽

High Resolution ◽

Membrane Proteins ◽

Xenopus Laevis ◽

Functional Study ◽

Xenopus Laevis Oocyte ◽

Force Microscopy ◽

Atomic Force ◽

Afm Imaging

AbstractXenopus laevis oocytes are an interesting model for the study of many developmental mechanisms because of their dimensions and the ease with which they can be manipulated. In addition, they are widely employed systems for the expression and functional study of heterologous proteins, which can be expressed with high efficiency on their plasma membrane. Here we applied atomic force microscopy (AFM) to the study of the plasma membrane of X. laevis oocytes. In particular, we developed and optimized a new sample preparation protocol, based on the purification of plasma membranes by ultracentrifugation on a sucrose gradient, to perform a high-resolution AFM imaging of X. laevis oocyte plasma membrane in physiological-like conditions. Reproducible AFM topographs allowed visualization and dimensional characterization of membrane patches, whose height corresponds to a single lipid bilayer, as well as the presence of nanometer structures embedded in the plasma membrane and identified as native membrane proteins. The described method appears to be an applicable tool for performing high-resolution AFM imaging of X. laevis oocyte plasma membrane in a physiological-like environment, thus opening promising perspectives for studying in situ cloned membrane proteins of relevant biomedical/pharmacological interest expressed in this biological system.

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Multiple regimes of operation in bimodal AFM: understanding the energy of cantilever eigenmodes

Beilstein Journal of Nanotechnology ◽

10.3762/bjnano.4.45 ◽

2013 ◽

Vol 4 ◽

pp. 385-393 ◽

Cited By ~ 30

Author(s):

Daniel Kiracofe ◽

Arvind Raman ◽

Dalia Yablon

Keyword(s):

Single Frequency ◽

Force Microscopy ◽

Atomic Force ◽

Afm Imaging ◽

Multiple Regimes ◽

Nanoscale Imaging ◽

Relative Kinetic ◽

Series Of Experiments ◽

Tapping Mode Afm ◽

Afm Cantilever

One of the key goals in atomic force microscopy (AFM) imaging is to enhance material property contrast with high resolution. Bimodal AFM, where two eigenmodes are simultaneously excited, confers significant advantages over conventional single-frequency tapping mode AFM due to its ability to provide contrast between regions with different material properties under gentle imaging conditions. Bimodal AFM traditionally uses the first two eigenmodes of the AFM cantilever. In this work, the authors explore the use of higher eigenmodes in bimodal AFM (e.g., exciting the first and fourth eigenmodes). It is found that such operation leads to interesting contrast reversals compared to traditional bimodal AFM. A series of experiments and numerical simulations shows that the primary cause of the contrast reversals is not the choice of eigenmode itself (e.g., second versus fourth), but rather the relative kinetic energy between the higher eigenmode and the first eigenmode. This leads to the identification of three distinct imaging regimes in bimodal AFM. This result, which is applicable even to traditional bimodal AFM, should allow researchers to choose cantilever and operating parameters in a more rational manner in order to optimize resolution and contrast during nanoscale imaging of materials.

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Self-assembly layer-by-layer fabrication using porphyrin dye anion and polycation

Journal of Porphyrins and Phthalocyanines ◽

10.1142/s1088424609001030 ◽

2009 ◽

Vol 13 (07) ◽

pp. 774-778 ◽

Cited By ~ 1

Author(s):

Byung-Soon Kim ◽

Young-A Son

Keyword(s):

Ultrathin Films ◽

Self Assembly ◽

Film Surface ◽

Layer By Layer ◽

Preparation Technique ◽

Force Microscopy ◽

Atomic Force ◽

Diallyldimethylammonium Chloride ◽

Afm Analysis ◽

Progressive Growth

In this study, self-assembled alternating film using poly(diallyldimethylammonium chloride) (PDDAC) and meso-tetrakis(4-carboxyphenyl)porphyrin (MTCP) was prepared as a multilayer deposition on glass substrate. This preparation technique for dye deposition may provide new feasibilities to achieve the manufacture of ultrathin films for nanotechnology application. The deposition films were characterized by UV-vis spectrophotometer and Atomic Force Microscopy (AFM) analysis. The results of UV-vis spectra showed that the absorbance characteristic of the multilayer films linearly increased with an increased number of PDDAC and MTCP bilayers. AFM analysis showed the film surface was relatively uniform and the progressive growth of layers was determined.

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Conducting Polymer nanoComposites (CPC): Nanocharacterisation of layer by layer sprayed PMMA-CNT vapour sensors by Atomic force Microscopy in current Sensing Mode (CS-AFM)

MRS Proceedings ◽

10.1557/proc-1143-kk02-06 ◽

2008 ◽

Vol 1143 ◽

Cited By ~ 1

Author(s):

Bijandra Kumar ◽

Mickaël Castro ◽

Jianbo Lu ◽

Jean-François Feller

Keyword(s):

Atomic Force Microscopy ◽

Spray Deposition ◽

Dynamic Mode ◽

Layer By Layer ◽

Initial State ◽

Contact Mode ◽

Current Sensing ◽

Multi Wall Carbon Nanotubes ◽

Force Microscopy ◽

Atomic Force

ABSTRACTOrganic vapour sensors based on poly (methylmethacrylate)-multi-wall carbon nanotubes (PMMA-CNT) conductive polymer nanocomposite (CPC) were developed via layer by layer technique by spray deposition. CPC Sensors were exposed to three different classes of solvents (chloroform, methanol and water) and their chemo-electrical properties were followed as a function of CNTcontent in dynamic mode. Detection time was found to be shorter than that necessary for full recovery of initial state. CNT real three dimensional network has been visualized by Atomic force microscopy in a field assisted intermittent contact mode. More interestingly real conductive network system and electrical ability of CPC have been explored by current-sensing atomic force microscopy (CS-AFM). Realistic effect of voltage on electrical conductivity has been found linear.

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