Simultaneous Determination of E, G and ν of Soft Hydrogels Using Theory of Elasticity

2009 ◽  
Author(s):  
Uday Chippada ◽  
Xue Jiang ◽  
Lulu Li ◽  
Rene Schloss ◽  
Bernard Yurke ◽  
...  
Keyword(s):  
Poisson’S Ratio ◽  
Theory Of Elasticity ◽  
Complete Characterization ◽  
Poisson's Ratio ◽  
Force Microscopy ◽  
Cellular Processes ◽  
Atomic Force ◽  
Significant Research

Hydrogels have been used as substrates by many researchers in the study of cellular processes. The mechanical properties of these gels play a significant role in the growth of the cells. Significant research using several methods like compression, indentation, atomic force microscopy and manipulation of beads has been performed in the past to characterize the stiffness of these substrates. However, most of the methods employed assume the gel to be incompressible, with a Poisson’s ratio of 0.5. However, Poisson’s ratio can differ from 0.5. Hence, a more complete characterization of the elastic properties of hydrogels requires that one experimentally obtain the value of at least two of the three quantities: Poisson’s ratio, shear modulus, and elastic modulus.

scholarly journals DETERMINATION OF FILLER STRUCTURE IN SILICA-FILLED SBR COMPOUNDS BY MEANS OF SAXS AND AFM

2015 ◽  
Vol 88 (4) ◽  
pp. 690-710 ◽  
Author(s):  
Jon Otegui ◽  
Luis A. Miccio ◽  
Arantxa Arbe ◽  
Gustavo A. Schwartz ◽  
Mathias Meyer ◽  
...  
Keyword(s):  
Force Microscopy ◽  
X Ray Scattering ◽  
Atomic Force ◽  
Filled Rubber ◽  
Rubber Compounds ◽  
Primary Particles ◽  
Styrene Butadiene ◽  
Filler Structure

ABSTRACT The structure of the silica particles network in two different solution styrene–butadiene rubbers (S-SBRs) was studied by means of small-angle X-ray scattering (SAXS) and atomic force microscopy (AFM). S-SBR compounds with different silica contents were analyzed in comparison with their oil extended counterparts. A study into the application of SAXS experiments was defined to quantify the structures of silica primary particles and clusters in filled rubber compounds up to very high levels of filler content. We propose a modified structure model that is physically more sound than the widely used Beaucage model and that leads to more robust quantification of the silica structures. In addition, an independent characterization of the filler structure was performed by means of AFM. The cluster and particle sizes deduced from both techniques are in close agreement, supporting the proposed approach. The synergetic application of SAXS and AFM allows a consistent and robust characterization of primary particles and clusters in terms of size and structure. These results were compared and discussed in the framework of previously published works.

Characterization of Surface Nanostructures on“Thin” Polyolephine Foils

2014 ◽  
Vol 27 ◽  
pp. 31-39
Author(s):  
Alena Řezníčková ◽  
Zdeňka Kolská ◽  
Petr Sajdl ◽  
Václav Švorčík
Keyword(s):  
Contact Angle ◽  
Surface Properties ◽  
Surface Polarity ◽  
X Ray ◽  
Force Microscopy ◽  
Complex Information ◽  
Atomic Force ◽  
Surface Nanostructures

Surface properties of nanostructures on 7 polyolephine foils were characterized using different analytical methods to discuss an effect of halogen presence in polymer chain to surface properties. Both sides of these foils were examined and compared. Surface roughness and morphology were determined by atomic force microscopy, contact angle by goniometry, surface polarity by electrokinetic analysis. X-ray photoelectron and ultraviolet visible spectroscopies were used for determination of surface chemistry. Combination of different analyses gives complex information about surface properties of the foils, which may be of importance for any future experiments, as well as for their application e.g. in tissue engineering and electronics.

scholarly journals Micromechanical Characterization of Complex Polypropylene Morphologies by HarmoniX AFM

2017 ◽  
Vol 2017 ◽  
pp. 1-12 ◽  
Author(s):  
S. Liparoti ◽  
A. Sorrentino ◽  
V. Speranza
Keyword(s):  
Elastic Moduli ◽  
Force Microscopy ◽  
Atomic Force ◽  
Indentation Tests ◽  
Injection Molded ◽  
Micromechanical Characterization ◽  
Complex Polymer ◽  
Good Agreement

This paper examines the capability of the HarmoniX Atomic Force Microscopy (AFM) technique to draw accurate and reliable micromechanical characterization of complex polymer morphologies generally found in conventional thermoplastic polymers. To that purpose, injection molded polypropylene samples, containing representative morphologies, have been characterized by HarmoniX AFM. Mapping and distributions of mechanical properties of the samples surface are determined and analyzed. Effects of sample preparation and test conditions are also analyzed. Finally, the AFM determination of surface elastic moduli has been compared with that obtained by indentation tests, finding good agreement among the results.

scholarly journals Function of Hemoglobin-Based Oxygen Carriers: Determination of Methemoglobin Content by Spectral Extinction Measurements

2021 ◽  
Vol 22 (4) ◽  
pp. 1753
Author(s):  
Kathrin Smuda ◽  
Jonas Gienger ◽  
Philipp Hönicke ◽  
Jörg Neukammer
Keyword(s):  
Light Scattering ◽  
Cross Sections ◽  
Oxygen Carriers ◽  
Extinction Cross Section ◽  
X Ray ◽  
Force Microscopy ◽  
Atomic Force ◽  
Analytical Centrifugation

Suspensions of hemoglobin microparticles (HbMPs) are promising tools as oxygen therapeutics. For the approval of clinical studies extensive characterization of these HbMPs with a size of about 750 nm is required regarding physical properties, function, pharmaco-kinetics and toxicology. The standard absorbance measurements in blood gas analyzers require dissolution of red blood cells which does not work for HbMP. Therefore, we have developed a robust and rapid optical method for the quality and functionality control of HbMPs. It allows simultaneous determination of the portion of the two states of hemoglobin oxygenated hemoglobin (oxyHb) and deoxygenated hemoglobin (deoxyHb) as well as the content of methemoglobin (metHb). Based on the measurement of collimated transmission spectra between 300 nm and 800 nm, the average extinction cross section of HbMPs is derived. A numerical method is applied to determine the composition of the HbMPs based on their wavelength-dependent refractive index (RI), which is a superposition of the three different states of Hb. Thus, light-scattering properties, including extinction cross sections can be simulated for different compositions and sizes. By comparison to measured spectra, the relative concentrations of oxyHb, deoxyHb, metHb are accessible. For validation of the optically determined composition of the HbMPs, we used X-ray fluorescence spectrometry for the ratio of Fe(II) (oxyHb/deoxyHb) and Fe(III) (metHb). High accuracy density measurements served to access heme-free proteins, size was determined by dynamic light scattering and analytical centrifugation and the shape of the HbMPs was visualized by electron and atomic force microscopy.

scholarly journals Liposomes with Caffeic Acid: Morphological and Structural Characterisation, Their Properties and Stability in Time

Processes ◽  
2021 ◽  
Vol 9 (6) ◽  
pp. 912
Author(s):  
Ioana Lavinia Dejeu ◽  
Laura Grațiela Vicaș ◽  
Tunde Jurca ◽  
Alin Cristian Teușdea ◽  
Mariana Eugenia Mureșan ◽  
...  
Keyword(s):  
Zeta Potential ◽  
Caffeic Acid ◽  
Pharmaceutical Research ◽  
Entrapment Efficiency ◽  
Multivariate Statistical ◽  
Structural Characterisation ◽  
Force Microscopy ◽  
Atomic Force

Medical and pharmaceutical research has shown that liposomes are very efficient in transporting drugs to targets. In this study, we prepared six liposome formulas, three in which we entrapped caffeic acid (CA), and three with only phospholipids and without CA. Determination of entrapment efficiency (EE) showed that regardless of the phospholipids used, the percentage of CA entrapment was up to 76%. The characterization of the liposomes was performed using Dynamic Light Scattering (DLS), Atomic Force Microscopy (AFM), zeta potential and polydispersity and showed that about 75–99% of the liposomes had dimensions between 40 ± 0.55–500 ± 1.45 nm. The size and zeta potential of liposomes were influenced by the type of phospholipid used to obtain them. CA release from liposomes was performed using a six-cell Franz diffusion system, and it was observed that the release of entrapped CA occurs gradually, the highest amount occurring in the first eight hours (over 80%), after which the release is much reduced. Additionally, the time stability of the obtained liposomes was analysed using univariate and multivariate statistical analysis. Therefore, liposomes offer great potential in CA entrapment.

scholarly journals Contact-free experimental determination of the static flexural spring constant of cantilever sensors using a microfluidic force tool

2016 ◽  
Vol 7 ◽  
pp. 492-500
Author(s):  
John D Parkin ◽  
Georg Hähner
Keyword(s):  
Noise Spectrum ◽  
Spring Constant ◽  
Nanoelectromechanical Systems ◽  
Force Microscopy ◽  
Cantilever Sensors ◽  
Atomic Force ◽  
Wide Range ◽  
Contact Free

Micro- and nanocantilevers are employed in atomic force microscopy (AFM) and in micro- and nanoelectromechanical systems (MEMS and NEMS) as sensing elements. They enable nanomechanical measurements, are essential for the characterization of nanomaterials, and form an integral part of many nanoscale devices. Despite the fact that numerous methods described in the literature can be applied to determine the static flexural spring constant of micro- and nanocantilever sensors, experimental techniques that do not require contact between the sensor and a surface at some point during the calibration process are still the exception rather than the rule. We describe a noncontact method using a microfluidic force tool that produces accurate forces and demonstrate that this, in combination with a thermal noise spectrum, can provide the static flexural spring constant for cantilever sensors of different geometric shapes over a wide range of spring constant values (≈0.8–160 N/m).

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