Simple yet effective methods to probe hydrogel stiffness for mechanobiology

AbstractIn spite of tremendous advances made in the comprehension of mechanotransduction, implementation of mechanobiology assays remains challenging for the broad community of cell biologists. Hydrogel substrates with tunable stiffness are essential tool in mechanobiology, allowing to investigate the effects of mechanical signals on cell behavior. A bottleneck that slows down the popularization of hydrogel formulations for mechanobiology is the assessment of their stiffness, typically requiring expensive and sophisticated methodologies in the domain of material science. Here we overcome such barriers offering the reader protocols to set-up and interpret two straightforward, low cost and high-throughput tools to measure hydrogel stiffness: static macroindentation and micropipette aspiration. We advanced on how to build up these tools and on the underlying theoretical modeling. Specifically, we validated our tools by comparing them with leading techniques used for measuring hydrogel stiffness (atomic force microscopy, uniaxial compression and rheometric analysis) with consistent results on PAA hydrogels or their modification. In so doing, we also took advantage of YAP/TAZ nuclear localization as biologically validated and sensitive readers of mechanosensing, all in all presenting a suite of biologically and theoretically proven protocols to be implemented in most biological laboratories to approach mechanobiology.

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Rapid, Refined, and Robust Method for Expression, Purification, and Characterization of Recombinant Human Amyloid-beta M1-42

10.26434/chemrxiv.7725002.v1 ◽

2019 ◽

Author(s):

Priya Prakash ◽

Travis Lantz ◽

Krupal P. Jethava ◽

Gaurav Chopra

Keyword(s):

Amyloid Beta ◽

Western Blots ◽

Force Microscopy ◽

E Coli ◽

Atomic Force ◽

Set Up ◽

Short Time

Amyloid plaques found in the brains of Alzheimer’s disease (AD) patients primarily consists of amyloid beta 1-42 (Ab42). Commercially, Ab42 is synthetized using peptide synthesizers. We describe a robust methodology for expression of recombinant human Ab(M1-42) in Rosetta(DE3)pLysS and BL21(DE3)pLysS competent E. coli with refined and rapid analytical purification techniques. The peptide is isolated and purified from the transformed cells using an optimized set-up for reverse-phase HPLC protocol, using commonly available C18 columns, yielding high amounts of peptide (~15-20 mg per 1 L culture) in a short time. The recombinant Ab(M1-42) forms characteristic aggregates similar to synthetic Ab42 aggregates as verified by western blots and atomic force microscopy to warrant future biological use. Our rapid, refined, and robust technique to purify human Ab(M1-42) can be used to synthesize chemical probes for several downstream in vitro and in vivo assays to facilitate AD research.

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Photocatalytic reduction of graphene oxide with cuprous oxide film under UV-vis irradiation

REVIEWS ON ADVANCED MATERIALS SCIENCE ◽

10.1515/rams-2020-0022 ◽

2020 ◽

Vol 59 (1) ◽

pp. 207-214 ◽

Cited By ~ 1

Author(s):

Yao Wang ◽

Jianqing Feng ◽

Lihua Jin ◽

Chengshan Li

Keyword(s):

Graphene Oxide ◽

Photoelectron Spectroscopy ◽

Low Cost ◽

Photocatalytic Reduction ◽

Force Microscopy ◽

Atomic Force ◽

Reduced Graphene ◽

Reduction Efficiency ◽

Metal Organic ◽

Reduction Effect

AbstractWe have grown Cu2O films by different routes including self-oxidation and metal-organic deposition (MOD). The reduction efficiency of Cu2O films on graphene oxide (GO) synthesized by modified Hummer’s method has been studied. Surface morphology and chemical state of as-prepared Cu2O film and GO sheets reduced at different conditions have also been investigated using atomic force microscopy (AFM) and x-ray photoelectron spectroscopy (XPS). Results show that self-oxidation Cu2O film is more effective on phtocatalytic reduction of GO than MOD-Cu2O film. Moreover, reduction effect of self-oxidation Cu2O film to GO is comparable to that of environmental-friendly reducing agent of vitamin C. The present results offer a potentially eco-friendly and low-cost approach for the manufacture of reduced graphene oxide (RGO) by photocatalytic reduction.

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Zinc Oxide Thin Film Morphology as Function of Substrate Position During Sputtering Process

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.900.103 ◽

2021 ◽

Vol 900 ◽

pp. 103-111

Author(s):

Christelle Habis ◽

Jean Zaraket ◽

Michel Aillerie

Keyword(s):

Thin Film ◽

Zinc Oxide ◽

Low Cost ◽

Linear Increase ◽

Oxide Thin Film ◽

Central Position ◽

Zinc Oxide Thin Film ◽

Force Microscopy ◽

Atomic Force ◽

Great Transparency

Transparent conductive oxides are materials combining great transparency with high conductivity. In photovoltaic applications, they are developed under thin layer for the realization of upper electrodes of solar cells. Among transparent oxide materials, Zinc Oxide (ZnO) presents unique properties, starting with its first qualities to be abundant, low-cost and non-toxic oxide. Zinc Oxide thin film was deposited on rectangular glass substrate by magnetron sputtering. After an overview of the properties expected for good transparent conductive materials, the effect of distance from the center of the cell on the morphology of the film was investigated by Atomic Force Microscopy (AFM). The scanning was done on different area of the sample as function of the distance from the central position of the direct sputtering jet. As far as the distance increased, it has been noticed a quasi-linear increase in thickness of the ZnO deposited film and a change in the grain shape from spherical to pyramidal with an increase in the size of the particles. Controlling the sputtering distance allows the control of texture, thus of the Haze factor, the photo-generation of excitons, as well the optical transmission of the TCO layer and finally an improvement in the efficiency of the so-built photovoltaic cells.

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Design and Construction of Low Temperature Attachment for Commercial AFM

Solid State Phenomena ◽

10.4028/www.scientific.net/ssp.209.137 ◽

2013 ◽

Vol 209 ◽

pp. 137-142

Author(s):

Abrarkhan M. Pathan ◽

Dhawal H. Agrawal ◽

Pina M. Bhatt ◽

Hitarthi H. Patel ◽

U.S. Joshi

Keyword(s):

Atomic Force Microscope ◽

Cryogenic Temperature ◽

Low Cost ◽

Perovskite Manganite ◽

Atomic Force ◽

Structure Of Nanomaterials ◽

Negative Bending ◽

Set Up ◽

Free Environment ◽

Repulsive Forces

With the rapid advancements in the field of nanoscience and nanotechnology, scanning probe microscopy has become an integral part of a typical R&D lab. Atomic force microscope (AFM) has become a familiar name in this category. The AFM measures the forces acting between a fine tip and a sample. The tip is attached to the free end of a cantilever and is brought very close to a surface. Attractive or repulsive forces resulting from interactions between the tip and the surface will cause a positive or negative bending of the cantilever. The bending is detected by means of a laser beam, which is reflected from the backside of the cantilever. Atomic force microscopy is currently applied to various environments (air, liquid, vacuum) and types of materials such as metal semiconductors, soft biological samples, conductive and non-conductive materials. With this technique size measurements or even manipulations of nano-objects may be performed. An experimental setup has been designed and built such that a commercially available Atomic Force Microscope (AFM) (Nanosurf AG, Easyscan 2) can be operated at cryogenic temperature under vacuum and in a vibration-free environment. The design also takes care of portability and flexibility of AFM i.e. it is very small, light weight and AFM can be used in both ambient and cryogenic conditions. The whole set up was assembled in-house at a fairly low cost. It is used to study the surface structure of nanomaterials. Important perovskite manganite Pr0.7Ca0.3MnO3thin films were studied and results such as morphology, RMS area and line roughness as well as the particle size have been estimated at cryogenic temperature.

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Novel Flexible NH3 Gas Sensor Prepared by Ink-Jet Printing Technique

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.506.39 ◽

2012 ◽

Vol 506 ◽

pp. 39-42 ◽

Cited By ~ 9

Author(s):

C. Wongchoosuk ◽

P. Jangtawee ◽

P. Lokavee ◽

S. Udomrat ◽

P. Sudkeaw ◽

...

Keyword(s):

Gas Sensor ◽

Low Cost ◽

Metal Electrode ◽

Ink Jet Printing ◽

Force Microscopy ◽

Sensing Mechanism ◽

Atomic Force ◽

Ink Jet ◽

Polymer Metal ◽

Jet Printing

We have fabricated a low-cost and flexible NH3 gas sensor using thermal ink-jet printing. The poly (3,4-ethylene dioxythiophene) doped with polystyrene sulfonated acid (PEDOT/PSS) with thickness of ~ 2 μm was used as a sensing film. The interdigitated electrode using patterned aluminum plate was attached over the sensing film. Atomic force microscopy results show the high homogeneous film and only small roughness is presented on the sensing film. This sensor exhibits high selectivity and sensitivity to NH3 at room temperature. The sensor response works linearly with gas concentrations between 100-1000 ppm. The modulation of conducting polymer/metal electrode interface plays a role in the sensing mechanism of NH3. Changes in the position of interdigitated electrodes can change the dominant sensing mechanism of typical polymer gas sensor.

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The Attachment of Carbon Nanotube on a Blunt AFM Tip Using Electric Fields

Electronic and Photonic Packaging, Electrical Systems Design and Photonics, and Nanotechnology ◽

10.1115/imece2004-61549 ◽

2004 ◽

Author(s):

Hyung Woo Lee ◽

Soon Geun Kwon ◽

Soo Hyun Kim ◽

Yoon Keun Kwak ◽

Chang Soo Han

Keyword(s):

Carbon Nanotubes ◽

Atomic Force Microscopy ◽

Carbon Nanotube ◽

Electric Fields ◽

Low Cost ◽

Reliable Technique ◽

Force Microscopy ◽

Atomic Force

We report a simple, low cost, reliable technique of making carbon nanotube (CNT) modified atomic force microscopy (AFM) tip. We used the dielectrophoresis and the electrophoresis to align and deposit carbon nanotubes on the end of the AFM tip. From the simulation and the various experiments, we obtained the optimal electric condition, 0.32Vpp/μm. Also, we found that the blunt shape of the tip’s apex is more effective than sharpened one. Through the experiments, we verified that the blunt shape is more effective over 50% than the sharpened one in the attachment of CNTs. By comparing the scanning results between the CNT modified tip and a normal AFM tip, we obtained the improvement in efficiency of 23%.

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UV-Polymerized Vinylimidazolium Ionic Liquids for Permselective Membranes

Membranes ◽

10.3390/membranes10110308 ◽

2020 ◽

Vol 10 (11) ◽

pp. 308

Author(s):

Fridolin O. Sommer ◽

Jana-Sophie Appelt ◽

Ingo Barke ◽

Sylvia Speller ◽

Udo Kragl

Keyword(s):

Ionic Liquids ◽

Material Science ◽

Membrane Properties ◽

Free Standing ◽

Surface Conditions ◽

Force Microscopy ◽

Atomic Force ◽

Neutral Compounds ◽

Universal Approach ◽

Alkyl Side Chains

Ionic liquids are highly charged compounds with increasing applications in material science. A universal approach to synthesize free-standing, vinylalkylimidazolium bromide-containing membranes with an adjustable thickness is presented. By the variation of alkyl side chains, membrane characteristics such as flux and mechanical properties can be adjusted. The simultaneous use of different ionic liquids (ILs) in the synthesis can also improve the membrane properties. In separation application, these charged materials allowed us to retain charged sugars, such as calcium gluconate, by up to 95%, while similar neutral compounds such as glucose passed the membrane. An analysis of the surface conditions using atomic force microscopy (AFM) confirmed the experimental data and explains the decreasing permeance and increased retention of the charged sugars.

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Atomic Force Microscopy in Microbiology: New Structural and Functional Insights into the Microbial Cell Surface

mBio ◽

10.1128/mbio.01363-14 ◽

2014 ◽

Vol 5 (4) ◽

Cited By ~ 92

Author(s):

Yves F. Dufrêne

Keyword(s):

Atomic Force Microscopy ◽

Cell Surface ◽

Cell Surface Molecules ◽

Microbial Cells ◽

Force Microscopy ◽

Surface Molecules ◽

Atomic Force ◽

Important Research Topic ◽

Sense And Respond ◽

Made In

ABSTRACT Microbial cells sense and respond to their environment using their surface constituents. Therefore, understanding the assembly and biophysical properties of cell surface molecules is an important research topic. With its ability to observe living microbial cells at nanometer resolution and to manipulate single-cell surface molecules, atomic force microscopy (AFM) has emerged as a powerful tool in microbiology. Here, we survey major breakthroughs made in cell surface microbiology using AFM techniques, emphasizing the most recent structural and functional insights.

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Enhanced Physical Absorption Properties of ZnO Nanorods by Electrostatic Self-Assembly with Reduced Graphene Oxide and Decorated with Silver and Copper Nanoparticles

Iraqi Journal of Physics (IJP) ◽

10.30723/ijp.v19i48.619 ◽

2021 ◽

Vol 19 (48) ◽

pp. 66-78

Author(s):

Lina Zeki Yahiya ◽

Mohamed K. Dhahir

Keyword(s):

Self Assembly ◽

Low Cost ◽

Zno Nanorods ◽

Zinc Oxide Nanorods ◽

Environmental Friendliness ◽

Force Microscopy ◽

Atomic Force ◽

Transmission Electron ◽

Oxide Nanorods ◽

Scale Preparation

The preparation and characterization of innovative nanocomposites based on zinc oxide nanorods (ZNR) encapsulated by graphene (Gr) nanosheets and decorated with silver (Ag), and cupper (Cu) nanoparticles (NP) were studied. The prepared nanocomposites (ZNR@Gr/Cu-Ag) were examined by different techniques including Field Emission Scanning Electron Microscope (FESEM), Transmission electron microscopy (TEM), Atomic force microscopy (AFM), UV-Vis spectrophotometer and fluorescence spectroscopy. The results showed that the ZNR has been good cover by five layers of graphene and decorated with Ag and Cu NPs with particles size of about 10-15 nm. The ZNR@Gr/Cu-Ag nanocomposites exhibit high absorption behavior in ultraviolet (UV) region of spectrum. In comparison with ZNR, the ZNR@Gr/Cu-Ag nanocomposites reveal superior absorption in the entire region of 387–1000 nm. Moreover, the band gap decreases from 3.2 eV of ZNR to 1.2 eV for ZNR@Gr/Cu-Ag nanocomposites. Taking into account the superiority of ZNR@Gr/Cu-Ag nanocomposites in terms of easy fabrication, low cost method, and environmental friendliness which made it favorable for huge-scale preparation in many applications such as water splitting, sensor, solar cell, antibacterial and optoelectronic devices.

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Investigation of WO3 Electrodeposition Leading to Nanostructured Thin Films

Nanomaterials ◽

10.3390/nano10081493 ◽

2020 ◽

Vol 10 (8) ◽

pp. 1493

Author(s):

G. Mineo ◽

F. Ruffino ◽

S. Mirabella ◽

E. Bruno

Keyword(s):

Energy Gap ◽

Rutherford Backscattering Spectrometry ◽

Low Cost ◽

Tungstic Acid ◽

X Ray Diffraction ◽

Cathodic Current ◽

Force Microscopy ◽

Atomic Force ◽

Gap Measurement ◽

Instantaneous Nucleation

Nanostructured WO3 represents a promising material for electrochromic and sensing devices. In this scenario, electrodeposition is a promising low-cost approach for careful production. The electrodeposition of tungsten oxide film from a peroxo-tungstic-acid (PTA) solution is investigated. WO3 is synthetized onto Indium doped Tin Oxide (ITO) substrates, in a variety of shapes, from a fragmentary, thin layer up to a thick continuous film. Samples were investigated by scanning electron (SEM) and atomic force microscopy (AFM), Rutherford backscattering spectrometry (RBS), X-ray Diffraction analysis (XRD), energy gap measurement. Electrodeposition current curves are compared with characterization results to model the growth process. Early stages of electrodeposition are characterized by a transient cathodic current revealing an instantaneous nucleation followed by a diffusion limited process. A quantitative analysis of W deposition rate and current at working electrode validates a microscopic model for WO3 electrodeposition driving the process towards nanostructured versus continuous WO3 film.

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