Soft glassy rheology of single cells with pathogenic protein aggregates.

A correlation between the mechanical properties of cells and various diseases has been emerging in recent years. Atomic force microscopy (AFM) has been widely used to measure a single cell's apparent Young's modulus by treating it as a fully elastic object. More recently, quantitative characterization of the complete viscoelasticity of single cells has become possible.

Protocol for measuring mechanical properties of live cells using atomic force microscopy.

Atomic force microscope (AFM) is a powerful and versatile tool to determine the physical properties of cells. The force-distance curves obtained from AFM experiments can be used to determine the stiffness and viscoelastic properties of cells. Here, we present a protocol for the determination of viscoelasticity from live cells such as Drosophila hemocytes or mouse embryonic stem cells using AFM.

Direct and Simultaneous Measurement of the Stiffness and Internal Friction of a Single Folded Protein.

The nanomechanical response of a folded single protein, the natural nanomachine responsible for myriad biological processes, provides insight into its function. The conformational flexibility of a folded state, characterized by its viscoelasticity, allows proteins to adopt different shapes to perform their function. Despite efforts, its direct measurement has not been possible so far.

Resistive Switching in HfO/LaSrMnO Heterostructures: An Intriguing Case of Low H-Field Susceptibility of an E-Field Controlled Active Interface.

High-performance nonvolatile resistive random access memories (ReRAMs) and their small stimuli control are of immense interest for high-speed computation and big-data processing in the emerging Internet of Things (IoT) arena. Here, we examine the resistive switching (RS) behavior in growth-controlled HfO/LaSrMnO (LSMO) heterostructures and their tunability in a low magnetic field. It is demonstrated that oxygen-deficient HfO films show bipolar switching with a high on/off ratio, stable retention, as well as good endurance owing to the orthorhombic-rich phase constitution and charge (de)trapping-enabled Schottky-type conduction.

Validity of point-mass model in off-resonance dynamic atomic force microscopy.

The quantitative measurement of viscoelasticity of nano-scale entities is an important goal of nanotechnology research and there is considerable progress with advent of dynamic atomic force microscopy. The hydrodynamics of cantilever, the force sensor in AFM measurements, plays a pivotal role in quantitative estimates of nano-scale viscoelasticity. The point-mass (PM) model, wherein the AFM cantilever is approximated as a point-mass with mass-less spring is widely used in dynamic AFM analysis and its validity, particularly in liquid environments, is debated.

Mechanism of Adhesion of Natural Polymer Coatings to Chemically Modified Siloxane Polymer.

Surface coatings play an important role in improving the performance of biomedical implants. Polydimethylsiloxane (PDMS) is a commonly used material for biomedical implants, and surface-coated PDMS implants frequently face problems such as delamination or cracking of the coating. In this work, we have measured the performance of nano-coatings of the biocompatible protein polymer silk fibroin (SF) on pristine as well as modified PDMS surfaces.

The nano-scale viscoelasticity using atomic force microscopy in liquid environment.

We measured viscoelasticity of two nanoscale systems, single protein molecules and molecular layers of water confined between solid walls. In order to quantify the viscoelastic response of these nanoscale systems in liquid environment, the measurements are performed using two types of atomic force microscopes (AFMs), which employ different detection schemes to measure the cantilever response. We used a deflection detection scheme, available in commercial AFMs, that measures cantilever bending and a fibre-interferometer based detection which measures cantilever displacement.

Differential tissue stiffness of body column facilitates locomotion of on solid substrates.

The bell-shaped members of the Cnidaria typically move around by swimming, whereas the polyp can perform locomotion on solid substrates in an aquatic environment. To address the biomechanics of locomotion on rigid substrates, we studied the 'somersaulting' locomotion in We applied atomic force microscopy to measure the local mechanical properties of 's body column and identified the existence of differential Young's modulus between the shoulder region versus rest of the body column at 3:1 ratio. We show that somersaulting primarily depends on differential tissue stiffness of the body column and is explained by computational models that accurately recapitulate the mechanics involved in this process.