Electron microscopy analysis of soft materials with freeze‐fracture techniques

Abstract

Electron microscopy (EM) is a technique that observes the complex microstructure of a sample with a resolution of several Å using high-energy electrons with a short wavelength. It is very effective for visualizing nanostructures that would not be observed with an optical microscope. However, there are limitations in that the observation must be carried out with a very thin film in a vacuum, and the electron beam may damage the samples. The sample may be out of the desired state or damaged, and the image may be distorted. As a solution to these problems, a freeze-fracture technique can be proposed. Freeze-fracture method is a process of rapidly freezing a sample and then fracturing it to produce a metal replica of the morphology of the bulk of the surface. This article includes an overview and principles of freeze-fracture techniques and examples of analysis of various soft structures.

On-Demand Aligned DNA Hydrogel Via Light Scanning

“…30−32 They are also investigated by scanning electron microscopy (SEM) to confirm microscopic alignment (Figure S4). 36 There are no distinct textures in the SEM images of the first, but bundlelike structures are observed on both top and crosssectional views in the light-scanned hydrogel. Based on the experimental results, the chain orientation can be schematically described in Figure 1g,h, showing random and uniaxial alignment.…”

Characterization Methods for Nanoparticle–Skin Interactions: An Overview

“…Conversely, a better resolution of NP morphology can be obtained by cryogenic electron transmission electron microscopy (cryo-TEM). The method is based on the preparation of specimens by the "thin film" technique that allows us to obtain vitrified samples by rapid immersion into liquid ethane or propane cooled to approximately −170 • C. The visualization of unstained, vitrified specimens sheds light on the supramolecular organization of nanoparticulate structures, providing high-quality images of NPs, revealing the inner organization of the particulate or vesicular disperse phases [100].…”

Patterned Hydrophobic Liquid Crystalline Fibers Fabricated from Defect Arrays of Reactive Mesogens via Electric Field Modulation

“…Liquid crystal (LC) materials have been widely studied as candidates for fabricating nano/microstructures because their morphology is easily controlled under surface treatment, − spatial confinement, − and external field applications − due to the anisotropic characteristics of the LC phase. The resulting LC structures can be used in various optical, − lithographic, − and particle-manipulating tools. ,, However, the LC material has poor mechanical properties since it is fluidic, limiting its further application and requiring unique equipment to observe its internal structure. , In this regard, reactive mesogen (RM), a liquid crystalline monomer with polymerizable end groups, has been receiving much attention along with its diverse functionalities. The polymerized RM forms an LC network (LCN), an anisotropic solid material that can be programmed with varied orientations, and the resulting LCN shows enhanced stability and programmed actuation. , In addition, a fibril polymer network is formed when less than 10 wt % RM is dispersed in a host LC and is subsequently polymerized, while a porous polymer film is formed when the concentration of the RM is higher than that .…”

“…13,22,23 However, the LC material has poor mechanical properties since it is fluidic, limiting its further application and requiring unique equipment to observe its internal structure. 24,25 In this regard, reactive mesogen (RM), a liquid crystalline monomer with polymerizable end groups, has been receiving much attention along with its diverse functionalities. The polymerized RM forms an LC network (LCN), an anisotropic solid material that can be programmed with varied orientations, and the resulting LCN shows enhanced stability 26 and programmed actuation.…”