Ultrahigh‐Water‐Content Photonic Hydrogels with Large Electro‐Optic Responses in Visible to Near‐Infrared Region

The embedding of photonic crystals within stimuli-responsive hydrogels has attracted tremendous interest because it provides new applications such as optical switches, displays, and sensors, among others. However, the production of electrically tunable photonic hydrogels with a wide range of color tunability, fast electrical response, and high stability for repeated use is still a challenging task. Here, electrically tunable photonic hydrogels were fabricated using ultrahigh-water-content polyelectrolyte layered hydrogels composed of thousands of bilayer domain structures. The layered hydrogel developed in this work exhibited versatile color tunability by applying an electric field parallel or perpendicular to the direction of the gel layers. The hydrogel exhibited homogeneous color tuning when a perpendicular electric field was applied, while it showed a large rainbow-like electric-optic response in the visible to near-infrared region when a parallel electric field was applied. Additionally, by a simple method using patterned electrodes, a reflective display showing the designed characters was demonstrated and maintained for hours under water without an external source of energy. Moreover, the electrically induced optical pattern can be erased, and the responsive photonic hydrogel showed excellent stability for repeated use. We anticipate that this study will provide the foundation for the development of responsive photonic hydrogels with new and large electro-optical effects for future chromatic applications

Biosynthesis of highly branched gold nanoparticles through structural engineering of fatty acids

Summary: Biomimetic approaches have been used to develop inorganic nanomaterials with complex morphologies and functions. Fatty acids are among the most important and decomposable biomolecules in nature. However, the controlled synthesis of branched gold nanoparticles using these biomolecules has not been reported. Herein, we demonstrate a strategy to produce highly branched gold nanoparticles through structural engineering of fatty acids. Furthermore, we developed a method for tailoring fatty acid molecules by altering their aliphatic chains to facilitate the morphological evolution of gold nanoparticles from spherical to branched shape. It is found that the growth of the nanoparticles is sensitive to characteristics of fatty acids, such as saturation degrees. The growth of the nanoparticle is visualized by high-speed atomic force microscopy. The reaction mechanisms and growth processes of branched gold nanoparticles are proposed. This work may serve as a cornerstone to the design in a biomimetic fashion for the controllable synthesis of metallic nanomaterials

Decoupling dual-stimuli responses in patterned lamellar hydrogels as photonic sensors

This work developed a photonic hydrogel that is responsive to, and can distinguish between two stimuli of stress and pH. Patterning is used to locally change the chemistry of a one-dimensional (1D) photonic gel, such that the native region is responsive to mechanical stress while the chemically modified region is responsive to both mechanical stress and pH. By combining the optical signals in the native region and the modified region, one can distinguish the stimuli between pH and stress. Specifically, the native 1D photonic gel is composed of periodically aligned polymeric bilayers in a soft polyacrylamide (PAAm) network. The chemical modification is done by partially hydrolyzing PAAm into sodium polyacrylic acid in some patterned regions, which imparts pH sensitivity, in addition to the stress sensitivity, to these regions

Mechano-actuated ultrafast full-colour switching in layered photonic hydrogels

Photonic crystals with tunability in the visible region are of great interest for controlling light diffraction. Mechanochromic photonic materials are periodically structured soft materials designed with a photonic stop-band that can be tuned by mechanical forces to reflect specific colours. Soft photonic materials with broad colour tunability and fast colour switching are invaluable for application. Here we report a novel mechano-actuated, soft photonic hydrogel that has an ultrafast-response time, full-colour tunable range, high spatial resolution and can be actuated by a very small compressive stress. In addition, the material has excellent mechanical stability and the colour can be reversibly switched at high frequency more than 10,000 times without degradation. This material can be used in optical devices, such as full-colour display and sensors to visualize the time evolution of complicated stress/strain fields, for example, generated during the motion of biological cells

3<i>L</i>, Three-<i>Lactobacilli</i> on Recovering of Microbiome and Immune-Damage by Cyclophosphamide Chemotherapy—A Pilot Experiment in Rats

We deal with various strains of Lactobacillus that can maintain the intestinal microbiome of rats treated with cyclophosphamide, an anticancer agent (chemotherapy). We use MiSeq and various types of statistical tests to prove that cyclophosphamide in rats alters the intestinal microbiome, favoring the growth of various fungi that are extremely harmful to intestinal metabolism. On the contrary, when Lactobacillus 3L is administered together with cyclophosphamide, we prove that the microbiome is preserved by having a much better intestinal metabolism