3 research outputs found
Biobased Wrinkled Surfaces Induced by Wood Mimetic Skins upon Drying: Effect of Mechanical Properties on Wrinkle Morphology
We
previously developed biobased wrinkled surfaces based on wood mimetic
skins in which microscopic wrinkles were fabricated on a chitosan
film by immersion in a phenolic acid solution, horseradish peroxidase-catalyzed
surface reaction, and drying. Here, we prepared a diverse range of
wrinkled films by immersion treatment at 30, 40, 50, and 60 °C
in <i>p</i>-coumaric acid and then investigated the correlation
between wrinkle morphology and mechanical properties. Wrinkle wavelengths gradually decreased as the immersion temperature
increased as well as the previous report. In order to clarify the
mechanisms responsible for the different wrinkle morphologies, the
films were subjected to elastic moduli measurement and GPC analysis
after immersion treatment. These experiments provided evidence that
the chitosan around the film surface decomposed along with the immersion
process. The decomposition was accelerated by higher immersion temperature,
suggesting that higher temperatures led to the formation of softer
skins, inducing smaller wrinkles. In fact, wrinkle morphologies with
this system were predominately determined by the hardness of the wood
mimetic skins. This phenomenon is consistent with the fundamentals
of surface wrinkling in nature. This study is the first to demonstrate
that artificial wrinkling triggered by water evaporation can be controlled
by precise control of the surface hardness of soft material
Molecular Complex Composed of β‑Cyclodextrin-Grafted Chitosan and pH-Sensitive Amphipathic Peptide for Enhancing Cellular Cholesterol Efflux under Acidic pH
Excess
of cholesterol in peripheral cells is known to lead to atherosclerosis.
In this study, a molecular complex composed of β-cyclodextrin-grafted
chitosan (BCC) and cellular cholesterol efflux enhancing peptide (CEEP),
synthesized by modifying pH sensitive amphipathic GALA peptide, is
introduced with the eventual aim of treating atherosclerosis. BCC
has a markedly enhanced ability to induce cholesterol efflux from
cell membranes compared to β-cyclodextrin, and the BCC-CEEP
complex exhibited a 2-fold increase in cellular cholesterol efflux
compared to BCC alone under weakly acidic conditions. Isothermal titration
calorimetry and fluorescence spectroscopy measurements demonstrated
that the random coil structure of CEEP at neutral pH converted to
the α-helical structure at acidic pH, resulting in a three-order
larger binding constant to BCC (<i>K</i> = 3.7 × 10<sup>7</sup> at pH 5.5) compared to that at pH 7.4 (<i>K</i> = 7.9 × 10<sup>4</sup>). Such high-affinity binding of CEEP
to BCC at acidic pH leads to the formation of 100-nm-sized aggregate
with positive surface charge, which would efficiently interact with
cell membranes and induce cholesterol efflux. Since the cholesterol
efflux ability of HDL is thought to be impaired under acidic environments
in advanced atherosclerotic lesions, the BCC-CEEP complex might serve
as a novel nanomaterial for treating atherosclerosis
Nanoporous Carbon Sensor with Cage-in-Fiber Structure: Highly Selective Aniline Adsorbent toward Cancer Risk Management
Carbon nanocage-embedded nanofibrous
film works as a highly selective adsorbent of carcinogen aromatic
amines. By using quartz crystal microbalance techniques, even ppm
levels of aniline can be repetitively detected, while other chemical
compounds such as water, ammonia, and benzene give negligible responses.
This technique should be applicable for high-throughput cancer risk
management