3 research outputs found
Preparation and characterization of dual-responsive spiropyran-based random copolymer brushes via surface-initiated atom transfer radical polymerization
<p>Silica nanoparticles (SiO<sub>2</sub>) were grafted with the precursor random copolymer of 1′-(2-acryloxyethyl)-3′,3′-dimethyl-6-nitrospiro-(2H-1-benzopyran-2,2′-indoline) (SPMA) and tert-butyl methacrylate (tBMA) by surface-initiated atom transfer radical polymerization (SI-ATRP), and SiO<sub>2</sub>-g-P(SPMA-co-methacrylic acid (MAA)) was obtained via chemical hydrolysis of the resulting precursor random copolymer in acidic conditions. From transmission electron microscopy, we observed the spherical morphology of monodispersed silica nanoparticles and core-shell structure of SiO<sub>2</sub>-g-P(SPMA-co-MAA). Energy dispersive spectroscopy, Fourier transform infrared spectra, X-ray photoelectron spectroscopy, and the thermogravimetric analysis indicated that the polymer had been successfully grafted onto the surface of silica nanoparticles. The dual-responsive properties were characterized by means of ultraviolet-visible spectrophotometer and dynamic light scattering. The average hydrodynamic diameter of SiO<sub>2</sub>-g-P(SPMA-co-MAA) increased from 185.7 to 212.7 nm under ultraviolet light irradiation for 5 min. Also, the particle size of SiO<sub>2</sub>-g-P(SPMA-co-MAA) increased with the rising pH value of surrounding condition.</p
Breath-Taking Patterns: Discontinuous Hydrophilic Regions for Photonic Crystal Beads Assembly and Patterns Revisualization
Surfaces patterned
with hydrophilic and hydrophobic regions provide robust and versatile
means for investigating the wetting behaviors of liquids, surface
properties analysis, and producing patterned arrays. However, the
fabrication of integral and uniform arrays onto these open systems
remains a challenge, thus restricting them from being used in practical
applications. Here, we present a simple yet powerful approach for
the fabrication of water droplet arrays and the assembly of photonic
crystal bead arrays based on hydrophilic–hydrophobic patterned
substrates. Various integral arrays are simply prepared in a high-quality
output with a low cost, large scale, and uniform size control. By
simply taking a breath, which brings moisture to the substrate surface,
complex hydrophilic–hydrophobic outlined images can be revisualized
in the discontinuous hydrophilic regions. Integration of hydrogel
photonic crystal bead arrays into the “breath-taking”
process results in breath-responsive photonic crystal beads, which
can change their colors upon a mild exhalation. This state-of-the-art
technology not only provides an effective methodology for the preparation
of patterned arrays but also demonstrates intriguing applications
in information storage and biochemical sensors
Regulation Effects of Biomimetic Hybrid Scaffolds on Vascular Endothelium Remodeling
The
formation of complete and well-functioning endothelium is critical
for the success of tissue-engineered vascular grafts yet remaining
a fundamental challenge. Endothelium remodeling onto the lumen of
tissue-engineered vascular grafts is affected by their topographical,
mechanical, and biochemical characteristics. For meeting multiple
requirements, composite strategies have recently emerged for fabricating
hybrid scaffolds, where the integrated properties are tuned by varying
their compositions. However, the underlying principle how the integrated
properties of hybrid scaffolds regulate vascular endothelium remodeling
remains unclear. To uncover the regulation effects of hybrid scaffolds
on vascular endothelium remodeling, we prepared different biomimetic
hybrid scaffolds using gelatin methacrylamide (GelMA) and poly-ε-caprolactone
(PCL) and then investigated vascular endothelial cell responses on
them. GelMA and PCL, respectively, conferred the resulting scaffolds
with biomimetic bioactivity and mechanical properties, which were
tuned by varying GelMA/PCL mass ratios (3:1, 1:1, or 1:3). On different
GelMA/PCL hybrid scaffolds, distinct vascular endothelial cell responses
were observed. Firm cell–scaffold/cell–cell interactions
were rapidly established on the hybrid scaffolds with the highest
mass ratio of bioactive GelMA. However, they were mechanically insufficient
as vascular grafts. On the contrary, the scaffolds with the highest
mass ratio of PCL showed significantly reinforced mechanical properties
but poor biological performance. Between the two extremes, the scaffolds
with the same GelMA/PCL mass ratio balanced the pros and cons of two
materials. Therefore, they could meet the mechanical requirements
of vascular grafts and support the early-stage vascular endothelial
cell remodeling by appropriate biological signaling and mechanotransduction.
This investigation experimentally proves that scaffold bioactivity
is the dominant factor affecting vascular endothelial cell adhesion
and remodeling, whereas mechanical properties are crucial factors
for the integrity of endothelium. This work offers a universal design
strategy for desirable vascular grafts for improved endothelium remodeling