13 research outputs found
High-Performance Strain Sensors Based on Spirally Structured Composites with Carbon Black, Chitin Nanocrystals, and Natural Rubber
In this research,
a new type of conductive composite with high
tensile strength, high elasticity, and cost competitiveness has been
developed through solution mixing–spraying–rolling methods.
Naturel rubber (NR) latex with chitin nanocrystals (ChNCs) as reinforcing
filler and carbon black (CB) are thermally sprayed on glass substrate
layer by layer, and then, spirally structured conductive composites
are obtained by rolling the sheets. When the CB content is 4.44%,
the conductivity of the NR/ChNCs-CB composite can reach 6.92 s/m.
The tensile strength of 5% ChNCs reinforced conductive composites
is 3.47 MPa, which is 3.1 times that of NR-CB composites without ChNCs.
The strain sensor exhibits a high gauge factor (GF ≈ 5) and
electrical conductivity stability in a small deformation range and
still shows good stability and recoverability upon 25%, 50%, and 100%
strain. The high-sensitivity strain sensors are further employed for
monitoring human activities such as finger movements and pronunciation,
which shows good reproducibility and reliability. This study provides
a routine of preparing highly stretchable and multifunctional strain
sensors based on inexpensive raw materials by a simple manner, which
opens up new opportunities for the development of stretchable electronic
devices
High-Performance Strain Sensors Based on Spirally Structured Composites with Carbon Black, Chitin Nanocrystals, and Natural Rubber
In this research,
a new type of conductive composite with high
tensile strength, high elasticity, and cost competitiveness has been
developed through solution mixing–spraying–rolling methods.
Naturel rubber (NR) latex with chitin nanocrystals (ChNCs) as reinforcing
filler and carbon black (CB) are thermally sprayed on glass substrate
layer by layer, and then, spirally structured conductive composites
are obtained by rolling the sheets. When the CB content is 4.44%,
the conductivity of the NR/ChNCs-CB composite can reach 6.92 s/m.
The tensile strength of 5% ChNCs reinforced conductive composites
is 3.47 MPa, which is 3.1 times that of NR-CB composites without ChNCs.
The strain sensor exhibits a high gauge factor (GF ≈ 5) and
electrical conductivity stability in a small deformation range and
still shows good stability and recoverability upon 25%, 50%, and 100%
strain. The high-sensitivity strain sensors are further employed for
monitoring human activities such as finger movements and pronunciation,
which shows good reproducibility and reliability. This study provides
a routine of preparing highly stretchable and multifunctional strain
sensors based on inexpensive raw materials by a simple manner, which
opens up new opportunities for the development of stretchable electronic
devices
Sustainable, High-Performance, and Biodegradable Plastics Made from Chitin
A high-performance
biodegradable plastic was made from a chitin
KOH/urea solution. The solution was transferred into a hydrogel by
cross-linking using epichlorohydrin and ethanol immersion, and a chitin
bioplastic was finally prepared by drying in a mold at 40 °C.
The solution concentration positively impacts viscosity, crystallinity,
and smoothness. A 4% chitin bioplastic exhibits high barrier properties,
flame retardancy, high-temperature resistance, mechanical properties
(tensile strength up to 107.1 MPa), and soil degradation properties.
The chitin bioplastic can be completely degraded by microorganisms
in 7 weeks. In addition, biosafety tests suggest that chitin is safe
for cells and crops (wheat and mung beans). The chitin bioplastic
was further applied to containers, straws, cups, and photoprotection,
and it was found that the water resistance and transparency were comparable
to those of commercial polypropylene plastics. Due to the excellent
performance, safety, and sustainability of the chitin bioplastic,
it is expected to become a good substitute for conventional fossil
fuel-based plastics
Sustainable, High-Performance, and Biodegradable Plastics Made from Chitin
A high-performance
biodegradable plastic was made from a chitin
KOH/urea solution. The solution was transferred into a hydrogel by
cross-linking using epichlorohydrin and ethanol immersion, and a chitin
bioplastic was finally prepared by drying in a mold at 40 °C.
The solution concentration positively impacts viscosity, crystallinity,
and smoothness. A 4% chitin bioplastic exhibits high barrier properties,
flame retardancy, high-temperature resistance, mechanical properties
(tensile strength up to 107.1 MPa), and soil degradation properties.
The chitin bioplastic can be completely degraded by microorganisms
in 7 weeks. In addition, biosafety tests suggest that chitin is safe
for cells and crops (wheat and mung beans). The chitin bioplastic
was further applied to containers, straws, cups, and photoprotection,
and it was found that the water resistance and transparency were comparable
to those of commercial polypropylene plastics. Due to the excellent
performance, safety, and sustainability of the chitin bioplastic,
it is expected to become a good substitute for conventional fossil
fuel-based plastics
Sustainable, High-Performance, and Biodegradable Plastics Made from Chitin
A high-performance
biodegradable plastic was made from a chitin
KOH/urea solution. The solution was transferred into a hydrogel by
cross-linking using epichlorohydrin and ethanol immersion, and a chitin
bioplastic was finally prepared by drying in a mold at 40 °C.
The solution concentration positively impacts viscosity, crystallinity,
and smoothness. A 4% chitin bioplastic exhibits high barrier properties,
flame retardancy, high-temperature resistance, mechanical properties
(tensile strength up to 107.1 MPa), and soil degradation properties.
The chitin bioplastic can be completely degraded by microorganisms
in 7 weeks. In addition, biosafety tests suggest that chitin is safe
for cells and crops (wheat and mung beans). The chitin bioplastic
was further applied to containers, straws, cups, and photoprotection,
and it was found that the water resistance and transparency were comparable
to those of commercial polypropylene plastics. Due to the excellent
performance, safety, and sustainability of the chitin bioplastic,
it is expected to become a good substitute for conventional fossil
fuel-based plastics
Stripe-like Clay Nanotubes Patterns in Glass Capillary Tubes for Capture of Tumor Cells
Here, we used capillary tubes to
evaporate an aqueous dispersion
of halloysite nanotubes (HNTs) in a controlled manner to prepare a
patterned surface with ordered alignment of the nanotubes . Sodium
polystyrenesulfonate (PSS) was added to improve the surface charges
of the tubes. An increased negative charge of HNTs is realized by
PSS coating (from −26.1 mV to −52.2 mV). When the HNTs
aqueous dispersion concentration is higher than 10%, liquid crystal
phenomenon of the dispersion is found. A typical shear flow behavior
and decreased viscosity upon shear is found when HNTs dispersions
with concentrations higher than 10%. Upon drying the HNTs aqueous
dispersion in capillary tubes, a regular pattern is formed in the
wall of the tube. The width and spacing of the bands increase with
HNTs dispersion concentration and decrease with the drying temperature
for a given initial concentration. Morphology results show that an
ordered alignment of HNTs is found especially for the sample of 10%.
The patterned surface can be used as a model for preparing PDMS molding
with regular micro-/nanostructure. Also, the HNTs rough surfaces can
provide much higher tumor cell capture efficiency compared to blank
glass surfaces. The HNTs ordered surfaces provide promising application
for biomedical areas such as biosensors
Self-Assembling Halloysite Nanotubes into Concentric Ring Patterns in a Sphere-on-Flat Geometry
Highly ordered and
concentric ring patterns consisting of halloysite
nanotubes (HNTs) with hierarchical cholesteric architectures are prepared
by evaporation-induced self-assembly in a sphere-on-flat geometry.
The structure and properties of HNTs are investigated. HNTs show a
perfect tubular morphology on the nanoscale with high dispersion stability
in water. Upon drying the HNTs aqueous suspension in a sphere-on-flat
confined space, regular concentric HNTs rings are formed on the substrate
via a self-assembly process. The widths of the inner and outer rings
and the spacing between the adjacent rings increase with an increase
in the concentration of the HNTs suspension. The highly ordered and
concentric HNTs rings show a pronounced Maltese cross-like pattern
under crossed polarizers, which suggests the formation of hierarchical
cholesteric architectures. Scanning electron microscopy and atomic
force microscopy observations show a disclination alignment of HNTs
in the ring strips, especially with a high concentration of the HNTs
suspension. The patterned rough surfaces of the HNTs show low cytotoxicity
and can be used as a cell-supporting scaffold. The HNTs rings can
guide the growth and orientation of C2C12 myoblast cells perpendicular
to the rings. This work provides a simple, repeatable, mild, and high-efficiency
method for obtaining HNTs with hierarchical architectures, which show
potential for a large variety of applications, for example, in vascular
grafts and skin regeneration
Functionalization of Halloysite Nanotubes via Grafting of Dendrimer for Efficient Intracellular Delivery of siRNA
Here,
polyamidoamine grafted halloysite nanotubes (PAMAM-<i>g</i>-HNTs) were synthesized for loading of siRNA in order to
intracellular delivery of siRNA and treat of breast cancer via gene
therapy. The successful grafting of PAMAM on HNTs was confirmed by
various analytical methods. The size, zeta potential, and grafting
ratio of PAMAM-<i>g</i>-HNTs is ∼206.2 nm, +19.8
mV, and 3.04%, respectively. PAMAM-<i>g</i>-HNTs showed
good cytocompatibility toward HUVECs (84.7%) and MCF-7 cells (82.3%)
even at high concentration of 100 μg/mL. PAMAM-<i>g</i>-HNTs/siRNA exhibited enhanced cellular uptake efficiency of 94.3%
compared with Lipofectamine 2000 (Lipo2000)/siRNA (83.6%). PAMAM-<i>g</i>-HNTs/small interfering RNA-vascular endothelial growth
factor (siVEGF) led to 78.0% knockdown of cellular VEGF mRNA and induced
33.6% apoptosis in the MCF-7 cells, which is also much higher than
that of Lipo2000/siVEGF. In vivo anti-cancer results demonstrated
that PAMAM-<i>g</i>-HNTs/siVEGF treated 4T1-bearing mice
showed enhanced anti-cancer efficacy than Lipo2000/siVEGF group. Also,
the nanocarrier system showed negligible toxic effects toward the
major organs of mice. In vivo fluorescence imaging studies showed
that there is a slight decrease in the fluorescence signal of PAMAM-<i>g</i>-HNTs/cy5-siVEGF after 72 h post-injection. Therefore,
PAMAM-<i>g</i>-HNTs show promising application as novel
nanovectors for siRNA delivery and gene therapy of cancer
3D Printing Drug-Free Scaffold with Triple-Effect Combination Induced by Copper-Doped Layered Double Hydroxides for the Treatment of Bone Defects
Tissue-engineered polyÂ(l-lactide) (PLLA) scaffolds
have
been widely used to treat bone defects; however, poor biological activities
have always been key challenges for its further application. To address
this issue, introducing bioactive drugs or factors is the most commonly
used method, but there are often many problems such as high cost,
uncontrollable and monotonous drug activity, and poor bioavailability.
Here, a drug-free 3D printing PLLA scaffold with a triple-effect combination
induced by surface-modified copper-doped layered double hydroxides
(Cu-LDHs) is proposed. In the early stage of scaffold implantation,
Cu-LDHs exert a photothermal therapy (PTT) effect to generate high
temperature to effectively prevent bacterial infection. In the later
stage, Cu-LDHs can further have a mild hyperthermia (MHT) effect to
stimulate angiogenesis and osteogenic differentiation, demonstrating
excellent vascularization and osteogenic activity. More importantly,
with the degradation of Cu-LDHs, the released Cu2+ and
Mg2+ provide an ion microenvironment effect and further
synergize with the MHT effect to stimulate angiogenesis and osteogenic
differentiation, thus more effectively promoting the healing of bone
tissue. This triple-effect combined scaffold exhibits outstanding
antibacterial, osteogenic, and angiogenic activities, as well as the
advantages of low cost, convenient procedure, and long-term efficacy,
and is expected to provide a promising strategy for clinical repair
of bone defects
Bone ECM-like 3D Printing Scaffold with Liquid Crystalline and Viscoelastic Microenvironment for Bone Regeneration
Implanting a 3D printing scaffold
is an effective therapeutic strategy
for personalized bone repair. As the key factor for the success of
bone tissue engineering, the scaffold should provide an appropriate
bone regeneration microenvironment and excellent mechanical properties.
In fact, the most ideal osteogenic microenvironment is undoubtedly
provided by natural bone extracellular matrix (ECM), which exhibits
liquid crystalline and viscoelastic characteristics. However, mimicking
a bone ECM-like microenvironment in a 3D structure with outstanding
mechanical properties is a huge challenge. Herein, we develop a facile
approach to fabricate a bionic scaffold perfectly combining bone ECM-like
microenvironment and robust mechanical properties. Creatively, 3D
printing a poly(l-lactide) (PLLA) scaffold was effectively
strengthened via layer-by-layer electrostatic self-assembly of chitin
whiskers. More importantly, a kind of chitin whisker/chitosan composite
hydrogel with bone ECM-like liquid crystalline state and viscoelasticity
was infused into the robust PLLA scaffold to build the bone ECM-like
microenvironment in 3D structure, thus highly promoting bone regeneration.
Moreover, deferoxamine, an angiogenic factor, was encapsulated in
the composite hydrogel and sustainably released, playing a long-term
role in angiogenesis and thereby further promoting osteogenesis. This
scaffold with bone ECM-like microenvironment and excellent mechanical
properties can be considered as an effective implantation for bone
repair