6 research outputs found
Self-Powered Multifunctional Organic Hydrogel Based on Poly(acrylic acid‑<i>N</i>‑isopropylacrylamide) for Flexible Sensing Devices
Human–machine interactions,
medical monitoring, and flexible
robots stimulate interest in hydrogel sensing devices. However, developing
hydrogel sensors with multifunctions such as good mechanics, electroconductivity,
resistance to solvent volatility as well as freezing, self-adhesion,
and independence on external power supply remains a challenge. In
the work, a poly(acrylic acid-N-isopropylacrylamide)
P(AA-NIPAm) organic hydrogel loading LiCl is prepared by ultraviolet
cross-linking in ethylene glycol/H2O. The organic hydrogel
exhibits favorable mechanical properties such as an elongation of
break at 700% and a breaking strength of 20 KPa, can adhere to various
substrates, and resists frost and solvent volatility. Especially,
it possesses an excellent conductivity of 8.51 S/m. The organic hydrogel
shows wide strain sensitivity based on resistance change, and the
gauge factor reaches 5.84 in the range of 300–700%. It has
short responsive and recuperative time and is still stable within
1000 rounds. Moreover, the organic hydrogel is also assembled into
a self-powered device in which the open-circuit voltage is 0.74 V.
The device can transform external stimuli such as stretching or compressing
into the output current change, so it detects human motion effectively
in real time. The work provides a perspective for electrical sensing
engineering
Self-Powered Multifunctional Organic Hydrogel Based on Poly(acrylic acid‑<i>N</i>‑isopropylacrylamide) for Flexible Sensing Devices
Human–machine interactions,
medical monitoring, and flexible
robots stimulate interest in hydrogel sensing devices. However, developing
hydrogel sensors with multifunctions such as good mechanics, electroconductivity,
resistance to solvent volatility as well as freezing, self-adhesion,
and independence on external power supply remains a challenge. In
the work, a poly(acrylic acid-N-isopropylacrylamide)
P(AA-NIPAm) organic hydrogel loading LiCl is prepared by ultraviolet
cross-linking in ethylene glycol/H2O. The organic hydrogel
exhibits favorable mechanical properties such as an elongation of
break at 700% and a breaking strength of 20 KPa, can adhere to various
substrates, and resists frost and solvent volatility. Especially,
it possesses an excellent conductivity of 8.51 S/m. The organic hydrogel
shows wide strain sensitivity based on resistance change, and the
gauge factor reaches 5.84 in the range of 300–700%. It has
short responsive and recuperative time and is still stable within
1000 rounds. Moreover, the organic hydrogel is also assembled into
a self-powered device in which the open-circuit voltage is 0.74 V.
The device can transform external stimuli such as stretching or compressing
into the output current change, so it detects human motion effectively
in real time. The work provides a perspective for electrical sensing
engineering
Self-Powered Multifunctional Organic Hydrogel Based on Poly(acrylic acid‑<i>N</i>‑isopropylacrylamide) for Flexible Sensing Devices
Human–machine interactions,
medical monitoring, and flexible
robots stimulate interest in hydrogel sensing devices. However, developing
hydrogel sensors with multifunctions such as good mechanics, electroconductivity,
resistance to solvent volatility as well as freezing, self-adhesion,
and independence on external power supply remains a challenge. In
the work, a poly(acrylic acid-N-isopropylacrylamide)
P(AA-NIPAm) organic hydrogel loading LiCl is prepared by ultraviolet
cross-linking in ethylene glycol/H2O. The organic hydrogel
exhibits favorable mechanical properties such as an elongation of
break at 700% and a breaking strength of 20 KPa, can adhere to various
substrates, and resists frost and solvent volatility. Especially,
it possesses an excellent conductivity of 8.51 S/m. The organic hydrogel
shows wide strain sensitivity based on resistance change, and the
gauge factor reaches 5.84 in the range of 300–700%. It has
short responsive and recuperative time and is still stable within
1000 rounds. Moreover, the organic hydrogel is also assembled into
a self-powered device in which the open-circuit voltage is 0.74 V.
The device can transform external stimuli such as stretching or compressing
into the output current change, so it detects human motion effectively
in real time. The work provides a perspective for electrical sensing
engineering
Artificial Peroxidase/Oxidase Multiple Enzyme System Based on Supramolecular Hydrogel and Its Application as a Biocatalyst for Cascade Reactions
Inspired by delicate structures and
multiple functions of natural multiple enzyme architectures such as
peroxisomes, we constructed an artificial multiple enzyme system by
coencapsulation of glucose oxidases (GOx) and artificial peroxidases
in a supramolecular hydrogel. The artificial peroxidase was a functional
complex micelle, which was prepared by the self-assembly of diblock
copolymer and hemin. Compared with catalase or horseradish peroxidase
(HRP), the functional micelle exhibited comparable activity and better
stability, which provided more advantages in constructing a multienzyme
with a proper oxidase. The hydrogel containing the two catalytic centers
was further used as a catalyst for green oxidation of glucose, which
was a typical cascade reaction. Glucose was oxidized by oxygen (O<sub>2</sub>) via the GOx-mediated reaction, producing toxic intermediate
hydrogen peroxide (H<sub>2</sub>O<sub>2</sub>). The produced H<sub>2</sub>O<sub>2</sub> further oxidized peroxidase substrates catalyzed
by hemin-micelles. By regulating the diffusion modes of the enzymes
and substrates, the artificial multienzyme based on hydrogel could
successfully activate the cascade reaction, which the soluble enzyme
mixture could not achieve. The hydrogel, just like a protective covering,
protected oxidases and micelles from inactivation via toxic intermediates
and environmental changes. The artificial multienzyme could efficiently
achieve the oxidation task along with effectively eliminating the
toxic intermediates. In this way, this system possesses great potentials
for glucose detection and green oxidation of a series of substrates
related to biological processes
Furfural-Based Polyamides with Tunable Fluorescence Properties via Ugi Multicomponent Polymerization
Polyamides (PAs) are regarded as attractive fluorescent
polymer
materials due to their nontraditional intrinsic luminescence. In this
work, a series of photoluminescence active PAs were prepared from
renewable furfural derivatives via the Ugi four-component polymerization.
Moreover, the fluorescence of dilute PA solutions can be accurately
controlled by the intramolecular hydrogen bonding interactions using
the furfural module as a switch, which was finally confirmed by DFT
theory. As a probe, PAs can selectively recognize Fe2+ and
Fe3+ among various metal ions by the fluorescence quenching
effect. This protocol provides an efficient and moderate strategy
for synthesizing biobased functional polymer materials with fluorescence
properties, demonstrating high synthetic efficiency and high selectivity
to Fe2+ and Fe3+
Hemin-Block Copolymer Micelle as an Artificial Peroxidase and Its Applications in Chromogenic Detection and Biocatalysis
Following an inspiration from the
fine structure of natural peroxidases, such as horseradish peroxidase
(HRP), an artificial peroxidase was constructed through the self-assembly
of diblock copolymers and hemin, which formed a functional micelle
with peroxidase-like activity. The pyridine moiety in block copolymer
polyÂ(ethylene glycol)-<i>block</i>-polyÂ(4-vinylpyridine)
(PEG-<i>b</i>-P4VP) can coordinate with hemin, and thus
hemin is present in a five-coordinate complex with an open site for
binding substrates, which mimics the microenvironment of heme in natural
peroxidases. The amphiphilic core–shell structure of the micelle
and the coordination interaction of the polymer to the hemin inhibit
the formation of hemin ÎĽ-oxo dimers, and thereby enhance the
stability of hemin in the water phase. Hemin-micelles exhibited excellent
catalytic performance in the oxidation of phenolic and azo compounds
by H<sub>2</sub>O<sub>2</sub>. In comparison with natural peroxidases,
hemin-micelles have higher catalytic activity and better stability
over wide temperature and pH ranges. Hemin-micelles can be used as
a detection system for H<sub>2</sub>O<sub>2</sub> with chromogenic
substrates, and they anticipate the possibility of constructing new
biocatalysts tailored to specific functions