Anisotropic Hydrogels Constructed via a Novel Bilayer-Co-Gradient Structure Strategy toward Programmable Shape Deformation

The bilayer hydrogel actuators have attracted extensive attention for their unique stimulus-responsive properties. Most of the current research studies only focused on changing the constituent materials of two layers in the fixed bilayer structure to enhance the responsive deformability of bilayer hydrogels without involving the exploration on a structural level, which limited its further development. In this study, we proposed a novel bilayer-co-gradient structure constructed via a simple and low-cost structural programming strategy, which was self-assembled by introducing an embedded gradient structure into a single bilayer structure with the assistance of gradient-dissolved oxygen in nature. This multistructure endowed the hydrogel with a faster bending response than a single bilayer structure due to the synergistic asymmetry of the simple bilayer structure and the embedded gradient structure. It was found that the prepared hydrogels exhibited significantly anisotropic electrical conductivity and swelling properties. Moreover, the stimulus-responsive shape deformation exhibited superior temperature- and pH-based deformation programmability. Additionally, this hydrogel could serve as a hydrogel gripper to perform grasping behavior, which demonstrated that our study opens up a new route for designing and fabricating smart actuators

Oxygen-<i>co</i>-Thermal Driver for Constructing Integrated Anisotropic Hydrogels with Programmable Shape Deformation, Superior Self-Healing, and Mechanical Performance

Gradient hydrogels hold great potential for applications in actuators due to their unique stimulus response performance and simple integrated structure. However, most of the currently available gradient structure programming strategies are dependent on complex external fields and employ a single structural driving force, which limits their further development. In this study, we proposed a novel oxygen-co-thermal driving structure programming strategy for constructing the integrated anisotropic bistructured hydrogels with multifunctionality. Namely, we utilized the simple and low-cost oxygen gradient dissolution behavior and heat transfer behavior in nature as the dual driving force of the gradient structure, combined with the spontaneous existence of electrostatic attraction between polyelectrolyte chains, to construct integrated hydrogels with both gradient and phase separation structures in a one-step method. It was shown that the designed hydrogels exhibited remarkable self-healing ability and mechanical property. Moreover, the hydrogel exhibited superior responsive deformation capability, and the deformation behavior was programmable depending on internal conditions (composition ratio and specific surface area) and external stimuli (pH and temperature). In addition, the successful construction of humidity alarms and grippers by the designed hydrogel demonstrated that our study provides new insights into the field of manufacturing smart actuators

Multifunctional, Degradable Wearable Sensors Prepared with an Initiator and Crosslinker-Free Method

The present zwitterionic hydrogel-based wearable sensor exhibits various limitations, such as limited degradation capacity, unavoidable toxicity resulting from initiators, and poor mechanical properties that cannot satisfy practical demands. Herein, we present an initiator and crosslinker-free approach to prepare polyethylene glycol (PEG)@poly­[2-(methacryloyloxy)­ethyl] dimethyl-(3-sulfopropyl) (PSBMA) interpenetrating polymer network (IPN) hydrogels that are self-polymerized via sunlight-induced and non-covalent crosslinking through electrostatic interaction and hydrogen bonding among polymer chains. The PEG@PSBMA IPN hydrogel possesses tissue-like softness, superior stretchability (∼2344.6% elongation), enhanced fracture strength (∼39.5 kPa), excellent biocompatibility, antibacterial property, reliable adhesion, and ionic conductivity. Furthermore, the sensor based on the IPN hydrogel demonstrates good sensitivity and cyclic stability, enabling effective real-time monitoring of human body activities. Moreover, it is worth noting that the excellent degradability in the saline solution within 8 h makes the prepared hydrogel-based wearable sensor free from the electronic device contamination. We believe that the proposed strategy for preparing physical zwitterionic hydrogels will pave the way for fabricating eco-friendly wearable devices

Multifunctional, Degradable Wearable Sensors Prepared with an Initiator and Crosslinker-Free Method

The present zwitterionic hydrogel-based wearable sensor exhibits various limitations, such as limited degradation capacity, unavoidable toxicity resulting from initiators, and poor mechanical properties that cannot satisfy practical demands. Herein, we present an initiator and crosslinker-free approach to prepare polyethylene glycol (PEG)@poly­[2-(methacryloyloxy)­ethyl] dimethyl-(3-sulfopropyl) (PSBMA) interpenetrating polymer network (IPN) hydrogels that are self-polymerized via sunlight-induced and non-covalent crosslinking through electrostatic interaction and hydrogen bonding among polymer chains. The PEG@PSBMA IPN hydrogel possesses tissue-like softness, superior stretchability (∼2344.6% elongation), enhanced fracture strength (∼39.5 kPa), excellent biocompatibility, antibacterial property, reliable adhesion, and ionic conductivity. Furthermore, the sensor based on the IPN hydrogel demonstrates good sensitivity and cyclic stability, enabling effective real-time monitoring of human body activities. Moreover, it is worth noting that the excellent degradability in the saline solution within 8 h makes the prepared hydrogel-based wearable sensor free from the electronic device contamination. We believe that the proposed strategy for preparing physical zwitterionic hydrogels will pave the way for fabricating eco-friendly wearable devices

Multifunctional, Degradable Wearable Sensors Prepared with an Initiator and Crosslinker-Free Method

The present zwitterionic hydrogel-based wearable sensor exhibits various limitations, such as limited degradation capacity, unavoidable toxicity resulting from initiators, and poor mechanical properties that cannot satisfy practical demands. Herein, we present an initiator and crosslinker-free approach to prepare polyethylene glycol (PEG)@poly­[2-(methacryloyloxy)­ethyl] dimethyl-(3-sulfopropyl) (PSBMA) interpenetrating polymer network (IPN) hydrogels that are self-polymerized via sunlight-induced and non-covalent crosslinking through electrostatic interaction and hydrogen bonding among polymer chains. The PEG@PSBMA IPN hydrogel possesses tissue-like softness, superior stretchability (∼2344.6% elongation), enhanced fracture strength (∼39.5 kPa), excellent biocompatibility, antibacterial property, reliable adhesion, and ionic conductivity. Furthermore, the sensor based on the IPN hydrogel demonstrates good sensitivity and cyclic stability, enabling effective real-time monitoring of human body activities. Moreover, it is worth noting that the excellent degradability in the saline solution within 8 h makes the prepared hydrogel-based wearable sensor free from the electronic device contamination. We believe that the proposed strategy for preparing physical zwitterionic hydrogels will pave the way for fabricating eco-friendly wearable devices

Enhanced Water Adsorption Performance of UiO-66 Modulated with <i>p</i>‑Nitrobenzoic or <i>p</i>‑Hydroxybenzoic Acid: Introduced Defects and Functional Groups

Adding appropriate modulators can effectively improve the porosity and adsorption performance of UiO-66. Herein, UiO-66 samples were synthesized with p-nitrobenzoic acid (PNBA) and p-hydroxybenzoic acid (PHBA) as modulators. All samples exhibited good crystallinity and thermal stability. The polar functional groups (−NO2 and −OH) and defects were introduced into UiO-66, which significantly improved its water adsorption performance and applications in adsorption heat transformation. With the addition of six equiv PNBA, the saturated water uptake of UiO-66 increased from 0.40 to 0.58 g/g. Also, 4eqPNBA-UiO-66 exhibited the highest water uptake under low relative pressure, which was almost twice that of “low-defect” LD-UiO-66. The addition of PHBA had little effect on the saturated water absorption. However, its highest water uptake at P/P0 = 0.3 is 0.23 g/g, which is equivalent to that of 4eqPNBA-UiO-66. Ten consecutive adsorption/desorption cycles indicated that these samples had good cycle stability

ActRIIA rescued the effect of miR-195 on cell invasion in HTR8/SVneo cells.

<p>HTR8/SVneo cells were transfected with miR-195 and ActRIIA alone or in combination, with scramble siRNA (NC) or pcDNA4 vector (pcDNA4) as corresponding negative control. Transwell insert assay was performed to monitor cell invasiveness (A) and Gelatin zymography was performed to measure MMP-2 and MMP-9 productions (B). The statistical analysis was carried out by ANOVA according to three independent experiments, and the values were presented as Mean±SEM. *, compared with corresponding group as indicated, <i>p</i><0.05.</p

Expression of miR-195 and ActRIIA in placentas derived from severe preeclamptic patients (PE) and gestational-week-matched normal pregnant women (Control).

<p>A, B and C, Quantitative real time PCR to reveal pri-miR-195 (A), mature miR-195 (B) levels and mRNA expression of ActRIIA (C) in placentas from PE and Control. *, **, compared with Control, <i>p</i><0.05, <i>p</i><0.01. D, Western blotting to show protein levels of ActRIIA in placentas from PE and Control. Upper panel, a typical result of Western blotting. Lower panel, bar chart according to the statistical analysis based on the result of three independently repeat experiments. *, compared with Control, <i>p</i><0.05.</p

Validation of ActRIIA as target gene of miR-195 in HTR8/SVneo cells.

<p>A. Real-time PCR to reveal change of ActRIIA mRNA level in HTR8/SVneo cells transfected with scramble siRNA (NC), miR-195 mimics (miR-195) or ActRIIA siRNA (si-ActRIIA). **, compared with NC, P<0.01. B. Western blot analysis to show change of ActRIIA protein level in HTR8/SVneo cells transfected with NC, miR-195 or si-ActRIIA. Upper panel, typical results of Western blotting; Lower panel, bar chart representing the statistical analysis by ANOVA according to three independent experiments. The density of ActRIIA was adjusted by that of GAPDH in the same blot, and the values were presented as Mean±SEM. *, compared with NC, <i>p</i><0.05. C. Schematic map for generating luciferase assay constructs. The constructs containing the region complementary to the seed sequence for miR-195 in 3′UTR segment of human ActRIIA gene are shown as BD1-WT and BD2-WT, and the mutant constructs are shown as BD1-MUT and BD2-MUT with asterisks indicating the mutation sites. D. Luciferase assay in HTR8/SVneo cells transfected with BD1-WT, BD2-WT, BD1-MUT or BD2-MUT reporter construct together with miR-195 mimics (miR-195) or scramble siRNA (NC). The value of corresponding control group (NC) was set as 100, and the results were presented as Mean±SEM according to three independent experiments. **, compared with corresponding NC, <i>p</i><0.01.</p

Effect of miR-195 on protein expression of CCND1 and CCND3 in HTR8/SVneo cells.

<p>A. Real-time PCR to reveal miR-195 level in HTR8/SVneo cells transfected with scramble siRNA (NC) or miR-195 mimics (miR-195). **, compared with NC, <i>p</i><0.01. B. Western blot analysis to show change of CCND1 and CCND3 protein level in HTR8/SVneo cells transfected with NC or miR-195. Upper panels, typical results of Western blotting; Lower panels, bar charts representing the statistical analysis by ANOVA according to three independent experiments. The densities of CCND1 and CCND3 were adjusted by that of Actin in the same blot, and the values were presented as Mean±SEM.</p