A versatile double‐network (DN) hydrogel with two noncovalent crosslinked networks is synthesized by multiple hydrogen bonding (H‐bonding) interactions. The DN hydrogels are synthesized via a ...heating–cooling photopolymerization process by adding all reactants of agar, N‐acryloyl glycinamide (NAGA) and N‐benzylacrylamide (NBAA) monomers, UV initiators to a single water pot. Poly(N‐acryloyl glycinamide‐co‐N‐benzyl acrylamide) (P(NAGA‐co‐NBAA)) with a triple amide in one side group is synthesized via UV‐light polymerization between NAGA and NBAA, forming a strong intermolecular H‐bonding network. Meanwhile, the intramolecular H‐bonding network is formed between P(NAGA‐co‐NBAA) and agars. The sol–gel phase transition of agars at 86 °C generates the molecular entanglement network. Such a double network enables the hydrogel high self‐healing efficiency (about 95%), good shape memory ability, and high mechanical strength (1.1 MPa). Additionally, the DN hydrogel is completely crosslinked by multiple hydrogen bonds (H‐bonds) and the physical crosslinking of agar without extra potential toxic chemical crosslinker. The DN hydrogels find extensive applications in the biomedical materials due to their excellent biocompatibility.
Poly(N‐acryloyl glycinamide‐co‐N‐benzyl acrylamide)/agar double‐network hydrogels crosslinked by multiple hydrogen bonds are synthesized. The double network gives the hydrogel high self‐healing efficiency (about 95%), high mechanical strength (1.1 MPa), and good shape memory ability.
Dielectric elastomers (DEs) have drawn much attention owing to their application prospects in artificial muscles and soft robotics, it is still a big challenge to prepare DEs with high ...electromechanical performances. This work reports a highly stretchable poly(thioether)-b-polysiloxane-b-poly(thioether) triblock copolymer based homogenous DEs with high electromechanical properties. The triblock copolymer (PSiPGE) was synthesized through the ring-opening polymerization (ROP) of phenyl glycidyl ether (PGE) and carbonyl sulfide (COS) catalyzed by silicon alkoxides. The dipoles (benzene rings) on the side groups of PSiPGE improved the dipole polarizations and the phase separation structure of this triblock copolymer enhanced the interfacial polarizations between poly(thioether) and polysiloxane, and thus improving the dielectric constant (ε’, up to 5.8). In addition, the PSiPGE exhibited low elastic modulus (Y, 0.04 MPa), and thus possessed high electromechanical sensitivity (β, ∼145 MPa−1) which is much higher than that of most homogenous DEs. This work provides a new strategy to construct homogenous DEs with excellent electromechanical performances, leading to a greater application aspect in the actuated devices.
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The improved dipole polarizations and the phase separation structure of poly(thioether)-b-polysiloxane-b-poly(thioether) triblock copolymer based homogenous DEs enable it high dielectric constant (ε’, up to 5.8) and high electromechanical sensitivity (β, ∼145 MPa−1).
Hypertrophic cardiomyopathy (HCM) is one of the most common inherited cardiovascular diseases and possesses a high risk for sudden cardiac death. Although mutations in more than 20 genes have been ...reported to be associated with HCM thus far, the genetic backgrounds of most HCM patients are not fully understood. We performed a genetic analysis in a Chinese family that presented with HCM using next-generation sequencing (NGS). Clinical data, family histories, and blood samples were collected from the proband and family members. Five patients showed typical clinical symptoms of HCM. One subject was the victim of sudden cardiac death. By NGS, we determined that these subjects with HCM symptoms carried a missense heterozygous genetic mutation c.2632C>A (p.V878L) in the myosin heavy chain 7 (MYH7) gene with an autosomal dominant pattern of inheritance. Individuals without this mutation showed no symptoms or cardiac structural abnormalities related to HCM. Bioinformatics evaluation predicted this mutant as "damaging" and "disease causing". Additionally, sequence alignment showed that this mutant is located in an evolutionarily conserved region of MYH7 in multiple species. Our results describe a potentially pathogenic mutation associated with HCM, which may extend the spectrum of HCM phenotypes related to MYH7 gene mutations.
Background
Regulatory molecule microRNAs (miRNAs) have been implicated in myocardial fibrosis. However, the specific mechanism by which they lead to myocardial fibrosis remains unclear. This study ...aimed to explore the roles of miR-208b, miR-21 and transforming growth factor-β1 (TGF-β1)/Smad-3 signaling pathway components in cardiac fibrosis development.
Materials and Methods
Thirty-six consecutive acute myocardial infarction (AMI) patients were included in this study. Plasma was collected on admission and at 24 h, 48 h and 6 d. The levels of plasma miR-208b, miR-21, TGF-β1, and Smad-3 were measured using reverse transcription-quantitative polymerase chain reaction (RT-qPCR), and cardiac calcium protein T (cTnT) and creatine kinase isoenzyme (CK-MB) were detected by electrochemiluminescence analysis. H9C2 cells were exposed to hypoxia and divided into 4 groups (hypoxia treatment for 6 h, 24 h, 48 h, and 72 h). These stimulated cells were then transfected with miRNA inhibitors and mimics for gene overexpression and inhibition. RT-qPCR was used to detect the expression of miR-208b, miR-21, TGF-β1, and Smad-3, and western blot analysis was used to detect TGF-β1 and Smad-3 protein expression.
Results
The plasma analysis showed cTnT and CK-MB expression peaked at 24 h after symptom onset; miR-208b, miR-21, TGF-β1, and Smad-3 levels showed no peak and increased gradually with time. Cell experiments revealed that miR-208b and TGF-β1 were upregulated along with increased hypoxia exposure; miR-21 expression peaked at 24 h and 72 h, with the highest peak at 72 h, and Smad-3 expression peaked at 6 h and 72 h, with the highest peak at 72 h. miR-208b and miR-21 expressions were positively correlated with TGF-β/Smad-3 expression. TGF-β1/Smad-3 mRNA and protein levels were elevated in the miR-208b and miR-21 overexpression groups and reduced in the miR-208b and miR-21 inhibition groups.
Conclusion
MiR-208b and miR-21 promote cardiac fibrosis progression through TGF-β1/Smad-3 signaling pathway activation.
The current study is to estimate the bisoprolol (BOP) oral treatment of rats against the myocardial infarction (MI) administrated by using isoproterenol (ISO).
Treatment of rats are MI administration ...by subcutaneous for two successive days of ISO (85 mg/kg). The tissue of heart is removed without delay, it is washed used isotonic chilled saline in this study. Plasma is separated from the collected rat blood and further analysis of biochemical parameters were carried out.
Group of ISO-treated rats have increased levels of glucose in blood, also observed the activity of lipids in plasma along fibres of muscle with hyalinization, compared to BOP treated rats, and ISO + BOP treated rats. The parameter values of BOP administered rat were close to control rats. Reports clearly state that ISO + BOP treated rat tissue of heart damage is reduced when compared to ISO treated rats.
Rats were treated with ISO + BOP to defend against hyperlipidaemia and tissue of cardiac damage and followed by MI. Hence, to investigate the biochemical and biophysical BOP mechanism against MI risk in rats.
Photothermal-induced self-healable and shape memory materials have drawn much attention due to the rapidly growing technical applications and environmental requirements. As epoxy natural rubber (ENR) ...is a kind of bio-based elastomer with good mechanical properties, weather resistance, and air impermeability, it is of great significance to incorporate ENR with recyclable, photothermal-induced self-healable and shape memory properties. In this study, we report a simple method to cross-link ENR with dodecanedioic acids (DAs) through esterification reaction, and during the cross-linking process, a little aniline trimer (ACAT, a kind of oligoaniline) was added at the same time. Then, the ENR-DA-ACAT vitrimers that were covalently cross-linked with recyclable, self-healable, and multiple responsive properties were obtained, which also possessed various functions. As a result of the transesterification reactions at elevated temperatures, the ENR-based vitrimers possess the ability to be reprocessed and self-healed, and the mechanical properties could be maintained even after three consecutive breaking/mold pressing cycles. Besides, the vitrimer is also responsive to near-infrared (NIR) light and pH with the introduction of ACAT, and we also find that ACAT can be used as a catalyst to accelerate the transesterification reaction. Moreover, it is demonstrated that the ENR-DA-ACAT vitrimer could also be used to construct the reconfigurable shape memory polymer; the shape fixing ratio and shape recovery ratio are both above 95% in the reconfiguration process, and the multistage shape memory performance can also be achieved by NIR irradiation, which will potentially lead to a wide application for ENR in the field of actuators.
The present 2 multicenter studies were designed to evaluate whether patients with essential hypertension derived equal benefits from use of combination therapy with a calcium antagonist and ...angiotensin-converting enzyme (ACE) inhibitor as from doubling the dose of the calcium antagonist. After a 2-week washout and a 2-week single-blind placebo run-in period, a total of 1,390 patients were treated with either nifedipine 30 mg (study 1) or amlodipine 5 mg (study 2) once daily for 4 weeks. The 1,079 patients whose diastolic blood pressure remained between 95 and 115 mm Hg were randomized to 8 weeks of double-blind therapy with amlodipine 5 mg/benazepril 10 mg, amlodipine 5 mg/benazepril 20 mg, nifedipine 30 mg or nifedipine 60 mg (study 1), and amlodipine 5 mg/benazepril 10 mg, amlodipine 5 mg/benazepril 20 mg, amlodipine 5 mg or amlodipine 10 mg (study 2). Both doses of the calcium antagonist/ACE inhibitor combination therapy lowered diastolic pressure as much as the high dose and significantly better than the lower dose of calcium antagonist monotherapy (with either nifedipine or amlodipine). However, 15% of patients in the nifedipine high-dose monotherapy group and 24% in the amlodipine high-dose monotherapy group presented with some form of edema. In contrast, the incidence of edema was similar for patients treated with both combination therapy and low-dose calcium antagonists. Thus, combination therapy with a calcium antagonist and an ACE inhibitor provides blood pressure control equal to that of high-dose calcium antagonist monotherapy but with significantly fewer dose-dependent adverse experiences such as vasodilatory edema.
Vitrimer is a new class of polymeric materials which can be reprocessed to any shape while being permanently cross-linked. We designed and synthesized a catalyst-free network with ...poly(dimethylsiloxane)etherimide (PDMS-NH2), terephthalaldehyde (TA), and tri(2-aminoethyl)amine (TREA) through the condensation reaction between amino groups and aldehyde groups. As a result of the exchange reaction of the dynamic imine bond obtained, this PDMS network exhibits the nature of vitrimer-like material, which is examined by solubility and stress-relaxation experiments, and the relaxation time is as short as 64 s at 130 °C. In addition, the vitrimer-like PDMS is malleable and capable of self-healing, and the mechanical properties can be maintained even after three consecutive breaking/mold pressing cycles. Especially, besides heating, this vitrimer-like PDMS can also be recycled and reshaped at ambient temperature due to the exchange reaction of dynamic imine bond when immersed in water, which will potentially lead to green processing of the elastomers.
We report a new method to prepare poly(thioether) grafted Ti3C2Tx MXene DE nanocomposites by using MXeneK-initiated decarboxylative ROP reaction between COS and FGE, followed by the DA reaction of ...BMI and MXeneK-FGE: the DE nanocomposites exhibit high actuated strain at low electric field (17.1%@11.9V/μm), better than the previous systems (0.7%∼10%@12 V/μm).
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•Poly(thioether) grafted Ti3C2Tx MXene DE nanocomposites were prepared through the pretreated MXene (MXeneK) initiated ring-opening polymerization of furfuryl glycidyl ether (FGE) and carbonyl sulfide (COS), followed by the Diels-Alder crosslinking reaction between furan groups and BMI;•The poly(thioether) chains are grafted onto the MXeneK surfaces, leading to the significant decrease of dielectric loss (below 0.04);•Low MXeneK content (below 1.0 wt%) resulted in high ε’ (∼12.3) and low elastic modulus (below 0.5 MPa);•The resultant DE nanocomposite present high area strain (17.1 %@11.9 V/μm), superior to previous systems (0.7 %∼10 %@12 V/μm).
Dielectric elastomers (DEs) with high actuated strains at low electric fields have been a great challenge over the past few decades. In this work, we report the preparation of poly(thioether) grafted Ti3C2Tx MXene DE nanocomposites (MXeneK-FGE-BMI) with high area strain at low driving voltage (17.1 %@11.9 V/μm) by two steps: the pretreated MXene (MXeneK) initiated decarboxylative ring-opening polymerization (ROP) of furfuryl glycidyl ether (FGE) and carbonyl sulfide (COS), followed by the Diels-Alder (DA) crossslinking reaction between furan groups and bismaleimide (BMI). The grafting of poly(thioether) chains onto the MXeneK surfaces enables MXeneK well dispersed in the matrix, leading to the significant decrease of dielectric loss (tan δ, below 0.04@103Hz). Low content of MXeneK (below 1.0 wt%) resulted in high ε’ (∼12.3@103Hz) and low elastic modulus (Y, below 0.5 MPa). Therefore, the resultant DE nanocomposite present a high area strain of 17.1 % at a driving voltage of 11.9 V/μm, superior to the previous reports (0.7 %∼10 %@12 V/μm). This work provides a facile strategy to prepare DE nanocomposites with excellent electromechanical performances at low driving voltage.
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