ABSTRACT
Osteoarthritis (OA) is a chronic joint disease, characterized by degenerative destruction of articular cartilage. Chondrocytes, the unique cell type in cartilage, mediate the metabolism of extracellular matrix (ECM), which is mainly constituted by aggrecan and type II collagen. A disintegrin and metalloproteinase with thrombospondin 5 (ADAMTS5) is an aggrecanase responsible for the degradation of aggrecan in OA cartilage. CCAAT/enhancer binding protein ß (C/EBPß), a transcription factor in the C/EBP family, has been reported to mediate the expression of ADAMTS5. Our previous study showed that 5,7,3',4'-tetramethoxyflavone (TMF) could activate the Sirt1/FOXO3a signaling in OA chondrocytes. However, whether TMF protected against ECM degradation by down-regulating C/EBPß expression was unknown. In this study, we found that aggrecan expression was down-regulated, and ADAMTS5 expression was up-regulated. Knockdown of C/EBPß could up-regulate aggrecan expression and down-regulate ADAMTS5 expression in IL-1ß-treated C28/I2 cells. TMF could compromise the effects of C/EBPß on OA chondrocytes by activating the Sirt1/FOXO3a signaling. Conclusively, TMF exhibited protective activity against ECM degradation by mediating the Sirt1/FOXO3a/C/EBPß pathway in OA chondrocytes.
Subject(s)
ADAMTS5 Protein , CCAAT-Enhancer-Binding Protein-beta , Chondrocytes , Extracellular Matrix , Osteoarthritis , Signal Transduction , ADAMTS5 Protein/metabolism , ADAMTS5 Protein/genetics , Humans , Extracellular Matrix/metabolism , Extracellular Matrix/drug effects , Signal Transduction/drug effects , Chondrocytes/metabolism , Chondrocytes/drug effects , Chondrocytes/pathology , Osteoarthritis/metabolism , Osteoarthritis/pathology , CCAAT-Enhancer-Binding Protein-beta/metabolism , Male , Sirtuin 1/metabolism , Aggrecans/metabolism , Flavonoids/pharmacology , Interleukin-1beta/metabolism , Cell Line , Forkhead Box Protein O3/metabolism , Cartilage, Articular/metabolism , Cartilage, Articular/pathology , Cartilage, Articular/drug effects , Middle Aged , Aged , Down-Regulation/drug effectsABSTRACT
BACKGROUND: Drug-induced immune hemolytic anemia (DIIHA) is a rare but potentially life-threatening pharmacogenic hematological adverse effect. Updating the risk of DIIHA among the currently available drugs based on spontaneously reported adverse event data is of great significance. OBJECTIVE: This study aimed to identify the top 50 drugs associated with immune hemolytic anemia in adults as well as common drugs that could cause immune hemolytic anemia in children based on the United States Food and Drug Administration Adverse Event Reporting System (FAERS) database. METHODS: We extracted adverse events (AE) in the FAERS database from Q1 2004 to Q3 2022 using Open vigil2.1. We use the high-level term "anaemias haemolytic immune" according to the Medical Dictionary for Regulatory Activities (MedDRA) Dictionary (version 24.0). The reported correlation between drugs and DIIHA risk was identified by reported odds ratio (ROR) and proportional reporting ratio (PRR). RESULTS: There were 10500309 AEs in FAERS from 2004Q1 to 2022Q3, of which 2326 (0.02%) were DIIHA cases. The incidence of DIIHA is comparable between males and females. The most common drugs associated with DIIHA in adults and children are summarized according to the number of AE reports. The top 3 categories in terms of quantity of drugs are antineoplastic agents, immunosuppressants, and antibiotics for systemic use. The top 5 drugs in terms of ROR and PRR are alemtuzumab, daclizumab, fludarabine, busulfan, and bendamustine in adults, with entecavir, treosulfan, vinorelbine, pegademase, and alemtuzumab for children. CONCLUSIONS: Our study identified the most common drugs that could induce DIIHA in adults and children, as well as the respective ROR and PRR value to discover new drug signals. This study provides references to clinicians for the management of rare DIIHA.
Subject(s)
Anemia, Hemolytic , Antineoplastic Agents , Drug-Related Side Effects and Adverse Reactions , Male , Adult , Child , Female , United States/epidemiology , Humans , Alemtuzumab , Anemia, Hemolytic/chemically induced , Drug-Related Side Effects and Adverse Reactions/epidemiology , Antineoplastic Agents/adverse effects , Anti-Bacterial Agents , United States Food and Drug Administration , Adverse Drug Reaction Reporting SystemsABSTRACT
BACKGROUND: Bevacizumab is used for the treatment of advanced malignant tumors; it acts by inhibiting angiogenesis. This study aimed to examine adverse events (AEs) of bevacizumab, especially hemorrhage, using the Food and Drug Administration Adverse Event Reporting System (FAERS) database. RESEARCH DESIGN AND METHODS: The reporting odds ratio (ROR) and proportional reporting ratio (PRR) were used to analyze the AEs of bevacizumab using FAERS registration data from January 2004 to September 2022. Clinical information regarding hemorrhagic signals was further analyzed. RESULTS: The number of bevacizumab-associated AE reports was 96,477. Our study found that 892 significant preferred terms (PTs) were spread throughout 25 organ systems. The system organ classes (SOCs) focus on general disorders, administration site conditions, blood and lymphatic system disorders, injury, poisoning, and procedural complications. A total of 2,847 bevacizumab-related hemorrhage cases were reported, and 37 hemorrhagic signals were identified. Hemorrhagic signals were focused on SOC levels in vascular, gastrointestinal, and nervous system disorders. Colorectal, lung, and breast cancers are the three most common malignancies associated with BV-induced hemorrhage. CONCLUSION: The AE report from the present study confirms the majority of label information for bevacizumab, while also identifying new AEs. In addition, this was a large descriptive study of bevacizumab-induced hemorrhage.
Subject(s)
Breast Neoplasms , Drug-Related Side Effects and Adverse Reactions , United States , Humans , Female , Bevacizumab/adverse effects , United States Food and Drug Administration , Pharmacovigilance , Drug-Related Side Effects and Adverse Reactions/epidemiology , Drug-Related Side Effects and Adverse Reactions/etiology , Hemorrhage/chemically induced , Hemorrhage/epidemiology , Adverse Drug Reaction Reporting SystemsABSTRACT
Inflammation, a mechanism of the human body, has been implicated in many diseases. Inflammatory responses include the release of inflammatory mediators by activating various signaling pathways. CCAAT/enhancer binding protein ß (C/EBPß), a transcription factor in the C/EBP family, contains the leucine zipper (bZIP) domain. The expression of C/EBPß is mediated at the transcriptional and post-translational levels, such as phosphorylation, acetylation, methylation, and SUMOylation. C/EBPß has been involved in inflammatory responses by mediating several signaling pathways, such as MAPK/NF-κB and IL-6/JAK/STAT3 pathways. C/EBPß plays an important role in the pathological development of inflammation-related diseases, such as osteoarthritis, pneumonia, hepatitis, inflammatory bowel diseases, and rheumatoid arthritis. Here, we comprehensively discuss the structure and biological effects of C/EBPß and its role in inflammatory diseases.
Subject(s)
Gene Expression Regulation , NF-kappa B , Humans , NF-kappa B/metabolism , Phosphorylation , Signal Transduction , InflammationABSTRACT
Osteoporosis (OP) is characterized by reduced bone mass, decreased strength, and enhanced bone fragility fracture risk. Activating transcription factor 4 (ATF4) plays a role in cell differentiation, proliferation, apoptosis, redox balance, amino acid uptake, and glycolipid metabolism. ATF4 induces the differentiation of bone marrow mesenchymal stem cells (BM-MSCs) into osteoblasts, increases osteoblast activity, and inhibits osteoclast formation, promoting bone formation and remodeling. In addition, ATF4 mediates the energy metabolism in osteoblasts and promotes angiogenesis. ATF4 is also involved in the mediation of adipogenesis. ATF4 can selectively accumulate in osteoblasts. ATF4 can directly interact with RUNT-related transcription factor 2 (RUNX2) and up-regulate the expression of osteocalcin (OCN) and osterix (Osx). Several upstream factors, such as Wnt/ß-catenin and BMP2/Smad signaling pathways, have been involved in ATF4-mediated osteoblast differentiation. ATF4 promotes osteoclastogenesis by mediating the receptor activator of nuclear factor κ-B (NF-κB) ligand (RANKL) signaling. Several agents, such as parathyroid (PTH), melatonin, and natural compounds, have been reported to regulate ATF4 expression and mediate bone metabolism. In this review, we comprehensively discuss the biological activities of ATF4 in maintaining bone homeostasis and inhibiting OP development. ATF4 has become a therapeutic target for OP treatment.
Subject(s)
Activating Transcription Factor 4 , Osteoporosis , Humans , Activating Transcription Factor 4/metabolism , Osteoclasts/metabolism , Cell Differentiation/physiology , Signal Transduction , Osteoblasts/metabolism , Osteogenesis/physiology , Osteoporosis/metabolismABSTRACT
Biodegradable composites consisting of Poly-(butylene adipate-co-terephthalate) (PBAT), thermoplastic starch, hydrophobically modified nanofibrillated cellulose (HMNC), and green surfactant (sucrose fatty acid ester) were prepared via the melt-mixing and film-blowing process (PBAT-HMNC). The composites were characterized using the Fourier transform infrared spectroscope (FT-IR), scanning electron microscope (SEM), and thermogravimetric analyzer (TGA). The mechanical and barrier properties were systematically studied. The results indicated that PBAT-HMNC composites exhibited excellent mechanical and barrier properties. The tensile strength reached the maximum value (over 13 MPa) when the HMNC content was 0.6% and the thermal decomposition temperature decreased by 1 to 2 °C. The lowest values of the water vapor transmission rate (WVTR) and the oxygen transmission rate (OTR) were obtained from the composite with 0.6 wt% HMNC, prepared via the film-bowing process with the values of 389 g/(m2·day) and 782 cc/(m2·day), which decreased by 51.3% and 42.1%, respectively. The Agaricus mushrooms still had a commodity value after 11 days of preservation using the film with 0.6 wt% HMNC. PBAT-HMNC composites have been proven to be promising nanocomposite materials for packaging.
Subject(s)
Food Packaging , Polyesters , Food Packaging/methods , Spectroscopy, Fourier Transform Infrared , Cellulose , AdipatesABSTRACT
CONTEXT: Lignin has an immense potential for the production of lignin-based functional materials. In this work, effect of 2-chloro-ethyltrimethyl ammonium chloride (AC)-grafted alkali lignin (AL) on the morphologies in water was investigated by dissipative particle dynamics (DPD) simulations. The results showed that AL molecules formed spherical micelles, but the corresponding phenylpropane units of AL were randomly distributed in spherical micelles. However, AC-grafted modification of phenolic hydroxyl groups in AL led to the formation of multilamellar spherical micelles. The formation of multilamellar spherical micelles of AL mainly went through four stages: small clusters, larger aggregates with a core-shell structure, trilaminar, and multilamellar spherical micelles. AL molecules resulted in dimethomorph molecules being randomly distributed in the spherical micelle, while the dimethomorph molecules were perfectly entrapped into the spherical micelles of AC-grafted AL. Various molecular weights of AL had no effect on the formation and size of multilamellar spherical micelles. With increasing the content of AC-grafted AL, small clusters, multilamellar spherical micelles, tube-like, and lamellar aggregates were observed successively. This work highlights the potential of lignin to prepare monodispersed lignin-based functional colloidal spheres. METHODS: Coarse-grained beads were performed energy minimization, geometric optimization, NPT ensemble (298 K and 1.0 bar), and NVT ensemble (298 K) calculations. DPD simulations were carried out at 300,000 steps in a 30×30×30 Rc3 cubic box with Materials Studio 7.0 program.
Subject(s)
Lignin , Micelles , Water/chemistryABSTRACT
Due to their excellent biocompatibility, outstanding mechanical properties, high strength-to-weight ratio, and good corrosion resistance, titanium (Ti) alloys are extensively used as implant materials in artificial joints. However, Ti alloys suffer from poor wear resistance, resulting in a considerably short lifetime. In this study, we demonstrate that the chemical self-assembly of novel two-dimensional (2D) diamond nanosheet coatings on Ti alloys combined with natural silk fibroin used as a novel lubricating fluid synergistically results in excellent friction and wear performance. Linear-reciprocating sliding tests verify that the coefficient of friction and the wear rate of the diamond nanosheet coating under silk fibroin lubrication are reduced by 54 and 98%, respectively, compared to those of the uncoated Ti alloy under water lubrication. The lubricating mechanism of the newly designed system was revealed by a detailed analysis of the involved microstructural and chemical changes. The outstanding tribological behavior was attributed to the establishment of artificial joint lubrication induced by the cross binding between the diamond nanosheets and silk fibroin. Additionally, excellent biocompatibility of the lubricating system was verified by cell viability, which altogether paves the way for the application of diamond coatings in artificial Ti joint implants.
Subject(s)
Fibroins , Fibroins/chemistry , Diamond , Titanium/chemistry , Materials Testing , Alloys/chemistry , Corrosion , Water , Surface PropertiesABSTRACT
Background: Neoadjuvant anti-programmed death receptor-1 (PD-1) blockade has been explored in the treatment of locally advanced esophageal squamous cell carcinoma (ESCC). We conducted this study to assess the efficacy and safety of neoadjuvant camrelizumab plus chemotherapy in locally advanced ESCC. Methods: We retrospectively enrolled ESCC patients who received surgery within 3 months of treatment with camrelizumab plus chemotherapy from June 2019 to January 2021. Results: A total of 34 eligible patients were enrolled. The neoadjuvant treatment was well tolerated with no serious treatment-related adverse events. Thirty-two (94.1%) patients achieved a R0 resection, and 14 patients (41.2%) developed postoperative complications. The objective response rate (ORR) was 61.8% and the disease control rate (DCR) was 100.0%. The major pathological response (MPR), pathological complete response (pCR), and clinical to pathological downstaging rate were 50.0%, 35.3%, and 79.4%, respectively. With a median follow-up of 14.8 months, 30 (88.2%) patients who underwent surgical resection remain alive. The disease-free survival (DFS) and overall survival (OS) at 12 months were 86.4% and 92.8%, respectively. Conclusion: Neoadjuvant camrelizumab plus chemotherapy is safe and efficacious in treating patients with locally advanced ESCC.
ABSTRACT
MiR-19b-3p has been reported in several types of human cancer. Nevertheless, the expression profile and biological functions of miR-19b-3p remain unclear in non-small cell lung cancer (NSCLC). The expression level of miR-19b-3p was evaluated in NSCLC tissues and cell lines using qRT-PCR. Survival analysis was performed using Kaplan-Meier curves, while the prognostic significance of miR-19b-3p was analyzed using Cox regression analysis in 80 NSCLC patients. The effects of miR-19b-3p on cell proliferation and invasion capacities were analyzed using CCK-8, crystal violet, and transwell assays. Target genes of miR-19b-3p were assessed using luciferase reporter assay, qRT-PCR, Western blot and rescue experiments. MiR-19b-3p was found to be upregulated in human NSCLC tissues and cell lines. The expression of miR-19b-3p was observed to be closely associated with TNM stage and metastasis. High expression of miR-19b-3p was found to be capable of predicting poor clinical prognosis in NSCLC patients. Whilst overexpression of miR-19b-3p was demonstrated to promote the proliferation and invasion of NSCLC cells, knockdown of miR-19b-3p showed an opposite inhibitory effect. Bioinformatics analysis and luciferase reporter assays confirmed that HOXA9 is a direct target of miR-19b-3p. Functional assays demonstrated that NSCLC cell proliferation and invasion were promoted by miR-19b-3p via negative regulation of HOXA9. Finally, overexpression of HOXA9 was shown to partially reverse the tumor promoting effect of miR-19b-3p. This study indicates that miR-19b-3p is a crucial prognostic biomarker of NSCLC, and that targeting of the miR-19b-3p/HOXA9 axis may be a promising strategy in NSCLC therapy.
Subject(s)
Carcinoma, Non-Small-Cell Lung , Lung Neoplasms , MicroRNAs , Biomarkers , Carcinoma, Non-Small-Cell Lung/pathology , Cell Line, Tumor , Cell Movement , Cell Proliferation/genetics , Gene Expression Regulation, Neoplastic , Gentian Violet , Humans , Lung Neoplasms/metabolism , MicroRNAs/metabolism , Prognosis , Sincalide/genetics , Sincalide/metabolismABSTRACT
In this study, feather keratin/polyvinyl alcohol/tris(hydroxymethyl)aminomethane (FK/PVA/Tris) bionanocomposite films containing graphene oxide (GO) (0.5, 1, 2, and 3 wt%) or graphene (0.5, 1, 2, and 3 wt%) were prepared using a solvent casting method. The scanning electron microscopy results indicated that the dispersion of GO throughout the film matrix was better than that of graphene. The successful formation of new hydrogen bonds between the film matrix and GO was confirmed through the use of Fourier-transform infrared spectroscopy. The tensile strength, elastic modulus, and initial degradation temperature of the films increased, whereas the total soluble mass, water vapor permeability, oxygen permeability, and light transmittance decreased following GO or graphene incorporation. In summary, nanoblending is an effective method to promote the application of FK/PVA/Tris-based blend films in the packaging field.
ABSTRACT
Feathers, which contain >90% keratin, are valuable natural protein resources. The aim of this study is to prepare antimicrobial feather keratin (FK)-based nanofibers by incorporating silver nanoparticles (AgNPs). A series of AgNPs-embedded feather keratin/poly(vinyl alcohol)/poly(ethylene oxide) (FK/PVA/PEO) composite nanofibers with varying amounts of AgNPs content were fabricated by electrospinning. Their morphology, crystallinity, thermal stability, tensile property, and antibacterial activity were systematically investigated. The average diameters of composite nanofibers gradually decreased with increases in the amount of AgNPs. The crystallinity, thermal stability, and antibacterial activity of FK/PVA/PEO nanofibers were enhanced by embedding AgNPs. When embedded with 1.2% AgNPs, both the tensile strength and elongation-at-break reached the highest level. This work has the potential to expand the application of FK-based nanofibers in the biomaterial field.
ABSTRACT
The development of edible films based on the natural biopolymer feather keratin (FK) from poultry feathers is of great interest to food packaging. Edible dialdehyde carboxymethyl cellulose (DCMC) crosslinked FK films plasticized with glycerol were prepared by a casting method. The effect of DCMC crosslinking on the microstructure, light transmission, aggregate structure, tensile properties, water resistance and water vapor barrier were investigated. The results indicated the formation of both covalent and hydrogen bonding between FK and DCMC to form amorphous FK/DCMC films with good UV-barrier properties and transmittance. However, with increasing DCMC content, a decrease in tensile strength of the FK films indicated that plasticization, induced by hydrophilic properties of the DCMC, partly offset the crosslinking effect. Reduction in the moisture content, solubility and water vapor permeability indicated that DCMC crosslinking slightly reduced the moisture sensitivity of the FK films. Thus, DCMC crosslinking increased the potential viability of the FK films for food packaging applications, offering a value-added product.
ABSTRACT
The use of waste plant protein obtained from underutilized and non-food-producing plants may be a promising strategy in the development of bioactive packaging. A series of blend films were prepared by casting from cottonseed protein (CP) and poly(vinyl alcohol) (PVA) and modified with different plasticizers. The morphology, structure, and crystallinity of each of the blend films were characterized by scanning electron microscopy, Fourier transform infrared spectroscopy, and X-ray diffraction. CP and PVA were found to be compatible in the appropriate ratios, and the CP/PVA blend films were partially crystalline. We compared the effects that four plasticizers, i.e., glycerol, triethanolamine (TEA), ethylene glycol, and polyethylene glycol, had on the performance of the CP/PVA blend films. Plasticizers altered the degree of interaction between CP and PVA, which changed the secondary structure of the CP but had little effect on the crystallinity of CP/PVA blend films. Among the different plasticizers tested, TEA was the most efficient at improving the elongation at the break, tensile strength, and oxygen barrier properties of the CP/PVA blend films. Such CP/PVA blend films plasticized using TEA can, therefore, be considered emerging and promising plastics for potential applications in food packaging and flower planting applications.
ABSTRACT
In this study, anisotropic graphene/graphene oxide (GO) aerogels (AGAs) were obtained by freeze-drying after direct participation of pristine graphene in the self-assembly of anisotropic gel by the heat flow method. After vacuum microwave treatment, the physical, chemical and structural characteristics of the AGAs were investigated. The results show that AGAs, in which the internal graphene sheets are parallel to the heat flow direction, are successfully prepared. After microwave treatment, the amount of oxygen and nitrogen reduces significantly and the sp2 domain increases. However, at the same time, many fragments and holes are generated in the graphene sheets. The effects of AGAs on the phase transition of paraffin is studied, and the results show that the melting enthalpy, solidification enthalpy and initial melting temperature of AGA/paraffin composites decreases as the GO content in the AGAs increases, whereas the melting range, solidifying range and subcooling degree increases. The highest axial thermal conductivity of the AGA/paraffin composite is 1.45 W/(mK), and the thermal conductivity enhancement efficiency is 884% (AGA content was 0.53 vol %). Compared with previously investigated, similar AGA/paraffin composites, the aerogels fabricated in this study have the obvious advantages of a simple fabrication process, a low cost and a high thermal conductivity enhancement efficiency. These aerogels possess the potential for application in phase-change energy storage (PES), thermal energy management and other fields.
ABSTRACT
In this study, we investigated the directional heating of graphene oxide (GO) dispersion to generate a temperature gradient and form a simulated "ocean current" inside the dispersion so that GO sheets could be aligned in a directional manner and then reduced and self-assembled into anisotropic reduced graphene oxide (rGO) gel. After freeze-drying and varying degrees of vacuum microwave treatment, anisotropic chemically derived graphene aerogels (AGAs) were obtained. Through performance detection and the analysis of the results, it was verified that the AGAs with certain characteristics of "ocean current" were prepared in this experiment, and its axial direction has obvious directional arrangement. After being treated by vacuum microwave for a short time (1 min.), the axial thermal conductivity of the composite materials (AGA-adsorbed paraffin) was observed to be 1.074 W/mK, and the thermal conductivity enhancement efficiency was 995%; as compared with similar thermal conductivity enhancement composites that were found in previous studies, the proposed method in this paper has the advantages of simple processing, high efficiency, and energy conservation.
ABSTRACT
As a new kind of functionalized polysiloxane with chemical reactivity, bio-phenol polysiloxane was synthesized through facile heterogeneous catalytic route. Bio-phenol polysiloxane/polycarbonate (Si/PC) block copolymer was synthesized via a three-step approach, and the effect of the amount of bio-phenol polysiloxane on the properties of Si/PC copolymer was then studied. The structure and morphology of Si/PC copolymer were characterized, showing that, when the amount of bio-phenol polysiloxane reached 20%, the pyrolysis temperature of Si/PC copolymer at 5% weight loss was 450.8 °C which was 76.1 °C higher than pure PC. The oxygen permeability of 20%Si/PC copolymer membrane was 502.65 cm3/m2·24h·0.1MPa, which was increased by 128.4% compared with pure PC membrane. The mechanical property and hydrophobicity of Si/PC copolymer had been improved.
ABSTRACT
In this study, feather keratin/polyvinyl alcohol/tris(hydroxymethyl)aminomethane (FK/PVA/Tris) bionanocomposite films containing two types of nanoparticles, namely one-dimensional sodium montmorillonite (MMT) clay platelets (0.5, 1, 3, and 5 wt%) and three-dimensional TiO2 nanospheres (0.5, 1, 3, and 5 wt%), are prepared using solvent casting method. X-ray diffraction studies confirm the completely exfoliated structure of FK/PVA/Tris/MMT nanocomposites. The successful formation of new hydrogen bonds between the hydroxyl groups of the film matrix and the nanofillers is confirmed by Fourier transform infrared spectroscopy. The tensile strength, elongation at break, and initial degradation temperature of the films are enhanced after MMT and TiO2 incorporation. The water vapor permeability, oxygen permeability, and light transmittance decrease with increase in TiO2 and MMT contents. In summary, nanoblending is an effective method to promote the application of FK/PVA/Tris blend films in the packaging field.
ABSTRACT
Silicone materials are widely used, from daily life to the military industry. With the advancement of science and technology and the increasing demands of industry, the requirement for high-performance precise structural silicone materials has increased. Therefore, the most important aspect in this field is finding a breakthrough in the synthetic methods. In this review, the latest research developments in controllable morphological structure and composite structure optimized synthesis of silicone materials using the Piersâ»Rubinsztajn (PR) reaction are summarized. The advantages of the PR reaction compared with traditional synthetic routes to silicone materials are presented. The highly controllable spatial structure of silicone materials and the structural combination of biomass or inorganic materials with silicone materials results in an improvement in performance or function. The morphological control of more complex silicone materials and the synthesis of non-traditional silicone materials with composite structures through the PR reaction will be the main research directions for the development of silicone materials in the future.
ABSTRACT
In view of their advantages (plasticity, low density, adjustable pore size, high porosity of >99.9%), three-dimensional graphene aerogels (GAs) are widely used for energy storage and adsorption separation, which has inspired the development and optimization of the corresponding synthetic techniques. In particular, self-assembly in the liquid phase features the benefits of tunability and sustainability and is viewed as a promising strategy of GA synthesis. During hydrothermal GA preparation, hydrophilic graphene oxide (GO) gradually turns lipophilic upon reduction, and the resulting phase transition separation and polarity change induce self-assembly into an aerogel. However, the effect of solution polarity on the structure or state of dispersed GO nanosheets, which affects the final property-determining process of automatic assembly, is still unclear. Herein, we prepared a series of GAs by hydrothermal reduction of unwashed GO with vitamin C in liquid-phase systems of different polarity and investigated the effects of polarity on the self-assembly process and aerogel properties using a range of instrumental techniques. The results showed that GO reduction is slowed down in weakly polar systems and further demonstrated that the shape of partially reduced graphene oxide (rGO) flakes depends on solution polarity. Flaky, layered, and stacked rGO particles obtained in strongly polar media self-assembled into anisotropic gully aerogels that were brittle and almost completely inelastic. Conversely, in weakly polar media, the prepared rGO sheets were twisted, which increased the number of contact points and modes between sheets and resulted in self-assembly into uniform-pore-structure honeycomb aerogels that showed good elasticity and could be repeatedly compressed.