Nitrogen-doped porous carbon nanomaterials synthesized using a magadiite template as efficient peroxidase mimics for colorimetric detection of ascorbic acid as an antioxidant.

Nanomaterials with intrinsic enzyme-like activity have gained substantial scientific attention as viable substitutes to natural biological enzymes owing to their cheap price and great stability. Numerous artificial enzyme mimics have been employed effectively in sectors such as sensing, environmental processing, and cancer treatment. In this study, novel nitrogen-doped porous carbon nanomaterials (CPs) were produced by modifying polypyrrole with magadiite using chemical oxidative polymerization and calcination methods. The obtained nitrogen-doped porous carbon nanomaterials exhibited improved peroxidase-like activity, which catalyzed the oxidation of 3,3,5,5-tetramethylbenzidine (TMB) in the presence of hydrogen peroxide (H2O2) to produce colorful compounds. Kinetic investigation revealed that the affinity for TMB of nitrogen-doped porous carbon peroxidase mimics was higher than that of genuine horseradish peroxidase (HRP). In addition, a sensitive assay with encouraging performance for the colorimetric detection of ascorbic acid (AA) was successfully fabricated employing nitrogen-doped porous carbon nanomaterials as peroxidase mimics. The results were satisfactory and demonstrated its potential application in antioxidant detection.

Chlorination Treatment of Meta-Aramid Fibrids and Its Effects on Mechanical Properties of Polytetramethylene Ether Glycol/Toluene Diisocyanate (PTMEG/TDI)-Based Polyurethane Composites.

Meta-aramid fibrids (MAF) have attracted much attention. However, it is difficult for this high mechanical performance fiber to form sufficient interface adhesion between the MAF and polyurethane (PU) matrix due to the chemical inertness of its surface. Thus, the surface activity of MAF should be improved to obtain a high-performance MAF/PU composite. A novel methodology to modify the surface of MAF with a sodium dichloroisocyanurate solution (DCCNa) was developed to obtain chlorinated MAF (MAFC) in this study. A series of MAFC/PU composites was prepared by in situ polymerization processes. The results of Fourier-transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS) demonstrated that the chlorine-contained chemical groups were introduced onto the MAF surfaces after chlorination. Dynamic contact angle analysis (DCAA) revealed that the surface wettability and the surface free energy of the MAFC were significantly improved, which allowed for strong chemical bonding to PU. Scanning electron microscopy (SEM) showed a uniform distribution of MAFC and good interfacing bonding between the MAFC and PU. With the incorporation of 1.5 wt% MAFC into the polyurethane matrix, the tensile and tear strength values of MAFC/PU were 36.4 MPa and 80.1 kN·m-1 respectively, corresponding to improvements of approximately 43.3% and 21.1%, as compared to those of virgin PU as 25.4 MPa and 66.1 kN·m-1, respectively.

Self-Amplified Fluorescent Nanoparticles for Rapid and Visual Detection of Xylene in Aqueous Media.

Pollutant detection is of great importance for quality control of drinking water and environmental protection. The common methods of pollutant detection suffer from time-consuming procedures, bulky and expensive instruments, and complicated sample pretreatment. Herein, a type of conceptually new self-amplified fluorescent nanoparticle (SAFN) is constructed based on aggregation-induced emission (AIE) luminogens for rapid and visual detection of xylene in aqueous media. AIE luminogens are self-assembled into SAFNs in aqueous media, which emit efficiently due to the aggregation of luminogen molecules. The SAFNs of AIE luminogens stick xylene molecules from aqueous media through multiple interactions including hydrophobic and π-π interactions. Upon capturing xylene, SAFNs swell, which quench the fluorescence of the whole SAFNs, showing the self-amplification effect. Such a self-amplification effect is entirely different from that of conjugated polymers in the literature. Importantly, fluorescence quenching of SAFNs by xylene can be readily observed by the naked eye, which enables visual xylene sensing. The SAFNs enable rapid and visual detection of xylene in aqueous media with a low detection limit (5 µg/L) in the order of seconds. Given high sensitivity, rapid response, simple and easy operation, and low cost, SAFNs of AIE luminogens present a promising platform for visual detection of organic pollutants in aqueous media.

Investigation on the Preparation and Properties of CMC/magadiite Nacre-Like Nanocomposite Films.

The layered hydrated sodium salt-magadiite (MAG), which has special interpenetrating petals structure, was used as a functional filler to slowly self-assemble with sodium carboxy-methylcellulose (CMC), in order to prepare nacre-like nanocomposite film by solvent evaporation method. The structure of prepared nacre-like nanocomposite film was characterized by Scanning Electron Microscope (SEM) and X-ray diffraction (XRD) analysis; whereas, it was indicated that CMC macromolecules were inserted between the layers of MAG to increase the layer spacing of MAG by forming an interpenetrating petals structure; in the meantime, the addition of MAG improved the thermal stability of CMC. The tensile strength of CMC/MAG was significantly improved compared with pure CMC. The tensile strength of CMC/MAG reached the maximum value at 1.71 MPa when the MAG content was 20%, to maintaining high transparency. Due to the high content of inorganic filler, the flame retarding performance and the thermal stability were also brilliant; hence, the great biocompatibility and excellent mechanical properties of the bionic nanocomposite films with the unique interpenetrating petals structure provided a great probability for these original composites to be widely applied in material research, such as tissue engineering in biomedical research.

Preparation and Characterization of Magadiite⁻Magnetite Nanocomposite with Its Sorption Performance Analyses on Removal of Methylene Blue from Aqueous Solutions.

The magadiite⁻magnetite (MAG⁻Fe3O4) nanocomposite has great potential applications in the field of biomaterials research. It has been used as a novel magnetic sorbent, prepared by co-precipitation method. It has the dual advantage of having the magnetism of Fe3O4 and the high adsorption capacity of pure magadiite (MAG). MAG⁻Fe3O4 was characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), and vibrating sample magnetometer (VSM). The results showed that Fe3O4 nanoparticles were deposited on the interlayer and surface of magadiite. MAG⁻Fe3O4 was treated as an adsorbent for methylene blue (MB) removal from aqueous solutions. The adsorption properties of MAG⁻Fe3O4 were investigated on methylene blue; however, the results showed that the adsorption performance of MAG⁻Fe3O4 improved remarkably compared with MA and Fe3O4. The adsorption capacity of MAG⁻Fe3O4 and the removal ratio of methylene blue were 93.7 mg/g and 96.2%, respectively (at 25 °C for 60 min, pH = 7, methylene blue solution of 100 mg/L, and the adsorbent dosage 1 g/L). In this research, the adsorption experimental data were fitted and well described using a pseudo-second-order kinetic model and a Langmuir adsorption isotherm model. The research results further showed that the adsorption performance of MAG⁻Fe3O4 was better than that of MAG and Fe3O4. Moreover, the adsorption behavior of MB on MAG⁻Fe3O4 was investigated to fit well in the pseudo-second-order kinetic model with the adsorption kinetics. The authors also concluded that the isothermal adsorption was followed by the Langmuir adsorption isotherm model; however, it was found that the adsorption of the MAG⁻Fe3O4 nanocomposite was a monolayer adsorption.

Sensitive and rapid detection of aliphatic amines in water using self-stabilized micelles of fluorescent block copolymers.

A kind of self-stabilized micelles of fluorescent block copolymers are constructed for rapid and sensitive detection of aliphatic amines in water based on capture-report strategy. An amphiphilic triblock copolymer functionalized with aggregation induced emission (AIE) chromophores self assembles into micelles with core-shell structures in aqueous solution. Hydrophobic AIE chromophores organize into cores, where hydrophobic interaction among the AIE chromophores inhibits the micelles from disassembling. The cores of AIE chromophores are surrounded by a corona of water-soluble polymer segments, endowing the micelles with superior dispersibility in water. Water-soluble polymer segments capture organic amines in water due to preferential hydrophobic interactions between them. The enriched amines in the corona subsequently diffuse into hydrophobic cores of micelles, quenching fluorescence of the AIE chromophores. The fluorescent micelles allow rapid detection of aliphatic amines in the order of seconds at a concentration as low as 8 µg/L.

Effects on the Mechanical Properties of Nacre-Like Bio-Hybrid Membranes with Inter-Penetrating Petal Structure Based on Magadiite.

Rigid biological systems are increasingly becoming a source of inspiration for the fabrication of the advanced functional materials due to their diverse hierarchical structures and remarkable engineering properties. As a bionic biomaterial with a clear layered structure, excellent mechanical properties, and interesting rainbow colors, nacre has become one of the most attractive models for novel artificial materials design. In this research paper, the tough and strong nacre-like bio-hybrid membranes with an interpenetrating petals structure were fabricated from chitosan (CS) and magadiite (MAG) clay nanosheets through the gel-casting self-assembling method. The analyses from X-ray diffraction (XRD), scanning electron microscope (SEM), and observations of water droplets on membranes indicated that the nacre-like hybrid membranes had a layered compact structure. Fourier transforms infrared spectroscopy (FTIR) analyses suggested that the CS molecular chains formed chemical bonds and hydrogen bonds with MAG layers. The inter-penetrating petal layered structure had a good effect on the mechanical properties of a nacre-like bio-hybrid membranes and the tensile strength of the hybrid membranes could reach at 78.6 MPa. However, the transmission analyses of the results showed that the hybrid membranes still had a certain visible light transmittance. Finally, the hybrid membranes possessed an intriguing efficient fire-shielding property during exposure to the flame of alcohol burner. Consequently, the great biocompatibility and excellent mechanical properties of the bio-hybrid membranes with the special interpenetrating petals structure provides a great opportunity for these composites to be widely applied in biomaterial research.

Research on 5-fluorouracil as a drug carrier materials with its in vitro release properties on organic modified magadiite.

The magadiite (MAG) was modified by cetyltrimethyl ammonium-Bromide (CTAB) and then further modified by Chitosan (CS) which is called organic modified-magadiite as magadiite-cetyltrimethyl ammonium bromide (MAG-CTAB) and magadiite-cetyltrimethyl ammonium bromide-Chitosan (MAG-CTAB-CS), respectively, in this research study. The MAG, MAG-CTAB, and MAG-CTAB-CS were used as 5-Fluorouracil (5-FU) drug carrier materials; the drug carrier's materials were marked as magadiite-5-Fluorouracil (MAG/5-FU), magadiite-cetyltrimethyl ammonium bromide-5-Fluorouracil (MAG-CTAB/5-FU), and magadiite-cetyltrimethyl ammonium bromide-Chitosan (MAG-CTAB-CS/5-FU). X-ray diffraction(XRD, Flourier transform infrared spectrometry (FTIR) and scanning electron microscopy (SEM) results were shown that 5-Fluorouracil was combined with carrier materials through physical apparent adsorption, ion exchange, chemical bond, hydrogen bond, and electrostatic interaction. The drug carriers in vitro release behavior in simulated gastric fluids (SGF，pH = 1.35) and intestinal fluids (SIF，pH = 7.40) were investigated. The drug loading capacity and accumulated release ration were as follows the order: MAG-CTAB-CS/5-FU > MAG-CTAB/5-FU > MAG/5-FU. The drug loading capacity of MAG-CTAB-CS/5-FU was 162.29 mg/g, 48 h later the drug accumulated release ratio was 61.24%, and the release amount was 97.52 mg/g for 24 h. Korsmeyer-Peppas model and First order model were found to be suitable to describe the vitro release behavior of 5-Fluorouracil. This would be an economically viable and efficient method for the preparation of advanced drug delivery system.

Adsorption Analyses of Phenol from Aqueous Solutions Using Magadiite Modified with Organo-Functional Groups: Kinetic and Equilibrium Studies.

Organically-modified magadiite (MAG⁻CTAB⁻KH550) was synthesized via ion-exchange method and condensation reaction in the presence of pure magadiite (MAG), cetyltrimethylammonium bromide (CTAB) and γ-aminopropyltriethoxysilane (KH550) in aqueous solution in this research. This new adsorbent material was studied using scanning electron microscope (SEM), X-ray diffraction (XRD), Fourier transforms infrared spectroscopy (FTIR), and N2 adsorption/desorption isotherms process. It was found that the MAG⁻CTAB⁻KH550 has high Brunaur-Emmet-Teller (BET) specific surface area and mesoporous pore size distribution which enhanced its ability to remove phenol in aqueous solution; and, the value of pH has a relatively large impact on the adsorption behavior of the sorbent. Finally, the adsorptive behavior of the mesoporous material on phenol was followed pseudo-second-order kinetic adsorption model. In contrast, the adsorption equilibrium isotherm was better performed Langmuir isotherm model than the Freundlich isotherm model; in addition, the results also showed that the MAG⁻CTAB⁻KH550 had a better adsorption capacity and removal efficiency than MAG.