氧化石墨烯对罗丹明B的吸附行为

将改进Hummer's法合成的氧化石墨烯(GO)用于水中罗丹明B(RB)的去除,探讨了pH值、吸附剂质量、吸附时间、离子强度以及共存离子对吸附性能的影响,并对吸附动力学和吸附机理进行分析.结果表明,强碱不利于GO对RB的吸附,离子强度的增大和共存离子的存在也会抑制GO对RB的吸附.GO对RB的吸附速率主要受电化学吸附控...     

H_2O_2辅助氧化石墨烯光降解罗丹明B

采用传统Hummer法制备氧化石墨烯(GO),以罗丹明B作为目标污染物,研究GO的光降解性能。研究结果表明,GO表现出优异的光降解罗丹明B性能,在GO投加质量浓度为0.15 g/L,罗丹明B质量浓度为10 mg/L(200 m L),300 W氙灯光照120 min后,对其降解率达到86.99%;加入1.0 m L H_2O_2,120 min后光降解率可达到96.14%;羟基自由基捕获实验证明H_2O_2/GO光催化罗丹明B主要遵循羟基自由基氧化机制。在GO投加质量浓度为0.15 g/L,H_2O_2用量为2.0 m L,罗丹明B质量浓度10 mg/L,pH为3,光照10 min降解率达到98%。     

Effect of graphene oxide on the pH-responsive drug release from supramolecular hydrogels

Polypseudorotaxane (PPR) hydrogels formed by inclusion complexes between poly(ethylene glycol) (PEG) and α-cyclodextrin (α-CD) are highlighted as promising biomaterial for drug delivery. Here, we report a novel injectable PPR hydrogel containing graphene oxide (GO) for pH-responsive controlled release of doxorubicin hydrochloride (DOX). Our results showed that the gelation rates of the PEG/α-CD supramolecular structures could be tailored depending on the reagent concentrations. The formation of PEG/α-CD inclusion complexes was confirmed by TEM and XRD, the latter further confirming that GO restricts their formation. The supramolecular hydrogels were easily loaded with DOX by simple addition into the PEG solution before the complex formation with the α-CD solution. Noteworthy, disruption of ionic interactions between DOX and GO in the nanocomposite at pH = 5.5 resulted in higher DOX release than under physiological conditions (pH = 7.4). This pH dependence was barely observed in pure PPR hydrogel. These findings introduce DOX-loaded supramolecular hydrogels nanocomposites as promising carriers for pH-responsive and therefore localized, drug delivery systems.     

GO/CaCO_3复合材料的制备及其药物缓释性能

以经氨基修饰的CaCO_3(CaCO_3-NH_2)和氧化石墨烯(GO)为反应物制备了复合材料(GO/CaCO_3-NH_2)。通过透射电镜(TEM)和傅里叶红外(FT-IR)对材料进行表征,发现GO成功地包裹在CaCO_3的表面,二者通过静电作用结合。对GO/CaCO_3-NH_2复合材料进行了药物布洛芬的载药和缓释性能的研究,结果表明:与CaCO_3相比,GO/CaCO_3-NH_2复合材料具有更高的载药量和更好的缓释性能。载药量从19.56%增加到39.70%,药物连续释药72 h时累积释放量达到53.49%,明显延长了药物作用时间。当质量浓度为75μg/m L时,复合材料的细胞增值率降至73%。GO/CaCO_3-NH_2复合材料在药物缓释体系中有潜在应用。     

In situ gelation and sustained release of an antitumor drug by graphene oxide nanosheets

Graphene oxide nanosheets were used to induce the in situ gelation of doxorubicin hydrochloride as an antitumor drug. When a very small amount of the graphene oxide was introduced into an aqueous solution of doxorubicin hydrochloride at room temperature, a strong and thixotropic gel was rapidly formed without any polymers or chemical additives. The gelation mechanism was investigated by fluorescence spectroscopy, X-ray diffraction and scanning electron microscopy. The encapsulated doxorubicin hydrochloride was found to show sustained release and antitumor efficacy.     

Glucosamine conjugated iron oxide and graphene oxide nanohybrid for smart drug delivery

Smart drug delivery systems have attracted a lot of attention as one of the new treatment methods for cancer. In this study, a smart drug delivery system carrying anticancer drugs was obtained by the intelligent synthesis of glucosamine (GA)-functionalized graphene oxide (GO)-based iron oxide nanoparticles (Fe₃O₄@GO-GA) using Hummers and chemical co-precipitation processes. Nanohybrids have a high surface area (280.26 m²/g) and superparamagnetic behaviour (Ms = 26.017 emu/g), indicating a significant loading capacity (373.78 mg/mg) and efficiency (96.3%) for pharmaceutical loading. An adsorption study of conventional daunorubicin (DNR) on this carrier showed that the drug release is more prone to occur under acidic conditions (pH = 5.5), at moderately high temperatures (T = 40°C), and in the absence of smart carriers. The toxicity of the smart nanohybrids was examined using the sulphorhodamine B (SRB) assay in Michigan Cancer Foundation-7 (MCF-7) cell lines. The rate of death of cells exposed to smart drug-containing systems in comparison to the systems without GA shows that GA reduces the toxicity of Fe₃O₄@GO.     

Hyaluronic acid conjugated graphene oxide for targeted drug delivery

Nano-sized graphene oxide (GO) is functionalized with adipic acid dihydrazide to introduce amine groups, and then hyaluronic acid (HA) is covalently conjugated to GO by the formation of amide bonds. The resulting HA-grafted GO (GO–HA) has negligible hemolytic activity and very low cytotoxicity towards HeLa and L929 cells, and it can be effectively taken up by cancer cells through receptor-mediated endocytosis. The histological, hematological and biochemical analysis results suggest no perceptible toxicity of GO–HA in mice at a high exposure level of 10 mg kg⁻¹ and at an exposure time of up to 10 days. Doxorubicin (DOX) can be efficiently loaded on the GO–HA, and the resulting GO–HA/DOX exhibits notable cytotoxicity to HeLa cells. The in vivo drug delivery capability of GO–HA is demonstrated by following the tumor growth in mice after intravenous administration of GO–HA/DOX. The results indicate that GO–HA can efficaciously deliver DOX to the tumors and suppress tumor growth.     

High-efficiency loading of hypocrellin B on graphene oxide for photodynamic therapy

A novel hybrid of graphene oxide (GO) and hypocrellin B (HB) was prepared using a simple noncovalent method. An efficient loading of HB on GO as high as 2 mg/mg was obtained. Mechanism analysis indicated that the π–π stacking interaction is the dominant driving force in the noncovalent interaction between HB and GO. Irradiation of HB and GO hybrid (HB–GO) results in efficient generation of singlet oxygen (¹O₂). In vitro studies have demonstrated the active uptake of HB–GO into the cytosol of tumor cells. Significant damage to such impregnated tumor cells was observed upon irradiation.     

The effects of graphene oxide on the properties and drug delivery of konjac glucomannan hydrogel

Konjac glucomannan (KGM) hydrogel has good potential application in food and medical science, although to achieve this, the physical and mechanical properties need further improvement. In this study, graphene oxide (GO) was used to improve the functionality of KGM hydrogel. KGM/GO hydrogels were prepared by freezing the alkaline KGM/GO sols. Rotational rheometer was used to study the rheological properties of different alkaline KGM/GO sols. Fourier transform infrared, Raman, differential scanning calorimetry, thermogravimetric analyses, and scanning electron microscopy were used to evaluate the structure and properties of the hydrogels. In addition, different pH solutions and an in vitro assay were used to study the swelling property and the release behavior of KGM/GO hydrogels, respectively. The result revealed strong hydrogen‐bond interaction between KGM and GO. The incorporation of GO highly improved the gel properties of KGM/GO sol, higher thermal stability, and more compact structure of KGM/GO hydrogels. KGM/GO hydrogels showed better swelling properties in deionized‐distilled water and pH 7.2 PBS. The release of 5‐aminosalicylic acid (5‐ASA) from KGM/GO (KG4) hydrogel was different in various pH media, but the initial burst release effect was very severe. Therefore, incorporation of GO have a good potential in enhancing the properties of KGM hydrogel, but KGM/GO hydrogel is not an ideal carrier for 5‐ASA release. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 45327.     

Real time monitoring of latex film dissolution by UVV technique

UV–visible (UVV) technique is used for monitoring of polymer film dissolution. These films are formed from pyrene (P)‐labeled poly(methyl methacrylate) (PMMA) latex particles, sterically stabilized by poly isobutylene (PIB, Annealing of films was performed above T_g at various temperatures for 30‐min time intervals. Diffusion of solvent molecules (chloroform) into the annealed latex film was followed by desorption of PMMA chains. Desorption of P‐labeled PMMA chains was monitored in real time by the absorbance change of P in the polymer–solvent mixture. A diffusion model with a moving boundary was used to quantify real time UVV data. Diffusion coefficients of desorbed PMMA chains were measured and found to be between 2 and 0.6 × 10⁻¹¹ cm² s⁻¹ in the 100 and 275°C temperature range. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 75: 1075–1082, 2000     

Mechanical properties and drug release of microcapsules containing quaternized‐chitosan‐modified reduced graphene oxide in the capsular wall

Reduced graphene oxide (rGO) sheets were first modified with 2‐hydroxypropyltrimethyl ammonium chloride chitosan (HACC), and these modified rGO sheets (named HACC–rGO) were used as reinforcement materials and introduced to the walls of chitosan (CS) microcapsules. All of the monodisperse microcapsules were conveniently generated by a gas–liquid microfluidic technique. The results of scanning electron microscopy, X‐ray diffraction, and thermogravimetric analysis all demonstrate that the HACC–rGO sheets existed and were dispersed in the capsular shell. The HACC–rGO‐reinforced CS microcapsules showed better mechanical strength and better chemical stability with an α‐cyclodextrin solution than the CS microcapsules without HACC–rGO. Importantly, the HACC–rGO‐reinforced CS microcapsules exhibited a slower drug‐release behavior and provide a method for the control of the release rate of drug‐loaded microcapsules. In an in vitro cytotoxicity evaluation by a 3‐(4,5‐dimethyl‐2‐thiazolyl)‐2,5‐diphenyl‐2‐H‐tetrazolium bromide assay, the Schwann cells still showed good cell viability after they were treated by extracts of the CS/HACC–rGO microcapsules with concentrations ranging from 0.02 to 2000 μg/mL. Therefore, the HACC–rGO‐reinforced CS microcapsules are promising for applications in the fields of drug delivery and controlled release. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 44549.     

基于声学法的堆积煤粉温度场实时监测

在煤粉制备、运输及储存过程中,堆积煤粉通常暴露于氧化环境中,当外界温度过高时极易发生自燃。低频声波具有衰减低、传播距离长的特点,以其作为声源的声学测温方式可有效弥补常规热电偶滞后预警的问题,实现实时测量,显著提升发电过程的智能化水平。主要探究了堆积煤粉的声吸收特性以及低频声波(频率在200～2 000 Hz)在堆积煤粉中的传播特性,试验以福泉煤矿的烟煤为研究对象,制备了4种不同粒径的煤样,研究了不同粒径煤粉以及堆积高度下的声吸收特性,发现堆积煤粉的声吸收曲线存在多峰值现象。进行了不同频率下低频声波在堆积煤粉中的传播特性试验,结果表明在1 000～2 000 Hz声衰减系数下降趋势明显;在实验室环境温度下,堆积煤粉的声速在142.261～142.851 m/s,试验标准差约0.1%,结果较稳定,验证了声学测量堆积煤粉温度分布的可行性。     

Effects of graphene oxide and chemically reduced graphene oxide on the curing kinetics of epoxy amine composites

The curing kinetics of epoxy nanocomposites prepared by incorporating graphene oxide (GO) and chemically reduced graphene oxide (rGO) have been studied using isothermal and nonisothermal differential scanning calorimetry. The kinetic parameters of the curing processes in these systems have been determined by a Kamal and Sourour phenomenological model expanded by a diffusion factor. The predicted curves determined using the kinetic parameters fit well with the isothermal DSC thermograms revealing the proposed kinetic equation clearly explains the curing kinetics of the prepared epoxy amine nanocomposites. Experimental and modeling results demonstrate the presence of an accelerating effect of the GO on the cure of the resin matrix. The use of rGO instead of GO resulted in a slight acceleration reaction rate due to the reduced presence of oxidation groups in rGO. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 44803.     

Enzymatic degradability and release properties of graphene oxide/silk fibroin nanocomposite films

The structure evolution of silk fibroin (SF) in the nanocomposite films with graphene oxide (GO) was investigated and related to the enzymatic degradability and release property. The interaction with GO was found to induce conformation transition of SF from random coil to β-sheet. However, the surface binding constrained the rearrangement of the silk chains, leading to a decrease of β-sheet when GO content was more than 1.0%. The crystal structure of SF played a key role in the degradation of GO/SF composites. The preferential degradation of the hydrophilic blocks resulted in a faster degradation of SF films with higher β-sheet content. The addition of GO to SF matrix led to a slower release and a reduction of the burst release of RhB, the model compound. The release profile was well fitted to the Rigter–Peppas equation, from which the characteristic constant decreased and the diffusional exponent increased with increasing GO content but quickly leveled off when GO content was more than 1.0%. Degradation of the composites had little influence on the characteristic constant of RhB release, however, led to an increased diffusional exponent, which was more evident for the composites with higher β-sheet content.     

Drug release study by a novel thermo sensitive nanogel based on salep modified graphene oxide

To develop more effective drug delivery systems, a novel thermo sensitive nanogels (TNGs) were prepared by crosslinking of NIPAM graft copolymerization onto salep modified graphene oxide (SMGO). The sizes of as-synthesized TNGs were about 93 nm. It was found that the concentration of GO, surfactant, and polymerization agent were strongly effected on the average size of TNGs. Besides, obtained TNGs display thermo-induced transmittance due to thermo-responsive PNIPAM contained in synthesized TNGs. Moreover, the TNGs presented high drug loading capacity and excellent drug release at higher temperate, without any burst release. It was also demonstrated that the loading drug onto TNGs greatly decreased the cytotoxicity of the drug onto HeLa cells. The results offered evidence that SMGO-based TNGs can serve as novel nanocarriers for anti-cancer drug delivery.     

Real time cure monitoring of composite structures using the techniques of mechanical impedence analysis

A dynamic mechanical apparatus, based on the concept of mechanical impedance analysis (MIA), was constructed for real-time cure monitoring of composites. The frequency response function (FRF), in terms of the inertance, impedance or admittance value, can be obtained from the ratio of the Fourier Transforms of excitation and response signals. Spectra during curing of several different kinds of composite materials were obtained with the Fast Fourier Transform spectrum analyzer while the material was continually excited with a random input generated by an electro-magnetic shaker. The dynamic properties, such as storage modulus (E′) and loss tangent (tan δ), of the composite can be obtained from the FRF spectra as a function of cure time and temperature. Variations of the inertance spectra with cure time, reflecting the changes in the dynamic mechanical properties, for the composite materials under various isothermal cure conditions are discussed. Optimal cure cycles of a new resin can be determined by characterizing the phase transformation of the material, which can be identified from the MIA measurement results. The MIA technique is found to be a sensitive and direct means for monitoring the overall cure state of composites. The signals obtained can be integrated in real-time in a closed-loop feedback control system for composite fabrication.     

Green fabrication of porous chitosan/graphene oxide composite xerogels for drug delivery

Porous chitosan (CS)/graphene oxide (GO) composite xerogels were prepared through a simple and “green” freeze‐drying method. Scanning electron microscopy, Fourier transform infrared spectrometry, powder X‐ray diffraction, and compressive strength measurements were performed to characterize the microstructures and mechanical properties of as‐prepared composite xerogels. The results show that the incorporation of GO resulted in an observable change in the porous structure and an obvious increase in the compressive strength. The abilities of the composite xerogels to absorb and slowly release an anticancer drug, doxorubicin hydrochloride (DOX), in particular, the influence of different GO contents, were investigated systematically. The porous CS/GO composite xerogels exhibited efficient DOX‐delivery ability, and both the adsorption and slow‐release abilities increased obviously with increasing GO content. Additionally, the best adsorption concentration of DOX was 0.2 mg/mL, and the cumulative release percentage of DOX from the xerogels at pH4 much higher than that at pH 7.4. Therefore, such porous CS/GO composite xerogels could be promising materials as postoperation implanting stents for the design of new anticancer drug‐release carriers. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2014 , 131, 40006.     

Multiscale patterning of graphene oxide and reduced graphene oxide for flexible supercapacitors

A simple and facile method for multiscale, in-plane patterning of graphene oxide and reduced graphene oxide (GO–rGO) was developed by region-specific reduction of graphene oxide (GO) under a mild irradiation. The UV-induced reduction of graphene oxide was monitored by various spectroscopic techniques, including optical absorption, X-ray photoelectron spectroscopy (XPS), Raman, and X-ray diffraction (XRD), while the resultant GO–rGO patterned film morphology was studied on optical microscope, scanning electron microscope (SEM), and atomic force microscope (AFM). Flexible symmetric and in-plane supercapacitors were fabricated from the GO–rGO patterned polyethylene terephthalate (PET) electrodes to show capacitances up to 141.2 F/g.