Assistance Of Microwave Irradiation Research Articles

Biocompatible chitosan-carbon nanocage hybrids for sustained drug release and highly efficient laser and microwave co-irradiation induced cancer therapy

Graphitic carbon nanocages (GCNCs) are unique graphene-based nanomaterials that can be used for cancer photothermal therapy (PTT). However, low toxicity GCNC-based organic/inorganic hybrid biomaterials for microwave irradiation assisted PTT have not yet been reported. In the present study, chitosan (CS)-coated GCNCs (CS-GCNCs) loaded with 5-fluorouracil (5Fu) were used for cancer therapy when activated by 808-nm laser and microwave co-irradiation. The cytotoxicity of GCNCs was significantly reduced after coating with CS. For example, fewer cell-cycle defects were caused by CS-GCNCs in comparison with non-coated GCNCs. The release rate of 5Fu from CS-GCNCs was significantly slower than that of 5Fu from GCNCs, providing sustained release. The release rate could be accelerated by 808-nm laser and microwave co-irradiation. The 5Fu in CS-GCNCs retained high cancer cell killing bioactivity by enhancing the caspase-3 expression level. The cancer cell killing and tumor inhibition efficiencies of the 5Fu-loaded nanomaterials increased significantly under 808-nm laser and microwave co-irradiation. The strong cell killing and tumor ablation activities were due to the synergy of the enhanced GCNC thermal effect caused by laser and microwave co-irradiation and the chemotherapy of 5Fu. Our research opens a door for the development of drug-loaded GCNC-based nano-biomaterials for chemo-photothermal synergistic therapy with the assistance of microwave irradiation. Statement of SignificanceGraphitic carbon nanocages (GCNCs) are graphene-based nanomaterials that can be used for both drug loading and cancer photothermal therapy (PTT). Herein, we showed that chitosan (CS)-GCNCs hybrid biomaterials had very low cytotoxicity, high ability for loading drug, and exhibited sustained drug release. In particular, although low-power microwaves alone are unable to trigger cancer cell damage by GCNCs, the cell killing and mouse tumor inhibition efficiencies were significantly improved by near-infrared (NIR) laser and microwave co-irradiation compared with laser-triggered PTT alone. This combined use of laser and microwave co-irradiation promises essential therapeutic modality and opens a new avenue for PTT.

Promoting effect of microwave irradiation on CeO2-TiO2 catalyst for selective catalytic reduction of NO by NH3

In this work we prepared several CeO2-TiO2 catalysts for the NH3-SCR reactionusing co-precipitation with assistance of microwave irradiation. The catalytic NH3-SCR activities over CeO2-TiO2 catalysts at low temperatures are largely enhanced by the treatment of microwave irradiation, the operation temperature window is also broadened. For better understanding the promotion mechanism, the catalyst prepared by conventional co-precipitation with and without microwave irradiation treatment was characterized with H2-TPR, NH3-TPD, XPS, XRD and BET. Microwave irradiation treatment accelerates the crystallite rate of CeO2-TiO2 catalysts, and greatly enlarges their surface area by adjusting their microstructures. The resistance to SO2 and H2O is also improved via regulating the hierarchical pore structure by the microwave irradiation. Microwave irradiation treatment can also improve the redox property and increase the acid sites over the catalyst surfaces. The result of in situ DRIFTS suggests that the microwave irradiation treatment generates more Brønsted acid sites on CeO2-TiO2-2 h catalyst, helpful in SCR reactions. XPS results show that after microwave irradiation on the CeO2-TiO2 catalysts, the surface demonstrates an elevated concentration of chemisorbed oxygen, consequently leading to better oxidation of NO to NO2. Additionally, the molar ratio of Ce3+/Ce4+ has been elevated after being treated by microwave irradiation, a vital factor in enhancing the NH3-SCR activities.

Dye removal efficiency of perovskite structured CaTiO3 nanospheres prepared by microwave assisted method

The nanostructured CaTiO3 photocatalyst is one of the most promising materials for the degradation of organic dyes owing to its unique properties. Perovskite structured CaTiO3 nanomaterial has been synthesized using the simple peroxo route with the assistance of microwave irradiation. The XRD analysis confirms the presence of perovskite structure of the prepared nanomaterials. FT-IR analysis endorses the presence of Ca-Ti-O vibrational bonds. The photocatalytic property was investigated using methylene blue (MB) dye. The present investigation clearly reveals that the synthesized CaTiO3 nanomaterials have a remarkable catalytic ability to degrade MB dye under UV light exposure.

Multifunctional Thin-Film Nanofiltration Membrane Incorporated with Reduced Graphene Oxide@TiO2@Ag Nanocomposites for High Desalination Performance, Dye Retention, and Antibacterial Properties.

High desalination performance, dye retention, and antibacterial properties were achieved with a multifunctional thin-film nanocomposite (MTFN) membrane, fabricated by the incorporation of a novel nanocomposite structure of reduced graphene oxide@TiO2@Ag (rGO@TiO2@Ag) into the polyamide active layer. The specific characteristics of the graphene-based nanocomposite, synthesized by the microwave-assisted irradiation process, favored water channelization and provided superhydrophilicity and antibacterial properties to the MTFN membranes. In comparison with the conventional methods, such as multistep chemical process using strong agents for reduction and long-term energy-consuming hydrothermal process, microwave irradiation facilitated a green, fast, and cost-effective route for the fabrication of GO-based nanocomposites for multifunctional applications. Interfacial polymerization was performed on a polyethersulfone/Si3N4 robust hollow fiber substrate using m-phenylenediamine aqueous solution and 1,3,5-benzenetricarbonyltrichloride organic solution. The structural and chemical characteristics of the synthesized nanocomposites and the MTFN membranes were thoroughly studied by a series of characterization analyses (transmission electron microscopy, field emission scanning electron microscopy, X-ray diffraction, Fourier transform infrared, energy-dispersive X-ray spectroscopy, X-ray photoelectron spectroscopy, and atomic force microscopy). The physicochemical properties and the nanofiltration performance of the MTFN membranes were investigated after the incorporation of rGO@TiO2@Ag at various concentrations. The water contact angles confirmed the superb surface hydrophilicity of the MTFN membranes. High permeability (52 L·m-2·h-1), desalination (96% for 1 g/L Na2SO4 feed solution), and dye retention (98% for 0.5 g/L rose bengal feed solution) were recorded for MTFN enriched with 0.2 wt % rGO@TiO2@Ag. A 90% reduction in the number of viable bacteria ( Escherichia coli), after 3 h of contact with MTFN membranes, confirmed the superior antibacterial activity of the produced membranes.

Effects of pretreatment applied to sugarcane bagasse on composition and morphology of cellulosic fractions

Due to the growing demand for renewable energy, the energy based on biomass plays an important role in energy policies of countries all over the world. Seven different pretreatments were performed on SCB to obtain yields, chemical composition, particle sizes and crystallinity indexes. The tools used to study the effects of pretreatments on SCB were X-ray diffraction (change in crystalline and amorphous regions) and SEM images. The application of microwave-assisted irradiation allowed the obtaining of the lowest cellulose removal with the fractions PT-6 and PT-7. FTIR spectra showed the removal of hemicellulose and lignin content during pretreatments. DP values decreased significantly suggesting higher digestibility of the seven cellulosic fractions by cellulolytic enzymes. In the present work, the presence of cellulose, hemicellulose and lignin structures in the sample of sugarcane bagasse and cellulosic fractions were indicated by the characteristic absorption bands (cm−1) of groups shown by the FTIR spectrum for hemicellulose and lignin. SEM images showed extensive degradation of the buddle of fibers of some cellulosic fractions. Mass loss (ML) obtained with SCB and cellulosic fractions were much greater under O2 atmosphere than under N2 atmosphere. The most relevant novelty of the present research was the use of chemical and physical methodologies to characterize sugarcane bagasse and their cellulosic fractions. The objective of this work was to determine the chemical composition and physical characteristics such as particle sizes as well as the removal of components resulting from seven different pretreatments. Nevertheless, future work is greatly required for improvement in this area.

Microwave-Assisted Synthesis of Bile Acids Derivatives: An Overview

: The first attempts at microwave-assisted (MW) syntheses of bile acid derivatives were performed in domestic MW appliances. However, the reproducibility of these syntheses, which were performed in uncontrolled conditions, was very low. In the first part of this overview, compounds synthesized under such conditions are presented. Consequently, with the development of MW technology, MW-assisted reactions in MW reactors became reproducible. Thus, in the second part of this review, syntheses of bile acidsbased compounds in MW reactors are presented. Among others, publications dealing with the following topics will be covered: : − Chemical transformations of hydroxyl and/or carboxyl functions of bile acids into esters or amides, : − Hydroxyl group oxidations, : − Derivatization of oxo-compounds with different nitrogen-containing compounds (e.g. 4-amino-3- substituted-1H-1,2,4-triazole-5-thiones, thiocarbohydrazides and thiosemicarbazides) : Bile acid-based molecular tweezers, capable of stereospecific molecular recognition : Reactions of hydroxyl functions to give chlorine derivatives, presenting reactive intermediates in substitution reactions with N- or O-containing nucleophilic arylhydrazides, urea derivatives, substituted thiadiazoles or triazoles or amino acid methyl esters, mainly in solvent-free conditions. : Some of the synthesized compounds expressed antimicrobial potential and/or good recognition properties as artificial receptors for specific amino acids or anions. : Detailed comparisons between conventional and MW-assisted procedures for chemical transformations of bile acids are given in most of the presented publications. Based on these results, MW irradiation methods are simpler, more efficient, cleaner and faster than conventional synthetic methods, meeting the requirements of green chemistry.

Improved one-pot synthetic conditions for synthesis of functionalized fluorescent coumarin-thiophene hybrids: Syntheses, DFT studies, photophysical and thermal properties

We have synthesized coumarin-thiophene hybrids using stepwise and one-pot methods under MWI and CM conditions, and then report the findings and conclusions: one-pot is better than stepwise in terms of high yields and fastness of getting products, and MWI is better than CM in terms of purity of compounds, better yields, and reaction period. Even though both protocols were found to be efficient, the microwave-assisted irradiation reactions were identified to be better, environmentally friendly, cost-effective, mild, more efficient, less time consuming but with high purity. The two protocols were employed for the synthesis of the target coumarin-thiophene hybrids via the Gewald reaction in stepwise and in one-pot three-component. The dyes 3a-j were prepared in good to excellent yields. Although, we recorded better yields via the stepwise protocol (80–96%), for the synthesis of the target molecules, as compared to the one-pot (82–90%), the stepwise condition is fraught with many changes such as long reaction conditions, extra use of solvents for purification of intermediates, and long reaction durations. Photophysical activities of all the target derivatives were investigated using a combination of UV–vis and fluorescence spectroscopies in different solvents. The umbelliferon-like derivative 3g was further investigated for possible use as a pH sensor via deprotonation (using TBAOH) and reverse protonation (using TFA), and was found to be applicable as pH sensor both in organic medium (DMSO) and partial aqueous binary (DMSO/H2O, v/v, 9:1) medium. Again, the ground and the excited state properties of the umbelliferon-like derivative 3g and its deprotonated form were also studied using the quantum chemical calculations. Finally, the thermal properties of all the target compounds were investigated using TGA in order to test their potency and applicability as optical dyes. All the dyes 3a-j have high thermal stability therefore they can be applicable as optical dyes.

Utilization of Activated Carbon Prepared from Pumpkin Seed Shell for the Removal of Dyestuff from Aqueous Solutions and Wastewater by Microwave Radiation

In this study, the aim was to investigate the removal of the cationic (Methylene Blue, MB) and anionic (Acid Blue 193, AB) dyestuff from aqueous solutions and wastewater (synthetic) using activated carbon prepared from pumpkin seed shell as adsorbent (as catalyst) by the microwave-assisted (MW) method. This process is the combination of MW irradiation, MW adsorbent (as catalyst) and oxidant. The effects of radiation time, dosages of adsorbent and oxidant and initial dyestuff concentration on the removal efficiency were investigated. With the initial dyestuff concentration of 100 mg/L, a 99 % dyestuff removal percentage was obtained applying low power in 3 min using 0.2 g activated carbon and 0.5 mL hydrogen peroxide for MB and a 90% removal percentage was obtained applying low power in 3 min using 0.6 g activated carbon and 0.5 mL hydrogen peroxide for AB. Results suggest that the prepared activated carbon from pumpkin seed shell has potential in remediation of dyestuff contaminated waters. Keywords : Activated carbon, Dyestuff, Aqueous solution, Wastewater, Microwave radiation DOI : 10.7176/JSTR/5-2-08

Efficient synthesis of BiFeO3 by the microwave-assisted sol-gel method: “A” site influence on the photoelectrochemical activity of perovskites

BiFeO3 (BF) and LaFeO3 (LF) perovskites were synthesized using a microwave-assisted (MW) and sol-gel (SG) methods. XRD, XPS, TEM, UV-DRS techniques were applied to study physicochemical properties of perovskites. In addition, Incident Photon-to-Current Efficiency (IPCE) measurements, Linear Sweep Voltammetry (LSV) and impedance spectroscopy were used to characterize electrochemical properties of the materials. The band gap energy increases in the following way: BF-MW (2.05 eV), LF-MW (2.18 eV), BF-SG (2.26 eV) and LF-SG (2.54 eV), demonstrating a remarkable influence of the synthesis method on the optical and electronic properties of the materials. Furthermore, XRD showed a significant impact of the synthesis methods on the crystal structure. Perovskites synthesized under MW irradiation showed a pure crystal structure compared to the perovskites prepared by SG method, which contained some admixtures. IPCE shows that LF-MW has a better charge separation ability compared to BF-MW. However, BF-SG showed the highest activity. Temperature programmed reduction tests (TPR) revealed a better ability of BF-MW to adsorb/desorb oxygen, compared to LF-MW. XPS measurements pointed at the presence of Fe4+. Finally, the photocatalytic activity of the perovskites was tested in solar water-splitting as a function of the synthesis method and presence of Bi and La in “A” sites of the ABO3 perovskites. We postulate, that the Jahn-Teller distortion effect in LF-MW increases its catalytic activity by decreasing the binding energy compared to BF-MW.

Synthesis of Pyridodiindoles with Anticancer Activity by a Three-Component Cascade Condensation.

A novel three-component cascade reaction was discovered and developed to synthesize pyridodiindoles with the assistance of microwave irradiation. A collection of pyridodiindoles was prepared by means of the mild reaction and simple operation procedure, which could be applicable to a broad scope of functional aldehydes. Screening demonstrated that compound 5g exhibited a good potency in HCT116 cell lines, and this work validated the feasibility of this novel reaction for generating promising bioactive compounds.

Structural, optical and magnetic properties of Zn1-xMnxFe2O4 (0 ≤ x ≤ 0.5) spinel nano particles for transesterification of used cooking oil

Pure and manganese doped zinc ferrite nanoparticles were prepared via sonication assisted microwave irradiation method and it's employed for biodiesel production from used cooking oil (UCO). The nanoparticles were characterized by XRD, FTIR, DRS, HR-SEM, EDX and VSM techniques. The X-ray diffraction (XRD) results confirmed the formation of cubic spinel structure with Fd-3m space group without any impurities. The average crystalline size of manganese doped and undoped zinc ferrites were in the range from 7.49 nm to 9.65 nm as calculated from Scherer's formula. Fourier transformed infrared spectroscopy (FTIR) studies show the characteristic bands at 550 cm−1 and 419 cm−1 which confirming the presence of Fe-O and Zn-O vibrational stretching frequencies related to octahedral and tetrahedral positions of the zinc ferrite spinel's. UV–vis diffuse reflectance spectroscopy (DRS) revealed the optical energy band gap values in the range 1.90 eV–1.99 eV. The magnetic parameter such as coercivity (Hc), remanence magnetization (Mr) and saturation magnetization (Ms) were determined from hysteresis curves recorded at room temperature. The prepared ferrite nanoparticles were employed for the production of biodiesel from used cooking oil by transesterification process. The maximum yield of biodiesel 98.3% was achieved with 4 wt% of Mn2+ doped ZnFe2O4 nanocatalyst (ZnMnF5), reaction time 50 min, reaction temperature about 65 °C and methanol to oil molar ratio of 21:1. The ZnMnF5 sample was reused atleast 10 times with less reduction in activity. The standard values of biodiesel was measured using ASTM D-6751 method. The formation and composition of fatty acid methyl esters (FAME) were conformed using Gas chromatography-Mass spectroscopy. Mechanism for the biodiesel production using the doped zinc ferrite nanoparticle was proposed.

The Synthesis of Carboxymethyl Cellulose‐Based Hydrogel from Sugarcane Bagasse Using Microwave‐Assisted Irradiation for Selective Adsorption of Copper(II) Ions

This study presents the sustainable applications of recycling agricultural waste. The cellulose from sugarcane bagasse (SCB) was extracted to prepare the carboxymethyl cellulose (CMC) used as the starting material for synthesizing CMC‐based hydrogel for the selective adsorption of Cu(II) ions in contaminated solution. Hydrogel fabrication was performed under microwave‐assisted irradiation, which helps to improve reaction efficiency and significantly reduces reaction time compared with using a conventional hotplate. The hydrogel of 25% CMC blended with poly(vinyl alcohol) (PVA) and using glutaraldehyde (GA) as a cross‐linking agent showed the property of selective adsorption for Cu(II) ions from the solution with an adsorption capacity of 2.3 mg/g (92.4% removal) under ambient temperature with pH 5.0. The adsorbed Cu(II) ions were effectively desorbed from the hydrogel by either 0.1 M HCl or 0.1 M EDTA. Thus, the prepared hydrogel could potentially be applied in the removal of Cu(II) ions from contaminated water, with promising potential for reuse after the regeneration process. Sugarcane bagasse was used as a starting material for the synthesis of hydrogel, which has selective adsorption property to Cu(II) ions. In addition, microwave‐assisted irradiation, technology that is able to save time and energy, was exploited for the polymer synthesis. Therefore, this study presents the sustainable applications of recycling agricultural waste for the purpose of water treatment. © 2018 American Institute of Chemical Engineers Environ Prog, 38: S157–S165, 2019

Diversity‐Oriented Synthesis of Functionalized Imidazopyridine Analogues with Anti‐Cancer Activity through a Transition‐Metal Free, One‐pot Cascade Reaction

AbstractA transition‐metal free, high yielding and efficient three‐component reaction was designed and incorporated into two sequential oxidation and cyclization reaction cascades in one‐pot with the assistance of microwave irradiation. A chemical collection of functionalized 3‐substituted imidazopyridines was prepared by means of the mild reaction and simple operational procedure. The reaction has a broad tolerance for a variety of substituted carbonyl aldehydes, anilines and 2‐phenyl‐imidazo[1,2‐a]pyridines. Screening in several cancer cell lines was conducted. Compound 9 i exhibited good potency against HeLa cell lines and this work validated the feasibility of the methodology for generating bioactive compounds.magnified image

Scalable exfoliation and activation of graphite into porous graphene using microwaves for high–performance supercapacitors

Activated few–layered graphene (a–FLG) materials with porous structures are prepared using a KOH–assisted microwave irradiation technique from natural graphite. The employment of KOH as a chemical etchant efficiently activates the surface pore structure of graphene during the exfoliation of graphite exposed to microwave irradiation. The resultant a–FLG materials exhibit favorable and tailorable large surface areas and porous structures for the deposition of electrochemically active MnO2. When measuring electrochemical characteristics, MnO2/a–FLG exhibits a high specific capacitance (265 F/g), high rate capability, and excellent long–term stability. Moreover, asymmetric supercapacitor devices fabricated using a–FLG as a negative electrode and MnO2/a–FLG as a positive electrode show high energy (40.8 Wh/kg) and power (16.3 kW/kg) densities with high capacitance retention (96% over 10000 cycles).

Synthesis of 5‐Substituted Benzo[h]quinoline Derivatives via Reactions Involving C(sp2)−Br Bond Activation

AbstractIn view of literature reports, benzo[h]quinoline and its substituted analogues, due to their structural similarity to 2‐phenylpyridine derivatives, appear to be very promising C,N‐cyclometalating ligands for iridium‐based Phosphorescent Organic Light Emitting Diode technology. 5‐bromo‐benzo[h]quinoline aroused our particular interest as a convenient precursor for further transformations, and was successfully functionalized in the course of transition metal‐promoted exclusive C−C, C−O and C−N bond formation, yielding a series of 5‐substituted benzo[h]quinoline derivatives with unique structures and properties. Some of the synthesized compounds seemed to be appropriate starting materials for subsequent transformations, and enabled the preparation of new benzo[h]quinoline‐based materials, for instance those with fluorine or silsesquioxane groups, which have not been synthesized by the conventional Scraup protocol. In selected transformations, the assistance of microwave irradiation as a non‐conventional energy carrier significantly improved efficiency, leading to the formation of desired products with yields of up to 99%.magnified image

Solvent-free Synthesis and Antimicrobial Properties of Some Novel Furanone and Spiropyrimidone Derivatives

Background: The regioselective synthesis of spiro-heterocyclic compounds is intriguing since those compounds have unique non-planar structures and great potential for binding to biomolecules because of their inherent rigid chiral structure. A novel class of furanone and spiro-heterocyclic derivatives were synthesized and evaluated for antifungal activities to establish structure-activity relationship (SAR). Results: The synthesis was carried out through one-pot multicomponent reaction (MCR) of 4-aryl-4-oxo-2- butenoic acids, camphor, urea, and hydrogen peroxide in the presence of sodium ethoxide as a catalyst using a microwave irradiation method and / or a traditional thermal method. They are used as key starting materials to synthesize some heterocyclic compounds. Structures of all synthesized compounds were elucidated by elemental analyses and spectroscopic data. Conclusion: A facile and efficient method for the preparation of a new furanone, chalcone and spiropyrimidone derivatives via the one-pot MCR with the microwave-assisted irradiation was established.

Converting Waste Papers to Fluorescent Carbon Dots in the Recycling Process without Loss of Ionic Liquids and Bioimaging Applications

Recycling is a fascinating topic in academia due to the environmental and economic benefits in industries. In this paper, we report on the method to recycle cellulose waste papers using a green (eco-friendly) approach based on ionic liquids (ILs) where the regenerated cellulose was converted to carbon dots (CDs). The addition of waste papers to the IL, 1-allyl-3-methylimidazolium chloride ([Amim][Cl]), disrupted the chemical arrangement of cellulose and completely dissolved the waste paper under microwave irradiation. Subsequent cellulose regeneration by an additional antisolvent, absolute ethanol, was carried out to recover IL and obtain cellulosic materials’ units from waste papers. Furthermore, we report a practical strategy to fabricate CDs under microwave-assisted irradiation. The CDs made by the regenerated cellulose (RC-CDs) were characterized by using analytical and spectroscopic techniques, such as transmission electron microscopy (TEM) and X-ray diffraction (XRD). Finally, we confirmed that RC-C...

Synthesis and characterizations of Ag-doped CdO nanoparticles for P-N junction diode application

This paper reports chemical route assisted microwave irradiation based synthesis of pure and Ag doped CdO nanoparticles. The effects of the Ag doping on the structural, optical, morphological and electrical properties of CdO nanoparticles are systematically analyzed. The XRD patterns exhibit cubic structure and calculated average particle size is in the range 35–22 nm. FTIR and XPS results confirm the formation of pure and Ag doped CdO. FESEM and TEM images display the hexagonal rod shape as concentration of Ag increases. The presence of elements Ag, Cd and O are confirmed by EDX analysis. UV-DRS results show that the optical band gap decreases with increase in Ag concentration. The I–V results show the activation energy range from 0.45 to 0.08 eV. The diode parameters such as ideality factor (n) and barrier height (Фb) of the fabricated n-AgCdO/p-Si are studied under darkness and halogen light conditions.

Ultrafast construction and biological imaging applications of AIE-active sodium alginate-based fluorescent polymeric nanoparticles through a one-pot microwave-assisted Döbner reaction

Aggregation-induced emission (AIE) is a unique fluorescence phenomenon that has attracted great interest for various applications especially for the fabrication of AIE-active polymeric nanoparticles. The AIE-active fluorescent polymeric nanoparticles (FPNs) showed attractive optical properties, which could elegantly overcome the lousy aggregation-caused quenching (ACQ) effect of FPNs based on conventional organic fluorogens. Although great advances and progress have been achieved for the fabrication of AIE-active FPNs, the preparation of AIE-active carbohydrate polymers is still challengeable for the poor solubility of carbohydrate polymers in organic solvents. In this work, we reported the sodium alginate-based fluorescent biopolymers (OSA-PA-PhE) with AIE characteristic could be facilely fabricated via an ultrafast one-pot multicomponent reaction (named as Döbner reaction) with the assistance of microwave irradiation. Among the Döbner reaction system, the oxidized sodium alginate (OSA) and AIE-active dye (named as PhE-NH2) were conjugated using pyruvic acid (PA) as the molecular “bridge”. A number of characterization techniques, such as proton nuclear magnetic resonance (1H NMR), fourier transform infrared (FT-IR) spectroscopy, UV–Vis absorption spectroscopy, fluorescent spectroscopy and transmission electron microscopy (TEM), have been utilized to confirm the successful preparation of OSA-PA-PhE biopolymers. The biological evaluation results confirmed that the OSA-PA-PhE FPNs possessed ultrahigh biocompatibility and desirable imaging properties. Moreover, compared with the previous work about FPNs, this work had at least two obvious advantages, one was the original materials of sodium alginate are resourceful, cheaper, and compatible for human tissue and cells, and another was the novel Döbner reaction is a facile conjugation reaction under mild experimental conditions (e.g. catalyst-free, air atmosphere and in the presence of water). Considered the features of microwave-assisted Döbner reaction and OSA, the OSA-PA-PhE FPNs should be of great potential for different biomedical applications.

Efficient large-scale preparation of defect-free few-layer graphene using a conjugated ionic liquid as green media and its polyetherimide composite

It is very important to obtain large-scale and high-quality graphene for its application. However, the efficient preparation of large-scale and defect-free graphene is difficult by using a general method. In this report, a conjugated ionic liquid (IL) is designed and synthesized, which is used as a green medium to easily exfoliate graphite into graphene with the assistance of microwave irradiation. The as-prepared IL-functionized graphene nanoplatelets (GNPIL) is few-layer, large-size and defect-free, which is attributed to the strong π-π and cation-π interactions between conjugated IL and graphene layers. And the results show that a relatively high yield of 40% is obtained. The high-quality GNPIL could be dispersed in organic solvent homogeneously and stably with a high content, which is beneficial for its further applications. Furthermore, this GNPIL is used to composite with polyetherimide (PEI) to improve the conductivity of polymer. As compared with pure PEI, a sharp decrease of 11 orders of magnitude in volume resistivity is obtained for PEI composite with only 0.75 wt% GNPIL, which keeps a good mechanical property as well.