Facile preparation of NiFe2O4 decorated chitosan-graphene oxide for efficient remediation of Co(II) and adsorption mechanism.

In the background of severe water pollution, adsorption is a charming technique for heavy metal remediation. In this work, NiFe2O4 decorated chitosan-graphene oxide (NFCG) was prepared by simple hydrothermal method for Co(II) remediation application. Adsorption mechanism was elaborately elucidated based on multiple evidences extracted from adsorption fitting (isotherms, thermodynamics and kinetics), spectroscopic test (XPS, UV-Vis absorption, fluorescent emission and Raman spectra) and the hard-soft acid-base (HSAB) theory inspection. Result shows, for Co(II) with initial concentration 200 mg·L-1, NFCG with dosage 500 mg·L-1 reaches adsorption equilibrium in 24 min, rendering removal percentage and adsorption amount 96.87 % and 387.48 mg·g-1, respectively. Owing to the efficient recovery enabled by paramagnetism, NFCG keeps adsorption amount 311.01 mg·g-1 for Co(II) after six consecutive cycles. Moreover, NFCG exhibits selectivity towards Co(II) under the coexistence of common interfering substances. Adsorption fitting suggests chemical adsorption based on heterogeneous affinity. Spectroscopic analysis discloses, CO, CO, -C(=O)NH-, OH and aromatic part contribute to Co(II) adsorption via electron donation, forming CoO bond. This atomic scale adsorption mechanism was substantiated by HSAB theory calculation. In brief, this work provides basic knowledge and technical support for fabricating high efficiency magnetic bio adsorbent.

Porous agarose/chitosan/graphene oxide composite coupled with deep eutectic solvent for thin film microextraction of chlorophenols.

In this project, a three-dimensional graphene oxide coated agarose/chitosan (ACGO) porous film was synthesized and utilized as sorbent in thin film microextraction (TFME) technique to extract 4-chlorophenol, 2,4-dichlorophenol, 3,5-dichlorophenol and 2,4,6-trichlorophenol as the model analytes in various real samples such as agricultural waste water, honey and tea samples. In addition, deep eutectic solvent made of tetra ethyl ammonium chloride/chlorine chloride was used as a desorption solvent. The effect of various variables, such as: extraction time, stirring rate, solvent desorption volume, desorption time, ionic strength and solution pH on the extraction efficiency of the method was studied and optimized. Under the optimized condition, the linear range of the method was obtained in the range of 0.1-500µgL-1 for testing analytes (4-chloropheol=0.1-500µgL-1, 2,4-dichlorophenol=0.2-500µgL-1, 3,5-dichlorophenol=0.5-500µgL-1 and 2,4,6-trichlorophenol=0.2-500µgL-1). The obtained correlation coefficients (r2) were between 0.9984 and 0.9994. The limits of detection (LODs) were also calculated between 0.03 - 0.13µgL-1. The relative standard deviations (RSDs%) were obtained in the range of 2.8 to 5.9%. The enrichment factor (EFs) values for the studied analytes were also obtained in the range of 33.4-35.8. In addition, the obtained results indicated that the prepared film can potentially be used for more applications in the field of environment, food safety, and drug analysis.

Combination mechanism of the ternary composite based on Fe3O4-chitosan-graphene oxide prepared by solvothermal method.

Magnetic nanohybrid combining chitosan and graphene have demonstrated promising application in environmental remediation. Herein, ternary composite MCG based on Fe3O4, chitosan (CS) and graphene oxide (GO) was facilely prepared via solvothermal method. The as prepared composite was characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FTIR), Raman, Brunauer/Emmett/Teller-Barret/Joyner/Halenda (BET-BJH) and thermo gravimetric-differential thermal analysis (TG-DTA). The combination mechanism of MCG was unveiled via employing the hard-soft acid-base (HSAB) theory and spectroscopic investigations including X-ray photoelectron spectroscopy (XPS), Ultraviolet-visible (UV-Vis) and fluorescent emission spectra. Particularly, combination mechanism of MCG was elucidated by the probable site to site interaction of the couplet components in MCG, as follows. (1) CS-Fe3O4. The primary interaction is N(NH2)-Fe(III), electron donates from N to Fe, transforming one half of the amino groups of chitosan into positive N+. (2) GO-CS. Amidation reaction is the primary interaction form, converting the other half of the amino groups of chitosan into -C(O)NH-. (3) GO-Fe3O4. Dominant interactions are those of epoxy, hydroxyl and aromatic ring with Fe(III). Moreover, MCG exhibits fair adsorption performance on divalent heavy metals in six consecutive cycles. These explorations may shed light on the design of efficient adsorbent based on Fe3O4-chitosan-graphene architecture.

Preparation, characterization and immune activity of Codonopsis pilosula polysaccharide loaded in chitosan-graphene oxide.

The purpose of this study was to investigate the effects of chitosan graphene oxide Codonopsis pilosula polysaccharide (CS-GO-CPP) complex on the immune function of macrophage cells (RAW264.7). In this experiment, chitosan (CS) was combined with graphene oxide (GO) by electrostatic action to prepare CS-GO nanocomposites, and it was used as a carrier to load Codonopsis pilosula polysaccharide (CPP) onto CS-GO to prepare CS-GO-CPP. Using infrared spectroscopy detection, zeta potential detection, and thermogravimetric analysis, we conduct a preliminary analysis of the structure of CS-GO-CPP. Macrophages were employed to evaluate CS-GO-CPP immunomodulatory activity and the possible mechanism responsible for the activation of macrophages in vitro. The results showed that compared with CPP, CS-GO-CPP did not change the basic structure of polysaccharide, and its thermal stability was improved. 0.78- 12.5 µg·mL-1 of CS-GO-CPP could significantly promote the phagocytic activity of RAW264.7 cells (P < 0.05) and significantly increase NO content, IL-4 and IFN-γ secretion, the expression of CD40, CD86, and F4/80 (P < 0.05). CS-GO-CPP might activate the NF-κB signaling pathway and induce the nuclear translocation of NF-κB p65. In conclusion, CS-GO-CPP has a capacity to activate RAW264.7 cells for an improvement of immunomodulation activities, which might be through NF-κB signaling pathway.

A Novel Aptamer-Imprinted Polymer-Based Electrochemical Biosensor for the Detection of Lead in Aquatic Products.

Lead contamination in aquatic products is one of the main hazard factors. The aptasensor is a promising detection method for lead ion (Pb(II)) because of its selectivity, but it is easily affected by pH. The combination of ion-imprinted polymers(IIP) with aptamers may improve their stability in different pH conditions. This paper developed a novel electrochemical biosensor for Pb(II) detection by using aptamer-imprinted polymer as a recognition element. The glassy carbon electrode was modified with gold nanoparticles and aptamers. After the aptamer was induced by Pb(II) to form a G-quadruplex conformation, a chitosan-graphene oxide was electrodeposited and cross-linked with glutaraldehyde to form an imprint layer, improving the stability of the biosensor. Under the optimal experimental conditions, the current signal change (∆I) showed a linear correlation of the content of Pb(II) in the range of 0.1-2.0 µg/mL with a detection limit of 0.0796 µg/mL (S/N = 3). The biosensor also exhibited high selectivity for the determination of Pb(II) in the presence of other interfering metal ion. At the same time, the stability of the imprinted layer made the sensor applicable to the detection environment with a pH of 6.4-8.0. Moreover, the sensor was successfully applied to the detection of Pb(II) in mantis shrimp.

Multi-Scale Photoacoustic Assessment of Wound Healing Using Chitosan-Graphene Oxide Hemostatic Sponge.

Hemostasis is vital to save lives, reducing risks of organ failure and hemorrhagic shock. Exploring novel hemostatic materials and precise monitoring of the hemostatic status is of great importance for efficient hemostasis. We present the development of chitosan-graphene oxide-based hemostatic composite and multi-scale photoacoustic evaluation of the hemostatic performance. The hemostatic sponge can quickly and efficiently absorb the blood with its porous cavity and specific surficial property. We inspect the hemostatic performance via an in vitro blood absorption test and in vivo mouse bleeding injury experiments. Results show that the synthesized hemostatic sponge can not only absorb plasma in blood fast with its interior porous structure but also stimulate the interfacial reaction with erythrocytes and platelets. The superiority of multi-scale photoacoustic imaging for guiding, monitoring, and evaluating the hemostatic stages of sponges is demonstrated with high spatial resolution and great sensitivity at depths. Photoacoustic evaluation of a chitosan-graphene oxide-based hemostatic sponge has the potential to be transferred toward the clinical assessment of wound healing.

Chitosan-Graphene Oxide Composite Membranes for Solid-Phase Extraction of Pesticides.

Solid-phase extraction (SPE) coupled to LC/MS/MS analysis is a valid approach for the determination of organic micropollutants (OMPs) in liquid samples. To remove the greatest number of OMPs from environmental matrices, the development of innovative sorbent materials is crucial. Recently, much attention has been paid to inorganic nanosystems such as graphite-derived materials. Graphene oxide has been employed in water-purification processes, including the removal of several micropollutants such as dyes, flame retardants, or pharmaceutical products. Polysaccharides have also been widely used as convenient media for the dispersion of sorbent materials, thanks to their unique properties such as biodegradability, biocompatibility, nontoxicity, and low cost. In this work, chitosan-graphene oxide (CS_GO) composite membranes containing different amounts of GO were prepared and used as sorbents for the SPE of pesticides. To improve their dimensional stability in aqueous medium, the CS_GO membranes were surface crosslinked with glutaraldehyde. The composite systems were characterized by Fourier transform infrared spectroscopy, scanning electron microscopy, thermogravimetric analysis, swelling degree, contact angle, and mechanical measurements. As the GO content increased, a decrease in surface homogeneity, an improvement of mechanical properties, and a reduction of thermal stability of the CS-based membranes were observed. The increased dimensional stability in water, together with the presence of high GO amounts, made the prepared composite membranes more efficacious than the ones based just on CS in isolating and preconcentrating different hydrophilic/hydrophobic pollutants.

Enhanced fluoride adsorption from aqueous solution by zirconium (IV)-impregnated magnetic chitosan graphene oxide.

In this study, zirconium (IV)-impregnated magnetic chitosan graphene oxide (Zr-MCGO) was synthesized for removing fluoride from aqueous solution in batch mode. Characterization approaches (pHpzc, FTIR, SEM, XRD, VSM, Raman, BET, and XPS) proved the successful incorporation of Zr into the adsorbent. Zr-MCGO exhibited a relatively favorable and stable capacity of defluoridation at lower pH with a wide range of pH from 4.0 to 8.0, while there was slightly negative effect of ionic strength on adsorption. In addition, Elovich kinetic model and Koble-Corrigan isotherm model could describe the uptake of fluoride well. The adsorption capacity was 8.84 mg/g at 313 K and Zr-MCGO was easily separated from mixtures using external magnet. Based on the experiments and XPS, electrostatic force, ligand exchange, and Lewis acid-base interaction might be potential adsorption mechanisms. Pseudo-second-order model was more compatible with the desorption process by 0.01 mol/L NaHCO3 solution. Therefore, Zr-MCGO was a promising candidate for defluoridation on wastewater pollution remediation.

Effects of Oridonin-loaded Chitosan Graphene Oxide on the Proliferation and Apoptosis of A 549 Cells / 中国药房

OBJECTIVE：To study the effects of chitosan graphene oxide car rier（CS-GO）loaded with oridonin （CS-GO- oridonin）on the proliferation and apoptosis of human lung cancer A 549 cells. METHODS ：Taking A 549 cells as objects ，the survival rate of cells were detected by CCK- 8 method after treated with different concentrations of CS-GO （3，6，12，24，48 μg/mL）and CS-GO-oridonin loaded with same mass of oridonin （3，6，12，24，48 μg/mL，by the weight of oridonin ，the same below）. IC 50 of CS-GO-oridonin was calculated. The cell morphology were observed by microscope after treated with CS-GO and CS-GO-oridonin（both 32 μg/mL）for 2，4，10，24 h. The uptake of CS-GO ，oridonin，CS-GO-orionin（all 32 μg/mL）by cells was observed with fluorescence labeling method. The apoptosis of cells and the content of ROS were observed by flow cytometry after treated with different concentrations of CS-GO （16，32，64 μg/mL）and CS-GO-oridonin （16，32，64 μg/mL）. The expression of anti-apoptosis related proteins （Mcl-1，Bax and Bak ）were detected by Western blot. RESULTS ：After treated with different concentrations of CS-GO ，the survival rate of cells was still above 90％ ；after treated with different concentrations of CS-GO-oridonin，the survival rate of cells showed a downward trend ，and was significantly lower than that of CS-GO group （P＜ 0.01）；IC50 of CS-GO-oridonin was 32.61 μg/mL. After CS-GO treatment，the cell morphology did not change significantly ；after CS-GO-oridonin treatment ，the cells shrunk and fell off in clusters ，and the suspended matter increased ；the fluorescence of oridonin and CS-GO-orionin taken up by cells was enhanced than CS-GO. Compared with blank group ，there was no significant change in the apoptosis rate ，the content of ROS and the expression of apoptosis-related protein in 16，32，64 μg/mL CS-GO groups（P＞0.05）；apoptosis rate ，the content of ROS ，the protein expression of Bax and Bak in 16，32，64 μg/mL CS- GO-oridonin groups were increased significantly ，while the protein expression of Mcl- 1 were decreased significantly. Above indexes were significantly high er or lower than the same concentration CS-GO group （P＜0.05）. CONCL USIONS：CS-GO dose not affect the proliferation and apoptosis of A 549 cells；CS-GO-oridonin has obvious inhibition and apoptosis promoting effect on cells ，which may be related to increasing ROS production and regulating the expression of apoptosis related proteins.

Palladium Supported on Porous Chitosan-Graphene Oxide Aerogels as Highly Efficient Catalysts for Hydrogen Generation from Formate.

Adsorption of Pd(NH3)42+ in preformed chitosan-graphene oxide (CS-GO) beads and their subsequent reduction with NaBH4 afford well-dispersed, high dispersion (~21%) of uniformly sized Pd nanoparticles (~1.7 nm). The resulting Pd/CS-GO exhibits interesting catalytic activity for hydrogen generation by ammonium formate decomposition. The optimal GO proportion of 7 wt% allows reaching, at 60 °C, a turnover frequency above 2200 h-1-being outstanding among the highest values reported for this process to date. Interestingly, no formation of CO or CH4 was detected. The catalyst did not leach, although it underwent gradual deactivation, probably caused by the increase in the Pd average size that became over 3 nm after three uses. Our results are relevant in the context of efficient on-board hydrogen generation from liquid organic hydrogen carriers in transportation.

Statistical and chemometric view of the variation in the concentration of selected organophosphates in peeled unwashed and unpeeled washed fruits and vegetables.

Fruits and vegetables play an important role in human nutrition. Study of the contamination sources which result from farming activities is of importance. For this reason, a chitosan-graphene oxide nanocomposite film was prepared and implemented as the extractive phase in thin film microextraction of six organophosphate residues (OPPs) in the samples using high-performance liquid chromatography. The optimized method was validated and the limits of detection (0.7-1.2 µg l-1), limits of quantification (2.3-4.0 µg l-1) and linear dynamic range (2.0-1000.0 µg l-1) were obtained. Principal component analysis revealed clustering of the fruit and vegetable samples based on the selected (OPPs) into two groups of unwashed-unpeeled and peeled-washed. This mapping was further investigated using descriptive method of boxplot. Washing and peeling of the samples, reduced the presence of OPPs to half or one third of interquartile range found in the unpeeled and unwashed samples.

Removal of pharmaceuticals by novel magnetic genipin-crosslinked chitosan/graphene oxide-SO3H composite.

A novel magnetic adsorbent genipin-crosslinked chitosan/graphene oxide-SO3H (GC/MGO-SO3H) composite was prepared and used as adsorbents of environmental pollutant. The GC/MGO-SO3H exhibit typical superparamagnetic behavior. The adsorption characteristics of GC/MGO-SO3H composite to pharmaceuticals were investigated through batch experiments. The maximum adsorption capacity of ibuprofen and tetracycline increases from 113.27 to 138.16 mg/g and 473.25 to 556.28 mg/g with the increase in temperature from 298 to 313 K. The adsorption kinetics and isotherms were investigated in detail to reveal that the kinetics and equilibrium adsorptions are well described by pseudo-second-order kinetic and Freundlich isotherm model, respectively. This study has demonstrated that the GC/MGO-SO3H composite could be utilized as an efficient and with high speed.

Ice-templated graphene oxide/chitosan aerogel as an effective adsorbent for sequestration of metanil yellow dye.

Graphene oxide/chitosan aerogel (GOCA) was prepared by a facile ice-templating technique without using any cross-linking reagent for metanil yellow dye sequestration. The adsorption performance of GOCA was investigated by varying the adsorbent mass, shaking speed, initial pH, contact time, concentration and temperature. The combined effects of adsorption parameters and the optimum conditions for dye removal were determined by response surface methodology. GOCA exhibited large removal efficiencies (91.5-96.4%) over a wide pH range (3-8) and a high adsorption capacity of 430.99 mg/g at 8 mg adsorbent mass, 400 mg/L concentration, 35.19 min contact time and 175 rpm shaking speed. The adsorption equilibrium was best represented by the Langmuir model. GOCA could be easily separated after adsorption and regenerated for re-use in 5 adsorption-desorption cycles thereby maintaining 80% of its adsorption capability. The relatively high adsorption and regeneration capabilities of GOCA render it an attractive adsorbent for treatment of azo dye-polluted water.

Efficient removal of Chromium(VI) from aqueous solution using chitosan grafted graphene oxide (CS-GO) nanocomposite.

The present study involves the adsorption of hexavalent Chromium(Cr(VI)) using chitosan grafted graphene oxide (CS-GO) nanocomposite in batch mode. The CS-GO nanocomposite material was prepared by ultrasonic irradiation technique. The CS-GO adsorbent was characterized by X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM) and Tunnelling electron microscopy (TEM), followed by Cr(VI) adsorption studies. The adsorption capacity of 104.16 mg/g was achieved at pH 2.0, in the contact time of 420 min. The adsorption process was described by the pseudo second order kinetic and Langmuir isotherm model. The nano-microstructural investigation validates the successful adsorption of Cr(VI) on CS-GO nanocomposite. The CS-GO material is recyclable up to 10 cycles with the minimum loss in adsorption capacity.

Binding Affinity of a Highly Sensitive Au/Ag/Au/Chitosan-Graphene Oxide Sensor Based on Direct Detection of Pb2+ and Hg2+ Ions.

The study of binding affinity is essential in surface plasmon resonance (SPR) sensing because it allows researchers to quantify the affinity between the analyte and immobilised ligands of an SPR sensor. In this study, we demonstrate the derivation of the binding affinity constant, K, for Pb2+ and Hg2+ ions according to their SPR response using a gold/silver/gold/chitosan-graphene oxide (Au/Ag/Au/CS-GO) sensor for the concentration range of 0.1-5 ppm. The higher affinity of Pb2+ to binding with the CS-GO sensor explains the outstanding sensitivity of 2.05 °ppm-1 against 1.66 °ppm-1 of Hg2+. The maximum signal-to-noise ratio (SNR) upon detection of Pb2+ is 1.53, and exceeds the suggested logical criterion of an SNR. The Au/Ag/Au/CS-GO SPR sensor also exhibits excellent repeatability in Pb2+ due to the strong bond between its functional groups and this cation. The adsorption data of Pb2+ and Hg2+ on the CS-GO sensor fits well with the Langmuir isotherm model where the affinity constant, K, of Pb2+ and Hg2+ ions is computed. The affinity of Pb2+ ions to the Au/Ag/Au/CS-GO sensor is significantly higher than that of Hg2+ based on the value of K, 7 × 105 M-1 and 4 × 105 M-1, respectively. The higher shift in SPR angles due to Pb2+ and Hg2+ compared to Cr3+, Cu2+ and Zn2+ ions also reveals the greater affinity of the CS-GO SPR sensor to them, thus supporting the rationale for obtaining K for these two heavy metals. This study provides a better understanding on the sensing performance of such sensors in detecting heavy metal ions.

Functionalization of magnetic chitosan with graphene oxide for removal of cationic and anionic dyes from aqueous solution.

In the present study, we decorated chitosan (©) with Fe3O4 nanoparticles followed by cross-linking with GO to prepare Fe3O4 supported chitosan-graphene oxide composite (Fe3O4©-GO). Different properties of synthesized material were investigated by SEM, XRD, FTIR, TGA and EDX. Batch adsorption experiments were performed to remove toxic cationic and anionic dyes from industrial wastewater. To maximize removal efficiency of composite material, effect of pH (4-12), time (0-80min), Fe3O4©-GO dosage (2-10mg), initial dye concentration (2-30µgmL̄ (1)) and temperature (303, 313, and 323K) were studied. The uptake of dyes presented relatively fast adsorption kinetics with pseudo-second-order equation as the best fitting model. To understand the interaction of dye with adsorbent, Langmuir and Freundlich isotherm were applied. Thermodynamic studies were conducted to calculate the changes in free energy (ΔG(0)), enthalpy (ΔH(0)) and entropy (ΔS(0)). In view of practical application, the influence of ionic strength, recycling as well as investigations based on percent recoveries from spiked real water samples were also taken into account.

Micro-solid phase extraction followed by thermal extraction coupled with gas chromatography-mass selective detector for the determination of polybrominated diphenyl ethers in water.

A method of analyzing environmental contaminants in water based on micro-solid phase extraction (µ-SPE) followed by thermal extraction (TE) and a cold-trapping step, coupled with gas chromatography-mass selective detection (GC-MSD) was developed and validated. µ-SPE-TE- GC-MSD was employed in the determination of five polybrominated diphenyl ethers. The µ-SPE sorbent was chitosan-graphene oxide (CS-GO) composite, which was prepared by mixing CS and GO by means of ultrasonication. The CS in the composite was cross-linked with glutaraldehyde. After µ-SPE, the analytes in the extract were extracted thermally in a thermal desorption unit tube combined with a cooled injection system, coupled to GC-MSD. The extraction conditions were optimized for the detection of the target compounds in water. This method provided linearity ranges of between 0.1 and 20µgL(-1) (depending on the analytes), with coefficients of determination, r(2), ≥0.9982. The calculated relative recoveries were between 71.52 and 96.15% whereas precision (based on % relative standard deviations) was between 3.54 and 11.36%. The method showed limit of detection and limit of quantification ranges of between 0.007 and 0.016µgL(-1), and between 0.023 and 0.054µgL(-1), for the two groups of analytes, respectively. The method was applied to the determination of the target analytes in water.