Synthesizing and characterizing the magnetic EDTA/chitosan/CeZnO nanocomposite for simultaneous treating of chromium and phenol in an aqueous solution

A new magnetic nanocomposite chitosan/EDTA/CeZnO(MEC-CeZnO)is synthesized as an efficient and eco-friendly bio-compound for the removal of chromium Cr(VI)metal ions and phenol organic matters from aqueous solutions.Nanocomposites are characterized using field emission scanning electron microscope,energy dispersive X-ray spectroscopy,transmission electron microscope,X-ray diffraction,X-ray photoelectron spectroscopy,Fourier transform infrared spectroscopy,diffuse reflection spectroscopy,and PL methods.The reduction rate of Cr(VI)ions and phenol degradation is evaluated under various experimental conditions,separately and simultaneously.The average pore diameter and specific surface of MEC-CeZnO nanocomposite are obtained 50 nm and 210 m^(2)·g^(-1)respectively,which suggest the successful synthesis of the nanocomposite because of the increased surface area and reduced pores in comparison to previous studies.Moreover,the best Cr(VI)and phenol reduction efficiencies are 98%and 92%at 180 min of retention time,both following the Langmuir-Hinshelwood first-order kinetics.The mechanisms of Cr(VI)and phenol removal from aqueous solutions involved Cr(VI)reduction,phenol oxidation,and adsorption.Examining the reusability of MEC-CeZnO showed that both degradation and recovery capacity is stable in 5 cycles.

Preparation of Magnetic Chitosan Nanoparticles and Immobilization of Laccase

The magnetic chitosan nanoparticles were prepared by reversed-phase suspension method using Span-80 as an emulsifier, glutaraldehyde as cross-linking reagent. And the nanoparticles were characterized by TEM, FT-IR and hysteresis loop. The results show that the nanoparticles are spherical and almost superparamagnetic. The laccase was immobilized on nanoparticles by adsorption and subsequently by cross-linking with glutaraldehyde. The immobilization conditions and charac-terizations of the immobilized laccase were investigated. The optimal immobilization conditions were as follows： 10 mL of phosphate buffer （0.1 M, pH 7.0） containing 50 mg of magnetic chitosan nanoparticles, 1.0 mg·mL-1 of laccase and 1% （v/v） glutaraldehyde, immobilization temperature of 4 ℃ and immobilization time of 4 h. The immobilized laccase exhibited an appreciable catalytic capability （480 units·g-1 support） and had good storage stability and operation stability. The Km of immobilized and free laccase for ABTS were 140.6 and 31.1 μM in phosphate buffer （0.1 M, pH 3.0） at 37 ℃, respectively. The immobilized laccase is a good candidate for the research and development of biosensors based on laccase catalysis.

Adsorptive Removal of Copper Ions from Aqueous Solution Using Cross-linked Magnetic Chitosan Beads

The performance of cross-linked magnetic chitosan, coated with magnetic fluids and cross-linked with ePichlorohydrin, was investigated for the adsorption of Copper （Ⅱ） from aqueous solutions. Infrared spectra of chitosan before and after modification showed that the coating and cross-linking are effective. Experiments were performed at different pH of solution and contact time, and appropriate conditions for the adsorption of Cu（Ⅱ） were determined. Experimental equilibrium data were correlated with Langmuir and Freundlich isotherms for determination of the adsorption potential. The results showed that the Langmuir isotherm was better compared with the Freundlich isotherm, and the uptake of Cu（Ⅱ） was 78.13 mg·g^- 1. The kinetics of adsorption corresponded with the first-order Langergren rate equation, and Langergren rate constants were determined.

Single-step synthesis of magnetic chitosan composites and application for chromate(Cr(Ⅵ))removal

Magnetic chitosan composites(Fe3O4@chitosan) were synthesized in one single-step, characterized and applied in Cr(VI) removal from water. With the increase of loading proportion of chitosan, Cr(Ⅵ) adsorption capacity of Fe3O4@chitosan composites increased from 10.771 to 21.040 mg/g. The optimum adsorption capacities of Cr(VI) on Fe3O4@chitosan-3 were found in a pH range of 3.0-5.0. Kinetic study results show that the adsorption process follows pseudo-second-order model, indicating that the rate-limiting step in the adsorption of Cr(Ⅵ) involves chemisorptions. Moreover, FT-IR spectra analysis confirms that the amine and hydroxyl groups of chitosan are predominantly responsible for binding. Results from this work demonstrate that the prepared Fe3O4@chitosan composites possess great potential in Cr(Ⅵ) removal from contaminated water.

Preparation and Characterization of Magnetic Resin Made from Chitosan and Cerium

In this study, the water-based ferromagnetic fluid and magnetic resin made from chitosan and cerium complex （MRCCC） were successfully prepared by using the chemical co-precipitation technique and by the reversed-phase suspension cross-linking polymerization. MRCCC presented uniform and narrow panicle size distribution as determined by the Laser Panicles Sizer. The Inductively Coupled Plasma-Atomic Emission Spectrometry （ICP-AES）, Fourier transform infrared spectroscopy （FT-IR）, differential scanning calorimetry （DSC） and X-ray powder diffraction （XRD） study demonstrated that there were iron and cerium existing in MRCCC. The movement of MRCCC under magnetic field proved its magnetic property. The swelling kinetics in water or solutions with different pH indicated that MRCCC could be applied in solutions with pH greater than 1.0. The ferromagnetic fluid particles were stable in MRCCC soaked in solutions with pH 〉2.0. In view of these results, MRCCC can be used as material for separation, clarification, adsorption, sustained release and hydrolysis activity.

Study on the Effect of A Magnetic Field on Pb(II) Removal Using Modified Chitosan

This work examined the removal of Pb(II) using a chitosan derivative (SB, synthesized from benzaldehyde) assisted by a magnetic field. The adsorption capacity for Pb(II) was investigated. It was found that 1) the pH and concentration of the ion solution, as well as exposure time and strength of magnetic field, affected the degree of adsorption;and 2) studies of the adsorption isotherms and kinetics of ions onto SB revealed that SB showed enhanced adsorption capacity towards Pb(II) ions in a magnetic field compared with magnetically untreated samples. The Langmuir and Freundlich isotherm were applied to describe the experimental adsorption, and the maximum adsorption capacity of SB for Pb(II) was 2.5040 mg/g, when assisted by a magnetic field of 480 kA/m.

Laccase biosensor using magnetic multiwalled carbon nanotubes and chitosan/silica hybrid membrane modified magnetic carbon paste electrode

A simple and rapid strategy to construct laccase biosensor for determination of catechol was investigated. Magnetic multiwalled carbon nanotubes (MMCNT) which possess excellent capability of electron transfer were prepared by chemical coprecipitation method. Scanning electron microscope (SEM) and vibrating sample magnetometer (VSM) were used to identify its surfacetopography and magnetization, respectively. Laccase was immobilized on the MMCNT modified magnetic carbon paste electrode by the aid of chitosan/silica (CS) hybrid membrane. Using current-time detection method, the biosensor shows a linear response related to the concentration of catechol in the range from 10-7 to 0.165×10-3 mol/L. The corresponding detection limit is 3.34×10-8 mol/L based on signal-to-noise ratios (S/N) ≥3 under the optimized conditions. In addition, its response current retains 90% of the original after being stored for 45 d. The results indicate that this proposed strategy can be expected to develop other enzyme-based biosensors.

Preparation and drug releasing property of magnetic chitosan-5-fluorouracil nano-particles

In order to synthesize the targeting drug carrier system,magnetic chitosan-5-fluorouracil nano-particles were prepared by using 5-fluorouracil(5-Fu)as model drug,Fe3O4 nano-particles as kernel,chitosan as enveloping material and glutaraldehyde as cross linking agent through ultrasonic technique.The morphology of the magnetic chitosan-5-Fu nano-particles was observed with a transmission electron microscope(TEM).The results showed that magnetic chitosan-5-Fu nano-particles were prepared in spherical structure with a size range of 50-60 nm.The delivering capacity and drug releasing properties of magnetic chitosan-5-Fu nano-particles were investigated by UV-vis spectrum analysis.The results showed that the loading capacity was 13.4%and the cumulative release percentage in the phosphate buffer(pH=7.2)solutions was 68%in 30 h.These data indicate that the wrapped drug of magnetic chitosan-5-Fu nano-particles was slowly-released.The magnetic response of magnetic chitosan-5-Fu nano-particles was studied by UV-vis spectrometer to detect the changes of solution absorbance.Without external magnetic field,the nano-particle deposition rate was slow.When being subjected to 8 mT magnetic field,the particle sedimentation rate was increased rapidly.The results showed that magnetic chitosan-5-Fu nano-particles have a magnetic stability and strong targeting characteristics.

Efficient Removal of Reactive Orange 107 Dye from Aqueous Media by Shrimp Shell Derived Chitosan Functionalized Magnetic Nanoparticles

In present work chitosan functionalized magnetic nanoparticles (CMNPs) were successfully prepared and investigated for the removal of Reactive Orange 107 dye (RO 107) from water. The chitosan was extracted from shrimp shells (Penaeus merguiensis) and was characterized by solubility test and fourier transform infrared spectroscopy (FTIR). Degree of deacetylation of chitosan was examined by 1H-NMR and potentiometric titration method. Thereafter, the chitosan was used for synthesis of CMNPs. The synthesized CMNPs were characterized by FTIR, scanning electron microscopy-energy dispersive spectroscopy (SEM-EDS), thermal gravimetric analysis (TGA) and atomic force microscopy (AFM). Effects of various variables such as contact time, pH, stirring speed, adsorbent dosage, temperature, and concentration of electrolyte on extraction efficiency were evaluated. Freundlich isotherm model fits better that shows the removal of RO 107 with CMNPs by multilayer adsorption behaviour. Furthermore, kinetic study showed that adsorption process followed pseudo-second order kinetic model regulated by chemisorption. Thermodynamic analysis explained that adsorption of RO 107 onto CMNPs was endothermic as well as spontaneous. The developed CNMPs were applied to environmental remediation of spiked RO 107 treated waste water samples with 96.20% removal potential, hence, offered an effective sorbent for removal of RO 107 contaminated water samples.

Selective adsorption behavior of ion-imprinted magnetic chitosan beads for removal of Cu(Ⅱ) ions from aqueous solution

Heavy metal ion is one of the major environmental pollutants.In this study,a Cu(Ⅱ)ions imprinted magnetic chitosan beads are prepared to use chitosan as functional monomer,Cu(Ⅱ)ions as template,Fe_(3)O_(4) as magnetic core and epichlorohydrin and glutaraldehyde as crosslinker,which can be used for removal Cu(Ⅱ)ions from wastewater.The kinetic study shows that the adsorption process follows the pseudosecond-order kinetic equations.The adsorption isotherm study shows that the Langmuir isotherm equation best fits for the monolayer adsorption processes.The selective adsorption properties are performed in Cu(Ⅱ)/Zn(Ⅱ),Cu(Ⅱ)/Ni(Ⅱ),and Cu(Ⅱ)/Co(Ⅱ)binary systems.The results shows that the ⅡMCD has a high selectivity for Cu(Ⅱ)ions in binary systems.The mechanism of ⅡMCD recognition Cu(Ⅱ)ions is also discussed.The results show that the ⅡMCD adsorption Cu(Ⅱ)ions is an enthalpy controlled process.The absolute value of DH(Cu(Ⅱ))and DS(Cu(Ⅱ))is greater than DH(Zn(Ⅱ),Ni(Ⅱ),Co(Ⅱ))and DS(Zn(Ⅱ),Ni(Ⅱ),Co(Ⅱ)),respectively,this indicates that the Cu(Ⅱ)ions have a good spatial matching with imprinted holes on ⅡMCD.The FTIR and XPS also demonstrates the strongly combination of function groups on imprinted holes in the suitable space position.Finally,the ⅡMCD can be regenerated and reused for 10 times without a significantly decreasing in adsorption capacity.This information can be used for further application in the selective removal of Cu(Ⅱ)ions from industrial wastewater.

Preparation of biocompatible magnetic microspheres with chitosan

Microsphere is a term used for small spherical particles, with diameters in the micrometer range (typically 1μm to 1000μm (1mm)). Microspheres are sometimes referred to as microparticles. Microspheres can be manufactured from various natural and synthetic materials. The present work we prepared chitosan magnetic microspheres (CMMS) with simple crosslinking method. The obtained CMMS were in size range of 1000-2600 nm with average particle size of 1800nm. All the essential characterizations of prepared CMMS were done and the results were in a good agreement with other magnetic microspheres prepared with different method. To test the biocompatibility of CMMS with blood, the effect of them on erythrocytes aggregation and blood hemolysis were studied. Our results showed that CMMS work as good compatible materials with blood.

壳聚糖/磁性生物炭复合物的制备及其对环丙沙星的吸附性能

本文以芦苇生物质和FeCl_(3)·6H_(2)O为原料,采用浸渍-热解法,控制浸渍比率、热解温度和热解时间制备磁性生物炭(Biochar, MB),再与壳聚糖(Chitosan, CTS)复合,制备了壳聚糖/磁性生物炭复合物(Magnetic biochar, CMB)。利用田口分析方法,以环丙沙星(Ciprofloxacin, CIP)为目标物,以吸附容量为评价指标,优化了CMB的制备条件。使用傅里叶变换红外光谱(FTIR)、X射线衍射分析(XRD)、X射线光电子能谱(XPS)、扫描电镜(SEM)、振动样品磁强计(VSM)和全自动比表面及孔隙度分析仪(BET)对其结构进行了表征。研究了CMB对CIP的吸附动力学和吸附热力学。结果表明,CMB的最佳制备条件为浸渍比率1∶3、热解温度800℃、热解时间4 h,以柠檬酸为交联剂、MB与CTS的质量比5∶1。CMB对CIP的吸附更符合Avrami模型和拟二级动力学模型,吸附过程可能是膜扩散和颗粒内扩散共同作用的结果。Freundlich吸附等温方程能较好地描述CMB对CIP的吸附行为。热力学参数表明,CMB对CIP的吸附是一个自发的吸热反应。

基于绿色化学制备印迹聚合物及富集丙溴磷的研究

基于绿色化学理念,采用水为溶剂,丙溴磷(PFF)为模板分子,壳聚糖为功能单体,戊二醛为交联剂,成功制备了高灵敏、高选择性的PFF磁性分子印迹聚合物(PFFMMIPs)。同时,利用扫描电镜、傅里叶变换红外光谱、X射线衍射仪等对聚合物进行了表征,并对PFF-MMIPs的吸附性能和选择性进行了考察。结果表明,PFF-MMIPs具有良好的热稳定、较强的磁性、较高的吸附量(33.6mg·g^(-1))、快速吸附能力(60min)以及高效选择性。对吸附性能数据进行数学拟合,结果表明PFF-MMIPs对目标化合物PFF的吸附过程符合Langmuir模型和伪二级动力学模型。

Synthesis of chitosan-based grafting magnetic flocculants for flocculation of kaolin suspensions

A series of novel chitosan-based magnetic flocculants FS@CTS-P(AM-DMC)was prepared by molecular structure control.The characterization results showed that FS@CTS-P(AM-DMC)had a uniform size of about 21.46 nm,featuring a typical core-shell structure,and the average coating layer thickness of CTS-P(AM-DMC)was about 5.03 nm.FS@CTS-P(AM-DMC)exhibited excellent flocculation performance for kaolin suspension,achieved 92.54% turbidity removal efficiency under dosage of 150 mg/L,pH 7.0,even at high turbidity(2000 NTU)with a removal efficiency of 96.96%.The flocculation mechanism was revealed to be dominated by charge neutralization under acidic and neutral conditions,while adsorption and bridging effects play an important role in alkaline environments.The properties of magnetic aggregates during flocculation,breakage,and regeneration were studied at different pH levels and dosages.In the process of magnetophoretic,magnetic particles collide and adsorb with kaolin particles continuously due to magnetic and electrostatic attraction,transform into magnetic chain clusters,and then further form three-dimensional network magnetic aggregates that can capture free kaolin particles and other chain clusters.Particle image velocimetry confirmed the formation of eddy current of magnetic flocs and experienced three stages:acceleration,stabilization,and deceleration.

磁性壳聚糖复合微球对血红素吸附性能的研究

以壳聚糖为基体,将Fe_(3)O_(4)包覆其中,形成磁性壳聚糖微球(MCS)。采用机械化学合成法合成了氢氧化镧-磁性壳聚糖微球复合材料(MCL)。考察MCS/La(OH)_(3)不同质量比和不同因素对血红素吸附量的影响。采用多种表征手段对MCL2形貌结构、热稳定和磁性能进行研究。通过BET和XPS图谱,结合吸附动力学对MCL2的吸附机理进行详尽分析。结果表明,MCL2即MCS/La(OH)_(3)质量比为1∶0.8时具有较好的吸附性能和磁性能。当血红素浓度为90 mg/L,45℃下反应1 h时可得到最佳吸附量19.7562 mg/g。MCL2为核壳结构,表面粗糙,热稳定性好,磁分离能力强。MCL2以化学和物理作用对血红素进行吸附,吸附过程符合准二级动力学模型。MCL2凭借优秀的吸附性能,有望成为一种有效富集纯化血红素的材料。

壳聚糖-聚丙烯酸磁性水凝胶制备及Cu^(2+)吸附

水中的重金属离子污染的危害性巨大,并且治理相对比较困难,是当今环境保护的一大难题。通过两步法,制备了物理交联的钴铁粒子-壳聚糖-聚丙烯酸-甲壳素(CoFe_(2)O_(4)-CS-PAA-CT)多重互穿网络磁性水凝胶,并对水凝胶的结构、热稳定性、磁性、吸附性能和再生性进行了研究。该CoFe_(2)O_(4)-CS-PAA-CT水凝胶具有良好的自修复性、再生性和吸附性,对Cu~(2+)的饱和吸附量为247.22 mg/g。CoFe_(2)O_(4)-CS-PAA-CT水凝胶在吸附重金属离子时,重金属离子浓度越高,吸附量越高;pH值≤5.0时,吸附效果最好;干扰离子浓度增大会降低水凝胶的吸附量。研究表明CoFe_(2)O_(4)-CS-PAA-CT多重互穿网络水凝胶能够作为未来处理重金属污水的一种新的选择。

Application of Paclitaxel-loaded EGFR Peptide-conjugated Magnetic Polymeric Liposomes for Liver Cancer Therapy

Developing the methodologies that allow for safe and effective delivery of therapeutic drugs to target sites is a very important research area in cancer therapy.In this study,polyethylene glycol(PEG)-coated magnetic polymeric liposome(MPL)nanoparticles(NPs)assembled from octadecyl quatemized carboxymethyl chitosan(OQC),PEGylated OQC,cholesterol,and magnetic NPs,and functionalized with epithelial growth factor receptor(EGFR)peptide,were successfully prepared for in-vivo liver targeting.The two-step liver targeting strategy,based on both magnetic force and EGFR peptide conjugation,was evaluated in a subcutaneous hepatocellular carcinoma model of nude mouse.The results showed that EGFR-conjugated MPLs not only accumulated in the liver by magnetic force,but could also diffuse into tumor cells as a result of EGFR targeting.In addition,paclitaxel(PTX)was incorporated into small EGFR-conjugated MPLs(102.0土0.7 nm),resulting in spherical particles with high drug encapsulation efficiency(>90%).The use of the magnetic targeting for enhancing the transport of PTX-loaded EGFR-conjugated MPLs to the tumor site was further confirmed by detecting PTX levels.In conclusion,PTX-loaded EGFR-conjugated MPLs could potentially be used as an effective drug delivery system for targeted liver cancer therapy.

Magnetic resonance imaging-three-dimensional printing technology fabricates customized scaffolds for brain tissue engineering

Conventional fabrication methods lack the ability to control both macro- and micro-structures of generated scaffolds. Three-dimensional printing is a solid free-form fabrication method that provides novel ways to create customized scaffolds with high precision and accuracy. In this study, an electrically controlled cortical impactor was used to induce randomized brain tissue defects. The overall shape of scaffolds was designed using rat-specific anatomical data obtained from magnetic resonance imaging, and the internal structure was created by computer- aided design. As the result of limitations arising from insufficient resolution of the manufacturing process, we magnified the size of the cavity model prototype five-fold to successfully fabricate customized collagen-chitosan scaffolds using three-dimensional printing. Results demonstrated that scaffolds have three-dimensional porous structures, high porosity, highly specific surface areas, pore connectivity and good internal characteristics. Neural stem cells co-cultured with scaffolds showed good viability, indicating good biocompatibility and biodegradability. This technique may be a promising new strategy for regenerating complex damaged brain tissues, and helps pave the way toward personalized medicine.

Study on Tat Mediated Magnetic Nanoparticles Having Composite Targeting Function

This paper describes a new formulation of magnetic nanoparticles coated by a novel polymer matrix-O-Carboxylmethylated Chitosan (O-CMC) as a drug/gene carrier. The O-CMC magnetic nanoparticles were derivatized with a peptide sequence from the HIV-tat protein and transferrin to improve the translocational property and cellar uptake of the nanoparticles. To evaluate the O-MNPs-Tat-Tf as a drug carrier, Methotrexate (MTX) was incorporated as a model drug and MTX-loaded O-MNPs-Tat-Tf with an average diameter of 75 nm were prepared and characterized by TEM, AFM and VSM.The cytotoxicity of MTX-loaded O-MNPs-Tat-Tf was investigated with C6 cells. The results showed that the MTX-loaded O-MNPs-Tat-Tf retained significant antitumor toxicity.

Specific Targeting MRI of Chitosan Oligosaccharide Modified Fe_(3)O_(4) Nanoprobe on Macrophage and the Inhibition of Macrophage Foam­ing Induced by ox-LDL

Atherosclerosis(AS)is a primary cause of morbidity and mortality all over the world.Molecular imaging techniques can enable early localization and diagnosis of atherosclerosis plaques.Recent newly developed chitooligosaccharides(CSO)is considered to be capable of target mannose receptors on the surface of macrophages and to inhibit foam cell formation.Here we present a targeting magnetic resonance imaging(MRI)nanoprobe,which was successfully constructed with polyacrylic acid(PAA)modified nanometer iron oxide(Fe_(3)O_(4))as the core,and coating with CSO molecules,possessing the abilities of targeted MRI and specifically inhibition of the formation of foamy macrophages in the atherosclerotic process.The experimental results showed that the distributions of PAA-Fe_(3)O_(4) and CSO-PAA-Fe_(3)O_(4) were uniform and the corresponding sizes were about 5.93 nm and 8.15 nm,respectively.The Fourier transform infrared spectra(FTIR)testified the CSO was coupled with PAA-Fe_(3)O_(4) successfully.After coupled with CSO,the r1 of PAA-Fe_(3)O_(4) was increased from 5.317 mM s-1 to 6.147 mM s-1,indicating their potential as MRI contrast agent.Oil Red O staining and total cholesterols(TC)determination showed that CSO-PAA-Fe_(3)O_(4) could significantly inhibit the foaming process of RAW264.7 cells induced by oxidatively modified low density lipoprotein(ox-LDL).In vitro cellular MRI displayed that,compared with PAA-Fe_(3)O_(4),CSO-PAA-Fe_(3)O_(4) could lower the T1 relaxation time of RAW264.7 cells better.In summary,construction of CSO-PAA-Fe_(3)O_(4) nanoprobe in this study could realize the targeted MRI of macrophages and inhibition of ox-LDL induced macrophage foaming process.This will provide a new avenue in the diagnosis and treatment of AS.