Magnetic Chitosan Microspheres Research Articles

Quaternary ammonium-functionalized magnetic chitosan microspheres as an effective green adsorbent to remove high-molecular-weight invert sugar alkaline degradation products (HISADPs)

• We elucidated the structural properties of HISADPs. • QAMCM was creatively synthesized and systematically characterized. • In vitro cytotoxicity tests were conducted to evaluate the food safety of QAMCM. • QAMCM adsorbed HISADPs well and exhibited good regenerability. • PFO–PSO and FPMT models described the adsorption mechanisms well. Quaternary ammonium-functionalized magnetic chitosan microspheres (QAMCM) were fabricated for the removal of high-molecular-weight invert sugar alkaline degradation products (HISADPs), the main class of colorants in beet juice. The equilibrium adsorption capacity of QAMCM for HISADP was 98.03 mg/g at 0.6 mg/mL QAMCM dosage, 333 K temperature, pH 7, and 60 mg/L initial HISADP concentration, and the corresponding removal rate reached 98.03%. The adsorption kinetics were studied by using a pseudo-first-order and pseudo-second-order (PFO–PSO) combined model. Results revealed that HISADP adsorption by QAMCM is a complex process because of the involvement of both chemisorption and physisorption instead of only one mechanism. However, chemisorption (electrostatic attraction and electron sharing) is the dominant kinetic mechanism. Analysis of the mass transfer mechanisms showed that the dynamic characters of the adsorption capacities of the liquid film around QAMCM and the pores of QAMCM could be well described using a film–pore mass transfer model, which could be used to provide insights into the adsorption mass transfer behaviors of the system. Additionally, HISADPs with smaller sizes were preferentially adsorbed by QAMCM compared with larger ones. Research on the isotherms and thermodynamics showed that HISADP adsorption by QAMCM occurred via an endothermic multi-layer process and was spontaneous. Overall, QAMCM was found to be an efficient, green, and recyclable decolorization adsorbent for beet juice.

Immobilization of lactase on magnetic chitosan microspheres and its effect on enzymatic properties

Immobilization of lactase on magnetic chitosan microspheres and its effect on enzymatic properties

Recyclable magnetic chitosan microspheres with good ability of removing cationic dyes from aqueous solutions

Sr3.8Fe25.7O70.4-chitosan magnetic microparticles (Sr3.8Fe25.7O70.4-CMNs) with a core-shell structure were synthesized, characterized and applied for the removal of two model cationic dyes. The results showed that these magnetic microparticles possess fast adsorption rate and high adsorption efficiency for both crystal violet (CV) and basic red 9 (BR9) at a temperature ranging 30 °C to 40 °C and suitable pH range (pH ≥ 7). The maximum removal efficiency for CV and BR9 attained to 94.5% and 97.5% in 30 min, which was significantly faster and higher than that of chitosan (<50% in 60 min) (P<0.01). And its maximum adsorption capacity for CV and BR9 reached 29.46 mg/g and 32.16 mg/g, respectively. The adsorption process of Sr3.8Fe25.7O70.4-CMNs follows the Langmuir isotherm with a high correlation coefficient (R2 > 0.97) and the pseudo-second-order model. Additionally, the synthesized Sr3.8Fe25.7O70.4-CMNs were easy to regeneration and reuse, and the removal rate remained above 90% after 5 recycle times. This study would provide a new more environmental friendly material and method for the treatment of wastewater containing toxic dyes.

Synthesis and characterization of a novel magnetic chitosan microsphere for lactase immobilization

A novel magnetic chitosan microsphere (MCM) as a carrier was synthesized for lactase immobilization. The morphology and structure were characterized using SEM, FT-IR, XRD and VSM. The immobilization conditions, stability as well as reusability on immobilized enzyme were studied in detail. The kinetic properties were also discussed based on the experimental. The results showed that the Fe3O4 nanoparticles were successfully coated into chitosan. The as-prepared MCM exhibited smooth spherical surface and good magnetic property. Compared with free enzyme, the immobilized enzyme displayed better pH, thermal, and storage stability. The calculated Km of immobilized lactase was higher than that of the free enzyme, indicating that the affinity weakened of lactase on MCM toward the substrate during immobilization process. The activity of immobilized lactase retained over 65 % after ten cycles using, indicating that MCM was expected to be a promising carrier for enzyme immobilization.

Cobalt-Tetraamide-Phthalocyanine Immobilized on Fe3O4/Chitosan Microspheres as an Efficient Catalyst for Baeyer-Villiger Oxidation.

Cobalt-Tetraamide-Phthalocyanine (CoTaPc) immobilized onto magnetic Fe3O4 chitosan microspheres (Fe3O4/CTO) was synthesized via a simple immersion method, which is an efficient catalyst for the oxidation of cyclic ketones to lactones with O2/benzaldehyde as the oxidant. The CoTaPc-Fe3O4/CTO catalyst was applied for the first time in the Baeyer–Villiger (B–V) oxidation reaction. Characterization results obtained from X-ray diffraction, UV–vis, Fourier transform infrared, and scanning electron microscopy showed that the combination of CoTaPc and magnetic Fe3O4/CTO microspheres was achieved. The catalyst could be easily separated from the reaction system with an external magnet and reused several times without the remarkable loss of activity. In addition, a possible radical mechanism for the B–V oxidation in this catalytic system is proposed and verified by controlled experiments.

Preparation of magnetic chitosan microspheres using iron sand particles prepared by ball milling method

Iron sand particles prepared by ball milling method have been used in the magnetic chitosan microspheres preparation. FTIR, XRD and SEM analyses were performed to characterize the magnetic chitosan microspheres. SEM images and FTIR spectra confirmed the formation of magnetic chitosan microspheres. The patterns of XRD showed the presence of iron sand particles reduced the crystallinity of chitosan. The adsorption experiments were conducted for mercury removal from aqueous solutions. AAS was performed to determine the mercury concentrations in the solutions after the adsorption process. The results showed the adsorption capacity (Q) of the magnetic chitosan microspheres was not significantly different from magnetic chitosan microspheres prepared using iron oxide.

Magnetic/pH-sensitive double-layer microrobots for drug delivery and sustained release

Remarkable evolution of drug-loaded microrobots has aroused growing interest in targeted therapy. However, existing microrobots encounter a number of challenges including maneuverability, biodegradability, and drug sustained release capabilities in medical applications. Designed double-layer drug-loaded microrobots (TDMs) were made of outer layer calcium alginate hydrogel and inner layer magnetic chitosan microspheres (mCSs). TDMs precisely deliver drug-loaded mCSs following the expected route towards the predefined destinations under a vision-guided magnetic driving system. In acidic conditions the outer layer of TDMs can protect mCSs, while in alkaline conditions calcium alginate hydrogel dissolves at an appropriate rate to render mCSs be continuously released. The mCSs fulfill drug sustained release tasks in vitro. The new designed low-cost microrobots will be competent for intestinal cancer targeted therapy after oral administration and bridge the gap between scientific research and market demand.

Synthesis and characterization of magnetic chitosan microspheres for drug delivery.

A novel magnetic microsphere was prepared by simple microemulsion polymerization for protein drug delivery systems. The Fe3O4 magnetic nanoparticles were successfully encapsulated in chitosan microspheres, which endowed the chitosan microspheres with good magnetism. The drug loading performance results indicated that the prepared magnetic chitosan microspheres exhibited a superior drug loading capacity, and the drug loading amount reached 947.01 mg g−1. Furthermore, the magnetic chitosan microspheres also showed a higher drug release rate (87.8%) and evident sustained-release performance in vitro. The magnetic microsphere carrier will be widely used in the biomedical field as a promising drug carrier.

Evaluation of novel magnetic targeting microspheres loading adriamycin based on carboxymethyl chitosan

Targeted drug delivery system delivers drug to diseased organ, tissue, or cells by utilizing some physical means and biological properties, such as pH gradients in the intestine, differences in capillary diameters, immune system, specific enzymatic degradation, receptor responses, and specific chemical environment at the site of the lesion. Combining two preparation techniques of magnetic microspheres and ion exchange, regarding the anticancer drug adriamycin (ADR) as a model drug, carboxymethyl chitosan (CMC) as carrier, and Fe3O4 ultrafine particles as magnetic material, novel drug-loaded magnetic microspheres-ADR loaded carboxymethyl chitosan magnetic microspheres (ADR-CMC-Mag-MS) were synthesized. In this study, cytotoxicity and in vivo pharmacokinetics of ADR-CMC-Mag-MS were evaluated. The 50% cell inhibiting concentration (IC50) value of ADR-CMC-Mag-MS was (0.051 ± 0.005) μg/mL. And the cytotoxicity against human hepatocellular (Hep3B) cells presented concentration dependence. The area under the curve (AUC) and the peak concentration (Cmax) of ADR-CMC-Mag-MS added magnetic field (mag field) were respectively (1061.68 ± 22.71) μg·min/mL and (6.18 ± 0.13) μg/mL, indicating that the prepared ADR-CMC-Mag-MS had good targeting ability. It was demonstrated that the novel microspheres could deliver the highly toxic anticancer drug to the target site, in order to maximize the drug efficacy and reduce the side effects under the action of the external magnetic field.

Uniform magnetic chitosan microspheres with radially oriented channels by electrostatic droplets method for efficient removal of Acid Blue

Abstract Chitosan is highly suitable for removing dyes from water, however, their sorption performance, stability and recycling are still critical issues in practical applications. In this work, porous magnetic chitosan microspheres were synthesized by electrostatic droplets (ESD) technology combining chemical crosslinking process. To better prepare the Fe3O4/chitosan hydrogel microspheres during the ESD process, sodium hydroxide was used for solidification of chitosan and the co-precipitation of ferro-gels containing ferrous and ferric cations, and glutaraldehyde was used as a crosslinking agent to fabricate the Fe3O4 nanoparticles embedded porous chitosan microspheres (Fe3O4/PCSM). The Fe3O4/PCSM was characterized by SEM, XRD, EDS, and TEM, and the feasibility for the adsorption of dyes by the composite was investigated systematically. The adsorption capacity of Fe3O4/PCSM for Acid Blue is determined as high as 142 mg g−1, which is comparable to some previous adsorbents. The adsorption isotherm and the adsorption kinetics can be well stimulated by the Langmuir model and the pseudo-second-order kinetic model, respectively. Moreover, the regeneration of used Fe3O4/PCSM is very easy and the recycled materials are efficient for the dyes removal in four cycles.

Enahanced biosorption of Cu(II) by magnetic chitosan microspheres immobilized Aspergillus sydowii (MCMAs) from aqueous solution

The magnetic chitosan microspheres immobilized Aspergillus sydowii (MCMAs) was prepared and characterized by SEM, BET, XRD and VSM analyses, and used to adsorb Cu(II) from aqueous solution under different influence factors such as contact time, initial Cu(II) concentration and biosorbent dose. Characterization results showed that MCMAs had large specific surface area and were rapidly separated from aqueous solution by using an adscititious magnetic field. Batch adsorption experiments showed that Cu(II) adsorption capacity of MCMAs was up to 119.21 mg g−l under the optimal condition. The CO, OH and NH groups played an important role in Cu(II) chelation observed from FTIR spectra. Cu(II) adsorption onto MCMAs was well described by pseudo-second-order kinetics and Langmuir isotherm, and the adsorption process involved surface and intra-particle diffusion. In addition, MCMAs showed good recyclable efficiency after four adsorption-desorption cycles.

Heterogeneous Fenton-like degradation of tetracyclines using porous magnetic chitosan microspheres as an efficient catalyst compared with two preparation methods

The construction of heterogeneous Fenton-like catalyst with high efficiency is crucial for wastewater treatment. In this study, magnetite nanoparticles were successfully embedded into chitosan beads to form a porous structure (Fe3O4-Cs) by in-situ or two-step method, and it was put forward as a kind of Fenton-like catalyst to degrade tetracyclines for the first time. SEM, TEM, XRD, FT-IR, XPS, TG and BET technologies were used to characterize its properties. After comparing the tetracycline hydrochloride (TC) degradation efficiencies of two prepared beads, the in-situ method was selected for subsequent studies. The influential factors of TC degradation efficiency were investigated, including iron content, pH value, the amount of H2O2, reaction temperature, catalyst dosage and initial TC concentration. The results showed that under the optimal conditions, about 96.0% of TC (48.09 mg/L) and 68.3% of total organic carbon (TOC) were degraded within 20 min and 120 min, respectively. The degradation efficiencies for the other two tetracyclines: oxytetracycline (OTC) and doxycycline hyclate (DOTC), have been explored as well. And the degradation process followed pseudo first order kinetic equation. In addition, these Fe3O4-Cs beads with saturated magnetization could be easily reused for 6 cycles without significantly reducing catalytic activity. High degradation performance of beads was attributed to the stable porous structure, abundant active sites and possible synergistic effects between two components, which promoted the formation of hydroxyl radicals (HO) for TC degradation. The possible reaction pathways and mechanism on TC degradation were discussed technically. In short, these results indicated that macroscopic Fe3O4-Cs beads (3–4 mm) with high efficiency, excellent stability and reusability exhibited a superior Fenton-like process on the removal of tetracyclines for future application.

Immobilization of Lipase onto Magnetic Nanoparticles for Enantiomer Selective Acetylation of Racemic 1-Phenylethylamine

In this study, magnetic chitosan microspheres (Fe3O4-CTS) were prepared via chemical co-precipitation and cross-linked with lipase using glutaraldehyde to form Fe3O4-CTS-glutaraldehyde-lipase particles. The textural characteristics of Fe3O4-CTS-glutaraldehyde-lipase particles were assessed by scanning electron microscopy. The optimal immobilization conditions were 2.1 mg/mL lipase, 10 mg/mL Fe3O4-CTS-glutaraldehyde, pH 7.5, 30 °C, 2 h. The loading amount of lipase was 126.0 mg/g carrier, and the specific activity reached to 46.7 U/mg. Fe3O4-CTS-glutaraldehyde-lipase particles was used in resolution of racemic 1-phenylethylamine in a solvent-free system. The conversion and enantiomeric excess of (R)-N-(1-phenylethyl)acetamide reached 33.6% and 97%.

Enhancement of catalytic activity of lipase-immobilized Fe3O4-chitosan microsphere for enantioselective acetylation of racemic 1-phenylethylamine

Racemic 1-phenylethylamine was resolved by enantiomer selective acetylation using Fe3O4-chitosan microsphere (CTS)-glutaraldehyde-lipase in a solvent-free system under an alternating magnetic field. Magnetic chitosan microspheres (Fe3O4-CTS) were prepared via chemical co-precipitation and cross-linked with lipase using glutaraldehyde to form Fe3O4-CTS-glutaraldehyde-lipase particles. The magnetic, physicochemical, and textural characteristics of Fe3O4-CTS-glutaraldehyde-lipase particles were assessed by Fourier transform infrared spectroscopy, X-ray diffraction, and scanning electron microscopy. The optimal immobilization conditions were 2.4 mg/mL lipase, 10 mg/mL Fe3O4-CTS-glutaraldehyde, pH 8.5, 35 °C, 3 h. The loading amount of lipase and the specific activity got to 132 mg/g carrier and 48 U/g. The optimal reaction conditions of the acylation reaction using Fe3O4-CTS-glutaraldehyde-lipase were 300 mmol/L 1-phenylethylamine, 150 mg immobilized lipase, 2 mL vinyl acetate, 12.6 ×g rotating speed, 40 °C, 8 h. The activity of the Fe3O4-CTS-glutaraldehyde-lipase particles and conversion were improved when they were exposed to an external alternating magnetic field. The optimum magnetic field was 12 Gs (500 Hz). The conversion, enantiomeric excess of (R)-N-(1-phenylethyl)acetamide, and E value reached 41.8%, 98.4%, and 264, respectively. Fe3O4-CTS-glutaraldehyde-lipase could be reused seven times. A kinetic model of the immobilized lipase-catalyzed resolution of 1-phenylethylamine was set up based on the ping-pong bi-bi mechanism. The kinetic constants were Vmax=1.62×10−2 mM/min, KA=2.84×10−4 mM, and KB=5.8×10−1 mM. The model data fit well with the experimental data.

Facile fabrication of functional chitosan microspheres and study on their effective cationic/anionic dyes removal from aqueous solution

This study provided a simple one-step chemical process for the preparation of aminated magnetic chitosan microspheres (TETA-MCTSms), which were applied for adsorbing anionic dye reactive brilliant red (RBR). Meanwhile, magnetic grafted microspheres (MCTSms-PMAA) were prepared based on magnetic chitosan microspheres via a surface-initiating system NH2/S2O82−, for adsorbing cationic dye methylene blue (MB). The physical properties and structure of the obtained microspheres were characterized by Fourier transform infrared (FT-IR) spectroscopy, scanning electron microscopy (SEM), X-ray diffraction (XRD), vibrating sample magnetometer (VSM) and thermogravimetric analysis (TGA), and their adsorption performance for removal of cationic dye MB and anionic dye RBR was also investigated. MCTSms-PMAA performed excellent performance for cationic dye MB, represented by the adsorption capacities reaching a maximum of 211.22 mg·g−1 at pH 12; TETA-MCTSms performed remarkable adsorption properties for anionic dye RBR, represented by the adsorption capacities reaching a maximum of 637.41 mg·g−1 at pH 2. The kinetic analyses and equilibrium adsorption behaviors of dye wastewater onto chitosan microspheres were investigated using various models. The adsorption mechanism was further analyzed by X-ray photoelectron spectroscopy (XPS), and it was found that the adsorption was mainly driven by hydrogen bonding and electrostatic interaction.

Thermoresponsive polymer brushes on magnetic chitosan microspheres: Synthesis, characterization and application in oily water of high salinity

Smart microspheres capable of responding to magnetic fields and temperature changes were prepared by encapsulating magnetic nanoparticles into cross-linked chitosan microspheres followed by poly(N-isopropylacrylamide) (PNIPAM) brushes formation on their surfaces (MCM-PNIPAM). The synthetized microspheres were characterized by Fourier transform infrared spectroscopy (FT-IR), transmission electron microscopy (TEM), vibrating sample magnetometry (VSM), thermogravimetry (TG) and differential scanning calorimetry (DSC). While most studies have focused on the graft copolymerization reaction between chitosan and NIPAM to get a soluble particle, the main finding of this study was to improve the lipophilicity of magnetic crosslinked chitosan microspheres with PNIPAM brushes, in order to be used in oily water treatment as a solid adsorbent. The thermoresponsive behavior of MCM-PNIPAM was confirmed by the sharp transition phase on DSC curves. The initial investigation of oil removal efficiency was performed to the synthesized microspheres with values higher than 97% for MCM-PNIPAM above the PNIPAM aggregation temperature.

Chitosan and chitosan coating nanoparticles for the treatment of brain disease

Since the application of chitosan magnetic cationic microspheres in brain drug delivery by Gallo in 1993, chitosan has been extensively studied in brain drug delivery. As the only natural alkaline polysaccharide with good biocompatibility and biodegradability, chitosan prepared nanoparticles which use chitosan as carrier material to encapsulate drug have been proved with advantages of protecting from enzyme degradation, control release and improved bioavailability. Besides, chitosan can enhance drug permeability across the blood-brain barrier by affecting the tight junction. And with positive charge on the surface, chitosan nanoparticles can absorb on the negatively charged cell membrane, thus increase its residence time on the nasal mucosa and benefit of the delivery of drugs from the nasal cavity to the brain. All these properties made chitosan nanoparticles especially suitable for brain delivery. What’s more, the free amino groups on the surface of chitosan nanoparticles allow specific chemical modification to form a wide range of chitosan derivatives. Surface modification of the nanoparticles with tumor targeting peptides like chlorotoxin and transferrin, can further improve the targeting property to brain tumor. This article gives a comprehensive review on the advantages and recent progresses in the treatment of brain disease by chitosan nanoparticles.

Removal of sulfate from aqueous solution by magnetic chitosan microspheres

Removal of sulfate from aqueous solution by magnetic chitosan microspheres

Magnetic chitosan-hydroxyapatite composite microspheres: Preparation, characterization, and application for the adsorption of phenolic substances

The phenolic substances in sugarcane juice seriously affect the color value of sugar products, and gallic acid is one of the main phenolic substances. To develop a new adsorbent able to effectively adsorb phenolic substances from sugarcane juice, magnetic chitosan (CS) hydroxyapatite (HA) microspheres (MCHAM) were prepared by growing HA on magnetic CS microspheres (MCM) in-situ. MCHAM could effectively adsorb gallic acid from sucrose solution, and the highest adsorption capacity was 40.77 mg g−1. The adsorption kinetics indicated that the adsorption process fit the pseudo-second-order mode, the dominant mechanism was chemisorption, and the Langmuir isotherm mode (qm = 48.12 mg g−1) described the adsorption behavior of MCHAM best. Recycling experiments indicated that the MCHAM adsorbent presented considerable repeatability. Compared to treating phenolic substances in sugarcane juice using traditional clarifying agents, treatment methods employing MCHAM can efficiently and simply remove phenolic substances without leaving residual sulfur in sugarcane juice.

A novel design and synthesis of multifunctional magnetic chitosan microsphere based on phase change materials

A new type of multifunctional magnetic chitosan microspheres based on phase change materials (M-PCM-CTS, M represents magnetic, PCM represents phase change materials and CTS represents chitosan) were designed and synthesized through multi-emulsification and cross-linking method. The chemical compositions and structures of M-PCM-CTS were confirmed by Fourier transform infrared spectroscopy (FTIR) and Scanning electron microscope (SEM). M-PCM-CTS presented a regular spherical morphology with a uniform diameter of 500 μm. Thermal analysis indicated that the M-PCM-CTS not only revealed reliable phase change performance with a maximum thermal enthalpy of 80 J/g, but also exhibited various melting and crystallization temperature depending on the length of alkanes chain. The multifunctional microspheres developed in this work would open up a new synthesis route for a wide range of multifunction polymers and finds novel opportunities for use in the fields of thermal energy storage, adsorption and magnetic effectiveness.