Chitosan-modified Magnetic Nanoparticles Research Articles

Evaluation of free and immobilized cellulase on chitosan-modified magnetic nanoparticles for saccharification of sorghum residue.

Enzymatic hydrolysis plays a pivotal role in transforming lignocellulosic biomass. Addressing alternate techniques to optimize the utilization of cellulolytic enzymes is one strategy to improve its efficiency and lower process costs. Cellulases are highly specific and environmentally benign biocatalysts that break down intricate polysaccharides intosimple formsofsugars. In contrast to the most difficult and time-consuming enzyme immobilization processes, in this research, we studied simple, mild, and successful techniques for immobilization of pure cellulase on magnetic nanocomposites using glutaraldehyde as a linker and used in the application of sorghum residue biomass. Fe3O4 nanoparticles were coated with chitosan from the co-precipitation method, which served as an enzyme carrier. The nanoparticles were observed under XRD, Zeta Potential, FESEM, VSM, and FTIR. The size morphology results presented that the Cs@Fe3O4 have 42.2nm, while bare nanoparticles (Fe3O4) have 31.2nm in size. The pure cellulase reaches to 98.07% of loading efficiency and 71.67% of recovery activity at optimal conditions. Moreover, immobilized enzyme's pH stability, thermostability, and temperature tolerance were investigated at suitable conditions. The kinetic parameters of free and immobilized enzyme were estimated as Vmax; 29 ± 1.51 and 27.03 ± 2.02µmolmin-1mg-1, Km; 4.7 ± 0.49mM and 2.569 ± 0.522mM and Kcat; 0.13s-1, and 0.89s-1. Sorghum residue was subjected to 2% NaOH pre-treatment at 50℃. Pre-treated biomass contains cellulose of 64.8%, used as a raw material to evaluate the efficiency of reducing sugar during hydrolysis and saccharification of free and immobilized cellulase, which found maximum concentration of glucose 5.42g/L and 5.12g/L on 72h. Thus, our study verifies the use of immobilized pure cellulase to successfully hydrolyze raw material, which is a significant advancement in lignocellulosic biorefineries and the reusability of enzymes.

Determination of bioactive flavonoids using β-cyclodextrin combined with chitosan-modified magnetic nanoparticles

To accurately determine flavonoids (rutin, quercetin or kaempferol), it is necessary to extract them from complex matrices. The ultrasound-assisted magnetic dispersion microsolid phase extraction technique has been predominantly used for separation and enrichment of the target analytes. The combination of magnetic chitosan nanoparticles and a deep eutectic supramolecular solvent (DESP) is likely to enhance the efficiency of flavonoid extraction from food. In this study, adsorbents were prepared by modifying chitosan with magnetic nanoparticles, and the eluent was a DESP derived from β-cyclodextrin and an organic acid. The successful preparation of these materials was confirmed by FTIR, XRD, FE-SEM and 1H NMR. The extraction recovery rates exceeded 93%, with limits of detection and quantitation ranging from 0.9 to 2.4μg/L and 2.7 to 7.2μg/L, respectively, and the flavonoid clearance rates for ABTS and DPPH radicals reached 100%. Therefore, the integration of magnetic chitosan nanoparticles with the DESP provides a new and efficient method for the extraction of flavonoids while also presenting a potential application of the DESP in separations.

Adsorption of Pb2+ ions from wastewater via microwave-assisted hydrothermal preparation of chitosan-modified magnetic nanoparticles

Adsorption of Pb2+ ions from wastewater via microwave-assisted hydrothermal preparation of chitosan-modified magnetic nanoparticles

Hematopoietic Bone Marrow Cells of Rat after Intravenous Administration of Chitosan-Modified Magnetite Nanoparticles

Chitosan-modified magnetic nanoparticles are a promising basis for the creation of new diagnostic agents and therapeutic drugs. The cells of erythroid, granulocytic, monocytic, lymphocytic, and megakaryocytic lineages of bone marrow of mature rats were investigated for 120 days after single injection of 0.14 g per 1 kg body weight chitosan-modified magnetic nanoparticles (Fe3O4). Light microscopy was applied to describe the structure of hematopoietic cells and morphometric study was performed on Romanowsky—Giemsa stained smears to measure cells size (µm) and relative number (%). Comparison of the biological effects of nonmodified and modified magnetite nanoparticles on hematopoietic cells of bone marrow revealed the advantages of modification. Chitosan-modified magnetite nanoparticles did not affect the structure of hematopoietic cells in the rat bone marrow, and their injection produced a reversible increase in the relative number of monocytes, stab neutrophils and segmented neutrophils, as well as polychromatic and oxyphilic normoblasts.

Magnetic assisted fluorescence immunoassay for sensitive chloramphenicol detection using carbon dots@CaCO3 nanocomposites

Analytical methods with high sensitivities and short assay times are urgently required for the screening of “zero tolerance” hazardous substances in food. Herein, we propose a fluorescent immunoassay for the highly sensitive and rapid analysis of chloramphenicol (CAP) based on carbon dots (CDs)-encapsulated CaCO3 nanospheres and magnetic nanoparticles (MNPs). The fluorescent immunoprobes were prepared by coupling the anti-CAP antibodies to carboxymethyl cellulose-functional CDs@CaCO3 nanospheres. Chitosan-modified MNPs with “core–shell” structures were prepared and then conjugated to the CAP hapten, acting as the nano-carrier and interface for the immunoreaction. With the assistance of MNPs, the established fluorescent immunoassay achieved the sensitive detection of CAP in chicken with a limit of detection of 0.03 μg kg−1 and recoveries ranging from 83.7%–105.0%. The analysis results of the fluorescent immunoassay were evaluated by the enzyme-linked immunosorbent assay, having a correlation coefficient of 0.981. Our work provides a rapid, facile, and reliable strategy for the highly sensitive analysis of food contaminants based on “green” fluorescent nanoprobes.

Stopped‐flow chemiluminescence determination of the anticancer drug capecitabine: Application in pharmaceutical analysis and drug‐delivery systems

Capecitabine is a chemotherapeutic agent used for the treatment of patients with metastatic cancers. This study aimed at determining the drug capecitabine in a simple chemiluminescence (CL) system of acidic potassium permanganate using the stopped-flow injection technique. Statistical methods were used to detect optimum conditions. The method showed two linear calibration ranges from 6.7 × 10-6 to 6.7 × 10-5 mol L-1 and from 6.7 × 10-5 to 2.7 × 10-3 mol L-1 with a detection limit of 1.5 × 10-6 mol L-1 . Chitosan-modified magnetic nanoparticles were studied in the drug-delivery experiments. According to the pH sensitivity of chitosan and low pH values in tumour cells, the chitosan-coated magnetic nanoparticles could provide a good targeting drug-delivery system to tumour sites. To evaluate the applicability of the method, the capecitabine-loaded magnetic chitosan nanoparticles were synthesized with two different cross-linkers; loading and releasing rates of the drug were investigated using the proposed CL method and an ultraviolet-visible light spectrophotometric method (absorption at 305 nm). The results showed a good correlation between the two methods, and it was found that the synthesized chitosan-modified magnetic nanoparticles could be used for pH-dependent release of capecitabine in cancer cells. Moreover, determination of capecitabine in tablets and synthetic samples was performed.

Adsorption of molybdenum (VI) in contaminated water using Fe3O4/CTS magnetic nanoparticles

To solve the problem of excess molybdenum, a new composite nanomaterial was prepared for adsorption and removal of Mo (VI). Chitosan-modified magnetic nanoparticles (Fe3O4/CTS) were prepared by the method of glutaraldehyde crosslinking. The morphology of the composite nanoparticles was characterized by a scanning electron microscope, and the magnetic properties of the nanoparticles were characterized by an external magnetic field. The content of Mo (VI) was determined by thiocyanate spectrophotometry. The relationship between adsorbent dosage, oscillation velocity, contact time and removal of Mo (VI) was studied. The results showed that when the dosage of Fe3O4/CTS magnetic nanoparticles was 0.4 g, the oscillation speed was 100 r min-1, and the contact time was 10 min, 100 ml of Mo (VI) solution was treated under the condition of initial pH =4, and the removal effect of Fe3O4/CTS magnetic nanoparticles on Mo (VI) was the best. Treatment effluent can reach the comprehensive sewage discharge standard in Liaoning Province. At the same time, it is proved that Fe3O4/CTS magnetic nanoparticles are a kind of adsorbent which is easy to recover, easy to separate magnetically, and has the ability to remove Mo (VI) efficiently.

Chitosan modified magnetic nanoparticles based solid phase extraction combined with ICP-OES for the speciation of Cr(iii) and Cr(vi)

Chitosan-modified magnetic nanoparticles were synthesized by an emulsion method and were characterized. The prepared chitosan-modified magnetic nanoparticles exhibit excellent adsorption performance for Cr(III) at pH 9 and total Cr (Cr(III) and Cr(VI)) at pH 6. Therefore, a new method by combining magnetic solid phase extraction with inductively coupled plasma optical emission spectrometry was developed for the speciation of Cr(III) and Cr(VI) in environmental water samples. The parameters affecting extraction and desorption of the target chromium species, such as pH, extraction time, sedimentation time and sample volume, were investigated and the optimized conditions were established. With a preconcentration factor of 100-fold, the limits of detection (LODs) were 0.02 and 0.03 ng mL−1 with the relative standard deviations of 4.8% and 5.6% (n = 7, c = 1 ng mL−1) for Cr(III) and Cr(total), respectively. The method was successfully applied to analyze East Lake water (Wuhan) and tap water at the campus of Wuhan University. In order to validate the accuracy of the proposed method, the certified reference material GSBZ50009-88 was analyzed, and the determined values were in good agreement with the certified values. The proposed method, with the merits of simple operation, rapid adsorption/desorption dynamics, high enrichment factor and low LODs, is suitable for the speciation of inorganic chromium in environmental water samples.