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1.
Synthesis and surface engineering of magnetic nanoparticles for environmental cleanup and pesticide residue analysis: A review 下载免费PDF全文
Ranjeet Kaur Abshar Hasan Nusrat Iqbal Samsul Alam Mahesh Kr Saini Syed Kalbe Raza 《Journal of separation science》2014,37(14):1805-1825
In recent years, water pollution and pesticide accumulation in the food chain have become a serious environmental and health hazard problem. Direct determination of these contaminants is a difficult task due to their low concentration level and the matrix interferences. Therefore, an efficient separation and preconcentration procedure is often required prior to the analysis. With the advancement in nanotechnology, various types of magnetic core–shell nanoparticles have successfully been synthesized and received considerable attention as sorbents for decontamination of diverse matrices. Magnetic core–shell nanoparticles with surface modifications have the advantages of large surface‐area‐to‐volume ratio, high number of surface active sites, no secondary pollutant, and high magnetic properties. Due to their physicochemical properties, surface‐modified magnetic core–shell nanoparticles exhibit high adsorption efficiency, high rate of removal of contaminants, and easy as well as rapid separation of adsorbent from solution via external magnetic field. Such facile separation is essential to improve the operation efficiency. In addition, reuse of nanoparticles would substantially reduce the treatment cost. In this review article, we have attempted to summarize recent studies that address the preconcentration methods of pesticide residue analysis and removal of toxic contaminants from aquatic systems using magnetic core–shell nanoparticles as adsorbents. 相似文献
2.
Despite the fact that the magnetic hyperthermia (MH) has been known for more than 75 years, it is still debated in its clinical applications. The generation of a higher temperature at a tumor is called hyperthermia. There is a different of temperature ranges going from 39 to 40 ?°C up to such high temperatures as 80–90 ?°C. However, due to its high potential, MH is used along with nanoparticles as heat intermediaries in the treatment of cancer. Many Magnetic Nanoparticles (MNPs) with several properties and morphological metallic structures have been useful to magnetics hyperthermia therapy. These MNPs are categorized into two groups; magnetic alloy nanoparticles (MANPs) and magnetic metal oxide nanoparticles (MMONPs). The principal challenges of this method are the control of local tumoral temperature and the increase in nanoparticles heating power. The hyperthermia agents derived from magnetic nanoparticles along with magnetic field. In the recent study, hyperthermia thought, dissimilar types of magnetic nanoparticles for hyperthermia, efficacy for cancer therapy, advances, challenges, and future chances have been examined. 相似文献
3.
A novel open‐tubular capillary electrochromatography (OT‐CEC) with modified core/shell magnetic nanoparticles coating as stationary phase was introduced using external magnetic force to fix magnetic nanoparticles. The magnetic nanoparticles coating inside the capillary columns could be easily regenerated by removing and re‐applying the external magnetic field. Magnetic field intensity, concentration and flow rate of nanoparticles suspension were investigated to achieve simple and stable preparation. Mixture of five organic acids was used as the marker sample to evaluate the OT‐CEC system, and the relative column efficiency of anthranilic acid reaches 220 000 plates/m. The excellent within‐column and between‐column repeatability has been testified with the RSDs of retention time of less than 1.51 and 5.29%, respectively. The aqueous extract of rhizoma gastrodiae was analyzed by the OT‐CEC system, and 23 peaks were eluted in 30 min. Compared with conventional open‐tubular capillary column, this new system shows faster separation speed and higher column efficiency from the larger surface area of nanoparticles. It has great potential in the method development for the analysis of complex samples, since magnetic coating can effectively prolong the column life by expediently replacing stationary phase to eliminate the pollution or irreversible adsorption. 相似文献
4.
Magnetic fluids are used in many fields of application, such as material separation and biomedicine. Magnetic fluids consist
of magnetic nanoparticles, which commonly display a broad distribution of magnetic and nonmagnetic parameters. Therefore,
upon application only a small number of particles contribute to the desired magnetic effect. In order to optimize magnetic
fluids for applications preference is given to methods that separate magnetic nanoparticles according to their magnetic properties.
Hence, a magnetic method was developed for the fractionation of magnetic fluids. Familiar size-exclusion chromatography of
two different magnetic fluids was carried out for comparison. The fractions obtained and the original samples were also magnetically
characterized by magnetic resonance and magnetorelaxometry, two biomedical applications. The size-exclusion fractions are
similar to those of magnetic fractionation, despite the different separation mechanisms. In this respect, magnetic fractionation
has several advantages in practical use over size-exclusion chromatography: the magnetic method is faster and has a higher
capacity. The fractions obtained by both methods show distinctly different magnetic properties compared to the original samples
and are therefore especially suited for applications such as magnetorelaxometry.
Received: 12 July 1999/Accepted in revised form: 9 November 1999 相似文献
5.
Immobilization of bioactive molecules on the surface of magnetic nanoparticles is of great interest, because the magnetic properties of these bioconjugates promise to greatly improve the delivery and recovery of biomolecules in biomedical applications. Here we present the preparation and functionalization of magnetite (Fe3O4) nanoparticles 20 nm in diameter and the successful covalent conjugation of the enzyme glucose oxidase to the amino-modified nanoparticle surface. Functionalization of the magnetic nanoparticle surface with amino groups greatly increased the amount and activity of the immobilized enzyme compared with immobilization procedures involving physical adsorption. The enzymatic activity of the glucose oxidase-coated magnetic nanoparticles was investigated by monitoring oxygen consumption during the enzymatic oxidation of glucose using a ruthenium phenanthroline fluorescent complex for oxygen sensing. The glucose oxidase-coated magnetite nanoparticles could function as nanometric glucose sensors in glucose solutions of concentrations up to 20 mmol L–1. Immobilization of glucose oxidase on the nanoparticles also increased the stability of the enzyme. When stored at 4°C the nanoparticle suspensions maintained their bioactivity for up to 3 months. 相似文献
6.
Using the stepwise heterocoagulation concept, fluorescent and highly magnetic submicronic core-shell polymer particles were
prepared. For this purpose a negatively charged oil-in-water magnetic emulsion was first modified by adsorbing the poly(ethyleneimine)
(PEI). Secondly, low glass transition temperature (T
g=10°C) anionic film-forming nanoparticles were adsorbed onto the cationic magnetic droplets. Finally the encapsulation was
induced by heating the heterocoagulates above the T
g of the film-forming nanoparticles. To produce labeled magnetic particles, fluorescent nanoparticles and film-forming nanoparticles
were simultaneously adsorbed. PEI adsorption was investigated. Also investigated was the influence of the amount of film-forming
nanoparticles and fluorescent nanoparticles on the encapsulation efficiency. 相似文献
7.
Functional magnetic nanoparticles are prepared and characterized for protein detection in a magnetic separation channel. This detection method is based on a competitive immunoassay of magnetic separation in thin channels using functional magnetic nanoparticles. We used protein A–IgG complex to demonstrate the feasibility. Free IgG and fixed number of IgG-labeled microparticles were used to compete for limited sites of protein A on the magnetic nanoparticles. Several experimental parameters were investigated for protein detection. The deposited percentages of IgG-labeled microparticles at various concentrations of free IgG were determined and used as a reference plot. The IgG concentration in a sample was deduced and determined based on the reference plot using the deposited percentage of IgG-labeled microparticles from the sample. The linear range of IgG detection was from 5.0 × 10−8 to 1.0 × 10−11 M. The detection limit was 3.69 × 10−12 M. The running time was less than 10 min. Selectivities were higher than 92% and the relative errors were less than 7%. The IgG concentration of serum was determined to be 3.6 mg ml−1. This measurement differed by 8.3% from the ELISA measurement. The recoveries of IgG spiked in serum were found to be higher than 94%. This method can provide simple, fast, and selective analysis for protein detection and other immunoassay-related applications. 相似文献
8.
9.
Selective extraction of berberine from Cortex Phellodendri using polydopamine‐coated magnetic nanoparticles 下载免费PDF全文
Hai‐Li Shi Shu‐Lin Peng Jun Sun Yi‐Ming Liu Yuan‐Ting Zhu Lin‐Sen Qing Xun Liao 《Journal of separation science》2014,37(6):704-710
A new extraction agent featuring dopamine self‐polymerized on magnetic Fe3O4 nanoparticles has been successfully synthesized and evaluated for the SPE of berberine from the extract of the traditional Chinese medicinal plant, Cortex Phellodendri. The nanoparticles prepared possessed a core–shell structure and showed super‐paramagnetism. It was found that these polydopamine‐coated nanoparticles exhibited strong and selective adsorption for berberine. Among the chemical components present in C. Phellodendri, only berberine was adsorbed by the nanoparticles and extracted by a following SPE procedure. Various conditions such as the amount of polydopamine‐coated nanoparticles, desorption solvent, desorption time and equilibrium time were optimized for the SPE of berberine. The purity of berberine extracted from C. Phellodendri was determined to be as high as 91.3% compared with that of 9.5% in the extract. The established SPE protocol combined advantages of highly selective enrichment with easy magnetic separation, and proved to be a facile efficient procedure for the isolation of berberine. Further, the prepared polydopamine‐coated magnetic nanoparticles could be reused for multiple times, reducing operational cost. The applicability and reliability of the developed SPE method were demonstrated by isolating berberine from three different C. Phellodendri extracts. Recoveries of 85.4–111.2% were obtained with relative standard deviations ranging from 0.27–2.05%. 相似文献