Carboxyl-functionalized Magnetic Nanoparticles Research Articles

High-efficient nucleic acid separation from animal tissue samples via surface modified magnetic nanoparticles

High efficiency nucleic acid (NA) separation via magnetic nanoparticles (MNPs) is a promising technology for bioengineering, healthcare, etc. Aimed to enhance the selection of MNPs and illustrate the separation mechanism for effective isolation of NAs from complex animal samples, this study fabricated hydroxy-, amino- and carboxyl-functionalized MNPs (MNPs-OH, MNPs-NH2 and MNPs-COOH) with different particle sizes to investigate the hybrid NA separation performance from animal tissue samples. Molecular dynamics (MD) simulation was introduced to predict the affinity action of MNPs with NA and typical impurities. The details of the kinetic separation behavior and the NA separation performance were then illustrated. MD simulation results showed MNPs-NH2 had a stronger affinity with NA, and in most experimental separation systems, NA separation yield via three kinds of MNPs showed a following order of MNPs-NH2 > MNPs-OH > MNPs-COOH. MNPs of different sizes had significantly different sedimentation and dispersion features, leading to diverse separation results. Combining with the proper lysis system, an optimized NA separation method at room temperature with high-throughput and low contamination risk was developed as a promising approach for large-scale samples extracted NA simultaneously. This work could provide a theoretical guidance for the fabrication strategy of advanced MNPs and the enhancement of NA separation from complex samples.

Performance evaluation of the new cobas e 801 instrument in medical routine

To a certain extent, uneven coating of nanoparticles may lead to exposure of their contents. In this work, a simulation system was established and exposed Fe3O4 magnetic nanoparticles (MNPs) were used to investigate the influence of the exposed case in a chemiluminescence immunoassay. Some factors such as the concentration of MNPs, coexistence of horseradish peroxidase (HRP), different particle sizes, and various treatment methods were investigated. It was confirmed that both the bodies of nanoparticles and metallic oxides on the exposed surface have associations with the detection signal. This conclusion may provide a new way to explain the deviation emerged in a chemiluminescence immunoassay. In addition, an exposed Fe3O4 MNPs based chemiluminescence immunoassay was developed to detect human chorionic gonadotropin (hCG). Carboxyl-functionalized MNPs were modified with anti-α-hCG antibody, and further used as solid-phase supports for sandwich-type immunoassay. The detection limit for hCG under optimal conditions was as low as 1.184 ng/mL with a linear response range of 2–100 ng/mL and a correlation coefficient of 0.989. The proposed method could be used for the determination of hCG in serum samples, which demonstrated their application potential in rapid and cost-effective detection of biological samples.

Influence of exposed magnetic nanoparticles and their application in chemiluminescence immunoassay

To a certain extent, uneven coating of nanoparticles may lead to exposure of their contents. In this work, a simulation system was established and exposed Fe3O4 magnetic nanoparticles (MNPs) were used to investigate the influence of the exposed case in a chemiluminescence immunoassay. Some factors such as the concentration of MNPs, coexistence of horseradish peroxidase (HRP), different particle sizes, and various treatment methods were investigated. It was confirmed that both the bodies of nanoparticles and metallic oxides on the exposed surface have associations with the detection signal. This conclusion may provide a new way to explain the deviation emerged in a chemiluminescence immunoassay. In addition, an exposed Fe3O4 MNPs based chemiluminescence immunoassay was developed to detect human chorionic gonadotropin (hCG). Carboxyl-functionalized MNPs were modified with anti-α-hCG antibody, and further used as solid-phase supports for sandwich-type immunoassay. The detection limit for hCG under optimal conditions was as low as 1.184ng/mL with a linear response range of 2–100ng/mL and a correlation coefficient of 0.989. The proposed method could be used for the determination of hCG in serum samples, which demonstrated their application potential in rapid and cost-effective detection of biological samples.

Efficient immobilization of agarase using carboxyl-functionalized magnetic nanoparticles as support

Background: A simple and efficient strategy for agarase immobilization was developed with carboxyl-functionalized magnetic nanoparticles (CMNPs) as support. The CMNPs and immobilized agarase (agarase-CMNPs) were characterized by transmission electron microscopy, dynamic light scattering, vibrating sample magnetometry, scanning electron microscopy, X-ray diffraction, thermogravimetric analysis, and zeta-potential analysis. The hydrolyzed products were separated and detected by ESI-TOF-MS. Results: The agarase-CMNPs exhibited a regular spherical shape with a mean diameter of 12 nm, whereas their average size in the aqueous solution was 43.7 nm as measured by dynamic light scattering. These results indicated that agarase-CMNPs had water swelling properties. Saturation magnetizations were 44 and 29 emu/g for the carriers and agarase-CMNPs, respectively. Thus, the particles had superparamagnetic characteristics, and agarase was successfully immobilized onto the supports. Agaro-oligosaccharides were prepared with agar as substrate using agarase-CMNPs as biocatalyst. The catalytic activity of agarase-CMNPs was unchanged after six reuses. The ESI-TOF mass spectrogram showed that the major products hydrolyzed by agarase-CMNPs after six recycle uses were neoagarotetraose, neoagarohexaose, and neoagarooctaose. Meanwhile, the end-products after 90 min of enzymatic treatment by agarase-CMNPs were neoagarobiose and neoagarotetraose. Conclusions: The enhanced agarase properties upon immobilization suggested that CMNPs can be effective carriers for agarase immobilization. Agarase-CMNPs can be remarkably used in developing systems for repeated batch production of agar-derived oligosaccharides. Normal 0 21 false false false ES-MX JA X-NONE /* Style Definitions */ table.MsoNormalTable {mso-style-name:Tabla normal; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-priority:99; mso-style-parent:; mso-padding-alt:0cm 5.4pt 0cm 5.4pt; mso-para-margin:0cm; mso-para-margin-bottom:.0001pt; mso-pagination:widow-orphan; font-size:10.0pt; font-family:Cambria,serif; mso-ansi-language:ES-MX;}

Preparation and characterization of κ-carrageenase immobilized onto magnetic iron oxide nanoparticles

Background: Carboxyl-functionalized magnetic nanoparticles were synthesized via chemical co-precipitation method and modified with oleic acid which was oxidized by potassium permanganate, and κ-carrageenase from Pseudoalteromonas sp. ASY5 was subsequently immobilized onto them. The immobilization conditions were further optimized, and the characterizations of the immobilized κ-carrageenase were investigated. Results: The κ-carrageenase was immobilized onto magnetic iron oxide nanoparticles, and the bonding was verified by Fourier transform infrared spectroscopy. The optimal conditions for κ-carrageenase immobilization were 2.5% (w/v) glutaraldehyde, 13.9 U κ-carrageenase for 20 mg of magnetic nanoparticles, a 2-h cross-linking time, and a 2-h immobilization time at 25°C. Under these conditions, the activity of the immobilized enzyme and the enzyme recovery rate were 326.0 U · g - 1 carriers and 46.9%, respectively. The properties of the immobilized κ-carrageenase were compared with those of the free enzyme. The optimum temperatures of the free and immobilized κ-carrageenase were 60 and 55°C, respectively, and the optimum pH of κ-carrageenase did not change before and after immobilization (pH 7.5). After immobilization, κ-carrageenase exhibited lower thermal stability and improved pH stability, as well as better storage stability. The immobilized κ-carrageenase maintained 43.5% of the original activity after being used 4 times. The kinetic constant value (Km) of κ-carrageenase indicates that the immobilized enzyme had a lower binding affinity for the substrate. Conclusions: Under optimal conditions, the activity of the immobilized enzyme and enzyme recovery rate were 326.0 U · g - 1 ·κ-carrageenase-CMNPs and 46.9%, respectively. The thermal, pH, and storage stabilities of κ-carrageenase-CMNPs were relatively higher than those of free κ-carrageenase.

A facile method for protein imprinting on directly carboxyl-functionalized magnetic nanoparticles using non-covalent template immobilization strategy

A facile strategy to prepare the core–shell magnetic imprinted nanoparticles for specific recognition of protein is presented. The core is carboxyl-modified Fe3O4 nanoparticles (Fe3O4@COOH) synthesized directly through a simple one-pot hydrothermal method. The formation of imprinted shell with specific recognition cavities includes three steps. Initially, the protein template is non-covalently anchored on Fe3O4@COOH. Next, the chemical oxidation of 3-aminophenylboronic acid takes place on the surface of Fe3O4@COOH-protein complex for further immobilization of template protein. Then, a thin imprinted layer is obtained on Fe3O4@COOH after the removal of the template protein. The resultant imprinted materials not only exhibit good dispersibility, uniform surface morphology, super-paramagnetic property, but also possess fast kinetics, high capacity, as well as favorable selectivity. In addition, the as-synthesized polymers could be used for six cycles of adsorption–desorption without obvious deterioration and applied to specifically separate and enrich target protein from real biological sample successfully. Furthermore, the result of versatility indicates that the facile preparation method is more suitable for basic proteins.

Cross-platform detection of epigenetic modifications from extracted chromatin in leucocytes from blood

Chromatin contains valuable epigenetic information comprising of both DNA and post translational histone modifications. Traditionally, detection of epigenetic modifications on DNA and histone proteins requires different and elaborate preparation steps. In this study we report on a facile and unique approach for the simultaneous detection and quantification of epigenetic modifications on DNA and histone proteins in one sample preparation step. Our novel one-pot technique consists of a chromatin extraction step from whole blood using bi-functional carboxyl-functionalized magnetic nanoparticles as solid-phase absorbents. Leucocytes enrichment from blood and chromatin extracted from the leucocytes by lysis was achieved with the same carboxyl-functionalized magnetic nanoparticles. The isolated chromatin was then eluted from the magnetic nanoparticles with PBS 1×. Using the eluted chromatin as substrate, we developed a quantitative method for simultaneous detection of epigenetic modifications on DNA and histone proteins by a biotin–streptavidin mediated enzyme-based immunosorbent assay (two-step EIA) on a 96-well plate. The simultaneous detection of epigenetic modifications on DNA and histone was validated by DNA-based EIA and histone-based Western blotting analysis performed separately with conventional protocols. By coupling cell separation and chromatin purification with a simple detection module, the global epigenetic information could be evaluated in less than 8h in leucocytes from blood. Our simplified cross-platform approach can be used by most laboratories for multiplex detection, uses non-hazardous materials and could be integrated with microfabrication methods for onchip analysis.

Carbodiimide-mediated immobilization of serratiopeptidase on amino-, carboxyl-functionalized magnetic nanoparticles and characterization for target delivery

A hybrid biomaterial of serratiopeptidase enzyme was prepared with magnetic nanoparticles (MNPs) via carboxyl and amino-functionalization and 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide (EDC) for direct immobilization. The average size of prepared MNPs was found to be 15.05 ± 3.06 nm. Attachment of amino and carboxyl groups was confirmed by Fourier transform infrared spectroscopy. X-ray diffraction confirmed the purity and phase integrity of Fe3O4. The MNPs and enzyme-loaded-MNPs (EMNPs) were of saturation magnetization 58 and 50 emu g−1, respectively. Thermogravimetric analysis of EDC-MNPs and EMNPs showed the presence of organic coating over MNPs. Serratiopeptidase immobilized on amino-functionalized magnetic nanoparticles showed loss of enzyme activity due to crosslinking of enzyme, while serratiopeptidase immobilized on carboxyl-functionalized magnetic nanoparticles was better and gave 115.78 mg protein g−1 MNPs, enzyme loading 168.32 U g−1 MNPs at optimized MNPs-to-enzyme ratio 1.0 mg mg−1. In vitro and in vivo studies showed that EMNPs with magnetic targeting is more effective in drug permeation and reduction in edema than free enzyme.

Rapid enrichment of leucocytes and genomic DNA from blood based on bifunctional core–shell magnetic nanoparticles

A series of protocols are proposed to extract genomic DNA from whole blood at different scales using carboxyl-functionalized magnetic nanoparticles as solid-phase absorbents. The enrichment of leucocytes and the adsorption of genomic DNA can be achieved with the same carboxyl-functionalized magnetic nanoparticles. The DNA bound to the bead surfaces can be used directly as PCR templates. By coupling cell separation and DNA purification, the whole operation can be accomplished in a few minutes. Our simplified protocols proved to be rapid, low cost, and biologically and chemically non-hazardous, and are therefore promising for microfabrication of a DNA-preparation chip and routine laboratory use.