Magnetite-Containing Spherical Silica Nanoparticles for Biocatalysis and Bioseparations

Abstract

The simultaneous entrapment of biological macromolecules and nanostructured silica-coated magnetite in sol-gel materials using a reverse-micelle technique leads to a bioactive, mechanically stable, nanometer-sized, and magnetically separable particles. These spherical particles have a typical diameter of 53 +/- 4 nm, a large surface area of 330 m(2)/g, an average pore diameter of 1.5 nm, a total pore volume of 1.427 cm(3)/g and a saturated magnetization (M(S)) of 3.2 emu/g. Peroxidase entrapped in these particles shows Michaelis-Mentan kinetics and high activity. The catalytic reaction will take place immediately after adding these particles to the reaction solution. These enzyme entrapping particles catalysts can be easily separated from the reaction mixture by simply using an external magnetic field. Experiments have proved that these catalysts have a long-term stability toward temperature and pH change, as compared to free enzyme molecules. To further prove the application of this novel magnetic biomaterial in analytical chemistry, a magnetic-separation immunoassay system was also developed for the quantitative determination of gentamicin. The calibration for gentamicin has a working range of 200-4000 ng/mL, with a detection limit of 160 ng/mL, which is close to that of the fluorescent polarization immunoassay (FPIA) using the same reactants.

Bifunctional Gold Nanoshells with a Superparamagnetic Iron Oxide−Silica Core Suitable for Both MR Imaging and Photothermal Therapy

“…The saturation moment per unit mass, M s , for SPIO-Au nanoshells was 3.5 emu/g at 20 kOe, which was about 5.9% of the M s for SPIO. This value for SPIO-Au is in accordance with previously reported data for silica-magnetite nanoparticles 20 . These data indicated that SPIO-Au nanoshells exhibit superparamagnetic characteristics.…”

Cetyltrimethylammonium Bromide-Coated Magnetic Nanoparticles for the Preconcentration of Phenolic Compounds from Environmental Water Samples

“…These materials have been used in various scientific fields such as biotechnology, engineering, biomedical, environmental, and material science (1)(2)(3)(4). Solidphase extraction (SPE) is a routine extraction method for determining trace level contaminants in environmental samples.…”

Barium alginate caged Fe3O4@C18 magnetic nanoparticles for the pre-concentration of polycyclic aromatic hydrocarbons and phthalate esters from environmental water samples

“…Among them SPE is the most popular one in environmental analysis for its high extraction efficiency, low consumption of organic solvents and easy operation. Nanomaterials, which possess nanosized diameter and large surface area, are being applied in numerous scientific fields [1][2][3][4]. In this regard many research groups have developed various types of nanosized SPE sorbents [5][6][7][8][9][10][11][12].…”