For simultaneous water purification from both inorganic and organic pollutants, a novel multifunctional hybrid nanoadsorbent has been produced. Core–shell magnetic submicro-particles with iron oxid...

Simultaneous Removal of Acetaminophen, Diclofenac, and Cd(II) by Trametes versicolor Laccase Immobilized on Fe3O4/SiO2-DTPA Hybrid Nanocomposites

Magnetically controlled enzymatic composites have received much attention for both therapeutic and industrial applications. Until now, such materials have been composed of at least four components: the enzyme, magnetic nanoparticles, their stabilizing components, and an organic or inorganic (or hybrid) matrix as a carrier. However, such compositions affect the magnetic response and the enzymatic activity, and also pose obstacles for intravenous administration, because of regulatory restrictions. Here, we present a methodology for the creation of magnetic bioactive nanocomposites composed of only two biocompatible components: an enzyme and magnetite nanoparticles. A series of magnetic biocomposites with a full set of therapeutical and industrial proteins (carbonic anhydrase, ovalbumin, horseradish peroxidase, acid phosphatase, proteinase, and xylanase) were successfully created by the direct entrapment of the proteins within a sol–gel magnetite matrix specially developed for these aims. The activity of the...

Entrapment of Enzymes within Sol–Gel-Derived Magnetite

Magnetically retrievable formulations of urease potentially promising for biomedical and environmental applications were constructed by immobilization of the enzyme on the surface of magnetite nanoparticles functionalized by siloxane layers with active thiol or thiol-and-alkyl moieties The latter were deposited using a hydrolytic polycondensation reaction of tetraethoxysilane with either 3-mercaptopropyltrimethoxysilane, or with 3-mercaptopropyltrimethoxysilane and methyltriethoxysilane, or alternatively n-propyltriethoxysilane Immobilization of urease was carried out in different ways for comparison: by adsorption, by entrapment during the hydrolytic polycondensation reaction, or by covalent bonding For entrapment the enzyme was introduced into solution before functionalization of the magnetite Entrapment bound high amounts of enzyme (more than 700 mg per g of carrier), but its activity was decreased compared to the native form to between 18 and 10% In the case of covalent binding of urease using Ellman's Reagent, binding of the enzyme was almost as efficient as in the case of entrapment but its residual activity was 75% The residual activity of urease immobilized by adsorption on the surface of thiol-functionalized particles was truly high as compared to that of the native enzyme (97%), but binding was significantly less efficient (46%) Introduction of alkyl functions permitted increase of the amounts of the adsorbed enzyme but its activity was somewhat decreased

Immobilization of urease on magnetic nanoparticles coated by polysiloxane layers bearing thiol- or thiol- and alkyl-functions

Composite sorbents based on porous ceramic substrate and hybrid amino- and mercapto-silica materials for Ni(II) and Pb(II) ions removal

High throughput covalent immobilization process for improvement of shelf-life, operational cycles, relative activity in organic media and enzymatic kinetics of urease and its application for urea removal from water samples

The surface of magnetite nanoparticles was coated with functional polysiloxane layers using reaction of hydrolytic copolycondensation of tetraethoxysilane and 3-aminopropyltriethoxysilane (or N-[3-trimethoxysilylpropyl]ethylendiamine), and also that of tetraethoxysilane, 3-aminopropyltriethoxysilane and methyltriethoxysilane (or n-propyltriethoxysilane). It was shown that these functionalized magnetically controllable particles (about 60–150 nm in size as aggregates), as opposed to magnetite, adsorb urease well from aqueous solutions (up to 1 g/g), and that the level of residual activity of adsorbed layers is up to 84 % in the case of a bifunctional sample. It was established that the activity of immobilized urease is normally gradually reduced during storage of the samples, but in the case of ethylenediamine functional group is not decreased for 45 days. The synthesized samples are promising for use as magnetically directed biocatalysts.

Guliam A. Seisenbaeva

Papers

Urease adsorption and activity on magnetite nanoparticles functionalized with monofunctional and bifunctional surface layers