Design of multifunctionalized γ-Fe 2 O 3 @SiO 2 core–shell nanoparticles for enzymes immobilization
ABSTRACT This article deals with the first covalent grafting of an enzyme on twice functionalized γ-Fe2O3@SiO2 core–shell magnetic nanoparticles. First, amino-PEG functionalized nanoparticles were synthesized in order to comply with
non-toxic platforms that would be stable in high concentration and would exhibit chemical groups to allow further coupling
with biomolecules. This approach produces a colloidal suspension of covalently grafted enzymes that remains stable for months
and mimics the enzyme–substrate interactions in solution. Secondly, nanoparticles synthesis and enzyme coupling process were
reported and the catalytic properties of bound enzymes were measured and compared with that of the free one. These new materials
appear to be useful tools for enzymatic catalysis research and may be extended to other biomolecules. Furthermore, magnetic
properties of these materials open the way to separation, purification, and transport under magnetic field.
- Biochemistry - BIOCHEMISTRY-USA. 01/1986; 25(9):2522-2529.
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ABSTRACT: Lipase was covalently bound onto Fe(3)O(4) magnetic nanoparticles (12.7 nm) via carbodiimide activation. The Fe(3)O(4) magnetic nanoparticles were prepared by coprecipitating Fe(2+) and Fe(3+) ions in an ammonia solution and treating under hydrothermal conditions. The analyses of transmission electron microscopy (TEM) and X-ray diffraction (XRD) showed that the size and structure of magnetic nanoparticles had no significant changes after enzyme binding. Magnetic measurement revealed the resultant lipase-bound magnetic nanoparticles were superparamagnetic with a saturation magnetization of 61 emu/g (only slightly lower than that of the naked ones (64 emu/g)), a remanent magnetization of 1.0 emu/g, and a coercivity of 7.5 Oe. The analysis of Fourier transform infrared (FTIR) spectroscopy confirmed the binding of lipase onto magnetic nanoparticles. The binding efficiency of lipase was 100% when the weight ratio of lipase bound to Fe(3)O(4) nanoparticles was below 0.033. Compared to the free enzyme, the bound lipase exhibited a 1.41-fold enhanced activity, a 31-fold improved stability, and better tolerance to the variation of solution pH. For the hydrolysis of pNPP by bound lipase at pH 8, the activation energy within 20-35 degrees C was 6.4 kJ/mol, and the maximum specific activity and Michaelis constant at 25 degrees C were 1.07 micromol/min mg and 0.4 mM, respectively. It revealed that the available active sites of lipase and their affinity to substrate increased after being bound onto magnetic nanoparticles.Biotechnology Progress 01/2003; 19(3):1095-100. · 1.85 Impact Factor
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ABSTRACT: Targeting specific sites in vivo for the delivery of therapeutic compounds presents a major obstacle to the treatment of many diseases. One targeted delivery technique that has gained prominence in recent years is the use of magnetic nanoparticles. In these systems, therapeutic compounds are attached to biocompatible magnetic nanoparticles and magnetic fields generated outside the body are focused on specific targets in vivo. The fields capture the particle complex resulting in enhanced delivery to the target site. This review will focus on technical aspects of magnetic targeting as well as nanoparticle design and animal and clinical trials. Drug Dev. Res. 67:55–60, 2006. © 2006 Wiley-Liss, Inc.Drug Development Research 05/2006; 67(1):55 - 60. · 0.87 Impact Factor