Sonochemical synthesis and characterization of cobalt doped iron oxide nanoparticles, and immobilization of enzymes on gamma-iron oxide nanoparticles.

摘要

Various concentrations of Cobalt doped Fe2O3 nanoparticles were prepared via sonochemistry and their magnetic and structural properties were investigated. All particles sizes were found to be in the range of ∼30 +/- 5nm. Samples with low cobalt concentrations possessed normal spinel structures and displayed paramagnetic properties with the lowest doped sample exhibiting superparamagnetic properties. High concentration cobalt samples were found to be ferrimagnetic and having normal spinel structures, while samples in the intermediate range of cobalt doping exhibited mixed phases as its structure transitions from that of an inverse spinel structure to a normal spinel structure as the cobalt concentration increases. Magnetic data for all samples were lower their bulk counterparts.; Five enzymes, one lipase (Candida Rugosa Lipase) and four restriction endonucleases (Apa I, Sac I, Xba I, Xho I) were covalent bound to functionalized magnetic gamma-Fe2O3 nanoparticles and their enzymatic activity studied. All enzyme-nanoparticle moieties displayed low activity rates when compared to the free enzyme but in all instances remarkable consistent activity was noted with little decrease in activity over a one week period and at most a 15% decrease in activity for Candida Rugosa Lipase after one month. The magnetic nature of the enzyme-nanoparticle moieties also demonstrated an easy retrieval method for separating the enzyme-nanoparticle moieties from the substrate solution as compared to free enzymes.