BackgroundImmobilization of lipase on appropriate solid supports is one way to improve their stability and activity, and can be reused for large scale applications. A sample, cost- effective and high loading capacity method is still challenging.ResultsA facile method of lipase immobilization was developed in this study, by the use of polydopamine coated magnetic nanoparticles (PD-MNPs). Under optimal conditions, 73.9% of the available lipase was immobilized on PD-MNPs, yielding a lipase loading capacity as high as 429 mg/g. Enzyme assays revealed that lipase immobilized on PD-MNPs displayed enhanced pH and thermal stability compared to free lipase. Furthermore, lipase immobilized on PD-MNPs was easily isolated from the reaction medium by magnetic separation and retained more than 70% of initial activity after 21 repeated cycles of enzyme reaction followed by magnetic separation.ConclusionsImmobilization of enzyme onto magnetic iron oxide nanoparticles via poly-dopamine film is economical, facile and efficient.

Anatase, viewed traditionally as a three-dimensional TiO 2 structure, has major applications in solar cells, hydrogen production, and catalysis. Here, we report the synthesis, characterization, and structural simulation of a layered nanosheet material that can be described as delaminated anatase along the [001] direction. Counting the outer and interlayer surfaces, such a nanosheet structure maximizes the areas of surfaces which are similar to anatase (001), believed to be the surface of central importance for the superior efficiency of anatase in various applications. Indeed, the important dissociative adsorption process of water predicted to occur on the anatase (001) surface is observed in such nanosheet material. It is also shown that the structure of titania nanotubes, an issue of debate for nearly a decade, can also be described by delaminated anatase along the [001] direction. Interestingly, the strains in such a curved tubular structure lead to major differences in surface chemistry such as water dissociation.

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