Enhanced bioreactors temperature

Applications of responsive gels in biotechnology have also been examined. For example, Dong and Hoffman proposed the use of temperature sensitive hydrogels for the immobilization of enzymes in bioreactors [110]. Enzyme activity can be turned on and off by causing the gel to swell or shrink when shrunken, the enzyme activity is turned off, since the pores are blocked to the substrate. Different applications are possible for this system besides enhanced bioreactor performance, including bioassays. 

The possibility of having membrane systems also as tools for a better design of chemical transformation is today becoming attractive and realistic. Catalytic membranes and membrane reactors are the subject of significant research efforts at both academic and industrial levels. For biological applications, synthetic membranes provide an ideal support to catalyst immobilization due to their biomimic capacity enzymes are retained in the reaction side, do not pollute the products and can be continuously reused. The catalytic action of enzymes is extremely efficient, selective and highly stereospecific if compared with chemical catalysts moreover, immobilization procedures have been proven to enhance the enzyme stability. In addition, membrane bioreactors are particularly attractive in terms of eco-compatibility, because they do not require additives, are able to operate at moderate temperature and pressure, and reduce the formation of by-products. 

The nanoparticle assemblies can also be used to enhance the chemical reactivity of biomolecules. Au nanoparticles assembled on polyurethane nucrospheres are used as permeable high-surface supports for the immobilization of enzymes such as pepsin to provide easy access of the substrate molecules to the enzyme active centers in the multilayer enzyme assembly. Proteins immobilized in this way exhibit biocataly tic activity higher than that of the free enzyme in solution and significantly enhanced temperature and pH stability [108]. In another approach, the layer-by-layer deposition of enzymes and magnetic particles is applied to prepare a bioreactor, which allows the biocatalytic layer to be stripped out with an external magnet when it is deactivated, so that the surface could be reloaded with a new active biocatalyst layer [109]. 

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