To improve the stability and recyclability of enzymes immobilized on metal-organic frameworks (MOFs), graphene oxide (GO) with surface oxygen-rich functional groups was selected to form ZIF-8/GO nanocomposites with the zeolitic imidazolate framework (ZIF-8) for cytochrome c (Cyt c) immobilization. It was found that the functional groups on the GO surface were involved in the growth of ZIF-8 without affecting the crystal structure but their particle size was reduced to about 200 nm. The storage stability and resistance to organic solvents of Cyt c were obviously improved after the immobilization on the ZIF-8/GO nanocomposite. On one hand, compared with Cyt c@ZIF-8 and Cyt c@GO with 30 and 60% protein leakage, Cyt c@ZIF-8/GO displayed little protein leakage after 60 h of storage. On the other hand, Cyt c@ZIF-8/GO retained a residual activity of approximately 100% after being stored in ethanol and acetone for 2 h, whereas the free enzyme, Cyt c@ZIF-8, and Cyt c@GO retained only about 10, 50, and 40%, respectively. In addition, the Cyt c@ZIF-8/GO nanocomposites can be utilized up to four cycles with virtually no loss of activity and may be further applied on HO biosensing systems. The synergistic effect between MOFs and GO in ZIF-8/GO nanocomposites provides infinite possibilities as immobilized enzyme carriers.
We measured the rheological properties of mesophase pitch + coal mixtures at temperatures up to 873 K and used quench tests during carbonization to observe the effects of coal particles on foaming and pore development in activated carbon discs (ACD). We observed that high ratios of coal to pitch increased the mixture's viscosity in a low pressure foaming process, which restricted growth of large bubbles during foaming and produced stronger carbon foams. The highest strength ACD, with compressive strength of 56±3 MPa, was obtained using a pitch to coal mass ratio of 1:2 (bulk density = 0.91 g•cm N2. These adsorption results suggest the activated carbon discs have potential as structured adsorbents for gas separation or storage applications.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.