Nano-Biocatalysts of Cyt c@ZIF-8/GO Composites with High Recyclability via a de Novo Approach

Abstract

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.

Metal–Organic Framework Disintegrants: Enzyme Preparation Platforms with Boosted Activity

“…We then evaluated the release efficiency of cyt c from cyt c@NKMOF-101-M, and the results indicated that cyt c could be completely released within 30 sfrom NKMOF-101-Mu nder mild conditions (for example,M ES buffer, pH 6.0; Supporting Information, Figure S5 and Table S2). [28][29][30] We also calculated and measured the concentration of metal ion and organic linker after the dissolution of MOFs.L ow concentrations of metal ion (0.67 mgmL À1 of Zn 2+ )and ligand (1.15 mgmL À1 of squaric acid) were observed, indicating trace amounts of impurities introduced. On the contrary,t he wellstudied MOF supports,ZIF-8 and ZIF-90, cannot disintegrate under this mild condition.…”

Smart Stimuli-Responsive and Mitochondria Targeting Delivery in Cancer Therapy

“… 67 , 71 Cyt C is secreted into the cytosol and induces apoptosis through a Mc pathway. 59 , 110 , 111 Cyt C aptamers have been attached on the outside of smart mesoporous silica-encapsulated gold nanorods 67 and bacterial magnetic nanoparticles 71 to allow them to efficiently accumulate in the Mc of cancer cells. Mc-targeting aptamers are a prospective strategy for St-Mc-DDSs.…”

Biocatalytic Metal–Organic Frameworks: Prospects Beyond Bioprotective Porous Matrices

“…[92] In addition, Zhu and co-workers recently found that there is a synergistic effect between ZIF-8 and graphene oxide (GO) as immobilized enzyme carriers (Figure 5d, i). [93] The cytochrome c (Cyt c)-ZIF-8/GO nanocomposites were synthesized by mixing the methanol solution of Cyt c, GO, Zn(NO 3 ) 2 , 2-HmIm and reaction for 24 h at room temperature. FESEM, XRD, TEM, FTIR and XPS were used to characterize CytZIF-8/GO.…”