Anderson-Evans type polyoxometalate group (Na6[TeW6O24]·22 H2O, TeW6) was combined with porous metal-organic framework ZIF-8 by electrostatic interaction to obtain a novel Anderson-Evans polyoxometalate-based metal-organic framework composite, TeW6 @ZIF-8. FT-IR, Raman, XRD, TG, DSC, SEM, and TEM were used to characterize the composite. It was proved that the Anderson-Evans type polyoxometalate group TeW6 was successfully hybridized with metal-organic framework ZIF-8, and the composite possesses good stability. Based on the potential interaction between TeW6 and proteins and the coordination between imidazole groups in ZIF-8 and proteins with a porphyrin ring structure, the adsorption selectivity towards different proteins on the TeW6 @ZIF-8 composite was studied in this work. The experiment results showed that the TeW6 @ZIF-8 composite was selectively adsorbed to cytochrome C. At pH 11.0, the adsorption efficiency of 94.01% was obtained for processing 1.0 mL 100 μg mL-1 cytochrome C with 3.0 mg TeW6 @ZIF-8 composite. The adsorption behavior of cytochrome C fits well with the Langmuir adsorption model, corresponding to a theoretical adsorption capacity of 232.56 mg g-1. The retained cytochrome C could be readily recovered by 1% SDS (m/m), giving rise to a recovery of 65.6%. Circular dichroism spectra indicate no conformational change for cytochrome C after the adsorption and desorption processes, demonstrating the favorable biocompatibility of TeW6 @ZIF-8 composite. In applying practical samples, SDS-PAGE results showed that cytochrome C was successfully isolated and purified by TeW6 @ZIF-8 composite from porcine heart protein extract, which is further identified with LC-MS/MS. Thus, a new strategy for separating and purifying cytochrome C from the porcine heart using TeW6 @ZIF-8 composite as an adsorbent was established.
Keywords: Anderson-Evans polyoxometalate; Cytochrome C; Metal-organic framework; Separation and purification; Solid phase extraction.
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