Two New Preyssler‐Type Polyoxometalate‐Based Coordination Polymers and Their Application in Horseradish Peroxidase Immobilization

Abstract

Enzyme immobilization is of increasing importance for biocatalysis, for which good supports are critical. Herein, two new Preyssler-type polyoxometalate (POM)-based coordination polymers, namely, {[Cu(H biim) ][{Cu(H biim) (μ-H O)} Cu(H biim)(H O) ]H[({Cu(H biim)(H O) } ) ((μ-C HN Cl ){Cu(H biim)} ){Z(H O)P W O }]⋅x H O} (1: Z=Na, x=9; 2: Z=Ag, x=10; H biim=2,2'-biimidazole) were designed and synthesized. Compounds 1 and 2 exhibit the same skeletons, which contain multiple Cu complex fragments and penta-supported {ZP W } (Z=Na, Ag) clusters. They were first employed to immobilize horseradish peroxidase (HRP). Results show that compounds 1 and 2 are good supports for HRP immobilization, and exhibit higher enzyme loading, lower loading times, and excellent reusability. The immobilized HRP (HRP/1 or HRP/2) was further applied to detect H O , and good sensitivity, wide linear range, low detection limit, and fast response were achieved. This work shows that POM-based hybrid materials are a new kind of promising support for enzyme immobilization.

A new hexamolybdate-based copper–2,2′-biimidazole coordination polymer serving as an acid catalyst and support for enzyme immobilization

“…According to literature methods (Lin et al, 2011;Du et al, 2017) and selecting HRP as a model enzyme, the typical procedure for preparing Cu-Mo 6 O 20 immobilized HRP through direct adsorption was as follows: 5.0 mg of ground Cu-Mo 6 O 20 powder was added to 500 ml of 0.1 mol l À1 PBS (pH 3.5-8.5) containing different concentrations of HRP. The mixture was then stirred gently at room temperature, resulting in a suspension.…”

“…The Worthington method (Nicell & Wright, 1997;Zhou et al, 2016;Du et al, 2017) was used to test the activity of the immobilized HRP, that is, the catalytic activity of the immobilized enzyme HRP/Cu-Mo 6 O 20 was evaluated by co-oxidation colour reaction of phenol and 4-AAP with H 2 O 2 ( Fig. S1 in the supporting information).…”

“…Most importantly, the insolubility of employed supports is vital for the successful immobilization process. To our knowledge, POMs have been studied and applied in protein crystallization (Molitor et al, 2016) and protein separation (Chen et al, 2015), but these applied POMs are all water soluble and no waterinsoluble solid POM example used as a support for enzyme immobilization has been reported except in our recent work (Du et al, 2017). Having stated the above, POM-based TMcoordination polymers obtained by hydrothermal methods can meet the above requirements and may become a new type of immobilizing enzyme-support material.…”

“…Recently, our group have synthesized two Preyssler-type POM-based Cu II -H 2 biim (H 2 biim is 2,2 0 -biimidazole) coordination polymers with high thermal stability and low solubility, and firstly used them as supports for enzyme immobilization (Du et al, 2017). A high HRP (horseradish peroxidase) loading (158.7 and 157.5 mg g À1 ) and excellent reusability were observed.…”

Yolk–shell microspheres assembled from Preyssler‐type NaP5W30O11014− polyoxometalate and MIL‐101(Cr) metal–organic framework: A new inorganic–organic nanohybrid for fast and selective removal of cationic organic dyes from aqueous media

“…Among the various POMs with different sizes and structures, the Preyssler‐type NaP 5 W 30 O 110 14− cluster (P 5 W 30 ) possesses an unusual doughnut‐shaped structure as depicted in Scheme and has recently shown good properties in catalysis and material science . The P 5 W 30 polyoxoanion possesses many merits: it has (i) an internal cavity that can accommodate distinct metal cations with appropriate scale, (ii) abundant oxygen‐rich surface, (iii) high stability over a large pH range of 1–10, (iii) high negative charges that can capture cationic species and (iv) high thermal stability, safety and greenness.…”