Defective copper-cobalt binuclear Prussian blue analogue nanozymes with high specificity as lytic polysaccharide monooxygenase-mimic via axial ligation of histidine

Degradation of polysaccharides based on lytic polysaccharide monooxygenases (LPMOs) has received considerably interest in the environment and energy fields since 2010. With the rapid development of nanozymes in various fields, it is highly desirable but challenging to develop LPMO-like nanozymes with high specificity and satisfied activity. Here, a defective copper-cobalt binuclear Prussian blue analogue (CuCoPBA) nanozyme was developed via a facile and ingenious methodology based on single histidine (His). For the first time, His-CuCoPBA nanozyme was found to exhibit LPMO-like activity with H2O2 as a cosubstrate at room temperature and neutral pH, which can efficiently catalyze the degradation of galactomannans selectively. Significantly, the high degradation activity at pH 10 expands the application of Fenton-like nanozymes in alkaline condition. Singlet oxygen (1O2), as a main reactive intermediate, plays a crucial role in the galactomannan degradation catalyzed by His-CuCoPBA nanozyme. Both control experimental and density functional theory (DFT) results indicate Cu-NxHis contributes to the efficiently and selectively catalytic activity of His-CuCoPBA nanozymes by emulating the binding and catalytic sites of LPMOs. The present work not only represents a fundamental breakthrough toward degradation of polysaccharide based on nanozyme, but also contributes to understanding the catalytic mechanism of natural Cu-dependent LPMOs.