The in vitro effects of immobilization of barley root oxalate oxidase onto three

metal oxide NPs were studied by Chauhan and coworkers. Barley root oxalate

oxidase was immobilized onto three NPs, i.e., zinc oxide (ZnO), copper oxide

(CuO) and manganese oxide (MnO2). As observed by X-ray diffraction and TEM

studies, the NPs with very fine crystalline structure and with a diameter in the range

of 30–70, 50–60, and 20–60 nm for ZnO-NPs, CuO-NPs and MnO2-NPs, respec-

tively, were produced. The immobilization improved the thermal and storage stabil-

ity as well as the activity of the enzyme. The maximum improvement was observed

in the case of MnO2-NPs, while ZnO-NPs and CuO-NPs displayed no substantial

improvement in their activities. The NPs displayed an increase in the optimum pH

value, while a decrease in the Km and optimum temperature was observed. The

immobilized oxalate oxidase enzyme would act as a promising agent in the medical

improvement of hyperoxaluria as well as in enzyme supplementation therapy for

calcium oxalate nephrolithiasis (Chauhan et al. 2013). In another study conducted by

Zhao and colleagues, a novel therapeutic for nephrolithiasis was developed by

encapsulating oxalate oxidase in a thin layer of zwitterionic polymer. The

nanocapsules produced enhanced the stability as well as the activity of oxalate

oxidase and reduced phagocytosis leading to a prolonged circulation half-life due

to reduced phagocytosis and also reduced immunogenicity. This nanocapsule design

provided an effective route for systemic delivery of oxalate oxidase for treatment of

calcium oxalate nephrolithiasis and hyperoxaluria (Zhao et al. 2017).

The investigation conducted by Lin and coworkers reported the immobilization

of oxalate decarboxylase enzyme on Eupergit C, a copolymer of N,N-o-methylene-

bis-(methacrylamide),

glycidyl

methacrylate,

allyl

glycidyl

ether

and

methacrylamide. Although this approach led to the development of microporous

beads rather than nanocapsules, the immobilized oxalate decarboxylase displayed

improved resistance against both thermal and pH denaturation (Lin et al. 2011).

Hence this analysis could be extended toward the development of NPs of oxalate

decarboxylase that could be employed as a therapeutic for nephrolithiasis and

hyperoxaluria.

Fig. 13.3 Dissolution of calcium oxalate stones by oxalate-degrading enzyme encapsulated

nanodrugs

210

G. Shruti and K. S. Singh