Enzyme Mimetic Activity of ZnO-Pd Nanosheets Synthesized via a Green Route.

Ravi Mani Tripathi,Sang J Chung,Yeong Mok Kim,Dohee Ahn

doi:10.3390/molecules25112585

Ravi Mani Tripathi, Sang J Chung + Show 2 more

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https://doi.org/10.3390/molecules25112585

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Abstract

Recent developments in the area of nanotechnology have focused on the development of nanomaterials with catalytic activities. The enzyme mimics, nanozymes, work efficiently in extreme pH and temperature conditions, and exhibit resistance to protease digestion, in contrast to enzymes. We developed an environment-friendly, cost-effective, and facile biological method for the synthesis of ZnO-Pd nanosheets. This is the first biosynthesis of ZnO-Pd nanosheets. The synthesized nanosheets were characterized by UV–visible spectroscopy, X-ray diffraction (XRD), scanning electron microscopy, transmission electron microscopy, and energy-dispersive X-ray. The d-spacing (inter-atomic spacing) of the palladium nanoparticles in the ZnO sheets was found to be 0.22 nm, which corresponds to the (111) plane. The XRD pattern revealed that the 2θ values of 21.8°, 33.3°, 47.7°, and 56.2° corresponded with the crystal planes of (100), (002), (112), and (201), respectively. The nanosheets were validated to possess peroxidase mimetic activity, which oxidized the 3,3′,5,5′-tetramethylbenzidine (TMB) substrate in the presence of H2O2. After 20 min of incubation time, the colorless TMB substrate oxidized into a dark-blue-colored one and a strong peak was observed at 650 nm. The initial velocities of Pd-ZnO-catalyzed TMB oxidation by H2O2 were analyzed by Michaelis–Menten and Lineweaver–Burk plots, resulting in 64 × 10−6 M, 8.72 × 10−9 Msec−1, and 8.72 × 10−4 sec−1 of KM, Vmax, and kcat, respectively.

Highlights

Nanomaterials have drawn attention owing to their unique optical, electronic, magnetic, and catalytic properties, and are widely used in various fields, including as catalysts [1–4], photocatalysts [5], antibacterials [6–8], colorimetric sensors [9], and drug delivery systems [10,11]
Plant extracts have gained substantial consideration compared to microorganism biomasses of fungi and bacteria because there are no requirements for specific conditions, media, or culture maintenance
The absorption spectrum of as-synthesized ZnO-Pd nanosheets exhibited no peak, because the peak was removed by the formation of zero valent palladium

Summary

Introduction

Nanomaterials have drawn attention owing to their unique optical, electronic, magnetic, and catalytic properties, and are widely used in various fields, including as catalysts [1–4], photocatalysts [5], antibacterials [6–8], colorimetric sensors [9], and drug delivery systems [10,11]. Procedures by involving plant extracts and organism biomasses ranging from bacteria to fungi. Plant extracts have gained substantial consideration compared to microorganism biomasses of fungi and bacteria because there are no requirements for specific conditions, media, or culture maintenance. Enzymes are good catalysts in many biological processes [16], but require specific physiological conditions to perform their optimal catalytic activity. The peroxidase enzyme catalyzes the oxidation of the substrate in the presence of hydrogen peroxide (H2 O2 ), acting as electron acceptor.

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