The myth of inactivity of inorganic materials in a biological system breaks down by the discovery of nanozymes. From this time, the nanozyme has attracted huge attention for its high durability, cost-effective production, and easy storage over the natural enzyme. Moreover, the multienzyme-mimicking activity of nanozymes can regulate the level of reactive oxygen species (ROS) in an intercellular system. ROS can be generated by peroxidase (POD), oxidase (OD), and Fenton-like catalytic reaction by a nanozyme which kills the cancer cells by oxidative stress; therefore, it is important in CDT (chemo dynamic therapy). Our current study designed to investigate the enzyme mimicking behavior and anticancer ability of cerium-based nanomaterials because the cerium-based materials offer a high redox ability while maintaining nontoxicity and high stability. Our group synthesized CeZrO 4 nanoparticles by a green method using β-cyclodextrin as a stabilizer and neem leaf extract as a reducing agent, exhibiting POD-and OD-like dual enzyme activities. The best enzyme catalytic activity is shown in pH = 4, indicating the high ROS generation in an acidic medium (tumor microenvironment) which is also supported by the Fenton-like behavior of CeZrO 4 nanoparticles. Inspired by the high ROS generation in vitro method, we investigated the disruption of human kidney cells by this nanoparticle, successfully verified by the MTT assay. The harmful effect of ROS in a normal cell is also investigated by the in vitro MTT assay. The results suggested that the appreciable anticancer activity with minimal side effects by this synthesized nanomaterial.
In this article, environmentally compatible, low cost and easy green synthesized pure and Al-doped ZnO nanoparticles from the Azadirachta indica leaves extract were prepared. The greenly produced nanoparticles were mainly studied for structural properties. The x-ray diffraction data show that these were crystalline with the hexagonal wurtzite phase. The average crystallite size and some other important physical parameters such as stress, strain and energy density were estimated from the Williamson Hall analysis with the help of Rietveld refinement data. It was observed that with increasing Al-concentration, the crystallite size decreased but the other parameters like stress, strain and energy density increased. It was also seen that with increasing Al addition from 0%–15% the inter-planar spacing d
hkl for each hkl set of the samples first decreased and then increased, which indicates the influence of the smaller size of Al ion addition on the inter-planar distance.
In recent decades, studies have focused on inorganic nanozymes to overcome the intrinsic drawbacks of bioenzymes due to the demands of improving the reaction conditions and lack of robustness to harsh environmental factors. Many biochemical reactions catalyzed by enzymes require light activation. Light-activated nanozymes have distinct advantages, including being regulated by light stimuli, activating the molecular oxygen to produce reactive oxygen species (ROS) without interfering supplementary oxidants, and often showing a synergistic effect to catalyze some challenging reactions. Only a few studies have been done on this connection. Therefore, it is still a big challenge to develop a nanozyme regulated by light activation. Herein, we uncovered the light-activated oxidase mimicking activity of a conducting polymer polyaniline nanofibers (PANI-NFs). PANI-NFs exhibit intrinsic lightactivated brilliant oxidase-like activity, can catalyze the colorless tetramethyl benzidine (TMB) to produce a blue product TMBox, and have a distinct K m = 0.087 mM and a high V max = 2.32 μM min −1 value, measured by using Hanes−Woolf kinetics. We also report the light-activated oxidase activity of some other renowned carbocatalysts graphene oxide and graphitic carbon nitride and compare them with PANI-NFs. This type of property shown by the conductive polymer is amazing. The density functional theory is used to verify the stability and the mode of adsorption of the PANI NFs-TMB composite, which corroborates the experimental results. Furthermore, the current nanozyme demonstrated a significant ability to kill both Gram-negative and Gram-positive bacteria as well as effectively destroy biofilms under physiological conditions. We believe that this work provides the motivation to create a link between optoelectronics and biological activity in the near future.
On page 5, the formula 'β s ≈ε/tan θ' would be replaced by the formula 'β s ≈εtan θ'. The slash symbol between the epsilon (ε) and tan θ would be removed.
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