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Graphene Nanoribbons, Fabrication, Properties, and Biomedical Applications
Published in Sarika Verma, Raju Khan, Avanish Kumar Srivastava, Advanced Nanocarbon Materials, 2022
Asha P. Johnson, H. V. Gangadharappa, K. Pramod
Graphene oxide can be presented as an economical, easy to make, multitarget-specific nanomaterial for preventing bacterial growth. Three possible mechanisms for antimicrobial activity have been observed: 1) sharp-edge penetration by GO and cell membrane damage to a bacterial cell, 2) masking of bacterial cells and inhibition of growth by the basal plane of GO, and 3) ROS production and antibacterial activity (Chen et al. 2014; Akhavan and Ghaderi 2010; Valentini et al. 2019; Liu et al. 2012). The size of the GO sheets also influences the antibacterial activity. Large-sized sheets can induce antibacterial activity by covering and isolating the cells from external nutrients. At the same time, small and defective GO sheets induced more oxidative stress-based inhibition (Liu et al. 2012; Perreault et al. 2015). One study showed that GO could act as an antibiotic and growth promoter at different concentrations. At a low concentration of GO, counterions promote the collision between cells and GO to produce an antibiotic effect, but, at high concentrations, large clusters of GO formed by counterions cause two opposite effects. At low zeta potential, floating scaffolds of GO clusters enhance bacterial growth, whereas, at high zeta potential, scaffolds of GO can inhibit bacterial growth (Palmieri et al. 2017). Very few studies have been reported on the antibacterial activity of GONRs, although mechanism of inhibition similar to those exhibited by GO can also be expected from GONRs.
Genotoxicity of Functionalized Nanoparticles
Published in Vineet Kumar, Praveen Guleria, Nandita Dasgupta, Shivendu Ranjan, Functionalized Nanomaterials II, 2021
Varsha Dogra, Gurpreet Kaur, Rajeev Kumar, Sandeep Kumar
Cells have the ability to reduce the ROS with an antioxidant defense system, either by interrupting the ROS formation or by turning back the oxidative damage. Antioxidants synthesized by the cells are separated into a primary and secondary defense mechanism. The primary defense mechanism includes enzymes such as glutathione peroxidase, superoxide dismutase, catalase, and thioredoxin reductase; secondary defense mechanisms include the reduced glutathione (Stahl et al. 1998).
Toxicology of Magnetic Nanoparticles
Published in Jeffrey N. Anker, O. Thompson Mefford, Biomedical Applications of Magnetic Particles, 2020
Stephen J. Klaine, Jordan T. Burbage, Paul W. Millhouse, Unaiza Uzair, Jeffrey N. Anker
Endpoints used in in vitro studies range from cell viability to assessments of specific mechanisms of toxic action. These include the MTT 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay for cell metabolic activity and cytotoxicity, apoptosis (programmed cell death) assay, assessment of reactive oxygen species (ROS) production, and genetic toxicity (e.g. DNA damage, comet assay) (Oberdörster 2010). Nel (2013) reviewed many of these endpoints and their relationship with the mechanistic injury pathways in whole organisms (Figure 12.3). ROS, such as oxygen ions and peroxides, react with many molecules including DNA, RNA, proteins, and lipids, and can cause DNA mutations, damage to cell structures, and cell death (also known as oxidative stress). Antioxidants and repair mechanisms help protect against this.
Catalytic applications of phosphorene: Computational design and experimental performance assessment
Published in Critical Reviews in Environmental Science and Technology, 2023
Monika Nehra, Neeraj Dilbaghi, Rajesh Kumar, Sunita Srivastava, K. Tankeshwar, Ki-Hyun Kim, Sandeep Kumar
Thermocatalysts offer great promise toward uninterrupted reactive oxygen species (ROS) generation due to persistent temperature differences in nature. ROS are the backbone of advanced oxidation processes (AOP) for a wide range of applications (e.g. pollution control, disinfection, and therapeutics). Thermocatalysts can inhibit electron-hole recombination due to temperature difference-induced fast charge separation. Conventional homo- or heterogeneous thermocatalysts (e.g. metal, metal oxides, and zeolites) face several challenges in terms of poor stability, complex product distribution, and unsatisfactory activity (Wang et al., 2019). The selection of a thermocatalyst depends upon the value of the Seebeck coefficient, which should be good enough to achieve efficient thermocatalytic performance (Lin et al., 2021). In the last few years, the development of ultrathin 2D materials with well-defined structures has offered new room for thermocatalytic applications (Shirvani et al., 2023). The use of ultrathin 2D materials in thermocatalysis is not much explored due to major concern about their activity and stability (Shirvani et al., 2023). Despite the efficiency of phosphorene as photocatalysts and electrocatalysts, the potential of phosphorene as a thermocatalyst has rarely been studied with respect to hydrogenation and oxidation reactions.
Synthesis, characterization and antioxidant activity of new β-benzylselenated Schiff bases and their palladium complexes
Published in Journal of Coordination Chemistry, 2022
Revanna Rajegowda H., Raghavendra Kumar P., Babulal Das
Selenium is an essential micronutrient required for everyday functions of a healthy human body [6]. Organoselenium compounds have different roles in biochemistry. Several biochemical reactions catalyzed by Se containing enzymes like selenocysteine, glutathione peroxidase (GPx) and thioredoxinreductases (TR, TrxR) [7] are effective antioxidants especially for removal of reactive oxygen species (ROS) as well as help in regenerating antioxidants like vitamin-C and thioredoxin in the body. ROS damage DNA and increase the oxidative stress on the human body causing several life-threatening diseases related to heart, kidney, thyroid, liver, skin, etc. [1, 3]. Synthetic organoselenium compounds have been reported to mimic the natural ones and exhibit several medicinal properties, such as antimicrobial, antioxidant, anticancer, etc. [8]. Se supplements are required to treat HIV and malnutrition caused due to inefficient absorption of micronutrients [9]. Selenated amines and their derivatives have been investigated as potential antioxidants especially for peroxynitrite (PN) [10]. However, studies on synthesis and coordination chemistry of selenated Schiff bases derived from chiral selenated amines are rare and biological applications of this type of ligands and their metal complexes needs to be explored [4f, 11].
Flocculation synergistic with nano zero-valent iron augmented attapulgite @ chitosan as Fenton-like catalyst for the treatment of landfill leachate
Published in Environmental Technology, 2022
The AOPs are one of the most effective methods for refractory organic matter removal using highly reactive oxygen species (ROS), such as (E0 = 2.85 V), (E0 = 2.6 V) and (E0 = 1.78 V) [16–19]. The ROS can degrade or even completely mineralize, refractory organics in wastewater by adding initiators (e.g. persulfate, hydrogen peroxide). The oxidation step can remove pollutants that cannot be completely degraded by the biological treatment technology [5]. Ozonation, Fenton and electrochemical oxidation processes can all generate ROS. and are non-selective oxidants with high redox potential, reacting quickly with organic pollutants and effectively decomposing stubborn DOM [19–21]. Among the AOP processes, Fenton is the most effective because it generates , which has have high oxidation capacity of E0 = 2.85 V, faster kinetics and enhanced chemical elimination instead of phase transfer [20,22].