Mechanisms of Action of Nanoparticles in Living Systems

Mechanisms of Action of Nanoparticles in Living Systems

Madhu Rawat, Yadukrishnan P., Nitin Kumar
Copyright: © 2018 |Pages: 17
DOI: 10.4018/978-1-5225-3126-5.ch014
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Nanoparticles are being formed continuously in processes like mineralization, natural calamities, and geological recycling of matter and present naturally in the environment. In the recent past, nanoparticles and their applications have become an extensive topic of research. Application of nanomaterials in different industries will surely enhance the chances of discharge of nanoparticles into the environment. So, a number of studies have been performed to explore the mode of action of nanoparticles on living organisms and their surroundings. The most reported modes of action of nanoparticles are antimicrobial activity, ROS-induced cytotoxicity, genotoxicity, plant growth promotion, etc. It has been successfully demonstrated that actions of nanoparticles are governed by their size, shape, dose, and concentration. However, a complete mechanism of action of nanoparticles has not been known. The present chapter focuses on the highlights of the mechanisms behind the mode of action of nanoparticles in plants and microorganisms.
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2. Ros And Antioxidant System In Plants

Reactive Oxygen Species (ROS) are unwelcome companions in entire aerobic life of an organism (Halliwell and Gutteridge, 1989). These partially reduced or activated derivatives of oxygen [singlet oxygen (1O2), superoxide anion (O2-), hydrogen peroxide (H2O2) and hydroxyl radical (HO.)] are highly reactive and toxic, and can lead to the oxidative destruction of cell components (Asada and Takahashi, 1987). Evolution has conferred efficient mechanisms for scavenging ROS in all the aerobic organisms involving anti-oxidative enzymes and anti-oxidant secondary metabolites. The enzymatic scavenging system for ROS is composed of a battery of anioxidative enzymes such as superoxide dismutase (SOD), catalase (CAT), ascorbate peroxidase (APX), glutathione reductase (GR), monodehydroascorbate reductase (MDHAR), dehydroascorbate reductase (DHAR), glutathione peroxidase (GPX) and glutathione-S-transferase (GST). This system is efficiently supported by non-enzymatic components like glutathione (reduced and oxidized forms), α-tocopherol and phenolic compounds (Gill and Tuteja, 2010). Plants control ROS effectively and use it beneficially as signaling molecule to control specialized processes such as plant growth, defense, hormonal signaling, and development (Ahmad et al., 2010).

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