Microbe-mediated synthesis of silver nanoparticles: A new drug of choice against pathogenic microorganisms

Abstract

Currently, scientists are interested in materials that are effective at the nanoscale such as gold and silver because of their natural and chemical characteristics.20.1 Introduction 403 20.2 Utility and beautility of nanomaterials 404 20.3 Different forms of nanomaterials and their roles 408 20.4 Titanium dioxide nanoparticles 410 20.5 Zinc oxide nanoparticles 410 20.6 Magnesium oxide and other nanoparticles 411 20.7 Copper oxide nanoparticles 411 20.8 Iron nanoparticles and aluminum nanoparticles 411 20.9 Magnetosomes nanoparticles 411 20.10 Use of nanomaterials and their risk management 413 20.11 Conclusion 414 Acknowledgments 414 References 414The introduction of inorganic nanomaterials in this century is a unique phenomenon, and their novel characteristic features are mentioned earlier. The inorganic nanomaterials exhibit well-adopted physical, chemical, and biological properties, though all the mentioned properties may vary in size based on their character as well as on specic pH and temperature. In the biological eld, nanomaterials are very much adopted due to their specic selectivity toward the targeted materials in the biological system. Moreover, recent studies clearly denote that the prepared metal oxide nanomaterials have increased antibacterial activity (Hamouda et al., 1999; Pal et al., 2007). Several experimental data are coming through that can predict in an effective way that inorganic metal silver is an antimicrobial agent (Table 20.1). These mentioned inorganic metals exhibit a very robust antibacterial activity (Novak and Feldheim, 2000; Wiley et al., 2005; Yamanaka et al., 2005). Now, it is well known that the compound and simple nature of silver nanomaterials are the reason for the unique bactericidal activity (Pal et al., 2007; Gopinath et al., 2015). Moreover, it should be remembered that random use of silver nanoparticles (AgNPs) in various elds has some possibility of toxicity in human beings as well as in the environment or in the ecosystem. The toxicity and cellular uptake experiments of several NPs clearly denote that the carbohydrate coating on silver nanoparticle modulates both oxidative stress and cellular uptake, and it can expose some toxicity in the physiological system. In this context, it has been observed that the bioactivity of AgNPs and other nanomaterials can change by using a carbohydrate coat (Kennedy et al., 2014). Different types of bacterial cells are multidrug tolerant and, therefore, able to survive antibiotic treatment. However, recent technological advances in microuidics and reporter genes have improved this scenario. Here, we summarize recent progress in the eld, revealing the ubiquitous bacterial stress alarm one ppGpp as an emerging central regulator of multidrug tolerance and persistence, both in stochastically and environmentally induced persistence. In several different organisms, toxin-antitoxin modules function as effectors of ppGpp-induced persistence (Maisoneuve and Gerdes, 2014). Therefore, the effects of different NPs on several biolms and also on several bacteria have been dealt with in this chapter.