Elemental zinc to zinc nanoparticles: is ZnO NPs crucial for life? Synthesis, toxicological, and environmental concerns

Abstract

The semi-conducting material zinc is one of the essential trace elements for humans, is a co-factor of more than 300 enzymes, and plays an important role in maintaining vital cellular functions. Deficiency of zinc may lead to cancer initiation; however, a high concentration also has toxic effects that might be life threatening. The toxicity can be addressed by the disequilibrium of zinc-mediated proteins and oxidative stress that produce nascent oxygen, hydroxyl radicals, and other reactive oxygen species. Zinc-based nanoparticles (NPs) are among the most important and multifunctional compounds. Zinc oxide (ZnO) NPs exhibit attractive antimicrobial and photocatalytic properties due to the smaller particle size and increased particle surface reactivity. Further, these are more biocompatible compared to other metallic NPs, easily synthesizable, and have high selectivity, enhanced cytotoxicity, and are a promising anticancer agent. However, some of the pertinent concerns regarding nano-zinc still needs to be clarified. Current research also demonstrates their usage in wastewater treatment, textile, medicine, etc. This review covers the importance of zinc for living systems and its NPs, with more emphasis on ZnO NPs. A comprehensive overview of ZnO NPs, their synthesis, characterization techniques, crystal structure, properties, and brief industrial applications are presented.

Synthesis, characterization and biological activities of monometallic and bimetallic nanoparticles using Mirabilis jalapa leaf extract

“…A study reported the antileishmanial activity of silver nanoparticles synthesized via Sargentodoxa cuneata by Ahmad et al, [ 27 ] as well as antileishmanial activity of ZnO nanoparticles synthesized via Linum usitatissimum L [ 28 ], comparing the activity of the bimetallic nanoparticles with monometallic nanoparticles. It is apparent that the activity of bimetallic is greater than monometallic, the higher the concentration of the nanoparticles the greater is the activity [ 29 ]. The synergistic effect of both metals (Zn and Ag) in for of nanoparticles or released ions has prognostic effect of antibacterial, antileishmanial and other biological activities.…”

Performance of silver, zinc, and iron nanoparticles-doped cotton filters against airborne E. coli to minimize bioaerosol exposure

“…Furthermore, the antibacterial activity of ZnO NPs was reported to be higher against the Gram-positive ( Staphylococcus aureus ) than the Gram-negative ( E. coli ) bacteria (Mirhosseini and Firouzabadi 2013 ). The difference in antibacterial activity is attributed to the particle size of the NPs, and their mechanism of antibacterial action is ascribed to damage of bacterial cell through the release of zinc (II) ions and generation of reactive oxygen species (Ali et al 2018b ; Gunalan et al 2012 ). Moreover, the presence of ZnO NPs reduces the effective pore sizes of the nanocomposite filters at little expense of energy consumption.…”

Phase change materials for building construction: An overview of nano-/micro-encapsulation

“…van der Waals forces and hydrogen bonds) composed of the aggregates of the sol particles [14,72]. Sol-gel process is utilised to synthesise various nano-inorganic materials or composite materials by the organic or inorganic materials of metal solution-gelation ("sol-gel") polymerisation process at low temperatures [73,74] and is considered as a highly flexible method for the synthesis of diverse range of materials, e.g. wide range of nano-/ micro-structures [75][76][77], and only requires mild conditions.…”