Metallic Nanoparticles: Production of the Reduced or Reduce the Production?

Author(s): Shampa Sen

Metallic nanoparticles (MNPs) have found their ways into our daily life through various ways of sophistication and miniaturization. Their varied applications ranging from cosmetics and electronics to medicine has encouraged industrial level production. A number of methods of synthesising MNPs have been developed over the past few decades, including physical, chemical, and biological routes of synthesis. Physical methods of production depend on shearing and shredding the bulk material into very small pieces, and is extremely energy-intensive, while the chemical methods of production depend on the reduction of metallic salts and/or other compounds, leading to the use of toxic reagents in concentrated form, making the MNPs unsuitable for medicinal use. Biological methods are prefered and depend upon the use of biologically-obtained reagents for reduction of metallic salts or the reduction of biological materials. However, biological methods are time-consuming and display very low yield. Thus, achieving the goal of industrial-scale production of MNPs has left researchers concerned about both the possible strategies for scaling up production, and also the adverse effects of releasing these nanoparticles to the environment due to their well-documented ecotoxic effects. Lack of recovery of the MNPs from the environment leads to biomagnification of their toxicity, and reaches the highest trophic level with significant levels of mutagenic and antimicrobial effects. The present review provides an insight into and critically discusses the strategies for scaling-up biological methods of MNP production, and the possible methods by which the pollution of the environment mediated by MNPs can be reduced.