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S. B. Jaffri and K. S. Ahmad
instance, polymeric micelles NPs are used as an active delivery agent of drugs in
case of tumor treatment. Iron oxide NPs coated with polymer can also be employed
of for division of bacterial clusters, leading to the greater potential of these NPs in
curing chronic diseases instigated due to bacteria. Furthermore, NPs have also been
filled with various proteinaceous substances equipped with an inherent ability of
stimulation of the immune response in humans and other organisms (Vigneshwaran
et al. 2006).
Over the years, novel compounds are fabricated (Mannam et al. 2017; Navalakhe
et al. 2009) aimed at different applications with an advancement in applications of
NPs. There has been a greater employment of various synthetic routes for NPs based
on the physical, chemical and biological procedures (Adebayo et al. 2019; Elegbede
et al. 2020). Variety of techniques, e.g., precipitative, thermal, pyrolytic, sol–gel, and
hydrothermal have been used for NPs synthesis. However, physicochemical modes,
though very effective and applied ones, have been rigorously challenged for their
elevated capital and operational costs, complexity in operation requiring extraordinarily alleviated temperature and pressure ranges, and above all release of environmentally toxic substance having profound persistence in form of by-products (Lateef
et al. 2016a; Jaffri and Ahmad 2017; Azeez et al. 2020). Often during such chemical and physical synthesis, environmental concerns are highly neglected. This can
be comprehended from the example of chemically processed synthesis of quantum
dots of cadmium selenide marked by imposition of the significant pollutant atmospheric, hydrospheric, and lithospheric load in form of various organic and inorganic substances. Furthermore, other dominant pollutants in the similar way can be
different types of soils, iron, chloride ions, sulfur, and sodium that are released into
the immediate environment. Additionally, utilization of different organophosphorus
solvents makes the cost of overall chemical routes reaching up to 90% of the total
NPs generation cost (Sirinakis et al. 2003). In order to gain the benefits related with
the nanoscale particles in different fields in a sustainable way, green chemists have
proposed and tested the solution to these limitations associated with physicochemical
routes. Greener synthesis of NPs is an effective alternative to physical and chemical
routes. It is a novel, efficacious, toxicity-free and economically viable procedure.
Greener routes employ the utilization of natural biotic resources, particularly renewable ones that have good replenishment and production spans such as plant parts,
microbes, human cells, and metabolites of arthropods among others (Adelere and
Lateef 2016; Lateef et al. 2016a, b, c). These bio-entities are completely toxicityfree, abundantly available and cost effective in provisioning natural reducing cum
stabilizing agents as a replacement for chemically obnoxious counterparts.
Among biological reducing agents, microbial species have been highly cherished
as nano-biofactories for reduction and stabilization of different NPs having profound
ability for alterations in tuning the shapes and sizes of NPs in addition to optical
characteristics (Gutiérrez et al. 2012). Nano-biofactories are usually based on bacterial, fungal, yeast, actinomycetes, algal, cyanobacterial, and viral genesis which are
employed for NPs production such as magnetite, silver, platinum, gold, magnesium,
copper, palladium, and zinc. Bacteria have been designated as one of these nanobiotechnological tools among all bio-entities in case of microbial resources for the
S. B. Jaffri and K. S. Ahmad
instance, polymeric micelles NPs are used as an active delivery agent of drugs in
case of tumor treatment. Iron oxide NPs coated with polymer can also be employed
of for division of bacterial clusters, leading to the greater potential of these NPs in
curing chronic diseases instigated due to bacteria. Furthermore, NPs have also been
filled with various proteinaceous substances equipped with an inherent ability of
stimulation of the immune response in humans and other organisms (Vigneshwaran
et al. 2006).
Over the years, novel compounds are fabricated (Mannam et al. 2017; Navalakhe
et al. 2009) aimed at different applications with an advancement in applications of
NPs. There has been a greater employment of various synthetic routes for NPs based
on the physical, chemical and biological procedures (Adebayo et al. 2019; Elegbede
et al. 2020). Variety of techniques, e.g., precipitative, thermal, pyrolytic, sol–gel, and
hydrothermal have been used for NPs synthesis. However, physicochemical modes,
though very effective and applied ones, have been rigorously challenged for their
elevated capital and operational costs, complexity in operation requiring extraordinarily alleviated temperature and pressure ranges, and above all release of environmentally toxic substance having profound persistence in form of by-products (Lateef
et al. 2016a; Jaffri and Ahmad 2017; Azeez et al. 2020). Often during such chemical and physical synthesis, environmental concerns are highly neglected. This can
be comprehended from the example of chemically processed synthesis of quantum
dots of cadmium selenide marked by imposition of the significant pollutant atmospheric, hydrospheric, and lithospheric load in form of various organic and inorganic substances. Furthermore, other dominant pollutants in the similar way can be
different types of soils, iron, chloride ions, sulfur, and sodium that are released into
the immediate environment. Additionally, utilization of different organophosphorus
solvents makes the cost of overall chemical routes reaching up to 90% of the total
NPs generation cost (Sirinakis et al. 2003). In order to gain the benefits related with
the nanoscale particles in different fields in a sustainable way, green chemists have
proposed and tested the solution to these limitations associated with physicochemical
routes. Greener synthesis of NPs is an effective alternative to physical and chemical
routes. It is a novel, efficacious, toxicity-free and economically viable procedure.
Greener routes employ the utilization of natural biotic resources, particularly renewable ones that have good replenishment and production spans such as plant parts,
microbes, human cells, and metabolites of arthropods among others (Adelere and
Lateef 2016; Lateef et al. 2016a, b, c). These bio-entities are completely toxicityfree, abundantly available and cost effective in provisioning natural reducing cum
stabilizing agents as a replacement for chemically obnoxious counterparts.
Among biological reducing agents, microbial species have been highly cherished
as nano-biofactories for reduction and stabilization of different NPs having profound
ability for alterations in tuning the shapes and sizes of NPs in addition to optical
characteristics (Gutiérrez et al. 2012). Nano-biofactories are usually based on bacterial, fungal, yeast, actinomycetes, algal, cyanobacterial, and viral genesis which are
employed for NPs production such as magnetite, silver, platinum, gold, magnesium,
copper, palladium, and zinc. Bacteria have been designated as one of these nanobiotechnological tools among all bio-entities in case of microbial resources for the