Environmental Engineering Reference
In-Depth Information
Nanoparticle
Amoxicillin
FiGurE 19.6
Binding of amoxicillin with silver nanoparticle (NP). Modified from Fing et al. [135].
19.14
riSinG concErn ovEr nAnoSilvEr toxicity
At lower concentrations, silver NPs exhibit strong antimicrobial activity. Silver NPs release silver ions, which have the
ability to destroy bacterial cells by lowering the transmembrane pH gradient and terminating its proton motive force.
Although this antimicrobial activity is highly potent, it has serious negative consequences at higher concentrations. As the
silver ions accumulate, their concentration increases and at higher concentrations the silver ions have a serious impact on
health and on the environment [136]. Certain skin diseases like argyrosis and argyria mainly result due to accumulation of
silver in the skin [137]. In the environment, silver NPs inhibit some helpful microbes like nitrogen-fixing and ammonifying
bacteria in the soil [138, 139]. They are also found to have an impact on aquatic life. The interaction of silver ions in the gills
of fishes affects Na
+
and K
+
uptake and indirectly affects osmo regulation in fishes [140]. These are the main concerns in the
widespread use of silver NPs.
19.15
concluSion
Green synthesis of NPs holds the future for nanotechnology. NPs have widespread applications due to their low cost, environmen-
tally friendly nature, ease of synthesis, and greater yield. When compared with other available methods for synthesis, like chemical
and physical, they have more potential. The chemically synthesized NPs are found to require an additional stabilizer to prevent
aggregation of the particles. Moreover, the chemical process used to synthesize NPs uses chemicals that are toxic to the environ-
ment. The physical method of synthesis is comparatively tedious and often produces lower yields. Hence, all these factors support
biogenesis for the synthesis of NPs. Among the various biological routes available for synthesis, the bacterial method is the most
widely preferred, as genetic manipulation is possible and handling is relatively easy. NPs have properties that differ greatly from
that of bulk particles. The unique properties of silver NPs make them a vital tool for many applications. As their synthesis does not
involve the use of any toxic substance, they have a wide array of medical and environmental applications. The biogenesis of NPs
results in bulk production of NPs. If this potential is rightfully utilized, they can have numerous industrial applications. One of the
rising concerns in the use of silver NPs is its toxicity at higher concentrations. If this problem can be overcome, silver NPs would
become one of the most sought-after resource in the future with biogenesis being the major route for synthesis.
