Page 50 - ACCB 2020

Revista de la Asociación Colombiana de Ciencias Biológicas
issn impreso 0120-4173, issn en línea 2500-7459
de NPs (ZnO, TiO and SiO ) against Gram-positive (105); antibiotics (106,107), hormones (108,109),
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Bacillus and Gram-negative E. coli present in water. dioxins (110,111), surfactants (112,113), pesticides
Comparatively, antibacterial activity for demonstrated (114,115) which appear as emergent water contami-
NPs is ZnO>TiO >SiO Also, the penetration into the nants (116), urging for new materials or techniques
2 2.
cell leads to disarranging the bacterial membrane upon applicable for their detection and removal from water
contact with these NPs. Apart from that, all tested NPs (117,118). Considerable progress has been made in the
showed effi cient inhibition of bacterial growth (97),. fi eld of water and wastewater decontamination (119),
Biogenic AgNPs were shown to be more advantageous however, a key-point remains unsolved regarding the
for such use. They were shown to possess the size and safe application of NPs and the control or disinfection
phytochemical dependant antibacterial activity against of toxic by-products (DBPs) 120 that are carcinogenic
E. coli and other bacteria. Furthermore, they were also or show deleterious effects (121,122).
reported to have high catalytic activity for the degra-
dation of toxic contaminants such as 4-nitrophenol and GO has been used to adsorb pharmaceutical compounds
methyl orange. Both antibacterial and catalytic activi- such as tetracyclines. Its adsorption occurred by π-π
ties of biogenic AgNPs suggest its application in the interaction and cation - π bonding either between GO
effective treatment of wastewater. electronic network and π electrons from the aromatic
chain or cations from tetracycline. In fact, several re-
Developing countries have diffi culties in managing search groups have taken advantage of π-π interactions
their sewage, which is directly released at potable water to adsorb dioxins as well as hormones at GO surface
sources; consequently, they are more vulnerable at epi- (123). The functional groups from GO are useful for
demics of cholera, bacillary dysentery, among others. adsorption of some types of DBPs (e.g. trihalometha-
Thus, in order to offer an alternative for people from nes, brominated haloacetonitriles - HANs) (59,124).
those countries, green synthesized AgNPs and ZnONPs Those functional groups are also important to combine
against V. cholerae and enterotoxic E. coli can be used GO with other materials and promote the detection of
(99). Both, AgNPs and ZnONPs, showed considerable hormones such as estradiol (125,126).
antibacterial activity against the tested strains. Howe-
ver, the application of those NPs was done in infected Considering that nonylphenols are potential disruptors
animal models for the development of potential emer- and xenostrogen due to its estrogen-like activity; its
gency treatment for cholera and dysentery; unfortuna- early detection in water and wastewater is necessary
tely, the action of those NPs at living animals remains (127,128). Thus, GO was used into gold electrodes to
unknown. detect nonylphenols (129), as DBPs from nonylpheno-
lethoxylates. Such application was viable by functiona-
Although, some research groups applied isolated NPs lization of GO with β- cyclodextrins. However, detec-
coated TiO anatase with AgNPs to obtain photoca- tion and removal of DBPs from drinking water by new
2
talytic activity and bactericidal activity against strains technologies is the need of the hour.
of enterohemorrhagic E. coli and Listeria monocytoge-
nes. Furthermore, those nanocomposites showed strong From all of the above discussion, it is imperative that
activity against deadly spores of C. perfringens, respon- nanomaterial-based technology is proving to be the
sible for human gas gangrene, which regularly spread boon for the effective treatment and/or purifi cation of
by water or sewage (100). various types of water bodies contaminated with va-
rious types of polluters. It has upper hand over various
4.5. Other applications of nanoparticles for water conventional methods of purifi cation and/or treatment
treatment or remediation of water. Various studies performed to date make a po-
Nowadays, emergent and complex pollutants are the int that this technology has huge potential to revolutio-
most challenging problem faced by governments nise water treatment technology in the 21 century.
st
worldwide, due to lack of knowledge concerning the
dynamics of those contaminants in environment (101), 5. Toxicity of nanoparticles
and their interaction with living organisms (102,103) or Although nanoparticles have shown various applica-
its spreading at food chain (104). While a majority of tions, there are a number of reports stating that they
developing countries still struggle to offer potable water could be harmful to humans and the environment. The
for their people by improving water treatment systems nanoparticles are released into water bodies through

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Rev. Asoc. Col. Cienc.(Col.), 2020; 32: 42-62.