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22 Biofunctionalized Nanomaterials for Sensing and Bioremediation of Pollutants

biosurfactant-producing microorganisms were identified to produce nanoparticles

of different sizes. Biosurfactants produced by these microorganisms are economi-

cally significant and can be used in bioremediation as an emulsifier, antimicrobial

agent, and oil recovery agent. However, the functionalization of these biosurfactants

to nanoparticles and the study of their impact and efficiency in remediation are yet

to be explored.

22.4.3

Nucleic Acid

The combination of nucleic acid with nanoparticles has been widely explored for

environmental application. Gold and silver nanoparticles conjugated with DNA

had been investigated for bioremediation of various hydrocarbon-based pollutants,

but the cost-effectiveness, large size of DNA/RNA, and sequestration over metallic

nanoparticle remain a significant problem, and thus they have limited applicability

for environmental remediation. Recent advances in the field of biotechnology had

let to the development of many double-stranded RNA-based fungicides. These

fungicides are more effective than conventional biochemical counterparts and

leave no harmful residues in the environment after use. In RNA-based fungicide

preparation, the double-stranded RNA is synthesized to hybridize with the mes-

senger RNA of fungal species. This RNA preparation is then sprayed on the area

of application, which leads to the silencing of vital housekeeping genes in fungi

and, eventually, the death of fungal species. However, the life span of naked RNA

is significantly less. To counter this issue, nanosheet protectants are used. These

protectants enhance the life of naked RNA and ensure extended biocidal action

[27, 28]. Magnetic nanoparticle-labeled DNA has been used to study the horizontal

gene transfer events in bacteria used in soil remediation. This technique provides

better insight into various bioreaction mechanisms and their role in bioremediation.

The recovery of these organisms having magnetic nanoparticles-labeled DNA can

be easily achieved under the external magnetic field [29]. The development of

micro/nanomachines for the removal of various heavy metals from water bodies

has also been demonstrated. These machines contain a self-propelled tube having

conjugated DNA that can bind selectively to a particular heavy metal.

22.4.4

Proteins and Peptides

Protein and peptide are made up of small amino acid chains linked by a peptide

bond. Protein and peptide-conjugated nanoparticles are widely used for environ-

mental remediation purposes. Protein-conjugated nanoparticles are efficient, pre-

cise, and specific in their action but are sensitive to pH and temperature. However,

their efficacy and speed of action make them an appropriate candidate for sustain-

able bioremediation. Protein and peptide are also used as stabilizing/binding agents

of various nanoparticles, which are used in bioremediation.

Sodium tetrachloropalladate(II) can bind to palladium and reduce it by increasing

the proportion of tryptophan progressively, which is an example of peptide-based

remediation of transition metal [30]. Many protein-conjugated nanoparticles have