22.3 Binding Techniques for Biofunctionalization of Nanoparticles

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22.2

Synthesis and Surface Modification Strategies

for Nanoparticles

Nanoparticles can be synthesized using either the top-down or bottom-up method.

There has been a massive development in the field of nanoparticle synthesis in recent

years. As per the requirement, nanoparticles can be synthesized in sophisticated

machines, or we can use the biosynthesis route in which microbes fabricate the syn-

thesis of nanoparticles. The top-down method is a destructive nanoparticle synthesis

mode in which material chunks are broken down into nano-range. The top-down

approach includes mechanical milling, chemical etching, LASER ablation, sputter-

ing, exfoliation, lithography, electro-explosion, and arc discharge. The bottom-up

synthesis method is a constructive way of producing high-quality nanoparticles. The

bottom-up approach includes biosynthesis, atomic condensation, DNA scaffolding,

LASER pyrolysis, microemulsion, melting mix, ultrasonication, sol–gel synthesis,

plasma spraying, microwave synthesis, and electrospinning techniques.

The application of nanomaterials for bioremediation requires controlled dis-

persion and interaction with other molecules near their vicinity, which can be

controlled by functionalization and surface modification. Surface modification sig-

nificantly impacts distribution, assembly, and stability in a colloidal solution. While

using nanoparticles for sensing application, specificity and selectivity features are

also influenced by surface modification. By customizing the surface properties,

attributes like electrical conductivity and corrosivity in a medium, hydrophilic,

and hydrophobic nature of nanoparticles can be modified. Biofunctionalization

of protein, peptide, and enzyme requires careful selection of nanoparticles with a

hydrophobic or hydrophilic surface. Hydrophobic surface modification of nanopar-

ticle is achieved by incorporating hydrophobic molecules like trioctylphosphine

oxide,

oleylamine,

tetraoctylammonium

bromide,

triphenylphosphine,

oleic

acid, or dodecanthiol. Similarly, hydrophilic surface modification is mediated by

hydrophilic molecules like mercaptosuccinic acid, mercaptoacetic acid, mercap-

topropionic acid, bis-sulfonated triphenylphosphine, mercaptoundecanoic acid,

dihydrolipoic acid, polyethylene glycol, mercaptosuccinic acid, or aminenated

polyethylene glycol.

22.3

Binding Techniques for Biofunctionalization

of Nanoparticles

The functionalization of biomolecules with nanoparticle is mediated by an inter-

action like covalent, non-covalent, encapsulation, and adsorption. The type of

binding techniques critically influences the applicability, usability, functionality,

and stability of biofunctionalized nanoparticle for remediation purposes. Properties

of biomolecules like shape, size, hydrophobicity, hydrophilicity, and type functional

group are examined thoroughly before functionalization.