Nano

technologyhigh reactivity

high surface area to volume

ratio

specific physicochemical characteristics

The nanosize: 1-100 nm in at

least one dimension

Nanoparticlesagriculture

textiles

health care cosmetics

electronics

optics

Nanoparticles can be synthesized by a variety of methods using gas, liquid

or solid phase processes. These include

1. gas phase processes of flame pyrolysis, high temperature evaporation,

plasma synthesis, microwave irradiation, physical and chemical vapor

deposition synthesis;

2. colloidal or liquid phase methods in which chemical reactions in

solvents lead to the formation of colloids, molecular self-assembly,

3. and mechanical processes of size reduction including grinding, milling

and alloying.

Once the NPs are produced and purified to a satisfactory level it

is often necessary to introduce surface modifications. The surface

modifications can be for the purposes of:

(a) Passivating a very reactive nanoparticle,

(b) Stabilizing a very aggregative nanoparticle in a medium

where the NPs are to be dispersed,

(c) Functionalizing the nanoparticle for applications, or

(d) Promoting the assembly of NPs.

Different approaches to surface modifications(a) Surface treatment. The treatment could be the charging of the surface or coating with ligands,

(b) Surface adsorption of a surfactant or a block copolymer to provide interparticle electrostatic and/or

steric repulsions, and

(c) Surface modification to make the nanoparticle functional in one of many ways including

hydrophobic or hydrophilic, the ability to bind to specific molecular recognition elements, DNA,

enzymes, bridge to other NPs, etc.

Assembling NPs for applications

(a) Nanoparticles with stabilizing polymer molecules around them in a random three dimensional

arrangement to create a porous nanoparticle system for catalytic or adsorption applications,

(b) Nanoparticles assembled on a polyelectrolyte or a DNA molecule to serve as a nanoelectrical wire,

and

(c) Nanoparticles assembled on a block copolymer patterned surface with NPs located at the domain

boundaries for a sensor application.

For most practical applications, the NPs have to be assembled in

one, two or three dimensions, similar to how atoms and molecules

are assembled into matter. It will be necessary to place the NPs in

specified locations on a substrate so that addressing and connecting

them to the macroscopic outside world will be possible

A new branch of nanotechnology is nanobiotechnology.

Nanobiotechnology combines biological principles with physical

and chemical procedures to generate nano-sized particles with

specific functions. Nanobiotechnology represents an economic

alternative for chemical and physical methods of NPs formation.

Nanobiotechnology describes an application of biological systems

for the production of new functional material such as NPs.

Biosynthetic methods can be employed either by microorganism

cells, plant extract or biodegradable polymers for NPs

production.

Nanotechnology has found limited applications in textiles such as

chemical and biological filters, nanofiber-based biological

scaffolds, NPs-coated repellant textiles and nanofiber filters,

which are relatively few compared to those in electronics and

healthcare. Defense, healthcare and environmental sectors use

nano-textiles and nanotechnology related textile products for

improved functionality and performance. More importantly,

nanofibers, due to their enhanced surface area and lightweight,

can be used as effective filter and barrier media in chemical and

biological defense clothing, face masks and filtration equipment.

Nano

technology

Antibacterial

Textiles

Smart Textiles

Conductive Textiles

Solar Textiles

Repellent Textiles

1. Chemical Synthesis of Nanoparticles

2. Biosynthesis (plant extracts, biodegradable

polymers, and enzymes/bacteria) of metal

and metal oxide NPs,

3. Photoinduced reduction of metal ions to

metal NPs, and

4. Textile application of metal and metal

oxide NPs.

Nanoparticle Synthesis

Chemical

BiologicalPhysical

chemical

DMF

Polyols

Sodium borohydride

Thiosulfate

Hydrazine

Cts (chitosan), Cts/gelatin and gelatin suspension were used as

the stabilizers for reducing AgNO3 using NaBH4 as strong reducing

agent. As a result, AgNO3 was successfully reduced by NaBH4 in the

presence of Cts/gelatin or either one, resulting in the formation of

AgNPs according to the following equations (1–3):

“green” product + environment friendly process

”green” reducing and

stabilizing agent

“green” solvent

precursor

5

Mechanical processes of size reduction including grinding,

milling and alloying.

physical

Microwave

Ultrasonic

UV-radiation

Shear

-radiation

Plasma

Synthesis of metal NPs has been demonstrated by many physical

and chemical means. Because most of these methods are capital

intensive, toxic, non eco-friendly and have low productivity, it is

a need of today’s nanotechnology to adopt a variety of green routes

for synthesis of NPs. Amongst these are those concerned with plant

extract, bacteria, fungi, enzymes, algae and biodegradable

polymers. Due to their amenability to biological functionalization,

the biosynthesized NPs are finding important applications in the

field of medicine, in particular that related to the antimicrobial

activity.

Biological

Plant extract

Bacteria

Fungi

Enzymes

Algae

Biodegradable polymers

Plant extractGreen tea extract

Geranium leaf extract

Citrus limon extract

Lemon leaves extract

Garlic extract

Ficus benghalensis leaf

Banana peel extract

Citrus sinensis peel

Dodonaea viscosa extract

Terminalia arjuna bark extract

All parts of a plant bearing antioxidants or sugars, including leaves, fruits, roots,

seeds, and stems, can be used in the synthesis process, replacing potentially hazardous

chemicals like sodium borohydride (NaBH4). They Can act as reducing and stabilizing

agents in the synthesis of metal NPs

The fungi are extremely good candidates in the synthesis of metal NPs.

The reduction of silver ions by several strains has been attributed to a nitrate-

dependent reductase.

Active metal transformation processes require viable microbes which

enzymatically catalyze the alteration of the metal.

The microorganisms probably play a role in providing a multitude of nucleation

centers and establish conditions for obtaining highly disperse nanoparticle

systems.

Microorganisms slow down or entirely prevent aggregation by immobilizing the

particles, and providing a viscous medium.

It is reported that polysaccharides extracted from algae have a dual effect as they

act as reducing agents of silver ions and as stabilizing agents for the formed silver

NPs.

Green Synthesis + Biocompatibility

Polysaccharides serve as both a reducing and a capping agent. In a case of dual

polysaccharide function, silver nanoparticles were synthesized by the reduction of

Ag+ inside of nanoscopic starch templates.

The so-called “alcohol reduction process” is a very general process for the

production of metal nanoparticles, often stabilized by organic polymers. In

general, the alcohols which were useful reducing agents contained 𝛼-hydrogen and

were oxidized to the corresponding carbonyl compounds. The oxidation of

primary alcohols (R–CH2OH) by Ag+ is also well established; the reaction is slow

and requires heating to be accelerated as follows:

The heart of the photochemical approach is the generation of M0 in such conditions that

their precipitation is thwarted. M0 can be formed through direct photoreduction of a

silver source, silver salt or complex, or reduction of silver ions using photochemically

generated intermediates, such as radicals. The photoreduction is often promoted by dyes

dispersed or dissolved in the polymer or present in the chemical structure of the matrix.

In this one-step approach, a strategy was reported involving the photoinduced formation

of homogeneous silver NPs in an acrylate polymer stemming from a crosslinking

photopolymerization of an acrylate monomer.

1. Silver nanoparticles were synthesized by exposing a mixture of 0.1 M [Ag(NH3)2]+

and diluted aqueous garlic extract under bright sunlight for 15 min. The garlic

extract components served as both reducing and capping agents in the synthesis of

silver nanoparticles while the sunlight acted as catalyst in the synthesis process.

2. In a similar study, silver nanoparticles were rapidly synthesized photochemically by

treating silver ions with lemon (Citrus limon) extract utilizing solar radiation. The

authors have hereby developed an energy efficient bio-based synthesis process

which produces silver nanoparticles rapidly.

3. Bhaduri et al reported a simple ‘green’ method of AgNP synthesis of using an

anionic surfactant without use of any additional reducing agents. They observed the

synthesis of AgNPs at room temperature (using sodium dodecyl sulphate and

sunlight). The nanoparticles are water soluble and the nature of the process is

amenable to scaling up.

Ag NPs (antibacterial,)

Cu/CuO NPs (electro-

conductive, antibacterial,

ZnO NPs (UV absorbers, anti-reflection

coatings, photo-catalysis , antibacterial)

TiO2 NPs (photo-catalytic,

self-cleaning, UV protection, antibacterial,

antiviral)

Metal and metal oxide nanoparticles have created a new

interesting field in all sciences for the continuous investigations

due to their undeniably unique properties. Their applications have

already led to the development of new practical productions.

These new fields in textile industry have been increasingly

welcomed. However, designing new applicable and affordable

techniques for manufacturing scale-up production will not only

create a new field of study, but meet the expanding human

requirements.

Thankyou

Questions?

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