Functional Finishing of Cotton Textiles Using Nanomaterials
47
3 Antimicrobial Finish
Our earliest work [18] reported the use of zinc oxide—soluble starch nanocomposites
to impart antibacterial activity on the surface of cotton fabrics and it demonstrated
excellent antibacterial activity against the two representative bacteria, Staphylococcus aureus (Gram positive) and Klebsiella pneumoniae (Gram negative). Later, nanosilver was also demonstrated to impart antibacterial activity on the surface of cotton [21]. Due to the ease of synthesis, nano-silver is the widely used material to
impart antibacterial activity in cotton textiles [27–31]. Though the nano-silver is a
potent nanomaterial for antibacterial activity, the challenge is to avoid the oxidation
of nano-silver during its exposure and uneven visible deposition on the surface of
cotton fabrics that is quickly shown due to its colour. Hence, the nano-ZnO and
nano-titania are also the viable alternative materials to impart antimicrobial finish on
cotton textiles.
ZnO is a bio-safe material that possesses photo-oxidizing and photocatalysis
impacts on chemical and biological species. The bactericidal and bacteriostatic
mechanisms of metal oxide nanoparticles are due to the generation of reactive oxygen species (ROS) like hydrogen peroxide, hydroxyl radicals and peroxide radicals.
ROS has been a major factor for several mechanisms including cell wall damage,
enhanced membrane permeability, and uptake of toxic dissolved metal ions. In some
cases, the antibacterial activity is also attributed to abrasive surface texture of nanomaterials. The mechanisms of antibacterial activity by nano-ZnO is discussed in
detail in a recent review [32]. The antibacterial activity of nano silver is mainly due
to its binding effect with the proteins/enzymes of the microbes and their inactivation.
The chitosan, a known antibacterial biopolymer, when converted to nano-form and
applied on the surface of cotton fabrics, exhibited excellent antibacterial property
[33]. Various mechanisms involved in the antibacterial activity of nanomaterials are
summarized in Fig. 3.
4 UV Protection Finish
Now a day, the level of ultraviolet (UV) radiation reaching the Earth’s surface has
increased due to the ozone depletion and other environmental related issues. It is
well known that small doses of UV rays are beneficial for the body as this is essential
for the synthesis of Vitamin D. However, an overdose of it can be highly detrimental
to the skin. UV rays react with the compound in the human skin which is called
as melanin (Fig. 4). As a protective mechanism, the precursors of melanin absorb
UV rays and getting converted into a black coloured polymer. But some of human
population doesn’t have much of melanin in their skin due to their genetic nature. This
can results in harmful health conditions including skin cancer, cataracts, premature
ageing and also sunburns. The use of textiles as a means of sun protection is getting
popular apart from the conventional use of sunscreen and lotions. UV protective
47
3 Antimicrobial Finish
Our earliest work [18] reported the use of zinc oxide—soluble starch nanocomposites
to impart antibacterial activity on the surface of cotton fabrics and it demonstrated
excellent antibacterial activity against the two representative bacteria, Staphylococcus aureus (Gram positive) and Klebsiella pneumoniae (Gram negative). Later, nanosilver was also demonstrated to impart antibacterial activity on the surface of cotton [21]. Due to the ease of synthesis, nano-silver is the widely used material to
impart antibacterial activity in cotton textiles [27–31]. Though the nano-silver is a
potent nanomaterial for antibacterial activity, the challenge is to avoid the oxidation
of nano-silver during its exposure and uneven visible deposition on the surface of
cotton fabrics that is quickly shown due to its colour. Hence, the nano-ZnO and
nano-titania are also the viable alternative materials to impart antimicrobial finish on
cotton textiles.
ZnO is a bio-safe material that possesses photo-oxidizing and photocatalysis
impacts on chemical and biological species. The bactericidal and bacteriostatic
mechanisms of metal oxide nanoparticles are due to the generation of reactive oxygen species (ROS) like hydrogen peroxide, hydroxyl radicals and peroxide radicals.
ROS has been a major factor for several mechanisms including cell wall damage,
enhanced membrane permeability, and uptake of toxic dissolved metal ions. In some
cases, the antibacterial activity is also attributed to abrasive surface texture of nanomaterials. The mechanisms of antibacterial activity by nano-ZnO is discussed in
detail in a recent review [32]. The antibacterial activity of nano silver is mainly due
to its binding effect with the proteins/enzymes of the microbes and their inactivation.
The chitosan, a known antibacterial biopolymer, when converted to nano-form and
applied on the surface of cotton fabrics, exhibited excellent antibacterial property
[33]. Various mechanisms involved in the antibacterial activity of nanomaterials are
summarized in Fig. 3.
4 UV Protection Finish
Now a day, the level of ultraviolet (UV) radiation reaching the Earth’s surface has
increased due to the ozone depletion and other environmental related issues. It is
well known that small doses of UV rays are beneficial for the body as this is essential
for the synthesis of Vitamin D. However, an overdose of it can be highly detrimental
to the skin. UV rays react with the compound in the human skin which is called
as melanin (Fig. 4). As a protective mechanism, the precursors of melanin absorb
UV rays and getting converted into a black coloured polymer. But some of human
population doesn’t have much of melanin in their skin due to their genetic nature. This
can results in harmful health conditions including skin cancer, cataracts, premature
ageing and also sunburns. The use of textiles as a means of sun protection is getting
popular apart from the conventional use of sunscreen and lotions. UV protective