144
S. Riaz and M. Ashraf
In most recent studies electrospinning is fascinating technique for nanofiber fabrication. Researchers are developing electrospun nanofibers for different biomedical, filtration applications. Solution of cellulose acetate (CA) was direct electrospun
containing AgNO 3 in small amount. Nanofibers containing Ag+ ions. AgNPs were
synthesized by direct UV irradiation of ultrafine CA fibers and stabilized by carbonyl
oxygen in CA, having strong antibacterial activity because of silver NPs and unreduced ions of silver [83]. In same way fibers chitosan/gelatin nanofibers containing
AgNPs were fabricated, only difference was that, instead of γ or UV irradiation
and heat treatment, AgNPs were synthesized by reducing agent like chitosan that
also act as stabilizer for silver NPs [99, 100]. Nano AgZ (Silver-loaded zirconium
phosphate nanoparticles) were added to PCL Poly(ε-caprolactone) and biocompatible fibers were electrospun for medical applications with enhanced bacteriostatic
activities [90].
Carbon nanotubes Ag-coated CNTs were prepared by ultrasonic irradiation of
dimethyl formamide (DMF) solution containing multi-walled carbon nanotubes, silver acetate solution. Dry mixing of nylon-6 powder and silver coated CNTs was
done, through melt spinning prepared fibers had enhanced bactericidal property [91],
because single-walled and multi-walled carbon nanotubes are well known for their
antibacterial activity [101, 102]. Hence, CNTs have great potential for being used as
antibacterial agent, in textile industry.
Detrimental effect of AgNPs, when they are used as antibacterial agent is of
particular concern as they come in contact with human skin. Size and surface area
have direct effect on cytotoxicity of silver NPs in relation to concentration. If size
of AgNPs is 2–3 nm and concentration of colloidal silver is 100 ppm then, it has
devastating effect on skin [92]. But, if the colloidal concentration is less i.e. 10,
20 ppm, etc. then, it is less toxic compared to 100 ppm.
In vitro cytotoxicity of AgNPs having diameter of about 15 nm, was studied in
male mammalian mouse germline stem cells. This study showed that if AgNPs are
used in concentration more than 5 μg/ml, it reduced the cell viability and function
of mitochondria by increasing lactase dehydrogenase (LDH) [103]. Therefore, the
trend is moving towards less toxic nanoparticles for antibacterial characteristics of
fibers. ZnO, TiO 2 and CuO nanoparticles are being used as a substitute of silver
for antibacterial characteristics. Photocatalysis is the main reason of bacterial inactivation in case of all these nanoparticles. The schematic illustration of the whole
photocatlytic process in given in Fig. 12.
7.2.2 Copper Oxide Nanoparticles
In one study CuO NPs in crystalline form of monoclinic phase were developed and
adsorbed directly onto raw cotton fibers surface by ultrasonic irradiation of metal
hydroxide, which could be used as highly antibacterial raw material for protective
clothing, medical textiles, sportswear etc. [104]. Thin film formation of nanoscale of
metal by direct sputtering had also been done on textile to inactivate bacteria. When
Cu react with air O 2 , CuO formation occurred. Semiconductor CuO (p-type) have
S. Riaz and M. Ashraf
In most recent studies electrospinning is fascinating technique for nanofiber fabrication. Researchers are developing electrospun nanofibers for different biomedical, filtration applications. Solution of cellulose acetate (CA) was direct electrospun
containing AgNO 3 in small amount. Nanofibers containing Ag+ ions. AgNPs were
synthesized by direct UV irradiation of ultrafine CA fibers and stabilized by carbonyl
oxygen in CA, having strong antibacterial activity because of silver NPs and unreduced ions of silver [83]. In same way fibers chitosan/gelatin nanofibers containing
AgNPs were fabricated, only difference was that, instead of γ or UV irradiation
and heat treatment, AgNPs were synthesized by reducing agent like chitosan that
also act as stabilizer for silver NPs [99, 100]. Nano AgZ (Silver-loaded zirconium
phosphate nanoparticles) were added to PCL Poly(ε-caprolactone) and biocompatible fibers were electrospun for medical applications with enhanced bacteriostatic
activities [90].
Carbon nanotubes Ag-coated CNTs were prepared by ultrasonic irradiation of
dimethyl formamide (DMF) solution containing multi-walled carbon nanotubes, silver acetate solution. Dry mixing of nylon-6 powder and silver coated CNTs was
done, through melt spinning prepared fibers had enhanced bactericidal property [91],
because single-walled and multi-walled carbon nanotubes are well known for their
antibacterial activity [101, 102]. Hence, CNTs have great potential for being used as
antibacterial agent, in textile industry.
Detrimental effect of AgNPs, when they are used as antibacterial agent is of
particular concern as they come in contact with human skin. Size and surface area
have direct effect on cytotoxicity of silver NPs in relation to concentration. If size
of AgNPs is 2–3 nm and concentration of colloidal silver is 100 ppm then, it has
devastating effect on skin [92]. But, if the colloidal concentration is less i.e. 10,
20 ppm, etc. then, it is less toxic compared to 100 ppm.
In vitro cytotoxicity of AgNPs having diameter of about 15 nm, was studied in
male mammalian mouse germline stem cells. This study showed that if AgNPs are
used in concentration more than 5 μg/ml, it reduced the cell viability and function
of mitochondria by increasing lactase dehydrogenase (LDH) [103]. Therefore, the
trend is moving towards less toxic nanoparticles for antibacterial characteristics of
fibers. ZnO, TiO 2 and CuO nanoparticles are being used as a substitute of silver
for antibacterial characteristics. Photocatalysis is the main reason of bacterial inactivation in case of all these nanoparticles. The schematic illustration of the whole
photocatlytic process in given in Fig. 12.
7.2.2 Copper Oxide Nanoparticles
In one study CuO NPs in crystalline form of monoclinic phase were developed and
adsorbed directly onto raw cotton fibers surface by ultrasonic irradiation of metal
hydroxide, which could be used as highly antibacterial raw material for protective
clothing, medical textiles, sportswear etc. [104]. Thin film formation of nanoscale of
metal by direct sputtering had also been done on textile to inactivate bacteria. When
Cu react with air O 2 , CuO formation occurred. Semiconductor CuO (p-type) have