Eco-friendly Surface Modification …
547
agent NaBH 4 . The proposed mechanism of silver ion adsorption and reduction to
nanoparticles is as follows:
Cotton - X H
−→ Cotton - X
−
(XH = OH, COOH)
Cotton - X
−
+ Ag
+
−→ Cotton - X
− Ag
+
Cotton - X
−
nAg
+
+ NaBH 4 −→ Cotton - X (Ag) n
The acrylic acid grafted and silver ion-loaded samples gave an active zone of
inhibition against test organisms E. coli and S. aureus as compared to untreated
samples indicating better loading efficiency as a result of plasma treatment. The
same plasma setup was used by researchers to enhance the antimicrobial activity
of acrylic acid grafted wool fibre using silver nanoparticles and Berberine natural
dye as two different kinds of antibacterial agents. From the SEM images, it was
clearly evident of nanosilver loading on the fabric surface which was attributed
due to increased surface roughness after plasma treatment, the formation of active
surface groups and removal of surface lipids layers. Compared to untreated fabrics,
Berberine dyed plasma pretreated samples showed better dye absorption and good
fastness to light, washing and rubbing along with an excellent antibacterial activity
to E. coli and S. aureus bacteria. Berberine which is an N containing quaternary
ammonium compound causes bacterial lysis by destroying the negatively charged
cell membrane with denaturing of protein and ultimately disrupting cell structure. In
order to replace metal mordant like alum due to toxic nature, the plasma pretreated
samples were grafted with β-cyclodextrin prior to dyeing with Berberine. The said
samples showed an increase in weight gain due to increased dye attachment along
with 99.9% bacterial reduction as compared to untreated dyed sample (48.1%) (Haji
2015).
Shahidi et al. studied the enhancement of antimicrobial characteristic in cotton
fabric by functionalizing it first with plasma and then with ZnO nanoparticles. Pre
functionalisation of the material was done using low-pressure DC magnetron plasma
sputtering device using air for 5 min. ZnO nanoparticles were then in situ synthesised
by sonochemical method at room temperature on both untreated and plasma-treated
fabrics. FESEM analysis of the samples reported the presence of spherical nanoparticles within the size range of 20–90 nm along with the generation of porous and rough
areas on the plasma-treated surface which is supposed to enhance the absorption of
solvents like ZnO nanoparticles and increase hydrophilicity. XRD analysis of the
treated samples also confirmed the presence of nanoparticles by giving peaks corresponding to the spherical type of ZnO. The FTIR study of the samples also showed
an overlap of –OH and –NH functional groups in the region of 3400 cm
−1 which
arise due to the reaction between the active plasma species and fabric surface atoms.
The antibacterial studies performed using colony count method concluded that the
untreated fabric does not have any antibacterial properties, whereas the ZnO plasmatreated samples demonstrated strong antibacterial efficiency. The difference in the
bactericidal property was explained to be due to the chemical interactions between
peroxide radicals of air plasma and membrane proteins as well as the lipid bilayer
547
agent NaBH 4 . The proposed mechanism of silver ion adsorption and reduction to
nanoparticles is as follows:
Cotton - X H
−→ Cotton - X
−
(XH = OH, COOH)
Cotton - X
−
+ Ag
+
−→ Cotton - X
− Ag
+
Cotton - X
−
nAg
+
+ NaBH 4 −→ Cotton - X (Ag) n
The acrylic acid grafted and silver ion-loaded samples gave an active zone of
inhibition against test organisms E. coli and S. aureus as compared to untreated
samples indicating better loading efficiency as a result of plasma treatment. The
same plasma setup was used by researchers to enhance the antimicrobial activity
of acrylic acid grafted wool fibre using silver nanoparticles and Berberine natural
dye as two different kinds of antibacterial agents. From the SEM images, it was
clearly evident of nanosilver loading on the fabric surface which was attributed
due to increased surface roughness after plasma treatment, the formation of active
surface groups and removal of surface lipids layers. Compared to untreated fabrics,
Berberine dyed plasma pretreated samples showed better dye absorption and good
fastness to light, washing and rubbing along with an excellent antibacterial activity
to E. coli and S. aureus bacteria. Berberine which is an N containing quaternary
ammonium compound causes bacterial lysis by destroying the negatively charged
cell membrane with denaturing of protein and ultimately disrupting cell structure. In
order to replace metal mordant like alum due to toxic nature, the plasma pretreated
samples were grafted with β-cyclodextrin prior to dyeing with Berberine. The said
samples showed an increase in weight gain due to increased dye attachment along
with 99.9% bacterial reduction as compared to untreated dyed sample (48.1%) (Haji
2015).
Shahidi et al. studied the enhancement of antimicrobial characteristic in cotton
fabric by functionalizing it first with plasma and then with ZnO nanoparticles. Pre
functionalisation of the material was done using low-pressure DC magnetron plasma
sputtering device using air for 5 min. ZnO nanoparticles were then in situ synthesised
by sonochemical method at room temperature on both untreated and plasma-treated
fabrics. FESEM analysis of the samples reported the presence of spherical nanoparticles within the size range of 20–90 nm along with the generation of porous and rough
areas on the plasma-treated surface which is supposed to enhance the absorption of
solvents like ZnO nanoparticles and increase hydrophilicity. XRD analysis of the
treated samples also confirmed the presence of nanoparticles by giving peaks corresponding to the spherical type of ZnO. The FTIR study of the samples also showed
an overlap of –OH and –NH functional groups in the region of 3400 cm
−1 which
arise due to the reaction between the active plasma species and fabric surface atoms.
The antibacterial studies performed using colony count method concluded that the
untreated fabric does not have any antibacterial properties, whereas the ZnO plasmatreated samples demonstrated strong antibacterial efficiency. The difference in the
bactericidal property was explained to be due to the chemical interactions between
peroxide radicals of air plasma and membrane proteins as well as the lipid bilayer