BSc -MSc

Technology development for incorporation of green synthesized silver
nanoparticles on naturally dyed fabrics
The study entitled “Technology development for incorporation of green
synthesized silver nanoparticles on naturally dyed fabrics” was conducted in the
Department of Molecular Biology and Biotechnology at College of Agriculture,
Vellayani with an objective to develop a technology for the incorporation of green
synthesized silver nanoparticles and natural pigments from Aerva lanata L. for
imparting antimicrobial property and colour to fabrics and standardization of pigment
extraction from callus.
Fresh leaves of Aerva lanata collected from Regional Ayurvedic Research Institute,
Papanamcode, Thiruvananthapuram were used for pigment extraction via boiling
method. The extract was used for dyeing of bleached white cotton fabric after scouring.
Dyeing was carried out by wet dipping method using different mordants (10% alum,
1% stannous chloride) and biomordants (5% seed extract of Terminalia chebula, 100%
banana pseudostem sap) and the fabric after drying was subjected to computer colour
matching. The colour of the dyed fabric was identified as Earl’s green for metallic
mordants and Olive green and Wild willow for Terminalia chebula and banana
pseudostem sap respectively.
Green synthesis of silver nanoparticles was carried out using leaf extract of Aerva
lanata and confirmed using UV-Visible spectroscopy at 420 nm. Silver nanoparticles
were incorporated into the dyed fabric by different methods viz., direct incorporation,
in-situ synthesis, direct incorporation along with chitosan and in-situ synthesis along
with chitosan and the antimicrobial activity of the fabric was tested by agar diffusion
method. Naturally dyed fabric without silver nanoparticles served as control. Colour
fastness of the fabric and durability of antimicrobial activity were tested after
consecutive 5, 10 and 20 washing cycles.
All fabrics incorporated with green synthesized silver nanoparticles by direct
incorporation and in-situ method exhibited antimicrobial activity. Mordant used did not
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affect the antimicrobial activity exhibited by silver nanoparticles incorporated by direct
method, while in in-situ method, fabrics treated with biomordants showed an increased
antimicrobial activity. Fabrics treated by direct incorporation retained the original dye
colour while in-situ treated fabrics exhibited shades of golden brown colour.
Incorporation of silver nanoparticles in both direct and in-situ methods along with
chitosan treatment did not show antimicrobial activity in the agar diffusion test which
may be due to superhydrophobicity.
Durability of antimicrobial fabrics was maximum for in-situ incorporated fabric
biomordanted with Terminalia chebula and the presence of silver nanoparticles in the
fabric was confirmed by Scanning Electron Microscopy (SEM).
Cent percent callus induction was observed from nodal segments of Aerva lanata
within four weeks in Murashige & Skoog (MS) medium supplemented with 1.5 mg/l
BA and 0.2 mg/l IAA and reddish pink colour development was observed within seven
weeks. Pigment extraction was done by cold extraction and soxhlet extraction using
methanol as solvent and subjected to column chromatography and the UV-visible
spectrum of the different fractions were compared. Absorption at 550 nm was higher
for the extract prepared by cold extraction method indicating a higher content of
anthocyanin. Ultra High Performance Liquid Chromatography Mass Spectroscopy
(UHPLC-MS) of the crude methanolic extract of the callus showed the presence of
compounds such as 7-methylaromadendrin, canthin-6-one, and 5-methoxycanthin-6-
one which are also reported in the plant. However, other compounds such as dalspinin
and O,O'-(4,4'-diaminobiphenyl-3,3‘-lene)di(glycollic acid) were also present in the
callus extract which are not reported in the plant.
To conclude, fabrics with durable antimicrobial property could be developed by insitu incorporation of silver nanoparticles after biomordanting followed by natural
dyeing using Aerva lanata in an eco-friendly manner. This is the first report of in-situ
incorporation of silver nanoparticles on naturally dyed fabric for antimicrobial activity.
Callus of Aerva lanata has potential for pigment extraction for natural dyeing process.