The SNPs were synthesized using 0.02 M, 0.05 M, and 0.1 M silver
nitrate solutions and hydro-alcoholic extract of seeds of C. arabica
(volume of extract was kept constant for all the three different concentrations).
Both the solutions were mixed to initiate the reduction of
AgNO3 solution into Ag+ ions. The mixturewas then stirred continuously
for about 10 min on a magnetic stirrer and the solution was further
incubated at room temperature for 2 h. Color changes were observed
from light brown to dark brown indicating that the reaction has terminated
(Fig. 1b–g). The reduced mixture was then purified by repeated
centrifugation at 4000 rpm for 5 min. The supernatant was transferred
to a clean dry beaker for further settlement of particles and repeated
process of centrifugation was carried out to purify SNPs. The sample
so obtained was dried under an infra-red lamp and was then stored
for further characterizations.