2.8 Antimicrobial studiesAntimicrob

2.8 Antimicrobial studiesAntimicrobial studies of biosynthesized AgNPs in differentextracts were carried out by the zone of inhibition method,according to test method AATCC 100–1998 [4–7, 12]. Theantibacterial efficiency of the AgNPs was monitored againstgram-positive bacteria S. aureus and gram-negative bacteriaE. coli. Freshly obtained colonies of S. aureus and E. coli weresuspended in Luria Broth and the turbidity was adjusted to 0.5McFarland standards. Two hundred microliters of this suspen￾sion was spread on Luria-Agar plates to obtain a semi￾confluent growth. AgNPs-impregnated disks (0.9 mm diame￾ter) and negative control disks were placed on the inoculatedplates. The plates were kept for incubation for 24 h at 37 °Cand the inhibition zones were measured using photographicimages of the agar plates.The interaction of the AgNPs with bacterial colonies andtheir mechanism of action against both E. coli and S. aureuswere observed by HRTEM. The bacterial cells were treatedwith colloidal solution of AgNPs for different time durations.The samples were prepared by adding one drop of the sampleonto a carbon-coated copper grid and then were dried at 40 °C.The presence of Ag inside the cell and interaction at the cellmembrane was confirmed using EDAX.3 Results and discussionThe present investigation is aimed at developing an eco￾friendly and cost-effective route for the synthesis of AgNPsusing Cinnamon zeylanicum bark extract. Cinnamonzeylanicum bark extracts were achieved by solvent extractionprocess in solvents having different polarities—aqueous, eth￾anol, and DMSO. The major component of the extract iscinnamaldehyde (~ 75%) which plays a vital role in the Agreduction process (Fig. 1). Subsequently, extracts in differentsolvents were used for the growth of AgNPs by the reductionof silver ions and also tuned the morphology and size of thenanoparticles. The influence of total polyphenol content, an￾tioxidant activity, and total aldehyde content in extracts wasinvestigated and discussed in the later sections.