Optimization and Characterization of Green Synthesis Chrysanthemum Morifolium Silver Nanoparticles and Evaluation of Its Antibacterial Activity

Leong, Lai Mun (2023) Optimization and Characterization of Green Synthesis Chrysanthemum Morifolium Silver Nanoparticles and Evaluation of Its Antibacterial Activity. Final Year Project (Bachelor), Tunku Abdul Rahman University of Management and Technology.

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Abstract

With the rise of microbial infections and antibiotic resistance, attention has been drawn for researchers to explore the therapeutic abilities of silver nanoparticles (AgNPs) as potential antimicrobial agents. This study is aimed to optimize the method for the green synthesis of AgNPs using Chrysanthemum morifolium (CM), and the assessment of its biological activity (TPC, TFC and DPPH) and antibacterial effects. The experimental control parameters, including the ratio of AgNO3 and CM extract, CM extract concentration, AgNO3 concentration, pH, temperature, and duration of incubation were optimized. Maximum synthesis of CM-AgNPs could be achieved with 6:4 ratio of AgNO3:CM, 20mg/mL of CM extract, 10mM AgNO3, pH 11, 40 °C and 3 hours incubation period. Characterization of AgNPs was conducted using UV-Vis spectrophotometry, Fourier transform infrared spectroscopy (FTIR) and Field Emission Scanning electron microscope (FESEM). A change in color from yellow to dark brown and an absorption maximum at 406 nm provided evidence for the synthesis of AgNPs. The CM-AgNPs were spherically shaped, with sizes ranging from 12 to 34 nm across. FTIR showed that many functional group moieties (-OH, -C-O, C=C, etc) are involved as capping and reducing agents in CM-AgNPs biosynthesis. The performed assays (TPC, TFC, and DPPH) indicated higher antioxidant contents and activities in CM-AgNPs compared to the aqueous CM extract. The antibacterial activity of CM-AgNPs was evaluated against four skin-infectious bacteria using the Mueller-Hinton broth microdilution method. The minimum inhibitory concentration (MIC) values of CM-AgNPs against P. mirabilis, S. aureus, P. aeruginosa, and K. pneumonia were 0.0117, 0.0117, 0.003125, and 0.1 mg/mL, respectively. The antibiofilm activity of CM-AgNPs was assessed via crystal violet staining. CM-AgNPs exhibited significant antibiofilm activity against P. mirabilis, S. aureus, and K. pneumonia, with inhibition percentages of 49.26%, 87.31% and 66.23% at their respective MIC value. These findings suggest that CM-AgNPs have antimicrobial effects and have the potential to be used as a novel antimicrobial agent for the treatment of multidrug resistant bacterial infections. Keywords: Chrysanthemum morifolium, Total phenolic content (TPC), Total flavonoid content (TFC), DPPH, Antibiofilm