Green synthesis of silver nanoparticles using five varieties of Cordyline fruticosa sp. leaves and reviewing their antimicrobial, antioxidant and photocatalytic properties

Abstract

The biological synthesis of nanoparticles using plants or microorganisms has gained attention in the recent past, mainly due to its eco-friendly nature and because they can be used in a vast variety of fields such as medicine, agriculture and textiles. The current study focuses on the green synthesis of silver nanoparticles (AgNPs) using five varieties of Cordyline fruticosa (candy cane, waihee rainbow, exotica, pink cascade and pink diamond) leaves, and assessing their antioxidant, photocatalytic and antimicrobial activities. SEM analysis of pink cascade-AgNPs shows they are spherical and in the range of 40-50nm. Band gap energy calculations reveal that synthesized AgNPs can act as semiconductors.  Total flavonoid content, total phenolic content and total antioxidant capacity were analyzed and the DPPH-free radical scavenging assay was performed. These showed that AgNPs had higher antioxidant activity compared to aqueous extracts. The antibacterial activity of AgNPs and aqueous extracts was assessed using cultures of Escherichia coli and Staphylococcus aureus. Extracts and AgNPs showed better bactericidal effect on S.aureus. Photocatalytic activity of synthesized AgNPs was assessed using malachite green as a model dye and significant degradation of the dye was observed when AgNPs were added together with catalyst NaBH4. According to the results obtained from this study, it can be seen that AgNPs synthesized using Cordyline fruticosa have potential in different aspects including treatment of free-radical mediated diseases, overcoming antibiotic resistance, treatment of bacterial diseases and overcoming environmental pollution.