Evaluation of silver nanoparticles synthetic potential of Couroupita guianensis Aubl., flower buds extract and their synergistic antibacterial activity

The present investigation demonstrates Couroupita guianensis flower buds extract mediated synthesis of stable silver nanoparticles (AgNPs). Instant formation of AgNPs was primarily confirmed by the appearance of yellowish brown colour and characteristic silver SPR band in the UV–visible spectrum. Elemental and crystalline natures of the AgNPs were identified from EDX and XRD pattern, respectively. Spherical morphology and the mono-disparity were revealed from TEM and AFM images. The particle size ranged from 5 to 30 nm and average size of 17 nm was consistent in XRD, TEM and AFM measurements. Possible reduction and stabilizing agents, viz., phenolics, flavonoids and proteins were identified from the characteristic FTIR peaks representing their functional groups. The strong antibacterial activity of synthesized AgNPs against Gram-positive and Gram-negative bacteria exhibited the potential for the formulation of synergistic bactericides by combining antibacterial properties of Couroupita flower buds extract and silver salts for biomedical applications.