BIOACTIVE COMPOUNDS FROM OPUNTIA FICUS-INDICA IN NANOTECHNOLOGY: BIOSYNTHESIS OF SILVER NANOPARTICLES AND APPLICATIONS

DALMASSO, P.R.; VILLALBA, G. F.; NAZARENO, M.A.; GALLUCCI, M.N.; FERREYRA MAILLARD, A.P.V.

Coquimbo

Congreso; IX International Congress on Cactus Pear and Cochineal; 2017

Nowadays, significant progress is made worldwide to scientifically demonstrate the functional and medicinal properties of cactus. Thus, cacti are considered an important source of bioactive substances and excellent candidates for food and pharmaceutical industries. There is a growing scientific interest on nanoparticles and mainly of silver nanoparticles (AgNPs) to develop different products. AgNPs possess unique properties, such as high electrical conductivity, chemical stability, catalytic and antimicrobial activity. Traditionally, AgNPs have been synthesized via physical and chemical procedures that often use toxic materials. Recently, biosynthetic methods using microorganisms or plant extracts have emerged as an attractive alternative based on an environment-friendly green chemistry.In this scenario, and regarding its composition in betalains, polyphenols, mucilage, and other specific bioactive compounds, cactus cladodes and fruits appear to be promising candidates as source of phytochemicals responsible for the reduction of Ag+ ions and stabilization of AgNPs. Thus, a simple, economic and efficient eco-friendly method for the biosynthesis of stable, monodisperse silver nanoparticles (AgNPs) using Opuntia ficus-indica cladode or fruit extracts is presented. Different reaction parameters (concentration of plant extract, substrate concentration, pH, temperature and reaction time) were optimized to synthesize AgNPs with controlled properties. Water was used as the environment benign reaction medium and plant metabolites as reducing and capping agent, making the process ecofriendly. AgNPs synthesis was confirmed by UV-vis spectroscopy and nanoparticles were characterized by transmission electron microscopy displaying spherical and pseudospherical morphology. The in vitro antimicrobial efficacy of AgNPs against representative Gram-positive and Gram-negative bacteria, was also evaluated showing antibacterial activity against clinical strains of Staphylococcus aureus, Escherichia coli, and Pseudomonas aeruginosa at picomolar concentration levels. In addition, a mechanistic study of the catalytic activity of biosynthesized AgNPs indicated that they can act as a redox catalyst in the methylene blue dye degradation. This work reports a green method for the synthesis of AgNPs using Opuntia ficus-indica extracts which act as both reducing and capping agent. These biosynthesized AgNPs showed that can be applied for antimicrobial strategies as well as environmental catalysts.