Phytosynthesis of silver nanoparticles using Maytenus ilicifolia

Keywords: silver nanoparticles, green chemistry, Maytenus ilicifolia

Introduction: Maytenus ilicifolia (Celastraceae) is endemic in Brazil and is commonly known as ‘espinheira-santa’. This species exhibits gastroprotective effects and its extracts are safer than marketed synthetic inhibitors of the proton pump, such as omeprazole, that presents side effects.1 Metal nanoparticles form the basis for advanced functional materials for medical, food and optical devices.2 Among noble metal nanoparticles, silver nanoparticles (AgNPs) have raised wide interest because of their properties such as chemical stability and good conductivity, what makes them good candidates for catalytic and biomedical applications.3 Conventional techniques used for the synthesis of AgNps are quite expensive and hazardous to the environment. In this context, the use of vegetal extracts to produce these nanoparticles represents a cheap and green methodology4 because plant biomolecules are able to reduce metallic ions in just one step. Therefore, investigations that focus on studying the application of plant extracts to obtain AgNps are relevant, because this can be a new technological use of these extracts.
Objective: The aim of this work was to evaluate the potential of M. ilicifolia leaf extract to promote the synthesis of silver nanoparticles.
Materials and Methods: M. ilicifolia leaves (500.7 g) were crushed and submitted to extraction with ethanol in a Sohxlet apparatus. After distillation under reduced pressure, 350 mL of extract was obtained. An aliquot of this material was diluted with distilled water in the proportion 1:1000. To 1.0 ml of this dilution, 19.0 ml of 1 mM aqueous silver nitrate solution was added. This mixture was then stirred and maintained at 60 °C for 60 min. Reduction of the Ag+ ions was monitored by measuring the UV-visible spectrum of the warm solution at each 15 minutes. The size and morphology of the AgNPs were characterized with a field emission electron gun (FEG) microscope.
Results and Discussion: The color of the AgNO3/ extract solution changed from light brown at 15 min reaction to dark brown after 60 min reaction. This color change pointed out the formation of AgNPs. The nanoparticles presented a UV−visible peak at 435 nm, ζ-potential (zetasizer) of −25.9 ± 5.09 and sizes (FEG analysis) in the range of 100−200 nm, what corroborated the formation of a spherical and stable material, although some clusters were observed.
Conclusion: An eco-friendly synthesis of AgNPs was successful using an ethanolic extract of M. ilicifolia leaves. Further studies will now be carried out to evaluate the biological activities of the particles.
References: 1 Tabach R et al. Phytother. Res. 2017, 31, 921–926.
2Ahmed S et al. .J. Adv.Res. 2016 7, 17–28
3Jadhav K et al. ACS Biomater. Sci. Eng. 2018, 4, 892−899.
4Vishnu Priya V et al. Int. J. Res. Pharm. Sci. 2018, 9, 263-267.