Development and characterization of silver nanoparticles obtained by green synthesis from leaves of Aguaribay (Schinus areira).

BORDON, ANAHI; FERREYRA MAILLARD, ANIKE PV; CUTRO, ANDREA; HOLLMANN, AXEL

Virtual

Congreso; XLIX Reunión Anual SAB; 2021

Sociedad Argentina de Biofisica

The increased emergence of antibiotic-resistant bacteria is a serious health problemworldwide. This situation has motivated the research of new antimicrobial agents. In thissense, nanoparticles have received increasing attention for their antimicrobial activity. Theobjective of this work was to obtain silver nanoparticles (AgNPs), from AgNO3, by greensynthesis using an aqueous extract of leaves of Schinus areira as a reducer and stabilizeragent, and characterization of its antimicrobial action against gram-positive and gram-negative bacteria. The AgNPs obtained were evaluated by UV-vis spectroscopy, ZetaPotential and DLS, confirming the presence of AgNps with a maximum absorbance at 420nm and the absorption intensity of the resulting spectra increased as a function of theamount of extract used (2 %, 4% and 8%). The AgNPs obtained with the lowconcentration of extract show the highest size and polydispersity (66,3±35,8 nm) whilethere were no significant differences between the other two remaining conditions with anaverage size around 40 nm. Later, the minimum inhibitory concentration (MIC) and theminimum bactericidal concentration (CBM) of the AgNPs obtained using 4% and 8% ofleaves extract were determined in E. coli and S. aureus. Both nanoformulations showedhigh antibacterial activity with MIC values of around 2 pM and CBM of 4 to 8 pM. To abetter knowledge of the antibacterial action, death curves were carried out. In agreementwith the CBM data, both syntheses at 2 x MIC managed to reduce 90% of the bacterialpopulation after 1 hour of incubation. Finally, to characterize the mechanism of action,determination of the oxygen reactive species (ROS) and membrane damage wereevaluated by spectrofluorometry. Both AgNPs tested were able to increase ROS levels in E.coli and S. aureus, as well as induce some damage in the bacterial membrane, but withsome differences among each synthesis. Overall, it can be concluded that thesebiosynthesized produce AgNPs that have colloidal stability and antibacterial activitytoward gram-positive and gram-negative bacteria. Regarding the mechanism of action,our findings suggest that the intracellular ROS induction by AgNPs could induce oxidativestress followed by damage to bacterial membrane leading to cell death.