Quantitative mechanical property mapping of bacteria with Peak Force QNM II: effect of Ag Nanoparticles

CAROLINA DIAZ,; MICAELA BIANCHI; DIEGO E. PISSINIS; ALEJANDRO MIÑAN; PATRICIA L. SCHILARDI; LIA PIETRASANTA

Congreso; XLIII Reunión Anual de la Sociedad Argentina de Biofísica; 2014

Bacterial resistance to antibiotics is considered one of the primary global risks facing the modern medicine. Ag nanoparticles are the most popular inorganic nanoparticles used as antimicrobial promoter. Nevertheless, it has not been yet fully elucidated a mechanism that correctly explains the antimicrobial action of Ag nanoparticles. Some researchers suppose that, Ag nanoparticles can induce pits and gaps in the bacterial membrane and then fragment the cell. The investigation of the effect of silver on bacterial cell wall is important since it can be useful to explain some aspects of the action mechanism of Ag nanoparticles and to further developed better antimicrobial therapies. The determination of the mechanical properties of the bacteria membrane in situ, without any immobilization treatment, has been a longtime challenge. Since its development, AFM is a powerful diagnostic and investigation tool. Nowadays, Peak Force QNM® allows quantitative nanomechanical mapping of material properties, including modulus, adhesion and dissipation, while simultaneously imaging sample topography at high resolution [1]. In the present work, we have studied the effect of Ag nanoparticles on Pseudomona aeruginosa (Gram(-)) and Staphylococcus aureus (Gram(+)) since they have structural differences in their cell walls. Acknowledgements: CONICET, UNLP, ANCyPT, FCEyN, UBA 1 Pittenger, B. et al., Bruker Application Note #128 (2011).