Core-shell nanoparticles based on zirconia covered with silver as an advantageous perspective for obtaining antimicrobial nanocomposites with good mechanical properties and less cytotoxicity

Antimicrobial nanoparticles perform a vast and promising strand of applications, among which, the silver ones stand out due to their broad antimicrobial spectrum. However, their toxicological potential in addition with their not always satisfying mechanical properties limit their wider application. In this sense, the use of core-shell systems can generate materials with improved properties. Thus, the goal of the present work was to obtain zirconia-silver core-shell nanoparticles and, after that, evaluate their properties in systems based on poly(lactide) PLA. Systems containing silver nanoparticles (AgNP), zirconium oxide (ZrNP), a physical mixture of both particles and core-shell nanoparticles (Core-shell NP) were evaluated. The Core-shell NP were characterized by dynamic light scattering (DLS), Energy Dispersive X-Ray (EDX), transmission electronic microscopy (TEM), and antimicrobial activity. The nanocomposite films were evaluated by Fourier transform infrared analysis (FTIR), thermogravimetric analysis (TGA), nano-hardness, tensile strength test, cytotoxicity, and antimicrobial activity. The results obtained from the DLS and EDX analyses confirmed the obtaining of systems covered with silver. Through the TEM analysis, the formation of the core-shell structure with a diameter of about 100 nm was observed. The films containing core-shell NP presented antimicrobial activity with a profile correspondent to the one observed for AgNP. As for cytotoxicity, these particles proved to be less cytotoxic and achieved higher values of hardness (10%), modulus (40%), and toughness (28%) than those observed for AgNP, and these properties were lower than those observed for ZrNP. The core-shell NP also exhibited even greater antimicrobial activities, less cytotoxicity, and largest elastic modulus (17%) than the physical mixture of the particles.