Functionalization of Ti surface with metal phenolic networks and “green” silver nanoparticles: in vitro evaluation of antimicrobial activity and cytocompatibility.

GONZALEZ A; PRIETO E; FAGALI NS; SCHILARDI PL; FERNANDEZ LORENZO, M

Mar del Plata

Congreso; XII Latin-American Congress of Artificial Organs and Biomaterials (12 COLAOB 2023); 2023

COLAOB

Introduction and objective: In recent years, there has been a significant increase in infections associated with biofilm growth on implantable materials due to acquired bacterial resistance to conventional antimicrobial therapies. New nanotechnological strategies have been proposed to prevent these infections including antimicrobials nanoparticles and nanocoatings. In this study, we first evaluated the functionalization of Ti surface with a nanocoating of pyrogallol-based metal phenolic network (MPN-PG-Ti) and then with the deposition of silver nanoparticles (AgNPs) obtained through “green” nanotechnology (AgNPs-MPN-PG-Ti). The antimicrobial activityagainst Staphylococcus aureus (the main bacteria involved in implant infections) and the cytocompatibility in the MC3T3-E1 pre-osteoblastic cell line were evaluated.Methodology: “Green” AgNPs were synthetized using AgNO3 and gallic acid as reductant agent (pH=10). AgNPs were characterized through UV-visible spectroscopy. The average diameter of AgNPs was measured using TEM images. To form MPN-PG-Ti, Ti samples were immersed in a solution containing PG, BufferTris-HCl and MgCl2 (pH=8.5) for 4h [1]. Subsequently, the MPN-PG-Ti samples were immersed in AgNPs suspension. AFM topographical and FTIR spectroscopic characterizations of AgNPs-MPN-PG-Ti were performed. The antimicrobial activity was assessed by counting the colony forming units (CFU/cm2) after a 24h-exposure. Cytocompatibility wasevaluated by acridine orange staining after 1, 2, 5 and 7d of incubation in MC3T3-E1 culture.Results and discussion: The UV−visible spectrum of AgNPs exhibits a single sharp band at 404nm. A bimodal size distribution was observed through TEM microscopy, with the main population having an average size of 18.5nm and another population with an average size of 40nm. The formation of MPN-PG-Ti was confirmed through FTIR spectra and AFM images. The FTIR-spectrum of MPN-PG-Ti depicted peaks at 3260 cm-1, 1630 cm-1, 1138 cm-1 and 1042 cm-1 corresponding to –OH groups, ketonic groups, C-H and C-O vibrations, respectively [2]. The AFM imagesrevealed that MPN-PG-Ti completely covers the Ti surface, resulting in flattened topography compared to polished Ti control. Additionally, numerous AgNPs were observed attached in isolated form on the coating. The antimicrobial effect evaluated against S. aureus demonstrated that the Ti control exhibited 2.85 ± 0.85 (E+06) CFU/cm2, whereas the MPN-PG-Ti and AgNPs-MPN-PG-Ti samples reduced the CFU count by 1 and 3 orders of magnitude, respectively, compared to the Ti control. This indicates that the addition of AgNPs enhanced the antimicrobial effect of the coating. The cytocompatibility of each sample was determined by percentage of the covered area by cells. The results showed that MPN-PG-Ti and AgNPs-MPN-PG-Ti samples exhibited similarcovered areas, demonstrating their similar cytocompatibility.Conclusions: The results demonstrated that MPN-PG was formed on the Ti surface using a simple technique, and the “green” synthesized AgNPs could be effectively adhered to the MPN-PG-Ti surface, leading to a significant increase in the antimicrobial effect against S. aureus. Moreover, considering the cytocompatibility of MPN-PG-Ti with AgNPs for pre-osteoblastic cells, this nanotechnological strategy holds great promise as an alternative approach to combat and prevent biofilm formation and associated infection linked to Ti implants.