Impaired Biofilm Development on Graphene Oxide-Metal Nanoparticle Composites

Agata Lange,1 Marta Kutwin,1 Katarzyna Zawadzka,1 Agnieszka Ostrowska,1 Barbara Strojny-Cieślak,1 Barbara Nasiłowska,2 Aneta Bombalska,3 Sławomir Jaworski1 1Department of Nanobiotechnology, Institute of Biology, Warsaw University of Life Sciences, Warsaw, Poland; 2Center for Biomedical Engineering, Institute of Optoelectronics, Military University of Technology, Warsaw, Poland; 3Department of Optoelectronic Technologies, Institute of Optoelectronics, Military University of Technology, Warsaw, PolandCorrespondence: Agata Lange, Department of Nanobiotechnology, Institute of Biology, Warsaw University of Life Sciences, Ciszewskiego 8, Warsaw, 02-786, Poland, Tel +48 22 593 66 69, Email [email protected]: Biofilms are one of the main threats related to bacteria. Owing to their complex structure, in which bacteria are embedded in the extracellular matrix, they are extremely challenging to eradicate, especially since they can inhabit both biotic and abiotic surfaces. This study aimed to create an effective antibiofilm nanofilm based on graphene oxide-metal nanoparticles (GOM-NPs).Methods: To create nanofilms, physicochemical analysis was performed, including zeta potential (Zp) (and the nanocomposites stability in time) and size distribution measurements, scanning transmission electron microscopy (STEM), energy dispersive X-ray analysis (EDX), and atomic force microscopy (AFM) of the nanofilm surfaces. During biological analysis, reactive oxygen species (ROS) and antioxidant capacity were measured in planktonic cells treated with the nanocomposites. Thereafter, biofilm formation was checked via crystal violet staining, biofilm thickness was assessed by confocal microscopy using double fluorescent staining, and biofilm structure was analyzed by scanning electron microscopy.Results: The results showed that two of the three nanocomposites were effective in reducing biofilm formation (GOAg and GOZnO), although the nanofilms were characterized by the roughest surface, indicating that high surface roughness is unfavorable for biofilm formation by the tested bacterial species (Staphylococcus aureus (ATCC 25923), Salmonella enterica (ATCC 13076), Pseudomonas aeruginosa (ATCC 27853)).Conclusion: The performed analysis indicated that graphene oxide may be a platform for metal nanoparticles that enhances their properties (eg colloidal stability, which is maintained over time). Nanocomposites based on graphene oxide with silver nanoparticles and other types of nanocomposites with zinc oxide were effective against biofilms, contributing to changes throughout the biofilm structure, causing a significant reduction in the thickness of the structure, and affecting cell distribution. A nanocomposite consisting of graphene oxide with copper nanoparticles inhibited the biofilm, but to a lesser extent. Keywords: biofilm, graphene oxide, metal nanoparticles, nanocomposites, nanofilms