Elucidating strategies to design tailored chitosan surfaces with enhanced antibiofouling and biocompatibility properties via plasma assisted processes

Bacteria colonization of surfaces is often an undesired process. It affects human activities across different fields, including agriculture, marine transportation, the food, textile, oil and biomedical industries. Its negative effects incur in economic and human lives losses. Bacteria colonization is a main component in biofouling, and it is a process that starts with the bacteria adhesion to a surface and subsequent biofilm formation. The production of materials that inhibit bacteria attachment and growth is desired. The emergence of antibiotic resistant (ABR) bacteria, first reported in the first half of the twentieth century, is directly linked to hundreds of thousands of deaths every year, a number that could increase to millions per year in the next decades. ABR has been catalogued a global health emergency. In the medical setting, infections linked to bacteria colonization are one of the leading causes of implant and biomaterial failures. The fate of a biomedical implant has been described as a race to the surface, between bacteria adhesion and cell integration. With ABR rendering antibiotics inefficient in some scenarios, new strategies to fight bacteria colonization are required. Chitosan is a natural biopolymer, derived from chitin, the second most abundant polymer in nature. Its applications extend to food packaging and preservation, biocatalysis, water treatment and bioengineering. Due to its unique biocompatibility, biodegradability and antibacterial properties, chitosan has sparked attention as a material for biomedical applications. The antimicrobial properties of silver have been well-known for centuries, and its derivatives were being used as an antimicrobial well before the discovery of antibiotics. Silver nanoparticles, more recently developed, share similar antimicrobial activity of silver in other forms, but offer other interesting properties. Their use has been popularized after the emergence of ABR as a potential alternative to antibiotics. This work focuses on the exploration of two strategies to design surfaces with antibacterial properties, based on plasma and ion irradiation processes. Chitosan and silver were used as the platform to produce antibacterial surfaces. The first part of this work focuses on the study of ion irradiation of chitosan membranes. This surface treatment induced chemical and structural changes to the surface of this biopolymer and evidenced the formation of ion irradiation-driven self-organized nanostructures. The tunability of the characteristics induced on the modified surfaces via variation of irradiation parameters was explored. In the second part, an atmospheric pressure plasma jet was used to drive the formation of silver nanoparticles from a precursor solution. The treated particles were incorporated into chitosan membranes to serve as a surface for testing. The antibacterial activity and biocompatibility of the ion-irradiated and atmospheric plasma-treated samples was studied. The nanostructured surface of chitosan membranes exhibited an enhancement of their antibacterial properties and an improvement of cell adhesion and proliferation. Silver-loaded chitosan membranes also exhibited reduced bacteria growth while retaining a reduced cytotoxicity. These results establish a step towards the design of advanced biointerfaces with high control over the tunability of their properties as an alternative of antibiofouling surfaces with low toxicity.LimitedAuthor requested closed access (OA after 2yrs) in Vireo ETD syste