Optimized transport mechanisms of bacteriophages for the development of antibacterial coatings – MAGENTA

Adhesion of micro-organisms, in particular bacteria, plays an important role in biofilms formation and the colonization of biotic or abiotic surfaces. These biofilms can be formed on any type of surfaces, and represent important financial losses e.g. in food and water treatment industries. Moreover, biofilms can constitute a major risk to public health (hospital environment, agro-industry). Bacterial cells forming the biofilms can indeed show higher resistance to bactericides, biocides and other antibiotic molecules as compared to that shown by planktonic bacteria. In the past decade, many strategies were developed to prevent biofilms formation. For instance, some of them consisted in chemically modifying surfaces by grafting antimicrobial molecules or by depositing an anti-adhesive layer. However, these strategies are generally not very satisfactory in terms of cost, environmental impact, toxicity and effectiveness in time. The project proposed here aims to design a new type of antibacterial coating to prevent biofilms formation at mid-term. The originality of our project lies in the choice to immobilize and store bacteriophages into a biomaterial matrix and to use viral infection processes as a basis for preventing biofilm formation. This may allow for the adhesion of other cells or bacteria onto the support. The selected coating/biomaterial is a polyelectrolyte multilayer film (PEM) able to trap, store and possibly release phages. In addition, it is expected that the chosen coating will be able to self-regenerate in terms of functionalization by reincorporating the phages released after bacterial lysis. Since the end of the 90’s, studies performed on biomaterials, in particular (PEM) films, highlighted that these new materials have innovating and flexible properties (viscoelasticity, hydrophobicity, hydration, tank effect) and a large range of potential applications in various fields (biomedicine, agrobusiness, aircraft, pharmaceutical industries). In addition, PEMs are not expensive, easy to manufacture and do not show environmental impact or toxicity. Infection mechanisms of bacteria by phages are a natural process, which constitutes a way to prevent effectively the formation of biofilms on surfaces. This is true both under conditions where bacteria are able to multiply (nutritive environments) and when growth is sluggish. The use of bacteriophages for that purpose remains at this time largely unexplored despite the major benefits that it could represent, not only because of the absence of harmful effects like those related to toxicity of antibiotics and other antimicrobial molecules, but also because the bacterial resistance to bacteriophages should be easier to avoid/inhibit with employing adequate cocktails of phages. Altogether, this offers a promising alternative to the conventional use of antibiotics. The design of a new antibacterial biomaterial made of polyelectrolytes functionalized by phages, requires a fundamental study of the physicochemical properties of the polymeric matrices (PEM), the transport processes (storage/release) of the phages in the PEMs and their infectious capacities with respect to targeted bacteria. Understanding the mechanisms that govern these transport phenomena, storage and salting out of the phages within/from the PEM matrix is necessary to develop and optimize biomaterial functionalization. It is anticipated that the successful realization of such a biofunctionalized material would be of major interest in applied sciences related to e.g. water transport issues, agrobusiness, biomedicine and pharmacy.