Novel anti-biofilm materials for medical devices based on biofunctionalized surfaces

The tendency of microorganisms to develop detrimental biofilms has been well documented for a number of implanted medical devices. Unfortunately, the traditional approaches including systemic antibiotic prophylaxis and local antimicrobial administrations are not consistently and universally effective against biofilm associated infections with devastating medical consequences in term of patient morbidity, mortality, prolonged hospitalization and increased healthcare costs1. In this contest the development of new improved effective therapeutic solutions able to replace the presently dominating drug/device products is becoming imperative. The aim of this work was to develop new effective antibiotic-free therapeutic strategies able to resist to biofilm over a working timescale. The ideal approach would create a permanently non-leaching, long-lasting bio-hybrid materials by covalent functionalization of already used medical device polymers with bio-inspired non-toxic and antibiotic-free anti-biofilm compounds (http://www.anfomat.unimi.it/). The new technology would be able to interfere with the key-steps that orchestrate device-pathogen interactions in order to hampering infection cascade. Depriving microorganisms of their virulence properties without affecting their existence may also decrease selection pressure for drug-resistant mutations, restoring the efficacy of traditional antimicrobial agents2. A new series of chemically modified molecules, related to zosteric acid and salicylic acid scaffold, were proved to be powerful anti-biofilm compounds and the structural characteristics responsible of their anti-biofilm activity were also investigated in order to identify the functional group necessary for their immobilization on the abiotic surface3. This biological study on E. coli growth led us to the identification of molecules as suitable anti-biofilm compounds for grafting the already used medical polymers. A physical and chemical treatment was employed to activate the polyethylene surface without changing their bulk properties and a linker was used to bind the selected bioactive compounds providing the new materials. The anti-biofilm performance of these innovative materials was investigated against E. coli biofilm using specific biofilm reactors (CDC reactor) able to simulate flow conditions normally encountered in vivo.