In last decades, several strategies based on antiadhesive, antiseptic or antibiotic coating of polymers have been developed to prevent biofilm formation on the outer and inner surfaces of medical devices. However, the so far developed medicated devices are able to delay microbial colonization in spite of definitively solving the problem of biofilm formation and related infections. In fact, these devices mainly suffer from a relatively short persistence of antimicrobial action as consequence of an early and rapid drug release. In the last years, we focused our research efforts in developing different experimental approaches to prevent microbial colonization of central venous catheters based on the adsorption of antimicrobial agents to synthesized and properly functionalized polyurethanes with the aim to control drug adsorption and release. The new antibiofilm strategies we are dealing with concern: i) the development of antimicrobial polymers by the use of polyurethanes able to coordinate metal ions (Ag+, Zn2+, etc); ii) the exploiting of the biofilm matrix-degrading enzyme, DispersinB, to enhance the penetration of antibiotics through the biofilm; iii) the set up of a magnetic nanoparticles (MNPs)-based targeting system to fight in situ catheter-related infections. As the metal ion-containing polymers are concerned, a carboxylated polyetherurethane (PEUA) was treated with silver, copper, zinc, aluminium and iron salts, thus obtaining PEUA-Ag, PEUA-Cu, PEUA-Zn, PEUA-Al and PEUA-Fe. A part from PEUA-Al, all polymers showed significant antimicrobial properties. The most active was PEUA-Ag which resulted to be able to inhibit S. epidermidis biofilm formation up to 16 days. As the Dispersin B is concerned, we carried out collaborative experiments with Jeff Kaplan group to evaluate the antibiofilm activity of this β-N-acetylglucosaminidase once adsorbed to our polyurethanes, either alone or in combination with antibiotics. Finally, we are currently developing a strategy to fight in situ biofilm development by the use of antibiotic loaded-MNPs to be intravenously injected in at risk patients and driven to the device implantation areas by the application of an external magnetic field. This approach will allow an in situ, on demand treatment of biofilm infections. Drugs are expected be released only in the close surroundings of the colonized device and when clinically required. If the planned experiments in animals will be successful, patients could be treated either immediately after the device implant or later in presence of signs of infection.
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|Titolo:||Novel strategies to prevent and control biofilm growth on central venous catheters|
|Data di pubblicazione:||2009|
|Appartiene alla tipologia:||04a Atto di comunicazione a congresso|