Bacterial colonization of medical devices and implants is a significant unsolved problem. However, antimicrobial protection of biomedical devices have proven to be an extremely challenging task, mostly due to depletion of antimicrobial activity of the coatings over time, accumulation of bacterial debris near surfaces, and/or development of bacterial resistance to treatment. Here, we describe two strategies to develop ultrathin antibacterial polymer coatings which can be assembled at a variety of surfaces using the layer-by-layer (LbL) technique. The first one includes constructing polymer matrices capable of hosting, protecting and delivering antibiofilm agents in response to bacterial infection. The coatings combine several advantageous features, whose synergistic action results in its outstanding performance. These features include high loading capacity to antimicrobial agents (AmAs), non-leaching nature of the coating, biocompatibility, and its unique capability to release AmAs only where and when needed. Specifically, the coatings do not release antibiotics in PBS at pH 7.4 in the absence of bacteria, but release increased amounts of antibacterial agents when pH is lowered locally from 7.4 to 5.5 in the presence of pH-lowering bacteria, such as Staphylococcus epidermidis, Staphylococcus aureus and Escherichia Coli. The second type of LbL antibacterial coatings does not contain antibiotics and kills bacteria through pH-triggered hydrophobicity. Importantly, all types of coatings were nontoxic toward murine osteoblast cells, supporting cell attachment and proliferation. We believe that these coatings present a promising way to provide antibacterial protection of surfaces, and might be especially useful for preventing bacterial colonization of orthopedic implants.

Self-defensive antibacterial polymer coatings

252nd National Meeting (2016)

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