A STUDY ON THE DEPENDENCE OF BACTERIA ADHESION ON THE POLYMER NANOFIBRE DIAMETER

Topography nanostructures have been extensively studied to reduce bacterial adhesion in medical, food and industrial contexts. Fibres have also been used in energy, water and wastewater treatments, and medical applications. Nanosized fibres, however, have rarely been analysed in interactions with bacteria, and they have always resulted as inhibiting bacterial adhesion and proliferation. We discussed here the size effect of polymer nanofibres on the attachment of bacteria. As a model system, a 3D self-standing electrospun nanofibrous poly(?-caprolactone)-based scaffold was fabricated, and Burkholderia terricola bacteria cells were used for testing the interactions. The initial reversible adhesion and the subsequent stable irreversible docking of bacteria to nanofibres through various mechanisms, the orientation of bacteria along nanofibres, and the communication between cells were explored. Bacteria initially attached preferentially to nanofibres with ?100 nm diameter, i.e. an order of magnitude smaller than that of bacteria, resulting in a bacteria-to-nanofibre diameter ratio as large as ?5. It is worth noting that interactions always occurred between bacteria and nanofibres coated with a conditioning film of organic substances of bacterial origin. The conditioning film, the outer membrane vesicles and the bacterial appendages resulted in having a remarkable role in facilitating the following adhesion of B. terricola cells to the electrospun poly(?-caprolactone) nanofibres. They also permitted bacteria to reversibly and then stably attach to the nanofibrous material and connect and communicate each other to form microcolonies embedded in exopolymeric substances, as an early step towards future biofilm formation. No inhibiting effect of the nanosized fibres on the adhesion, proliferation and vitality of the bacterial cells were observed.