Vertically aligned multi walled carbon nanotubes prevent biofilm formation of medically relevant bacteria.

A significant part of human infections is frequently associated with the establishment of biofilms by (opportunistic) pathogens. Due to the increasing number of untreatable biofilms, there is a rising need to develop novel and effective strategies to prevent biofilm formation on surfaces in medical as well as in technical areas. Bacterial initial attachment and adhesion to surfaces followed by biofilm formation is highly influenced by the physical properties of the surfaces. Consequently, changing these properties or applying different nanostructures is an attractive approach to prevent biofilm formation. Here we report on the effect(s) of surface grown and anchored vertically aligned multi walled carbon nanotubes (MWCNT), which have been made wettable by immersion through a graded ethanol series, on biofilm formation of Klebsiella oxytoca, Pseudomonas aeruginosa, and Staphylococcus epidermidis. We evaluated the biofilm formation under continuous flow conditions by confocal laser scanning microscopy and scanning electron microscopy, and demonstrated significant inhibition of biofilm formation of all the different pathogens by MWCNT of different lengths. Furthermore, the anti-adhesive effects of the MWCNT increased with their overall length. The application potential of our findings on surface grown and anchored vertically aligned MWCNT may represent a suitable contact mechanics based approach to prevent biofilm formation on medical devices or technical sensors operating in fluid environments.

Biofuel cells based on direct enzyme-electrode contacts using PQQ-dependent glucose dehydrogenase/bilirubin oxidase and modified carbon nanotube materials.

Two types of carbon nanotube electrodes (1) buckypaper (BP) and (2) vertically aligned carbon nanotubes (vaCNT) have been used for elaboration of glucose/O2 enzymatic fuel cells exploiting direct electron transfer. For the anode pyrroloquinoline quinone dependent glucose dehydrogenase ((PQQ)GDH) has been immobilized on [poly(3-aminobenzoic acid-co-2-methoxyaniline-5-sulfonic acid), PABMSA]-modified electrodes. For the cathode bilirubin oxidase (BOD) has been immobilized on PQQ-modified electrodes. PABMSA and PQQ act as promoter for enzyme bioelectrocatalysis. The voltammetric characterization of each electrode shows current densities in the range of 0.7-1.3 mA/cm(2). The BP-based fuel cell exhibits maximal power density of about 107 µW/cm(2) (at 490 mV). The vaCNT-based fuel cell achieves a maximal power density of 122 µW/cm(2) (at 540 mV). Even after three days and several runs of load a power density over 110 µW/cm(2) is retained with the second system (10mM glucose). Due to a better power exhibition and an enhanced stability of the vaCNT-based fuel cells they have been studied in human serum samples and a maximal power density of 41 µW/cm(2) (390 mV) can be achieved.