In many environmental scenarios, the fate and impact
of polymer nanocomposites (PNCs) that contain carbon nanotubes
(CNT/PNCs) will be influenced by their interactions with
microorganisms, with implications for antimicrobial properties and
the long-term persistence of PNCs. Using oxidized single-wall (OSWCNTs)
and multi-wall CNTs (O-MWCNTs), we explored the
influence that CNT loading (mass fraction <0.1%-10%) and type
have on the initial interactions of Pseudomonas aeruginosa with OCNT/
poly(vinyl alcohol) (PVOH) nanocomposites containing welldispersed
O-CNTs. LIVE/DEAD staining revealed that, despite
oxidation, the inclusion of O-SWCNTs or O-MWCNTs caused
PNC surfaces to exhibit antimicrobial properties. The fraction of
living cells deposited on both O-SWCNT and O-MWCNT/PNC
surfaces decreased exponentially with increasing CNT loading, with
O-SWCNTs being approximately three times more cytotoxic on a % w/w basis. Although not every contact event between
attached microorganisms and CNTs led to cell death, the cytotoxicity of the CNT/PNC surfaces scaled with the total contact
area that existed between the microorganisms and CNTs. However, because the antimicrobial properties of CNT/PNC surfaces
require direct CNT-microbe contact, dead cells were able to shield living cells from the cytotoxic effects of CNTs, allowing
biofilm formation to occur on CNT/PNCs exposed to Pseudomonas aeruginosa for longer time periods.
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Environ. Sci. Technol. 2015, 49, 5484-5492
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