High Aspect Ratio Nanostructures Kill Bacteria via Storage and Release of Mechanical Energy.

Linklater, Denver P 
Baulin, Vladimir A 
Werner, Marco 
Jessl, Sarah 

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The threat of a global rise in the number of untreatable infections caused by antibiotic-resistant bacteria calls for the design and fabrication of a new generation of bactericidal materials. Here, we report a concept for the design of antibacterial surfaces, whereby cell death results from the ability of the nanofeatures to deflect when in contact with attaching cells. We show, using three-dimensional transmission electron microscopy, that the exceptionally high aspect ratio (100-3000) of vertically aligned carbon nanotubes (VACNTs) imparts extreme flexibility, which enhances the elastic energy storage in CNTs as they bend in contact with bacteria. Our experimental and theoretical analyses demonstrate that, for high aspect ratio structures, the bending energy stored in the CNTs is a substantial factor for the physical rupturing of both Gram-positive and Gram-negative bacteria. The highest bactericidal rates (99.3% for Pseudomonas aeruginosa and 84.9% for Staphylococcus aureus) were obtained by modifying the length of the VACNTs, allowing us to identify the optimal substratum properties to kill different types of bacteria efficiently. This work highlights that the bactericidal activity of high aspect ratio nanofeatures can outperform both natural bactericidal surfaces and other synthetic nanostructured multifunctional surfaces reported in previous studies. The present systems exhibit the highest bactericidal activity of a CNT-based substratum against a Gram-negative bacterium reported to date, suggesting the possibility of achieving close to 100% bacterial inactivation on VACNT-based substrata.

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carbon nanotubes, interface interactions, mechanobactericidal mechanism, nanoscale mechanics, storage of elastic energy, vertically aligned carbon nanotubes
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ACS Nano
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American Chemical Society
EPSRC (1470335)
European Research Council (337739)
European Commission Horizon 2020 (H2020) Marie Sk?odowska-Curie actions (702435)
European Commission (608184)
MDV and SJ acknowledge support from the ERC Starting Grant HIENA 337739. V.A.B. M.W. and E.P.I. acknowledge funding from Marie Curie Actions under EU FP7 Initial Training Network SNAL 608184.