30 research outputs found
Bioinspired bactericidal surfaces with polymer nanocone arrays
Infections resulting from bacterial biofilm formation on the surface of medical devices are challenging to treat and can cause significant patient morbidity. Recently, it has become apparent that regulation of surface nanotopography can render surfaces bactericidal. In this study, poly(ethylene terephthalate) nanocone arrays are generated through a polystyrene nanosphere-mask colloidal lithographic process. It is shown that modification of the mask diameter leads to a direct modification of centre-to-centre spacing between nanocones. By altering the oxygen plasma etching time it is possible to modify the height, tip width and base diameter of the individual nanocone features. The bactericidal activity of the nanocone arrays was investigated against Escherichia coli and Klebsiella pneumoniae. It is shown that surfaces with the most densely populated nanocone arrays (center-to-center spacing of 200 nm), higher aspect ratios (>3) and tip widths <20 nm kill the highest percentage of bacteria (∼30%)
Sonochemically-Produced Metal-Containing Polydopamine Nanoparticles and Their Antibacterial and Antibiofilm Activity
A facile
one-pot sonochemical synthesis of Cu-, Ag-, and hybrid
Cu/Ag-based polydopamine nanoparticles (Cu-, Ag-, and Cu/Ag-PDA-NPs)
and the mechanisms by which they exert antibacterial and antibiofilm
activities are reported. We showed that the nanoparticles are spherical
with a core–shell structure. Whereas Cu is chelated to the
shell of Cu-PDA-NPs in oxidation states of +1/+2, the core of Ag-PDA-NPs
is filled with elemental Ag°. Sonochemical irradiation of dopamine
in the presence of both Cu<sup>2+</sup> and Ag<sup>+</sup> generates
hybrid Cu/Ag-PDA-NPs, whose shells are composed of Cu-chelated PDA
with Ag° in the core. The redox potential of the metals was found
to be the main determinant of the location and oxidation state of
the metals. Leaching studies under physiological conditions reveal
a relatively fast release of Cu ions from the shell, whereas Ag leaches
very slowly from the core. The metal-containing PDA-NPs are highly
microbicidal and exhibit potent antibiofilm activity. The combination
of both metals in Cu/Ag-PDA-NPs is especially effective against bacteria
and robust biofilms, owing to the dual bactericidal mechanisms of
the metals. Most importantly, both Ag- and Cu/Ag-PDA-NPs proved to
be significantly more antibacterial than commercial Ag-NPs while exhibiting
lower toxicity toward NIH 3T3 mouse embryonic fibroblasts. Mechanistically,
the metal-containing PDA-NPs generate stable PDA-semiquinone and reactive
oxygen species under physiological conditions, which contribute at
least partly to the antimicrobial activity. We also demonstrated that
simple treatment of surfaces with Ag-PDA-NPs converts them to antibacterial,
the activity of which was preserved even after prolonged storage under
ambient conditions