2 research outputs found
Nanopatterned Smart Polymer Surfaces for Controlled Attachment, Killing, and Release of Bacteria
Model
surfaces with switchable functionality based on nanopatterned,
thermoresponsive poly(<i>N</i>-isopropylacrylamide) (PNIPAAm)
brushes were fabricated using interferometric lithography combined
with surface-initiated polymerization. The temperature-triggered hydration
and conformational changes of nanopatterned PNIPAAm brushes reversibly
modulate the spatial concealment and exposure of molecules that are
immobilized in the intervals between nanopatterned brushes. A biocidal
quaternary ammonium salt (QAS) was used to demonstrate the utility
of nanopatterned PNIPAAm brushes to control biointerfacial interactions
with bacteria. QAS was integrated into polymer-free regions of the
substrate between nanopatterned PNIPAAm brushes. The biocidal efficacy
and release properties of these surfaces were tested against <i>Escherichia coli</i> K12. Above the lower critical solution
temperature (LCST) of PNIPAAm, desolvated, collapsed polymer chains
facilitate the attachment of bacteria and expose QAS moieties that
kill attached bacteria. Upon a reduction of the temperature below
the LCST, swollen PNIPAAm chains promote the release of dead bacteria.
These results demonstrate that nanopatterned PNIPAAm/QAS hybrid surfaces
are model systems that exhibit an ability to undergo noncovalent,
dynamic, and reversible changes in structure that can be used to control
the attachment, killing, and release of bacteria in response to changes
in temperature
“End-Only” Functionalized Oligo(phenylene ethynylene)s: Synthesis, Photophysical and Biocidal Activity
It is essential to develop alternative strategies to treat infections, especially those infections caused by Staphylococcus aureus, which is responsible for most skin infections. Among those strategies, light-induced inactivation of pathogens appears to be a promising candidate. We present four novel “end only” oligo(phenylene ethynylene)s (EO-OPE-1s) that have the ends functionalized with cationic groups and are powerful light-activated biocides against Escherichia coli, Staphylococcus epidermidis, and S. aureus. We have correlated the light-induced biocidal activities with singlet oxygen quantum yields Φ (<sup>1</sup>O<sub>2</sub>) of EO-OPE-1s, and a higher Φ (<sup>1</sup>O<sub>2</sub>) correlates with a better light-induced biocidal activity. Coupled with our previous work on the interactions of EO-OPE-1s with dioleoyl-<i>sn</i>-glycero-3-phosphocholine (DOPC)/cholesterol vesicles, we believe the biocidal process involves the following: (1) EO-OPE-1s penetrate the bacterial membrane, (2) EO-OPE-1s photosensitize the generation of singlet oxygen and/or other reactive oxygen species, and (3) singlet oxygen and/or reactive oxygen species trigger the cytotoxicity