Owusu, EGA;
Yaghini, E;
Naasani, I;
Parkin, IP;
Allan, E;
MacRobert, S;
(2020)
Synergistic Interactions of Cadmium-free Quantum Dots Embedded in a Photosensitised Polymer Surface: Efficient Killing of Multidrug-Resistant Strains at Low Ambient Light Levels.
Nanoscale
10.1039/c9nr10421f.
(In press).
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Abstract
Cadmium-free quantum dots (QD) were combined with crystal violet photosensitising dye and incorporated into medical grade polyurethane via a non-covalent dipping process known as ‘swell-encapsulation-shrink’. The antibacterial efficacy of the prepared quantum dot-crystal violet polyurethane substrates (QD + CV PU) was investigated under low power visible light illumination at similar intensities (500 lux) to those present in clinical settings. The antibacterial performance of QD + CV PU was superior to the constituent polymer substrates, eliminating ~99.9% of an environmental P. aeruginosa strain, a clinical P. aeruginosa strain from a cystic fibrosis patient and a clinical E. coli strain. The nature of the reactive oxygen species (ROS) involved in antibacterial activity of the QD + CV surface was investigated using ROS inhibitors and time-resolved optical spectroscopy. The photophysical interaction of the green-emitting QDs with CV leads to a combination of Type I and II electron transfer and energy transfer processes, with the highly potent ROS singlet oxygen playing a dominant role. This study is the first to demonstrate highly efficient synergistic killing of clinical and environmental strains of intrinsically resistant and multi-drug resistant Gram-negative bacteria using light-activated surfaces containing biocompatible cadmium-free QDs and crystal violet dye at ambient light levels.
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