  Photodynamically active fibres (PAFs) are a novel class of stimulus-sensitive
systems capable of triggering antibiotic-free antibacterial effect on-demand
when exposed to light. Despite their relevance in infection control, however,
the broad clinical applicability of PAFs has not yet been fully realised due to
the limited control in fibrous microstructure, cell tolerance and antibacterial
activity in the physiologic environment. We addressed this challenge by
creating semicrystalline electrospun fibres with varying content of
poly[(L-lactide)-co-(glycolide)] (PLGA), poly(epsilon-caprolactone) (PCL) and
methylene blue (MB), whereby the effect of polymer morphology, fibre
composition and photosensitiser (PS) uptake on wet state fibre behaviour and
functions was studied. The presence of crystalline domains and PS-polymer
secondary interactions proved key to accomplishing long-lasting fibrous
microstructure, controlled mass loss and controlled MB release profiles (37
degC, pH 7.4, 8 weeks). PAFs with equivalent PLGA:PCL weight ratio successfully
promoted attachment and proliferation of L929 cells over a 7-day culture with
and without light activation, while triggering up to 2.5 and 4 log reduction in
E. coli and S. mutans viability, respectively. These results support the
therapeutic applicability of PAFs for frequently encountered bacterial
infections, opening up new opportunities in photodynamic fibrous systems with
integrated wound healing and infection control capabilities.
