Photooxidation Properties of Photosensitizer/Direct Dye Patterned Polyester/Cotton Fabrics

Towards the goal of developing anti-infective textiles based on a photodynamic inactivation mechanism, here we present the design, dyeing procedure, characterization, substrate photooxidation studies, and antibacterial efficacy of methylene blue-dyed polyester fabrics, termed MB-polyester. Dye-uptake and apparent K/S (absorption and scattering coefficient) values as a function of MB concentration % (o.w.f) were determined, and were found to correlate. Photooxidation studies employing the model substrate 1,5-dihydroxynaphthalene (1,5-DHN) revealed that the MB-polyester fabrics were able to generate singlet oxygen in an illumination time-dependent manner. Antibacterial efficacy was evaluated against Staphylococcus aureus (ATCC-29213), with our best results achieving a 99.89 % (~3 log units) reduction in Colony-Forming Units (CFU)/mL after only 30 min illumination (Xenon lamp, 3500 mW/cm 2 , 420–780 nm). On the basis of these results with MB-polyester, we subsequently designed patterned dual-dyed polyester/cotton fabrics, wherein an alternating pattern of MBdyed polyester was combined with direct dyes-dyed cotton, and showed that their ability to sensitize singlet oxygen ( 1 O 2 ) in the photooxidation reaction of 1,5-DHN was maintained. Taken together, these findings suggest that MB is a suitable photosensitizer (PS) against S. aureus for the practical development of low-cost polyester-based antimicrobial textiles, and can potentially be used in the production of diverse form-patterned textiles that possess a photodynamic antimicrobial inactivation mechanism.