Photodynamic inactivation studies employing the above bacteria were performed in triplicate as previously described [24 (link), 25 (link), 27 (link), 35 (link), 37 (link)]. Briefly, three fabric samples (1 × 1 cm, ∼40 mg) were individually placed into adjacent wells of two identically prepared 24-well plates. A 100 μL PBS aliquot containing 107–109 CFU/mL of bacteria was added to each of the three wells per plate. The 24-well plate was illuminated at a distance of 12 cm for a defined time period with a xenon lamp (500 W) equipped with a long-pass filter (λ ≥ 420 nm) to provide a light fluence of ~ 65 ± 5 mW/cm2, while an identically prepared 24-well plate was kept without illumination as the dark control. Following illumination, 0.9 mL of sterile PBS was added to each well in both the illuminated and the dark control plates, and the plates were manually stirred with a pipet for 10 s to resuspend the bacteria. Each sample well was then 1:10 serially diluted (100 μL in 0.9 mL aliquots of PBS) six times, and 10 μL from each diluted well were separately plated in columns on gridded six column square plates (TS-agar for S. aureus and MRSA; LB-agar for E. coli), followed by overnight dark incubation at 37 °C. A material-free dark control was prepared by aliquotting 100 μL bacterial PBS solution into 0.9 mL sterile PBS, and following the same dilution process. The number of visible colonies on the agar plates was determined by colony counting, and the survival rate was determined by the ratio of CFU/mL of the illuminated plate versus that of the corresponding material-free dark control. The minimum detection limit was 10 CFU/well (based on the plated 10 μL aliquot from the 1 mL undiluted well), and the detection limits of bacterial survival for S. aureus and E. coli were 0.001% and 0.01%, respectively.