Infection-responsivity of commercial dressings through halochromic drop-casting

Infection control remains one of the most challenging tasks in wound care, due to growing antimicrobial resistance and ineffective infection diagnostic tools at the point-of-care. To integrate therapeutic wound dressings with wound monitoring capability at the point-of-care to enable informed clinical decision-making, we investigate the encapsulation of a halochromic dye, i.e. bromothymol blue (BTB), onto two commercial dressings, i.e. Aquacel® Extra™ and Promogran®, through a simple drop-casting method. Our concept leverages the infection-associated rise in wound pH, on the one hand, and BTB’s colour change capability in the pH range of healing (pH: 5-6) and infected wounds (pH > 7), on the other hand. BTB-encapsulated samples show a prompt colour switch (yellow/orange Æ blue) following 1-hour incubation at pH 8. The effect of swelling ratio, chemical composition and microstructure is then explored to draw relationships between colour change capability and dressing dye retention.