  The spread of antimicrobial resistance calls for chronic wound management
devices that can engage with the wound exudate and signal infection by prompt
visual effects. Here, the manufacture of a two-layer fibrous device with
independently-controlled exudate management capability and visual infection
responsivity was investigated by sequential free surface electrospinning of
poly(methyl methacrylate-co-methacrylic acid) (PMMA-co-MAA) and poly(acrylic
acid) (PAA). By selecting wound pH as infection indicator, PMMA-co-MAA fibres
were encapsulated with halochromic bromothymol blue (BTB) to trigger colour
changes at infection-induced alkaline pH. Likewise, the exudate management
capability was integrated via the synthesis of a thermally-crosslinked network
in electrospun PAA layer. PMMA-co-MAA fibres revealed high BTB loading
efficiency (> 80 wt.%) and demonstrated prompt colour change and selective dye
release at infected-like media (pH > 7). The synthesis of the
thermally-crosslinked PAA network successfully enabled high water uptake (up to
nearly 2500 wt.%) and swelling index (up to nearly 300 a.%), in contrast to
electrospun PAA controls. This dual device functionality was lost when the same
building blocks were configured in a single-layer mesh of core-shell fibres,
whereby significant BTB release (~ 70 wt.%) was measured even at acidic pH.
This study therefore demonstrates how the fibrous configuration can be
conveniently manipulated to trigger structure-induced functionalities critical
to chronic wound management and monitoring.
