Compact poly-electrolyte complex hydrogels of gelatin and sodium alginate for sensing wound status

•Developed pH sensitive poly-electrolyte complex hydrogels for sensing wound status.•Gallic acid, the active sensory ingredient, induces the formation of the hydrogels.•Gallic acid invert the zeta potential value of aqueous gelatin solution (pH-7).•In acidic pH (pH < 7), colour (pale yellow/off white) of the hydrogels remains intact.•Hydrogels enable visual detection of infected wound by changing its colour at pH > 7.