PVA/PAA based electrospun nanofibers with pH-responsive color change using bromothymol blue and on-demand ciprofloxacin release properties

In this study, a nanofibrous mat of polyvinyl alcohol (PVA) and polyacrylic acid (PAA) loaded with pH-responsive dye bromothymol blue (BTB) and antibacterial drug ciprofloxacin was fabricated by using the electrospinning method. The nanofibrous mats were crosslinked by heat treatment to enhance stability in an aqueous medium. The pH-responsive property of PAA and halochromic BTB were utilized to functionalize the mats for on-demand ciprofloxacin release and wound condition monitoring, respectively. The yellowish color of the nanofiber mat changed to green and blue at pH 7 and 8.5 which simulates wound condition. The ionization of –COOH bonds of PAA at higher pH causes repulsion among -COO- which causes incorporated drug to release faster than the release at lower pH condition. The release of the drug doubled, from 15% to 33%, within 2 h at a higher pH release medium. The swelling of the nanofibrous mats was 1378% at pH 7 and 1565% at pH 8.5 environment compared to 545% at pH 4 environment. The water vapor transmission rates (WVTR) of the nanofibrous mats were higher than the required WVTR value for efficient wound healing. Antibacterial drug ciprofloxacin enhanced the functionality of the potential wound dressing by showing excellent antibacterial property against both gram-positive and gram-negative bacteria.