A multifunctional electrospun and dual nano-carrier biobased system for simultaneous detection of pH in the wound bed and controlled release of benzocaine

Novel multifunctional bio-based nanofibrous mats were prepared which contain the commonly used pain reducing local anesthetic benzocaine (BZC) and the in situ pH-detecting dye bromocresol green (BCG). These can serve as a dual nano-carrier system for wound healing applications, especially in the treatment of infected wounds. BZC and BCG were introduced into cellulose acetate (CA) based nanofibers using a single-step needleless electrospinning process. The resulting CA nanofibers show a homogenous fiber diameter distribution around 600 nm, hydrophobicity with a water contact angle of 134°, and simultaneous porosities on the nano-micro- scale. In spite of their hydrophobic character, the nanofibrous mats showed a huge water absorption capacity (1657%), as well as good stability at physiological pH (negligible degradation). All the mentioned properties remain unchanged upon the inclusion of either BZC or BCG. Results from the in vitro drug release studies showed a pH dependent (i.e. controllable) release of BZC, and confirmed the expected maximum drug release rate at pH 9.0, which would correspond clinically to the pH of an infected wound. The accompanying color change of the nanofibrous mats, provided through the encapsulated BCG (from yellow to blue), is noticeable within a few seconds after the pH changes from acidic to alkaline. This rapid response of NSAID, together with the visible absorption of included dye, show the capacity of the proposed nanofibrous mats as an in situ pH-detecting system. Finally, the biocompatibility of the proposed nanofibrous mats was proven using human skin fibroblast cells, confirming their potential to be used in wound treatment.