Preparation of porous alginate-based smart dressings used in real-time monitoring of pH in chronic wounds by evaluating two fabrication routes: freeze-drying vs. electrospinning

Timely recognition the on-set of infection is very important for management and treatment of wounds. Regarding various biomarkers, pH of the wound milieu could be mentioned as one of the most effective tools for this purpose. In this work, some smart dressings were fabricated for detection of the change of pH in wounds due to infection. To do this, phenol red as a pH-indicator dye was incorporated into an alginate-based matrix. Two groups of dressings containing phenol red were prepared via freeze-drying and electrospinning techniques. Pore size of the freeze-dried dressings as well as mean diameter and pores size of the electrospun samples were estimated to be 62.24 μm, 204 nm, and 2.03 μm, respectively. Remarkable fluid absorption was determined for both electrospun (2125%) and freeze-dried (860%) samples. Measurements according to CIE L*a*b* and RGB color spaces revealed that the color difference between samples in buffers with different pHs of 4, 6, 7, 8, 9, and 10 could be distinguished well by the naked eye. In spite of less fluid absorption for the freeze-dried samples in comparison to electrospun ones, they exhibited better resistance to dye leaching and preserved their structure better after soaking in different pH buffers. Biological evaluation using adipose-derived mesenchymal stem cells, revealed no cytotoxic effects for samples containing phenol red. Moreover, the alginate matrix provides proper conditions for attachment as well as proliferation of the cells. Overall, the results suggest that samples which were fabricated through freeze-drying method could be considered as good candidates for application in management and monitoring of chronic wounds.