Autofluorescent Activity of Thermosensitive, Hemostatic, and Wound Healing Biopolymer Hydrogels

Thermosensitive biopolymer gelatin-alginate hydrogels are promising for use as dressings for wound healing and drug delivery. This work presents fluorescence arising from the internal fluorophores of alginate and gelatin biopolymers in thermosensitive hydrogels modified with calcium- and sodium-containing humic acids before and after their impregnation with the hemostatic drug aminocaproic acid. A new approach of using fluorescence emission spectra, along with the analysis of morphological features, optical properties, and the elemental composition of dried hydrogels, is used as a tool for monitoring the ability of these hydrogels for the thermosensitive delivery of a hemostatic drug. A comparative analysis made it possible to select the optimal composition of hydrogels suitable for the targeted delivery of aminocaproic acid through a gel-sol transition at physiological temperatures. Optimal concentrations of sodium-containing humic acids in gelatin-alginate hydrogels of 2.5 wt.% and 5 wt.% provided a gel-sol transition temperature of about 37 °C. The quantum yield of fluorescence of 8-10% upon introduction of 20 wt.% aminocaproic acid into these hydrogels indicates that this hemostatic drug does not destroy three-dimensional networks formed by molecules of gelatin, alginate, and humic acids, the gel-sol transition temperature for which is maintained at a physiological level without significant contracture of the wound dressing.