Fluorescent pH-sensing bandage for point-of-care wound diagnostics

Diabetic foot ulcers(DFUs)are a serious and prevalent complication of diabetes.Current diagnostic options are limited to macroscopic wound analysis such as wound size,depth,and infection.Molecular diagnostics promise to improve DFU diagnosis,staging,and assessment of treatment response.Here,we developed a rapid and easy-to-use fluorescent pH-sensing bandage for wound diagnostics.In a fluorescent dye screen,we identified pyranine as the lead compound due to its suitable pH-sensing properties in the clinically relevant pH range of 6-9.To minimize the release of this dye into the wound bed,we screened a library of ionic microparticles and found a strong adhesion of the anionic dye to a cationic polymeric microparticle.These dye-loaded microparticles showed a strong fluorescence response in the clinically relevant pH range of 6-9 and a dye release below 1%after 1 day in biological media.The dye-loaded microparticles were subsequently encapsulated in a calcium alginate hydrogel to minimize the interaction of the microparticles with the wound tissue.This pH-sensing diagnostic wound dressing was tested on full thickness dorsal wounds of mice,and a linear fluorescence response(R^(2)=0.9909)to clinically relevant pH values was observed.These findings encourage further development of this pH-sensing system for molecular diagnostics in DFUs.