Monitoring of the evolution of human chronic wounds using a ninhydrin-based sensory polymer and a smartphone

The healing processes in cutaneous wounds, i.e., chronic wounds, represent a health problem affecting 1?2 % of the population. The evaluation of these wounds is mainly based on subjective parameters, although there is a medical consensus on protease activity as the best marker for healing disorders. Here we show the correlation of the amino acid concentration on chronic wounds and with their evolution, and the development of a test kit to straightforward determining this evolution. Our test kit is a colorimetric sensory polymer film that change its colour upon contacting amino acids. The kit allows for the quantification of the overall amino acid concentration by simply analysing the colour definition parameters of the sensory film obtained from of a photograph taken with a smartphone. We analysed with the kit the amino acid concentration of human chronic wounds of 34 patients and we mathematically demonstrate that there is a correlation with the amino acid concentration, related with the protease activity, and the evolution of the wound?s diagnoses. This kit can help diagnosis of human chronic wounds, usually evaluated and treated along time by different physicians, or even by different medical teams, providing an analytical tool not subjected to subjective evaluation.