Detailed investigation of ROS arisen from chlorophyll a/Chitosan based-biofilm.

The aim of this work is to study the nature of reactive oxygen species, ROS, arisen from Chitosan/2-HP-β-Cyclodextrin/Chlorophyll a (CH/CD/Chla) blended biofilm under a photodynamic activity. Suitable molecules, called primary acceptors, able to react selectively with ROS, in turn generated by the photosensitizer (PS), herein Chla, are used to attempt this purpose. The changes of the absorption and the emission spectra of these acceptors after the irradiation of aqueous solution containing the active biofilm have provided the specific nature of ROS and thus the main pathway of reaction followed by PS, in our condition. The (1)O2 formation was unveiled using Uric Acid (UA) and 9,10-diphenilanthracene (DPA). On the other hand, 2,7- dichlorofluorescin and Ferricytochrome c (Cyt-c) were used to detect the formation of hydrogen peroxide and superoxide radical anion, respectively. Results suggest that among the possible pathways of reaction, namely Type I and Type II, potentially followed by PSs, in our condition the hybrid biofilm CH/CD/Chla follows mainly Type II mechanism with the formation of (1)O2. However, the latter is involved in subsequent pathway of reaction involving Chla inducing, in addition, the formation of O2(-) and H2O2.