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--Cyclodextrin/Chlorophyll a (CH/CD/Chla) blended biofilm under a photodynamic activity. Suitablemolecules, called primary acceptors, able to react selectively with ROS, in turn generated by the pho-tosensitizer (PS), herein Chla, are used to attempt this purpose. The changes of the absorption and theemission spectra of these acceptors after the irradiation of aqueous solution containing the active biofilmhave provided the specific nature of ROS and thus the main pathway of reaction followed by PS, in ourcondition. The1O2formation was unveiled using Uric Acid (UA) and 9,10-diphenilanthracene (DPA). Onthe other hand, 2,7- dichlorofluorescin and Ferricytochrome c (Cyt-c) were used to detect the formationof hydrogen peroxide and superoxide radical anion, respectively. Results suggest that among the possiblepathways of reaction, namely Type I and Type II, potentially followed by PSs, in our condition the hybridbiofilm CH/CD/Chla follows mainly Type II mechanism with the formation of1O2. However, the latter isinvolved in subsequent pathway of reaction involving Chla inducing, in addition, the formation of O2•−and H2O2.