Supramolecular assemblies based on polymeric cyclodextrin nanosponges and a cationic porphyrin with antimicrobial photodynamic therapy action

Within of the increasing requirement of alternative approaches to fight emerging infections, nano-photosensitisers (nanoPS) are currently designed with the aim to optimize the antimicrobial photodynamic (aPDT) efficacy. The utilize of less expensive nanocarriers prepared by simple and eco-friendly methodologies and commercial photosensitisers are highly desiderable. In this direction, here we propose a novel nanoassembly composed of water soluble anionic polyester beta-CD nanosponges (beta-CD-PYRO hereafter named beta NS) and the cationic 5,10,15,20-tetrakis(1-methylpyridinium-4-yl)porphine (TMPyP). Nanoassemblies were prepared in ultrapure water by mixing PS and beta NS, by exploiting their mutual electrostatic interaction, and characterized by various spectroscopic techniques such as UV/Vis, Steady-State and Time Resolved Fluorescence, Dynamic Light Scattering and zeta-potential. NanoPS produce appreciable amount of single oxygen similar to free porphyrin and a prolonged stability after 6 days of incubations in physiological conditions and following photoirradiation. Antimicrobial photodynamic action against fatal hospital-acquired infections such as P. aeruginosa and S. aureus was investigated by pointing out the ability of cationic porphyrin loaded-CD nano-sponges to photo-kill bacterial cells at prolonged time of incubation and following irradiation (MBC99 = 3.75 mu M, light dose = 54.82 J/cm2).