Antimicrobial Photodynamic Polymeric Films Bearing Biscarbazol Triphenylamine End-Capped Dendrimeric Zn(II) Porphyrin.

A novel biscarbazol triphenylamine end-capped dendrimeric zinc(II) porphyrin () was synthesized by click chemistry. This compound is a cruciform dendrimer that bears a nucleus of zinc(II) tetrapyrrolic macrocycle substituted at the positions by four identical substituents. These are formed by a tetrafluorophenyl group that possesses a triazole unit in the position. This nitrogenous heterocyclic is connected to a 4,4'-di(-carbazolyl)triphenylamine group by means of a phenylenevinylene bridge, which allows the conjugation between the nucleus and this external electropolymerizable carbazoyl group. In this structure, dendrimeric arms act as light-harvesting antennas, increasing the absorption of blue light, and as electroactive moieties. The electrochemical oxidation of the carbazole groups contained in the terminal arms of the was used to obtain novel, stable, and reproducible fully π-conjugated photoactive polymeric films (). First, the spectroscopic characteristics and photodynamic properties of were compared with its constitutional components derived of porphyrin and carbazole moieties in solution. The fluorescence emissions of the dendrimeric units in were more strongly quenched by the tetrapyrrolic macrocycle, indicating photoinduced energy transfer. In addition, film showed the Soret and Q absorption bands and red fluorescence emission of the corresponding zinc(II) porphyrin. Also, film was highly stable to photobleaching, and it was able to produce singlet molecular oxygen in both ,-dimethylformamide (DMF) and water. Therefore, the porphyrin units embedded in the polymeric matrix of film mainly retain the photochemical properties. Photodynamic inactivation mediated by film was investigated in and . When a cell suspension was deposited on the surface, complete eradication of and a 99% reduction in survival were found after 15 and 30 min of irradiation, respectively. Also, film was highly effective to eliminate individual bacteria attached to the surface. In addition, photodynamic inactivation (PDI) sensitized by film produced >99.99% bacterial killing in biofilms formed on the surface after 60 min irradiation. The results indicate that film represents an interesting and versatile photodynamic active material to eradicate bacteria as planktonic cells, individual attached microbes, or biofilms.