Electrochemical Generation of Porphyrin-Porphyrin and Porphyrin-C60 Polymeric Photoactive Organic Heterojunctions

Potentiation Effect of Iodine Species on the Antimicrobial Capability of Surfaces Coated with Electroactive Phthalocyanines

The spreading of different infections can occur through direct contact with glass surfaces in commonly used areas. Incorporating the use of alternative therapies in these materials seems essential to reduce and also avoid bacterial resistance. In this work, the capability to kill microbes of glass surfaces coated with two electroactive metalated phthalocyanines (ZnPc-EDOT and CuPc-EDOT) is assessed. The results show that both of these materials are capable of producing reactive oxygen species; however, the polymer with Zn(II) (ZnPc-PEDOT) has a singlet oxygen quantum yield 8-fold higher than that of the Cu(II) containing analogue. This was reflected in the in vitro experiments where the effectiveness of the surfaces was tested in bacterial suspensions, monitoring single microbe inactivation upon attachment to the polymers, and eliminating mature biofilms. Furthermore, we evaluated the use of an inorganic salt (KI) to potentiate the photodynamic inactivation mediated by an electropolymerized surface. The addition of the salt improved the efficiency of phototherapy at least two times for both polymers; nevertheless, the material coated with ZnPc-PEDOT was the only one capable of eliminating >99.98% of the initial microbes loading under different circumstances.

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

A novel biscarbazol triphenylamine end-capped dendrimeric zinc(II) porphyrin (DP 5) was synthesized by click chemistry. This compound is a cruciform dendrimer that bears a nucleus of zinc(II) tetrapyrrolic macrocycle substituted at the meso positions by four identical substituents. These are formed by a tetrafluorophenyl group that possesses a triazole unit in the para position. This nitrogenous heterocyclic is connected to a 4,4'-di(N-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 DP 5 was used to obtain novel, stable, and reproducible fully π-conjugated photoactive polymeric films (FDP 5). First, the spectroscopic characteristics and photodynamic properties of DP 5 were compared with its constitutional components derived of porphyrin P 6 and carbazole D 7 moieties in solution. The fluorescence emissions of the dendrimeric units in DP 5 were more strongly quenched by the tetrapyrrolic macrocycle, indicating photoinduced energy transfer. In addition, FDP 5 film showed the Soret and Q absorption bands and red fluorescence emission of the corresponding zinc(II) porphyrin. Also, FDP 5 film was highly stable to photobleaching, and it was able to produce singlet molecular oxygen in both N,N-dimethylformamide (DMF) and water. Therefore, the porphyrin units embedded in the polymeric matrix of FDP 5 film mainly retain the photochemical properties. Photodynamic inactivation mediated by FDP 5 film was investigated in Staphylococcus aureus and Escherichia coli. When a cell suspension was deposited on the surface, complete eradication of S. aureus and a 99% reduction in E. coli survival were found after 15 and 30 min of irradiation, respectively. Also, FDP 5 film was highly effective to eliminate individual bacteria attached to the surface. In addition, photodynamic inactivation (PDI) sensitized by FDP 5 film produced >99.99% bacterial killing in biofilms formed on the surface after 60 min irradiation. The results indicate that FDP 5 film represents an interesting and versatile photodynamic active material to eradicate bacteria as planktonic cells, individual attached microbes, or biofilms.

Photodynamic inactivation of bacteria using novel electrogenerated porphyrin-fullerene C60 polymeric films

A porphyrin-fullerene C60 dyad (TCP-C60) substituted by carbazoyl groups was used to obtain electrogenerated polymeric films on optically transparent indium tin oxide (ITO) electrodes. This approach produced stable and reproducible polymers, holding fullerene units. The properties of this film were compared with those formed by layers of TCP/TCP-C60 and TCP/ZnTCP. Absorption spectra of the films presented the Soret and Q bands of the corresponding porphyrins. The TCP-C60 film produced a high photodecomposition of 2,2-(anthracene-9,10-diyl)bis(methylmalonate), which was used to detect singlet molecular oxygen O2((1)Δg) production in water. In addition, the TCP-C60 film induced the reduction of nitro blue tetrazolium to diformazan in the presence of NADH, indicating the formation of superoxide anion radical. Moreover, photooxidation of L-tryptophan mediated by TCP-C60 films was found in water. In biological media, photoinactivation of Staphylococcus aureus was evaluated depositing a drop with 2.5 × 10(3) cells on the films. After 30 min irradiation, no colony formation was detected using TCP-C60 or TCP/TCP-C60 films. Furthermore, photocytotoxic activity was observed in cell suspensions of S. aureus and Escherichia coli. The irradiated TCP-C60 film produced a 4 log decrease of S. aureus survival after 30 min. Also, a 4 log reduction of E. coli viability was obtained using the TCP-C60 film after 60 min irradiation. Therefore, the TCP-C60 film is an interesting and versatile photodynamic active surface to eradicate bacteria.