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• Donor-acceptor heterojunctions were formed by electrochemical polymerization. • Photoinduced charge separation was observed in electropolymerized heterojunctions. • Photogenerated electrons travelled to the external C 60 layer and holes to the inner layer. • The heterojunctions were used as photoactive materials in photoelectrochemical cells. • Photoelectrochemical cells were able to reduce electron acceptors under illumination. Fully polymeric donor-acceptor organic-organic heterojunctions were successfully formed by successive electrochemical polymerization steps. C 60 holding polymer acted as an electron acceptor layer when it was electrochemically deposited on the top of a porphyrin based conducting polymer with dendrimeric structure. Porphyrin fluorescence emission quenching and energy dependent surface photovoltage analysis demonstrated that the heterojunctions produced photoinduced charge separated states. Also, it was found that after irradiation of heterojunctions the photogenerated electrons traveled to the C 60 external surface, while the holes moved to the inner hole transport layer. When the heterojunctions were used in photoelectrochemical cells, the generated light-induced charge separated states were able to electrochemically reduce electron acceptors in aqueous media. Image, graphical abstract [ABSTRACT FROM AUTHOR]

A new BODIPY (BDP 1) bearing a dimethylaminopropoxy group attached to a phenylene unit was synthesized. This compound was brominated to obtain the halogenated analog BDP 2, which was designed to enhance the photodynamic effect of BODIPY to kill bacteria without an intrinsic cationic charge. The basic amino group located at the end of the propoxy bridge can acquire a positive charge by protonation in an aqueous medium, increasing the binding to bacterial cells. Interaction and photokilling activity mediated by these compounds was evaluated in Staphylococcus aureus and Escherichia coli. BDP 1 and BDP 2 were rapidly bound to bacterial cells, showing bioimages with green emission. Complete elimination of S. aureus was detected when cells were incubated with 1 μM BDP 2 and irradiated for 5 min. Comparable photoinactivation was obtained with E. coli , after an irradiation of 30 min. Furthermore, BDP 2 was effective to kill bacteria at very low concentration (0.5 μM). Thus, BDP 1 showed mainly interesting properties as a fluorophore, whereas BDP 2 was highly effective photosensitizer as a broad-spectrum antibacterial agent. BODIPY derivatives are a promising molecular architecture for use as a broad-spectrum antimicrobial photosensitizer. The presence of a basic amine group in the BODIPY structure allows a better binding to bacterial cells, leading to a highly effective photoinactivation. This molecular design of a phototherapeutic agent augurs very well for possible future clinical applications. Unlabelled Image • New BODIPYs containing a dimethylaminopropoxy group were synthesized. • The basic aliphatic amino group provides effective binding to bacterial cells. • The highly fluorescent BODIPY is an interesting fluorophore for bioimaging. • Brominated BODIPY was highly effective to eradicate bacteria at low concentrations. [ABSTRACT FROM AUTHOR]

The effect of photodynamic inactivation (PDI) sensitized by 5,10,15,20-tetra(4-N,N,N-trimethylammoniophenyl)porphyrin (TMAP 4+ ) on different components of mono- and dual-species biofilms of Staphylococcus aureus and Escherichia coli was determined by different methods. First, the plate count technique showed that TMAP 4+ -PDI was more effective on S. aureus than E. coli biofilm. However, crystal violet staining revealed no significant differences between before and after PDI biofilms of both bacteria. On the other hand, the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide method indicated a reduction in viable cells as the light exposure time increases in both, mono- and dual-species biofilms. Furthermore, it was determined that as the irradiation time increases, the amount of extracellular polymeric substances present in the biofilms decreased. This effect was presented in both strains and in the mixed biofilm, being more evident in S. aureus mono-specie biofilm. Finally, scanning electron microscopy analysis showed a decrease in the number of cells forming the biofilm after photosensitization treatments. This information makes it possible to determine whether the photodynamic action is based on damage to metabolic activity, extracellular matrix and/or biomass, which may be useful in establishing a fully effective PDI protocol for the treatment of microorganisms growing as biofilms., (© 2024. The Author(s), under exclusive licence to the European Photochemistry Association, European Society for Photobiology.)

The development of functional organic materials is crucial for the advancement of various fields, such as optoelectronics, energy storage, sensing, and biomedicine. In this context, we successfully prepared a stable ambipolar perfluoroporphyrin-based polymeric film by electrochemical synthesis. Our strategy involved the synthesis of a novel tetra-pentafluorophenyl porphyrin covalently linked to four 3,4-ethylenedioxythiophene (EDOT) moieties. The resulting monomer, EDOT-TPPF 16 , was obtained through a straightforward synthetic approach with a good overall yield. The unique molecular structure of EDOT-TPPF 16 serves a dual function, with EDOT moieties allowing electropolymerization for polymeric film formation, while the electron-acceptor porphyrin core enables electrochemical reduction and electron transport. The electrochemical polymerization permits the polymer (PEDOT-TPPF 16 ) synthesis and film formation in a reproducible and controllable manner in one step at room temperature. Spectroelectrochemical experiments confirmed that the porphyrin retained its optoelectronic properties within the polymeric matrix after the electrochemical polymerization. The obtained polymeric material exhibited stable redox capabilities. Current charge-discharge cycles and electrochemical impedance spectroscopy of the electrochemically generated organic film demonstrated that the polymer could be applied as a promising active material in the development of supercapacitor energy storage devices., Competing Interests: There are no conflicts to declare., (This journal is © The Royal Society of Chemistry.)

A porphyrin-BODIPY dyad (P-BDP) was obtained through covalent bonding, featuring a two-segment design comprising a light-harvesting antenna system connected to an energy acceptor unit. The absorption spectrum of P-BDP resulted from an overlap of the individual spectra of its constituent parts, with the fluorescence emission of the BODIPY unit experiencing significant quenching (96 %) due to the presence of the porphyrin unit. Spectroscopic, computational, and redox investigations revealed a competition between photoinduced energy and electron transfer processes. The dyad demonstrated the capability to sensitize both singlet molecular oxygen and superoxide radical anions. Additionally, P-BDP effectively induced the photooxidation of L-tryptophan. In suspensions of Staphylococcus aureus cells, the dyad led to a reduction of over 3.5 log (99.99 %) in cell survival following 30 min of irradiation with green light. Photodynamic inactivation caused by P-BDP was also extended to the individual bacterium level, focusing on bacterial cells adhered to a surface. This dyad successfully achieved the total elimination of the bacteria upon 20 min of irradiation. Therefore, P-BDP presents an interesting photosensitizing structure that takes advantage of the light-harvesting antenna properties of the BODIPY unit combined with porphyrin, offering potential to enhance photoinactivation of bacteria., (© 2024 Wiley-VCH GmbH.)

Pseudomonas aeruginosa is one of the most refractory organisms to antibiotic treatment and appears to be one of the least susceptible to photodynamic treatment. TMPyP is effective in the photoinactivation of P. aeruginosa, and the co-administration with the cationic polymer Eudragit®-E100 (Eu) potentiates this effect against isolates both sensitive and resistant to antibiotics. The fluorescent population (>98%) observed by flow cytometry after exposure to Eu + TMPyP remained unchanged after successive washings, indicating a stronger interaction/internalization of TMPyP in the bacteria, which could be attributed to the rapid neutralization of surface charges. TMPyP and Eu produced depolarization of the cytoplasmic membrane, which increased when both cationic compounds were combined. Using confocal laser scanning microscopy, heterogeneously distributed fluorescent areas were observed after TMPyP exposure, while homogeneous fluorescence and enhanced intensity were observed with Eu + TMPyP. The polymer caused alterations in the bacterial envelopes that contributed to a deeper and more homogeneous interaction/internalization of TMPyP, leading to a higher probability of damage by cytotoxic ROS and explaining the enhanced result of photodynamic inactivation. Therefore, Eu acts as an adjuvant without being by itself capable of eradicating this pathogen. Moreover, compared with other therapies, this combinatorial strategy with a polymer approved for pharmaceutical applications presents advantages in terms of toxicity risks., (© 2023 American Society for Photobiology.)

To improve bacterial photodynamic inactivation (PDI), this work analyzes the photodynamic effect caused by the combination of photosensitizers (PSs) on two bacterial models and different growth mode. Simultaneous administration of PSs from different families, zinc(II) 2,9,16,23-tetrakis[4-(N-methylpyridyloxy)]phthalocyanine (ZnPPc 4+ ), 5,10,15,20-tetra(4-N,N,N-trimethylammonium phenyl)porphyrin (TMAP 4+ ), meso-tetrakis(9-ethyl-9-methyl-3-carbazoyl)chlorin (TEMCC 4+ ) and 5,10,15,20-tetrakis[4-(3-N,N-dimethylaminopropoxy)phenyl] chlorin (TAPC) was investigated against Staphylococcus aureus and Escherichia coli, in planktonic form, biofilm and growth curve. Various PSs combinations showed greater inactivation compared to when used separately under the same conditions but at twice the concentration. However, differences were found in the effectiveness of the PSs combinations on Gram positive and negative bacteria, as well as in planktonic or biofilm form. Likewise, the combination of three PSs completely stopped E. coli growth under optimal nutritional conditions. PSs combination allows extending the range of light absorption by agents that absorb in different areas of the visible spectrum. Therefore, PDI with combined PSs increases its antimicrobial capacity using agents' concentrations and light fluences lower than those necessary to cause the same effect as single PS. These advances represent a starting point for future research on the potentiation of PDI promoted by the combined use of PSs., (© 2023. The Author(s), under exclusive licence to European Photochemistry Association, European Society for Photobiology.)

Invasive candidiasis is an important cause of morbidity and mortality, and its occurrence is increasing due to the growing complexity of patients. In particular, Candida albicans exhibits several virulence factors that facilitate yeast colonization in humans. In this sense, the photodynamic inactivation of yeasts is a promising new alternative to eliminate fungal infections. Herein, the photodynamic activity sensitized by a free-base chlorin (TPCF 16 ) and its complexes with Zn(II) (ZnTPCF 16 ) and Pd(II) (PdTPCF 16 ) was investigated in order to eliminate C. albicans under different forms of cell cultures. A decrease in cell survival of more than 5 log was found in planktonic cells incubated with 5 μM TPCF 16 or ZnTPCF 16 upon 15 min of white-light irradiation. The mechanism of action mainly involved a type II pathway in the inactivation of C. albicans cells. In addition, the photodynamic action induced by these chlorins was able to suppress the growth of C. albicans in a culture medium. These photosensitizers were also effective to photoinactivate C. albicans pseudohyphae suspended in PBS. Furthermore, the biofilms of C. albicans that incorporated the chlorins during the proliferation stage were completely eradicated using 5 μM TPCF 16 or ZnTPCF 16 after 60 min of light irradiation. The studies indicated that these chlorins are effective photosensitizing agents to eliminate C. albicans as planktonic cells, pseudohyphae, and biofilms.

Phthalocyanine derivatives have been proposed as photosensitizers for the treatment of several microbial infections. In this review, the progress in the structures of phthalocyanines was analyzed, considering that these compounds can easily functionalize and can form complexes with various metal ions. In this sense, different substituents were used to increase the interaction with the microorganisms, improving their photodynamic inactivation. Furthermore, these photosensitizers absorb strongly at phototherapeutic window, emit red fluorescence, and efficiently produce the formation of reactive oxygen species. Subsequently, the influence of binding, bacteria types, cell density, washing effect, and media on photoinactivation was remarked to elimination of microbes. Finally, photokilling of bacterial biofilm by phthalocyanines and the mechanism of action were discussed. Therefore, this review brings together the main features of phthalocyanines as antimicrobial phototherapeutic agents., (© 2022 The Chemical Society of Japan & Wiley-VCH GmbH.)

A novel BOPHY-fullerene C 60 dyad (BP-C 60 ) was designed as a heavy-atom-free photosensitizer (PS) with potential uses in photodynamic treatment and reactive oxygen species (ROS)-mediated applications. BP-C 60 consists of a BOPHY fluorophore covalently attached to a C 60 moiety through a pyrrolidine ring. The BOPHY core works as a visible-light-harvesting antenna, while the fullerene C 60 subunit elicits the photodynamic action. This fluorophore-fullerene cycloadduct, obtained by a straightforward synthetic route, was fully characterized and compared with its individual counterparts. The restricted rotation around the single bond connecting the BOPHY and pyrrolidine moieties led to the formation of two atropisomers. Spectroscopic, electrochemical, and computational studies disclose an efficient photoinduced energy/electron transfer process from BOPHY to fullerene C 60 . Photodynamic studies indicate that BP-C 60 produces ROS by both photomechanisms (type I and type II). Moreover, the dyad exhibits higher ROS production efficiency than its individual constitutional components. Preliminary screening of photodynamic inactivation on bacteria models (Staphylococcus aureus and Escherichia coli) demonstrated the ability of this dyad to be used as a heavy-atom-free PS. To the best of our knowledge, this is the first time that not only a BOPHY-fullerene C 60 dyad is reported, but also that a BOPHY derivative is applied to photoinactivate microorganisms. This study lays the foundations for the development of new BOPHY-based PSs with plausible applications in the medical field., (© 2021 Wiley-VCH GmbH.)

The widespread use of antibiotics has led to a considerable increase in the resistance of microorganisms to these agents. Consequently, it is imminent to establish new strategies to combat pathogens. An alternative involves the development of photoactive polymers that represent an interesting strategy to kill microbes and maintain aseptic surfaces. In this sense, a conjugated polymer (PZnTEP) based on Zn(II) 5,10,15,20-tetrakis-[4-(ethynyl)phenyl]porphyrin (ZnTEP) was obtained by the homocoupling reaction of terminal alkyne groups. PZnTEP exhibits a microporous structure with high surface areas allowing better interaction with bacteria. The UV-visible absorption spectra show the Soret and Q bands of PZnTEP red-shifted by about 18 nm compared to those of the monomer. Also, the conjugate presents the two red emission bands, characteristic of porphyrins. This polymer was able to produce singlet molecular oxygen and superoxide radical anion in the presence of NADH. Photocytotoxic activity sensitized by PZnTEP was investigated in bacterial suspensions. No viable Staphylococcus aureus cells were detected using 0.5 µM PZnTEP and 15 min irradiation. Under these conditions, complete photoinactivation of Escherichia coli was observed in the presence of 100 mM KI. Likewise, no survival was detected for E. coli incubated with 1.0 µM PZnTEP after 30 min irradiation. Furthermore, polylactic acid surfaces coated with PZnTEP were able to kill efficiently these bacteria. This surface can be reused for at least three photoinactivation cycles. Therefore, this conjugated photodynamic polymer is an interesting antimicrobial photoactive material for designing and developing self-sterilizing surfaces.

A photostable and photodynamic antimicrobial surface was successfully obtained and applied to photoinactivate microorganisms. This approach was based on the synthesis of a fullerene C 60 derivative (EDOT-C 60 ) where fullerene C 60 is covalently linked to 3,4-ethylenedioxythiophene (EDOT) through a 1,3-dipolar cycloaddition reaction. This dual-functional monomer bears an EDOT center connected via an alkyl chain to a fullerene C 60 moiety. In this structure, EDOT acts as an electropolymerizable unit that allows the film formation over conducting substrates, while fullerene C 60 performs the photodynamic antimicrobial activity. Electrochemical polymerization of EDOT was used to obtain stable and photodynamic polymeric films (PEDOT-C 60 ) in a controllable procedure. Cyclic voltammetry and UV-visible spectroscopy studies showed that the fullerene C 60 units were not altered during the electropolymerization process, obtaining surfaces with high fullerene content. Photobleaching measurements demonstrated that the electropolymerized films were highly photostable. Moreover, photodynamic properties of PEDOT-C 60 were compared with fullerene C 60 and showed that electrodeposited films were able to generate reactive oxygen species (ROS) through the two photomechanisms, producing singlet molecular oxygen (type II) and superoxide radical anion (type I). All studies demonstrated that fullerene C 60 moieties covalently attached to the polymeric matrix mainly conserve the photodynamic characteristics. Hence, photodynamic action sensitized by PEDOT-C 60 was assessed in vitro against Staphylococcus aureus . The photosensitized inactivation by the electropolymerized films on bacteria suspensions produced >99.9% reduction in S. aureus survival. Fluorescence microscopy experiments with S. aureus adhered to the PEDOT-C 60 surface showed a complete microbe annihilation. Also, the eradication of biofilms formed on PEDOT-C 60 surfaces resulted in a photokilling >99.9% after visible light irradiation. Our results demonstrated that these antimicrobial photodynamic polymeric films are a promising and versatile platform to photoinactivate microorganisms and to obtain photostable self-sterilizing surfaces., Competing Interests: There are no conflicts to declare., (This journal is © The Royal Society of Chemistry.)

Different experimental conditions can be used to detect the presence of reactive oxygen species (ROS) in the photodynamic inactivation of microorganisms. Here, we describe the effect of the media and the addition of ROS scavengers to obtain insight about the oxidative processes that take place during the photokilling of bacteria. In addition, 9,10-dimethylanthracene was used to sense the generation of singlet molecular oxygen, O 2 ( 1 Δ g ), in microbial cells. Thus, the contribution of type I or type II pathways in the photocytotoxicity action can be rapidly detected and compared between different photosensitizers.

A nanoplatform concept was developed to synthesize accessible photoactive magnetic nanoparticles (MNPs) of Fe 3 O 4 coated with silica. This approach was based on the covalent binding of 5,10,15,20-tetrakis(pentafluorophenyl)porphyrin (TPPF 20 ) to aminopropyl-grafted MNPs by nucleophilic aromatic substitution reaction (S N Ar) to obtain conjugate MNP-P1. After in situ modification, the remaining pentafluorophenyl groups of TPPF 20 attached to MNPs were substituted by dimethylaminoethoxy groups to form MNP-P2. The basic amine group of these conjugates can be protonated in aqueous media. In addition, MNP-P1 and MNP-P2 were intrinsically charged to produce cationic conjugates MNP + -P1 and MNP + -P2 + by methylation. All of them were easily purified by magnetic decantation in high yields. The average size of the MNPs was ∼15 nm, and the main difference between these conjugates was the greater coating with positive charges of MNP + -P2 + , as shown by the zeta potential values. Absorption spectra exhibited the Soret and Q bands characteristic of TPPF 20 linked to MNPs. Furthermore, these conjugates showed red fluorescence emission of porphyrin with quantum yields of 0.011-0.036. The photodynamic effect sensitized by the conjugates indicated the efficient formation of singlet molecular oxygen in different media, reaching quantum yield values of 0.17-0.34 in N , N -dimethylformamide. The photodynamic activity of the conjugates was evaluated to inactivate the Gram-positive bacteria Staphylococcus aureus , the Gram-negative bacteria Escherichia coli, and the yeast Candida albicans . The modified cationic MNP + -P2 + was the most effective conjugate for photodynamic inactivation (PDI) of microorganisms. Binding of this conjugate to bacteria and photoinactivation capability was checked by means of fluorescence microscopy. Also, sustainable use by recycling was determined after three PDI treatments. Therefore, this methodology is a suitable scaffold for the in situ modification of conjugates, and in particular, MNP + -P2 + represents a useful photodynamic active material to eradicate microorganisms.

Chromophore-fullerene C60 hybrids possess interesting properties that enable them to act as heavy atom-free photosensitizers and reactive oxygen species (ROS) producers. Here, two new diketopyrrolopyrrole-C60 conjugates were efficiently synthesized and characterized. The conjugates show broadband absorption in the visible spectral region, in which diketopyrrolopyrrole dyes act as light-harvesting antenna with very high capacity to populate excited triplet states. Furthermore, the ability of diketopyrrolopyrrole-C60 systems to generate singlet molecular oxygen was explored for the first time in solvents of different polarities. The experimental results show that these architectures exhibit very high production rates of this ROS. In addition, a preliminary study on Staphylococcus aureus cell suspensions indicates that both conjugates exhibit phototoxicity after irradiation with green LED light. Thus, the data obtained provide evidence that these diketopyrrolopyrrole-C60 architectures act as potential heavy atom-free photosensitizers in photodynamic inactivation of microorganisms and other singlet oxygen-mediated applications.

The antimicrobial capability and recyclability of two conjugates that combines the versatility of iron oxide magnetic nanoparticles (MNPs) with the high photosensitizing proficiency of boron-dipyrromethene (BODIPY) dyes are assessed. By a relatively simple synthetic pathway, two conjugates were obtained. The first one, MNP-B1, contains a highly fluorescent dye for bioimaging and suitable inactivating properties. The other one, MNP-B2, is optimized to improve the production of cytotoxic reactive oxygen species (ROS) by incorporating heavy atoms in the BODIPY core. In vitro experiments in bacterial cell suspensions and at the single bacterium level reveal that both conjugates can inactivate either Gram-positive (methicillin-resistant Staphylococcus aureus ) and Gram-negative ( Escherichia coli ) bacteria. By means of fluorescence microscopy, not only cellular uptake of the conjugates but also recyclability and sustained performance over the cycles of photodynamic inactivation (PDI) are demonstrated. This is the first time that MNPs functionalized with BODIPY dyes are utilized to obtain fluorescent images of bacterial cells and photoinactivate pathogens.

A covalently linked BODIPY-fullerene C 60 dyad (BDP-C 60 ) was synthesized as a two-segment structure, which consists of a visible light-harvesting antenna attached to an energy or electron acceptor moiety. This structure was designed to improve the photodynamic action of fullerene C 60 to inactivate bacteria. The absorption spectrum of BDP-C 60 was found to be a superposition of the spectra of its constitutional moieties, whereas the fluorescence emission of the BODIPY unit was strongly quenched by the fullerene C 60 . Spectroscopic, calculations, and redox studies indicate a competence between photoinduced energy and electron transfer. Protonating the dimethylaminophenyl substituent through addition of an acidic medium led to a substantial increase in the fluorescence emission, triplet excited state formation, and singlet molecular oxygen production. At physiological pH, photosensitized inactivation of Staphylococcus aureus mediated by 1 μM BDP-C 60 exhibited a 4.5 log decrease of cell survival (>99.997 %) after 15 min irradiation. A similar result was obtained with Escherichia coli using 30 min irradiation. Moreover, proton-activated photodynamic action of BDP-C 60 turned this dyad into a highly effective photosensitizer to eradicate E. coli. Therefore, BDP-C 60 is an interesting photosensitizing structure in which the light-harvesting antenna effect of the BODIPY unit combined with the protonation of dimethylaminophenyl group can be used to improve the photoinactivation of bacteria., (© 2019 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

The photodynamic action mechanism sensitized by a non-charged porphyrin-fullerene C 60 dyad (TCP-C 60 ) and its tetracationic analogue (TCP-C 60 4+ ) was investigated in solution and in Staphylococcus aureus cells. The ability of both dyads to form a photoinduced charge-separated state was evidenced by the reduction of methyl viologen in N , N -dimethylformamide (DMF). Moreover, the formation of superoxide anion radicals induced by these dyads was detected by the reduction of nitro blue tetrazolium. Also, photosensitized decomposition of l-tryptophan (Trp) was investigated in the presence of reactive oxygen species (ROS) scavengers. The addition of β-carotene and sodium azide had a slight effect on reaction rate. However, photooxidation of Trp mediated by TCP-C 60 was negligible in the presence of d-mannitol, while no protection was found using TCP-C 60 4+ . In a polar medium, these dyads mainly act by a contribution of type I pathway with low generation of singlet molecular oxygen, O 2 ( 1 Δ g ). In S. aureus cell suspensions, an aerobic atmosphere was required for the photokilling of this bacterium. The photocytotoxicity induced by TCP-C 60 was increased in D 2 O with respect to water, while a small effect was found using TCP-C 60 4+ . Furthermore, photoinactivation of microbial cells was negligible in the presence of sodium azide. The addition of d-mannitol did not affect the photoinactivation induced by TCP-C 60 . In contrast, S. aureus cells were protected by d-mannitol when TCP-C 60 4+ was used as a photosensitizer. Also, generation of O 2 ( 1 Δ g ) in the S. aureus cells was higher for TCP-C 60 than TCP-C 60 4+ . Therefore, TCP-C 60 appears to act in microbial cells mainly through the mediation of O 2 ( 1 Δ g ). Although, a contribution of the type I mechanism was found for cell death induced by TCP-C 60 4+ . Therefore, these dyads with high capacity to produce photoinduced charge-separated state represent interesting photosensitizers to inactivate microorganisms by type I or type II mechanisms. In particular, TCP-C 60 may be located in a non-polar microenvironment in the cells favoring a type II pathway, while a contribution of the type I mechanism was produced using the cationic TCP-C 60 4+ ., Competing Interests: There are no conflicts to declare., (This journal is © The Royal Society of Chemistry.)

The photodynamic inactivation mediated by 5,10,15,20-tetrakis[4-(3-N,N-dimethylaminopropoxy)phenyl]porphyrin (TAPP) and 5,10,15,20-tetrakis[4-(3-N,N,N-trimethylaminepropoxy)phenyl]porphyrin (TAPP(4+)) were compared in Candida albicans cells. A strong binding affinity was found between these porphyrins and the yeast cells. Photosensitized inactivation of C. albicans increased with both photosensitizer concentration and irradiation time. After 30 min irradiation, a high photoinactivation (∼5 log) was found for C. albicans treated with 5 μM porphyrin. Also, the photoinactivation of yeast cells was still elevated after two washing steps. However, the photocytotoxicity decreases with an increase in the cell density from 10(6) to 10(8) cells/mL. The high photodynamic activity of these porphyrins was also established by growth delay experiments. This C. albicans strain was susceptible to fluconazole with a MIC of 1.0 μg/mL. The effect of photosensitization and the action of fluconazole were combined to eradicate C. albicans. After a PDI treatment with 1 μM porphyrin and 30 min irradiation, the value of MIC decreased to 0.25 μg/mL. In addition, a complete arrest in cell growth was found by combining both effects. TAPP was similarly effective to photoinactivate C. albicans than TAPP(4+). This porphyrin without intrinsic positive charges contains basic amino groups, which can be protonated at physiological pH. Moreover, an enhancement in the antifungal action was found using both therapies because lower doses of the agents were required to achieve cell death., (Copyright © 2015 Elsevier B.V. All rights reserved.)

The effect of divalent cations, EDTA and chitosan (CS) on the uptake and photoinactivation of Escherichia coli produced by 5,10,15,20-tetrakis(4-N,N,N-trimethylammoniumphenyl)porphyrin (TMAP(4+)), 5,10-di(4-methylphenyl)-15,20-di(4-N,N,N-trimethylammoniumphenyl)porphyrin (MPAP(2+)) and 5,10,15,20-tetra(4-sulphonatophenyl)porphyrin (TPPS(4-)) were examined under different conditions. These porphyrins were rapidly bound to E. coli cells (<2.5min) and the uptake of photosensitizers was not dependent on incubation temperature, reaching values of 0.61, 0.18 and 0.08nmol/10(8) cells for TMAP(4+), MPAP(2+) and TPPS(4-), respectively. The addition of Ca(2+) or Mg(2+) to the cultures enhanced the uptake of MPAP(2+) and TPPS(4-) by cells. In contrast, the amount of TMAP(4+) bound to cells was decreased. The presence of EDTA produced an increase in the uptake of porphyrins by cells, while CS mainly enhanced the amount of TPPS(4-) bound to E. coli. The photoinactivation of E. coli cells mediated by TMAP(4+) was highly effective even at low concentration (1μM) and short irradiation period (5min). However, a reduction in the phototoxicity was found for TMAP(4+) in presence of Ca(2+) and Mg(2+). In contrast, the phototoxic activity mediated by MPAP(2+) and TPPS(4-) was increased. Addition of EDTA did not show effect on the photoinactivation induced by cationic porphyrins, while a small enhance was found for TPPS(4-). Moreover, inactivation of E. coli cells was achieved in the presence CS. This cationic polymer was antimicrobial by itself in the dark. Using a slightly toxic CS concentration, the phototoxic activity induced by TMAP(4+) was diminished. This effect was mainly observed at lower concentration of TMAP(4+) (0.5-1μM). In contrast, an increase in E. coli photoinactivation was obtained for MPAP(2+) and TPPS(4-) in presence of CS. Thus, this natural polymeric destabilizer agent mainly benefited the photoinactivation mediated by TPPS(4-)., (Copyright © 2014 Elsevier B.V. All rights reserved.)

A covalently linked porphyrin-fullerene C60 dyad 5 was synthesized by 1,3-dipolar cycloaddition using 5-(4-formylphenyl)-10,15,20-tris[3-(N-ethylcarbazoyl)]porphyrin, N-methylglycine and fullerene C60. Methylation of 5 was used to obtain a cationic dyad 6. Spectroscopic properties were compared in toluene, N,N-dimethylformamide (DMF) and toluene/sodium bis(2-ethylhexyl)sulfosuccinate (AOT)/water reverse micelles. Absorption spectra of the dyads were essentially a superposition of the spectra of the porphyrin and fullerene reference compounds, indicating a very weak interaction between the chromophores in the ground state. The fluorescence emission of the porphyrin moiety in the dyads was strongly quenched by the attached fullerene C60 unit. The singlet molecular oxygen, O2((1)Δg), productions (ΦΔ) were strongly dependent on the solvent polarity. Similar ΦΔ values were obtained for 5,10,15,20-tetrakis[3-(N-ethylcarbazoyl)]porphyrin (TCP) in both solvents. Also, dyad 5 showed a high O2((1)Δg) generation in toluene. However, O2((1)Δg) production mediated by 5 considerably diminished in the more polar solvent DMF. Also, a high photodynamic activity involving O2((1)Δg) was found for both dyads in a simple biomimetic system formed by AOT reverse micelles. The photoinactivation ability of these dyads was investigated in Staphylococcus aureus cell suspensions. Photosensitized inactivation of S. aureus by dyad 6 exhibits a 4.5 log decrease of cell survival (99.997% cell inactivation), when the cultures are treated with 5 μM photosensitizer and irradiated with visible light (350-800 nm) for 30 min. Under these conditions, a lower photocytotoxic effect was found for 5 (3.2 log decrease). Furthermore, photoinactivation induced by 6 was higher than those obtained with the separate moieties of the dyad. Therefore, molecular structures formed by porphyrin-fullerene C60 dyads represent interesting photosensitizers to inactivate S. aureus., (Copyright © 2014 Elsevier Masson SAS. All rights reserved.)

The photodynamic activity of brominated derivatives of New Fuchsin and Azure B was studied in solution and in cell suspensions of Candida albicans. The spectroscopic and photodynamic properties of these photosensitizers were compared with those of Crystal Violet and Azure B, which represent active photosensitizer related to each family of compounds. Triarylmethane derivatives absorb intensely with a band centered at ∼ 570 nm, while the phenothiazinium dyes at ∼ 650 nm. Photooxidation of 9,10-dimethylanthracene was observed using phenothiazinium compounds indicating the formation of singlet molecular oxygen, while it was not detected using triarylmethane agents. However, triarylmethane dyes were able to photooxidize l-tryptophan. In yeast cell suspensions, the photosensitized inactivation of C. albicans increases with photosensitizer concentration, causing a ∼ 5 log decrease of cell survival, when the cultures are treated with 20 μM of Crystal Violet and irradiated for 60 min. Under these conditions, the photodynamic activity of 50 μM Azure B induced a ∼ 3 log decrease of cell survival. Studies of photodynamic action mechanism indicated that photoinactivation of C. albicans cells induced by triarylmethane compounds involves mainly type I photoprocess. Although, phenothiazinium derivatives produce singlet molecular oxygen, a contribution of other reactive oxygen species cannot be discarded in the photoinactivation of C. albicans., (Copyright © 2014 Elsevier B.V. All rights reserved.)

The photodynamic mechanism of action induced by N,N-dimethyl-2-(4'-N,N,N-trimethylaminophenyl)fulleropyrrolidinium iodide (DTC60(2+)) was investigated on Candida albicans and Escherichia coli cells. First, photogeneration of superoxide anion radical by DTC60(2+) in the presence of NADH was detected using nitro blue tetrazolium method in reverse micelles. In C. albicans suspensions, 10 μM DTC60(2+) was an effective photosensitizer, producing a ∼5log decrease of cell survival when the cultures were irradiated for 30 min with visible light. Also, C. albicans cells growth was not detected in the presence of 10 μM DTC60(2+) and irradiation. Photodynamic mechanism investigations were compared in both C. albicans and E. coli cells. Studies under anoxic conditions indicated that oxygen was required for the photodynamic inactivation of these microorganisms. The photocytotoxicity induced by DTC60(2+) was similar in D2O than in water cell suspensions. Furthermore, photoinactivation of microbial cells was negligible in the presence of azide ion, while the addition of mannitol produced a photoprotective effect on the cellular survival. These results indicate that DTC60(2+) has potential as agent to the photodynamic inactivation of microbial cells. Also, the photocytotoxicity activity induced by this cationic fullerene derivative can involve the intermediacy of both superoxide anion radical and singlet molecular oxygen., (Copyright © 2013 Elsevier B.V. All rights reserved.)

Photoinactivation of Streptococcus mitis induced by zinc(II) 2,9,16,23-tetrakis[2-(N,N,N-trimethylamino)ethoxy]phthalocyanine (ZnEPc(4+)) was studied under different experimental condition in order to obtain information about the photodynamic processes and the cellular damage. A 3 log decrease in S. mitis survival was found in cell suspensions (~2×10(8) cells/mL) incubated with 2 μM ZnEPc(4+) and irradiated for 30 min with visible light (54 J/cm(2)). Also, S. mitis cells growth was not detected in broth treated with 5 μM ZnEPc(4+) under continuous irradiation. Studies of photodynamic action mechanism showed that the cells were protected in the presence of azide ion, while the addition of mannitol did not produce a significant effect on the survival. Moreover, the photocytotoxicity was increased in D2O indicating the interference of singlet molecular oxygen. On the other hand, it was found that ZnEPc(4+) interacts strongly with calf thymus DNA in solution but photocleavage of DNA was only detected after long irradiation periods. After S. mitis photoinactivation, modifications of genomic DNA were not observed by electrophoresis. In contrast, the transmission electron microscopy showed structural changes in the S. mitis cells, exhibiting mesosome-like structures. After 2h irradiation, the cytoplasm showed segregation patterns and PDI appeared to have effects on the cell wall, including variability in wall thickness. Also, the presence of bubbles was detected on the cell surface by scanning electron microscopy. However, the photodamage to the cell envelope was insufficient to cause the release of intracellular biopolymers. Therefore, modifications in the cytoplasmic biomolecules and alteration in the cell barriers could be mainly involved in S. mitis photoinactivation. It can be concluded that photosensitization by ZnEPc(4+) mainly involved a type II photoprocess, while alteration in the cytoplasmatic components and modifications in the cell envelope were the major cause for the photoinactivation of S. mitis., (Copyright © 2013 Elsevier B.V. All rights reserved.)

Photodynamic inactivation (PDI) of Escherichia coli has been studied in cultures treated with zinc(II) 2,9,16,23-tetrakis[4-(N-methylpyridyloxy)]phthalocyanine (ZnPPc(+4)) to obtain insight about the mechanism of damage. This phthalocyanine is rapidly bound to cells, reaching a value of approximately 0.8 nmol/10(6) cells when the cultures were incubated with 2 microM sensitizer. After 30 min of irradiation, a 4 log decrease of E. coli survival was observed. The photocytotoxic action was investigated in plasmid and genomic DNA by electrophoretic analysis. Absorption spectroscopic studies showed that this cationic phthalocyanine interacts strongly with DNA (K(DNA)=4.7 x 10(6)M(-1)). Photocleavage of calf thymus DNA sensitized by ZnPPc(+)4 was not found even after long irradiation periods. Similar results were also observed in genomic DNA extracted from E. coli cells after PDI treatment. Modifications of plasmid DNA isolated from bacteria were only observed after long irradiation periods. However, under these conditions transmission electron microscopy of the PDI bacteria revealed an aggregation of cytoplasmic macromolecules and irregularities in cell barriers. Also, scanning electron microscopy showed a shrunken appearance in cells after PDI. Even so, release of intracellular biopolymers was not detected by absorption. On the other hand, outer and inner membranes permeabilization assays showed an increase in the permeability. Consequently, alterations in the cell membrane functionality induced by ZnPPc(+4) appear to be the major cause of E. coli inactivation upon PDI.

Photodynamic therapy (PDT) was investigated using the phthalocyanine photosensitizer Zinc (II) 2,9,16,23-tetrakis (methoxy) phthalocyanine (ZnPc(OCH(3))(4)) on BALB/c mice. Animals bearing tumor were treated with 0.2mg/kg body weight (bw) ZnPc(OCH(3))(4) and 24h later were irradiated with 70, 140 and 210 J/cm(2) of visible light from a source delivering 39 mW/cm(2). In this study, we have tested the efficiency of ZnPc(OCH(3))(4) liposomal formulation on mice. Biodistribution studies were performed in tumor-free mice and tumor-bearing mice at various time points up to 24h after ZnPc(OCH(3))(4)-PDT treatment. The tumor sizes were evaluated over different period in parallel experiments. The maximal efficiency and selectivity of photosensitizer accumulation in tumor tissue take place at 24h after drug administration of 0.2mg/kg bw ZnPc(OCH(3))(4). In the tumor sections for biochemical studies, apoptosis was visualized by activation of caspase-3. ZnPc(OCH(3))(4)-PDT tumors showed a significant delay in growth as compared to untreated control mice. In all cases, ZnPc(OCH(3))(4)-PDT-treated tumors showed a significant regression. The results indicated a dramatic decrease of tumors size after 10 days post-irradiation with 210 J/cm(2) and no recurrence of the disease was detectable within at least 90 days. The phototherapeutic agent ZnPc(OCH(3))(4) demonstrated preferential accumulation in tumor in comparison with skin tissues, except in the case of kidney. The ratio of tumor/skin tissues ranged a value of 8. These results suggest that ZnPc(OCH(3))(4)-PDT may be of particular importance in the treatment of accessible malignancies.

The mechanistic aspects of Escherichia coli photodynamic inactivation (PDI) have been investigated in bacteria treated with 5,10,15-tris[4-(3-N,N,N-trimethylammoniumpropoxy)phenyl]-20-(4-trifluoromethylphenyl)porphyrin iodide (A3B3+) and visible light. The photosensitization activity of A3B3+ porphyrin was compared with that of 5,10,15,20-tetra(4-N,N,N-trimethylammonium phenyl)porphyrin p-tosylate (TMAP4+), which is an active tetracationic sensitizer to eradicate bacteria. The PDI damages on plasmid and genomic DNA were analyzed by electrophoresis. DNA photocleavage was observed after a long period of irradiation, when the bacterial cells are largely photoinactivated. Transmission electron microscopy (TEM) revealed structural changes with appearance of low density areas into the cells and irregularities in cell barriers, which could affect the normal cell membrane functionality. Also, damages on the cell-wall were not detected by scanning electron microscopy (SEM) and release of intracellular biopolymers was not found after PDI. These results indicate that the photodynamic activity of these cationic porphyrins produces DNA photodamage after a long period of irradiation. Therefore, an interference with membrane functions could be the main cause of E. coli photoinactivation upon short PDI treatments.

The photophysical properties and photodynamic effect of Zn(ii), Pd(ii), Cu(ii) and free-base 5-(4-(trimethylammonium)phenyl)-10,15,20-tris(2,4,6-trimethoxy phenyl)porphyrin (H2P) iodide have been studied in N,N-dimethylformamide (DMF) and in different biomimetic systems. The absorption, fluorescence, triplet state and singlet molecular oxygen production of the metal complexes were all referred to H2P. The photodynamic activity was first analyzed using 9,10-dimethylanthracene and guanosine 5'-monophosphate in N,N-dimethylformamide. The photooxidation processes were also investigated in benzene/benzyl-n-hexadecyldimethyl ammonium chloride/water reverse micelles. Photosensitization efficiency of these porphyrins was H2P approximately ZnP > PdP in homogeneous solution and ZnP > H2P > PdP in micelles, whereas no photooxidation effect was detected using the Cu(ii) complex. Human erythrocytes were used as a biological membrane model. The photohemolytic activity depended on irradiation time, sensitizer and concentration of the agent. When cells were treated with 1 microM sensitizer, the hemolytic activity was H2P > ZnP >> CuP. However, it was H2P > ZnP approximately CuP using 5 microM of the respective porphyrin. Although CuP could undergo a type I photoreaction, in all cases the photohemolytic effect considerably diminishes in anoxic conditions, indicating that an oxygen atmosphere is required for the mechanism of cellular membrane damage. The behavior of these amphiphilic metallo porphyrins provides information on the photodynamic activity of these agents in biomimetic microenvironments.

Photodynamic therapy (PDT) is an innovative treatment for several types of malignant and non-malignant disease. In the present study, ZnPcOCH(3) was investigated on a human larynx-carcinoma cell line (Hep-2) for its use in PDT. This drug exhibited favourable properties as a photosensitizer in vitro because ZnPcOCH(3) is able to penetrate efficiently in the cytoplasm of cultured cancer cells and is partially localized in lysosomes. The results show that ZnPcOCH(3)-PDT-induced apoptosis by caspase dependent pathway. The new compound shows a good photosensitizing efficiency in vitro on Hep-2 cells, encouraging further in vivo studies.

New suitable approaches were investigated to visualize the photodynamic inactivation (PDI) of bacteria immobilized on agar surfaces. The PDI capacities of a cationic photosensitizer (5,10,15,20-tetra(4-N,N,N-trimethylammoniumphenyl)porphyrin) and an anionic photosensitizer (5,10,15,20-tetra(4-sulfonatophenyl)porphyrin) were analyzed on a typical Gram-negative bacterium Escherichia coli following two procedures. In Experiment I, the E. coli cells were grown as lawn on agar surface containing the sensitizers spread in a small area (10 nmol in ∼0.6 cm(2) ). After irradiation with visible light (10 min, 90 milliwatts/cm(2) ), no cells were grown in the area containing the cationic porphyrin. In Experiment II, small colonies (∼2-mm diameter) of E. coli on agar were treated with a solution of sensitizer (10 nmol) and irradiated with visible light for 3 h. Overnight incubation at 37 °C shows a growth delay of E. coli colonies treated with the cationic photosensitizer. In contrast, the anionic porphyrin did not produce appreciable photodamage. These experiments could be either used in an undergraduate project for natural science advance students or used for a postgraduate practical training course. This methodology illustrates the application of PDI to treat bacteria growing as localized foci of infection., (Copyright © 2007 International Union of Biochemistry and Molecular Biology, Inc.)

The photodynamic activity of 5,10,15-tris[4-(3-N,N,N-trimethylammoniumpropoxy)phenyl]-20-(4-trifluoromethylphenyl)porphyrin iodide (A3B3+) has been studied in vitro on a typical Gram-negative bacterium Escherichia coli immobilized on agar surfaces. The results obtained for the tricationic A3B3+ porphyrin were compared with those of 5,10,15,20-tetra(4-N,N,N-trimethylammoniumphenyl)porphyrin p-tosylate (TTAP4+), which is a standard active sensitizer established to eradicate E. coli in cellular suspension. The photobleaching of these porphyrins in solution was evaluated by decay in absorbance and in fluorescence. In both cases, a higher photostability was found for A3B3+ than for TTAP4+. Photodynamic inactivation capacities of these sensitizers were analyzed in E. coli cells immobilized on agar surfaces. Small colonies were treated with different amount of sensitizer (0-14 nmol) and irradiated with visible light for 3h. The light source used was either a projector or midday sun. The A3B3+ porphyrin produced a growth delay of E. coli colonies on agar surfaces. Similar result was obtained irradiating only one isolated colony through an optical fiber. Under these conditions, A3B3+ porphyrin shows a high activity to inactivate localized bacterial cells. The higher photodynamic activity of A3B3+ was confirmed by mechanical spreading of the colonies before treatment. This procedure produces complete inactivation of E. coli cells on the agar surface. Therefore, tricationic A3B3+ porphyrin is an interesting sensitizer with potential applications in photodynamic inactivation of bacteria growing as localized foci of infection.

The photodynamic effect of novel cationic porphyrins, with different pattern of meso-substitution by 4-(3-N,N,N-trimethylammoniumpropoxy)phenyl (A) and 4-(trifluoromethyl)phenyl (B) groups, have been studied in both solution bearing photooxidizable substrates and in vitro on a typical Gram-negative bacterium Escherichia coli. In these sensitizers, the cationic groups are separated from the macrocycle ring by a propoxy spacer. Thus, the charges have a high mobility and a minimal influence on photophysical properties of the porphyrin. These compounds produce singlet molecular oxygen, O2(1Delta(g)), with quantum yields of approximately 0.41-0.53 in N,N-dimethylformamide. In methanol, the l-tryptophan photodecomposition increases with the number of cationic charges in the sensitizer. In vitro investigations show that cationic porphyrins are rapidly bound to E. coli cells in approximately 5 min. A higher binding was found for A3B3+ porphyrin, which is tightly bound to cells still after three washing steps. Photosensitized inactivation of E. coli cellular suspensions follows the order: A3B3+ > A44+>> ABAB2+ > AB3+. Under these conditions, a negligible effect was found for 5,10,15,20-tetra(4-sulfonatophenyl)porphyrin (TPPS4(4-)) that characterizes an anionic sensitizer. Also, the results obtained for these new cationic porphyrins were compared with those of 5,10,15,20-tetra(4-N,N,N-trimethylammonium phenyl)porphyrin (TTAP4+), which is a standard active sensitizer established to eradicate E. coli. The photodynamic activity of TTAP4+ is quite similar to that produced by A4(4+). Studies in an anoxic condition indicate that oxygen is necessary for the mechanism of action of photodynamic inactivation of bacteria. The higher photodynamic activity of A3B3+ was confirmed by growth delay experiments. Photodynamic inactivation capacities of these sensitizers were also evaluated in E. coli cells immobilized on agar surfaces. Under these conditions, A3B3+ porphyrin retains a high activity to inactivate localized bacterial cells. Therefore, tricationic porphyrin A3B3+ is an interesting sensitizer with potential applications in photodynamic inactivation of bacteria in liquid suspensions or on surfaces.

Phase-transfer catalysis (PTC) is a widely accepted methodology in organic synthesis. Although a great number of organic syntheses were reported in PTC conditions, systematic kinetic studies are scarce. In the present report, a detailed study of the kinetics of the reaction between 2-chloro-5-nitrotrifluoromethylbenzene (CNTFB) and 2-phenylpropionitrile anion (HPP-), under PTC, was performed under several conditions. The reaction was carried out either in toluene or chlorobenzene as the organic phase, in the presence of a concentrated aqueous solution of NaOH using tetraalkylammonium (Q+X-) salts as phase-transfer catalysts. The major product was 2-(4-nitro-2-trifluoromethylphenyl)-2-phenylpropionitrile, and its yield depends on the experimental conditions. Different aspects of the mechanism are discussed and quantified. Kinetic data were explained by means of an interfacial mechanism that involves the deprotonation of the adsorbed nucleophile precursor followed by its catalyst-mediated extraction to the organic phase. A multicomponent Langmuir-type interface was assumed. Although the extraction of OH- by catalyst to the organic phase is usually disregarded, the formation of the substrate hydrolysis product that leads to catalyst poisoning was also investigated. The influence of this side reaction on the yield of the main product was established. A discussion about the influence of this side process on the main reaction and the operating mechanism is presented.

The photodynamic activity of a cationic Zn(II) tetramethyltetrapyridinoporphyrazinium salt (ZnPc ) was compared with that of a non-charged Zn(II) tetrapyridinoporphyrazine (ZnPc 1), both in vitro using human red blood (HRB) cells and a typical Gram-negative bacterium Escherichia coli. Absorption and fluorescence spectroscopic studies were analyzed in different media. Fluorescence quantum yields (phi(F)) of 0.35 for ZnPc 1 and 0.30 for ZnPc 2 were calculated in N,N-dimethylformamide (DMF). The singlet molecular oxygen, O(2)((1)Delta(g)), production was evaluated using 9,10-dimethylanthracene (DMA) in DMF yielding values of Phi(Delta)= 0.56 for ZnPc 1 and 0.50 for ZnPc 2. In biological medium, the photodynamic effect was first evaluated in HRB cells. Both phthalocyanines produce similar photohemolysis of HRB cells, reaching values >90% of lysis after 5 min of irradiation with visible light. The photodynamic effect is accompanied by an increase in the membrane fluidity of HRB cells. However, these studies on E. coli cells showed that the cationic ZnPc 2 produces a higher photoinactivation of Gram-negative bacteria than ZnPc 1. Also, these results were established by stopped of growth curves for E. coli. Therefore the studies show that cationic ZnPc 2 is an efficient phototherapeutic agent with potential applications in tumor cell and Gram-negative bacteria inactivation by photodynamic therapy.