Unusual dark-field hyperspectral and confocal Raman microscopy features of a nanoporous gold electrode coated with porphyrazine complex.

Nanoporous gold electrodes are of great interest in electroanalytical chemistry, because of their unusual activity and large surface area. The electrochemical activity can be further improved by coating with molecular catalysts such as the tetraruthenated cobalt-tetrapyridylporphyrazines investigated in this work. The plasmonic enhancement of the scattered light at the nanoholes and borders modifies the electrode's optical characteristics, improving the transmission through the surface-enhanced Raman scattering (SERS) effect. When monitored by hyperspectral dark-field and confocal Raman microscopy, this effect allows probing of the porphyrazine species at the plasmonic nanholes, improving the understanding of the chemically modified gold electrodes.

Unraveling of Functional Activity of Primary Hippocampal Neuron-Glial Networks in Photodynamic Therapy Based on Tetracyanotetra(aryl)porphyrazines.

The current efforts in photodynamic therapy (PDT) of brain cancer are focused on the development of novel photosensitizers with improved photodynamic properties, targeted specific localization, and sensitivity to the irradiation dose, ensuring the effectiveness of PDT with fewer side effects for normal nerve tissue. Here, we characterize the effects of four photosensitizers of the tetracyanotetra(aryl)porphyrazine group (pz I-IV) on the functional activity of neuron-glial networks in primary hippocampal cultures in their application in normal conditions and under PDT. The data revealed that the application of pz I-IV leads to a significant decrease in the main parameters of the functional calcium activity of neuron-glial networks and pronounced changes in the network characteristics. The observed negative effects of pz I-IV were aggravated under PDT. Considering the significant restructuring of the functional architectonics of neuron-glial networks that can lead to severe impairments in synaptic transmission and loss of brain functions, and the feasibility of direct application of PDT based on pz I-IV in the therapy of brain tumors is highly controversial. Nevertheless, the unique properties of pz I-IV retain a great prospect of their use in the therapy of tumors of another origin and cellular metabolism.

Azaporphyrins Embedded on Carbon-Based Nanomaterials for Potential Use in Electrochemical Sensing-A Review.

Phthalocyanines and porphyrazines as macrocyclic aza-analogues of well-known porphyrins were deposited on diverse carbon-based nanomaterials and investigated as sensing devices. The extended π-conjugated electron system of these macrocycles influences their ability to create stable hybrid systems with graphene or carbon nanotubes commonly based on π-π stacking interactions. During a 15-year period, the electrodes modified by deposition of these systems have been applied for the determination of diverse analytes, such as food pollutants, heavy metals, catecholamines, thiols, glucose, peroxides, some active pharmaceutical ingredients, and poisonous gases. These procedures have also taken place, on occasion, in the presence of various polymers, ionic liquids, and other moieties. In the review, studies are presented that were performed for sensing purposes, involving azaporphyrins embedded on graphene, graphene oxide or carbon nanotubes (both single and multi-walled ones). Moreover, possible methods of electrode fabrication, limits of detection of each analyte, as well as examples of macrocyclic compounds applied as sensing materials, are critically discussed.

Cyanoarylporphyrazines with High Viscosity Sensitivity: A Step towards Dosimetry-Assisted Photodynamic Cancer Treatment.

Despite the significant relevance of photodynamic therapy (PDT) as an efficient strategy for primary and adjuvant anticancer treatment, several challenges compromise its efficiency. In order to develop an "ideal photosensitizer" and the requirements applied to photosensitizers for PDT, there is still a need for new photodynamic agents with improved photophysical and photobiological properties. In this study, we performed a detailed characterization of two tetracyanotetra(aryl)porphyrazine dyes with 4-biphenyl (pz II) and 4-diethylaminophenyl (pz IV) groups in the periphery of the porphyrazine macrocycle. Photophysical properties, namely, fluorescence quantum yield and lifetime of both photosensitizers, demonstrate extremely high dependence on the viscosity of the environment, which enables them to be used as viscosity sensors. PzII and pz IV easily enter cancer cells and efficiently induce cell death under light irradiation. Using fluorescence lifetime imaging microscopy, we demonstrated the possibility of assessing local intracellular viscosity and visualizing viscosity changes driven by PDT treatment with the compounds. Thus, pz II and pz IV combine the features of potent photodynamic agents and viscosity sensors. These data suggest that the unique properties of the compounds provide a tool for PDT dosimetry and tailoring the PDT treatment regimen to the individual characteristics of each patient.

Tuning the Acceptor Unit of Push-Pull Porphyrazines for Dye-Sensitized Solar Cells.

A family of four push-pull porphyrazines of A3B type, where each unit A contains two peripheral propyl chains and the unit B is endowed with a carboxylic acid, were prepared. The carboxylic acid was attached to the ß-position of the pyrrolic unit, either directly (Pz 10), or through cyanovinyl (Pz 11) and phenyl (Pz 7) groups. The fourth Pz (14) consisted in a pyrazinoporphyrazine wherein the dinitrogenated heterocycle provided intrinsic donor-acceptor character to the macrocycle and contained a carboxyphenyl substituent. The direct attachment of the carboxylic acid functions and their linkers to the porphyrazine core produces stronger perturbation on the electronic properties of the macrocycle, with respect to their connection through fused benzene or pyrazine rings in TT112 and 14, respectively. The HOMO and LUMO energies of the Pzs, which were estimated with DFT calculations, show little variation within the series, except upon introduction of the cyanovinyl spacer, which produces a decrease in both frontier orbital energetic levels. This effective interaction of cyanovinyl substitution with the macrocycle is also evidenced in UV/Vis spectroscopy, where a large splitting of the Q-band indicates strong desymmetrization of the Pz. The performance of the four Pzs as photosensitizers in DSSCs were also investigated.

Fluorescence properties and quantum-chemical modeling of tert-butyl-substituted porphyrazines: Structural and ionization effect.

Synthesis and identification of tetrakis-[5,6-bis(4-tert-butylphenyl)pyrazino] porphyrazine, tetra-(4-tert-butyl)phthalocyanine and octakis-(4-tert-butylphenyl)porphyrazine were carried out. Spectrophotometric method was used to study the spectral, acidic and fluorescence properties of the synthesized compounds. It was determined that the synthesized tert-butyl-substituted porphyrazines exhibit a high sensitivity of fluorescence to the molecule ionization. To understand the features of the spectral properties the geometry optimization and an analysis of energy levels and localization of highest occupied and lowest unoccupied molecular orbitals of the studied compounds were performed on the basis of density functional theory with the BP86 functional and the def2-TZVP basis set. The effect of substituents in molecular fragments of the macrocycle on the acidic and electro-optical properties of the studied compounds is revealed. Materials with pH-tunable fluorescence were designed.

Azides and Porphyrinoids: Synthetic Approaches and Applications. Part 2-Azides, Phthalocyanines, Subphthalocyanines and Porphyrazines.

The reaction between organic azides and alkyne derivatives via the Cu(I)-catalyzed azide-alkyne cycloaddition (CuAAC) is an efficient strategy to combine phthalocyanines and analogues with different materials. As examples of such materials, it can be considered the following ones: graphene oxide, carbon nanotubes, silica nanoparticles, gold nanoparticles, and quantum dots. This approach is also being relevant to conjugate phthalocyanines with carbohydrates and to obtain new sophisticated molecules; in such way, new systems with significant potential applications become available. This review highlights recent developments on the synthesis of phthalocyanine, subphthalocyanine, and porphyrazine derivatives where CuAAC reactions are the key synthetic step.

Model of Ovarian Adenocarcinoma Spheroids for Assessing Photodynamic Cytotoxicity.

The aim of the study was to compare the relevance of ovarian adenocarcinoma spheroids with that of a monolayer culture for assessing photodynamic effect of the tetrakis(4-benzyloxyphenyl)tetracyanoporphyrazine photosensitizer. MATERIALS AND METHODS: The work was performed on SKOV-3 human ovary adenocarcinoma cells grown in vitro in a monolayer culture and in the form of tumor spheroids obtained using culture plates with ultra-low attachment. We determined the photoinduced toxicity of porphyrazine on a monolayer culture using the MTT assay; the effect on the spheroids was tested by assessing the dynamics of their growth. Cellular uptake of porphyrazine was analyzed by confocal microscopy. RESULTS: Porphyrazine has a pronounced photodynamic effect on SKOV-3 cells. When exposed to light at a dose of 20 J/cm2, the IC50 value 24 h after exposure was 2.3 µM for SKOV-3 monolayer culture. For the spheroids, the effect manifested after a latency period: significant growth retardation of the treated spheroids appeared no sooner than 5 and 9 days after exposure. Notably, no decrease in the initial size of the treated spheroids was observed under any of the photodynamic regimes. The penetration depth of porphyrazine into spheroids was 50-100 µm during 24 h incubation. CONCLUSION: The limited penetration of the photosensitizer into the body of spheroids and its predominant accumulation in the surface layers can be one of the key factors behind the significant differences in the photodynamic response between the surface and deep layers of a spheroid. For cells located close to the spheroid surface, the photodynamic effect is comparable to that for a monolayer culture, while in deeper layers, the cells remain viable and support/maintain the growth of the spheroid even under intense photo-exposure. The fact that the in vitro distribution is similar to the inhomogeneous accumulation of photosensitizers in tumors in vivo allows us to consider spheroids more relevant than a monolayer culture for studying photodynamic anti-tumor effects.

Liposomal formulations of magnesium sulfanyl tribenzoporphyrazines for the photodynamic therapy of cancer.

Photodynamic therapy of cancer comprises the activation of photosensitizer molecules delivered to cancer cells, to generate reactive oxygen species that mediate cytotoxicity. In this study, previously synthesized dendritic magnesium tribenzoporphyrazines were incorporated into four types of liposomes containing either 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC) or 1,2-dioleoyl-sn-glycero-3-phosphoethanolamine (DOPE) as the zwitterionic lipids. The addition of either l-α-phosphatidyl-dl-glycerol (PG) or 1,2-dioleoyl-3-trimethylammoniumpropane (DOTAP) imparted a negative or positive charge, respectively. Novel formulations were tested in oral squamous cell carcinoma cell lines (CAL 27, HSC-3) as well as cervical adenocarcinoma cells (HeLa). Positively charged DOTAP:POPC liposomes were the most effective carriers for all tested tribenzoporphyrazines. Calculated IC50 values for DOTAP:POPC liposomes indicated that the incorporation of tribenzoporphyrazines into these liposomes can improve photocytotoxicity up to 50-fold compared to the free forms of macrocycles. Oral cancer cells (CAL 27 and HSC-3) were more sensitive to liposomal photodynamic treatment than HeLa cells.

Panchromatic Photosensitizers Based on Push-Pull, Unsymmetrically Substituted Porphyrazines.

A series of five push-pull porphyrazines of A3 B type, in which unit B is an isoindole 4-carboxylic acid, has been prepared. The units A have been endowed with thioether, amine, ether and alkyl functions, either directly attached to the ß-position of the pyrrolic units, or connected to the porphyrazine core through p-substituted phenyl groups. Attaching the electron-donor functions to the porphyrazine periphery produces strong perturbations in the electronic and redox properties of the dyes. Their HOMO and LUMO energies, estimated from the optical and redox data, as well as with DFT calculations, raise upon functionalization with amines, while the corresponding frontier orbital energetic levels lower upon functionalization with thioethers, p-methoxyphenyl or p-tert-butylphenyl groups. The effective interaction of peripheral substitution with the macrocycle produces chromophores with panchromatic absorption between 300 and 750-850 nm.

Activity of Zn and Mg phthalocyanines and porphyrazines in amyloid aggregation of insulin.

Formation of the deposits of protein aggregates-amyloid fibrils in an intracellular and intercellular space-is common to a large group of amyloid-associated disorders. Among the approaches to develop of therapy of such disorders is the use of agents preventing protein fibrillization. Polyaromatic complexes-porphyrins and phthalocyanines-are known as compounds possessing anti-fibrillogenic activity. Here, we explore the impact of related macrocyclic complexes-phthalocyanines (Pc) and octaphenyl porphyrazines (Pz) of Mg and Zn-on aggregation of amyloidogenic protein insulin. Pz complexes are firstly reported as compounds able to affect protein fibrillization. The effect of Pc and Pz complexes on the kinetics and intensity of insulin aggregation was studied by the fluorescent assay using amyloid sensitive cyanine dye. This has shown the impact of metal ion on the anti-fibrillogenic properties of macrocyclic complexes-the effect on the fibrillization kinetics of Mg-containing compounds is much more pronounced comparing to that of Zn analogues. Scanning electron microscopy experiments have demonstrated that filamentous fibrils are the main product of aggregation both for free insulin and in the presence of macrocyclic complexes. However, those fibrils are distinct by their length and proneness to lateral aggregation. The Pc complexes cause the increase in variation of fibrils length 0.9 to 2.7 nm in opposite to 1.4 to 2.0 nm for free insulin, whereas Pz complexes cause certain shortening of the fibrils to 0.8 to 1.6 nm. The averaged size of the fibrils population was estimated by dynamic light scattering; it correlates with the size of single fibrils detected by scanning electron microscopy.

Phenylene-Bridged Expanded Porphyrazines.

Novel expanded porphyrazines comprising o- and p-phenylene units were synthesized from self-condensation reactions of acyclic [2+1]-type precursors prepared from 1,3-diiminoisoindoline and the corresponding phenylenediamines. Möbius and Hückel topological structures of [4+2]-type and [3+2]-type expanded porphyrazines, respectively, were elucidated by X-ray crystallography. Despite the Möbius and Hückel [4n]π-electron systems, these expanded porphyrazines are virtually nonaromatic as a result of their flexible structures in solution, which may diminish intrinsic aromaticity and antiaromaticity.

Effective delivery of porphyrazine photosensitizers to cancer cells by polymer brush nanocontainers.

Efficient drug delivery can be assigned to tasks that attract the most acute attention of researchers in the field of anticancer drug design. We have reported the first case of using amphiphilic polymer brushes as nanocontainers for photosensitizer delivery to cancer cells. Regular graft-copolymers of hydrophobic polyimides with hydrophilic polymethacrylic acid side chains were loaded with photosensitive dye tetra(4-fluorophenyl)tetracyanoporphyrazine (Pz) providing a sufficiently stable homogeneous fraction of fluorescent Pz-loaded nanoparticles with a size of 100-150 nm. Pz-loaded polymer brushes were substantially more efficient for Pz delivery into cells compared with other types of particles examined, Pz-polyethyleneglycol and Pz-methylcellulose. In vivo, an efficient Pz delivery to tumor can also be expected since the Pz-PB particle size is in the optimal range for passive targeting. Pz-PB showed pronounced photodynamic activity, while, that is important, in the absence of irradiation the PB carrier itself was significantly less toxic than the dye itself. Summing up, water-soluble polymer brushes with polyimide backbones and polymethacrylic acid side chains can be regarded as a novel type of nanocontainers providing efficient intracellular drug delivery for photodynamic therapy of cancers.

Diazepinoporphyrazines containing peripheral styryl substituents and their promising nanomolar photodynamic activity against oral cancer cells in liposomal formulations.

The photochemical properties and photodynamic activity of three porphyrazines (Pzs) containing annulated diazepine rings, including novel demetalated porphyrazine-possessing bis(styryl)diazepine moieties were investigated. The porphyrazines were evaluated in terms of their electronic absorption and emission properties, their tendency to undergo aggregation and photodegradation, as well as their singlet oxygen generation efficiency. The in vitro photodynamic activity of the porphyrazines and their liposomal formulations were examined by using two oral squamous cell carcinoma cell lines. Magnesium(II) tribenzodiazepinoporphyrazine (1) revealed the highest phototoxic effect in both cell lines used, H413 and HSC-3. Encapsulation of Pz 1 into L-α-phosphatidyl-D,L-glycerol:1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine liposomes resulted in a nearly threefold increase in photocytotoxicity relative to that of the solution of Pz 1 (IC50 values of 45 and 129 nM, respectively).