The Effect of Biological Substrates on the Ultrafast Excited-state Dynamics of Zinc Phthalocyanine Tetrasulfonate in Solution

Zinc Phthalocyanine Photochemistry by Raman Imaging, Fluorescence Spectroscopy and Femtosecond Spectroscopy in Normal and Cancerous Human Colon Tissues and Single Cells

Photodynamic therapy is a clinically approved alternative method for cancer treatment in which a combination of nontoxic drugs known as photosensitizers and oxygen is used. Despite intensive investigations and encouraging results, zinc phthalocyanines (ZnPcs) have not yet been approved as photosensitizers for clinical use. Label-free Raman imaging of nonfixed and unstained normal and cancerous colon human tissues and normal human CCD18-Co and cancerous CaCo-2 cell lines, without and after adding ZnPcS4 photosensitizer, was analyzed. The biochemical composition of normal and cancerous colon tissues and colon cells without and after adding ZnPcS4 at the subcellular level was determined. Analyzing the fluorescence/Raman signals of ZnPcS4, we found that in normal human colon tissue samples, in contrast to cancerous ones, there is a lower affinity to ZnPcS4 phthalocyanine. Moreover, a higher concentration in cancerous tissue was concomitant with a blue shift of the maximum peak position specific for the photosensitizer from 691-695 nm to 689 nm. Simultaneously for both types of samples, the signal was observed in the monomer region, confirming the excellent properties of ZnPcS4 for photo therapy (PDT). For colon cell experiments with a lower concentration of ZnPcS4 photosensitizer, c = 1 × 10-6 M, the phthalocyanine was localized in mitochondria/lipid structures; for a higher concentration, c = 9 × 10-6 M, localization inside the nucleus was predominant. Based on time-resolved experiments, we found that ZnPcS4 in the presence of biological interfaces features longer excited-state lifetime photosensitizers compared to the aqueous solution and bare ZnPcS4 film on CaF2 substrate, which is beneficial for application in PDT.

The interaction between the light source dose and caspase-dependent and -independent apoptosis in human SK-MEL-3 skin cancer cells following photodynamic therapy with zinc phthalocyanine: A comparative study

The aim of this study is to determine the behavior of relative expression of Bcl-2, caspase-8, caspase-9, and caspase-3 genes of/in SK-MEL-3 cancer cells and explore molecular mechanisms responsible for the apoptosis response during an in vitro photodynamic therapy (PDT) with Zinc Phthalocyanine (ZnPc) using different doses of the light source. In this study, firstly the cytotoxic effects of ZnPc-PDT on SK-MEL-3 cells were evaluated. By irradiating the laser, ZnPc induced a significant amount of apoptosis on SK-MEL-3 cells in three IC₅₀s including 0.064±0.01, 0.043±0.01, and 0.036±0.01μg/mL at the doses of 8, 16, and 24J/cm², respectively. Moreover, flow cytometry and QRT-PCR experiments were done. The high percentage of apoptotic cells was seen in the early apoptosis stage. The expression of Bcl-2 and caspase-8 genes at all doses of laser experienced an obvious reduction in comparison to the control group. On the other hand, although the expression of caspase-9 and caspase-3 genes remains almost constant at 8J/cm², but they faced an increment at 16 and 24J/cm² doses. These data reveal caspase-dependent apoptosis in high and caspase-independent apoptosis in low doses of laser. Based on the results of present work, it can be suggested that the dose of the light source is a key factor in induction of caspase-dependent and caspase-independent apoptosis pathways following PDT.

A non-aggregated and tumour-associated macrophage-targeted photosensitiser for photodynamic therapy: a novel zinc(ii) phthalocyanine containing octa-sulphonates

A novel non-aggregated zinc(ii) phthalocyanine bearing octa-sulphonates has been prepared which exhibits specific affinity to macrophages via the scavenger receptor-A, and can selectively accumulate in tumour site.

Photodamage in a mitochondrial membrane model modulated by the topology of cationic and anionic meso-tetrakis porphyrin free bases

The photodynamic effects of the cationic TMPyP (meso-tetrakis [N-methyl-4-pyridyl]porphyrin) and the anionic TPPS4 (meso-tetrakis[4-sulfonatophenyl]porphyrin) against PC/CL phosphatidylcholine/cardiolipin (85/15%) membranes were probed to address the influence of phorphyrin binding on lipid damage. Electronic absorption spectroscopy and zeta potential measurements demonstrated that only TMPyP binds to PC/CL large unilamellar vesicles (LUVs). The photodamage after irradiation with visible light was analyzed by dosages of lipid peroxides (LOOH) and thiobarbituric reactive substance and by a contrast phase image of the giant unilamellar vesicles (GUVs). Damage to LUVs and GUVs promoted by TMPyP and TPPS4 were qualitatively and quantitatively different. The cationic porphyrin promoted damage more extensive and faster. The increase in LOOH was higher in the presence of D2O, and was impaired by sodium azide and sorbic acid. The effect of D2O was higher for TPPS4 as the photosensitizer. The use of DCFH demonstrated that liposomes prevent the photobleaching of TMPyP. The results are consistent with a more stable TMPyP that generates long-lived singlet oxygen preferentially partitioned in the bilayer. Conversely, TPPS4 generates singlet oxygen in the bulk whose lifetime is increased in D2O. Therefore, the affinity of the porphyrin to the membrane modulates the rate, type and degree of lipid damage.

Characterization of sulfonated phthalocyanines by mass spectrometry and capillary electrophoresis

We report the characterization of sulfonated phthalocyanines using capillary electrophoresis and mass spectrometry. Derivatives investigated included the copper, cobalt, zinc and metal-free sulfonated phthalocyanines. In general, sulfonated phthalocyanines were found as aggregates in capillary electrophoresis separations, even at low concentration. Separations were much better at pH 9.0 than at pH 2.5. The addition of β-cyclodextrin did not alter the electropherograms significantly. The electropherograms of commercially available copper phthalocyanine-3,4',4″,4‴-tetrasulfonic acid and 4,4',4″,4‴-tetrasulfonic acid were very different, consistent with the latter compound having a structure that is not fully sulfonated. Matrix-assisted laser desorption/ionization (MALDI) and electrospray ionization (ESI) were used to characterize the sulfonated phthalocyanines. In general, MALDI gave better results than ESI. Mass spectral evidence was obtained for a pentasulfonated species of both the metal-free phthalocyanine and zinc phthalocyanine when these species were made by sulfonation of the metal-free phthalocyanine (followed by zinc insertion in the latter case). Sulfonated tetraphenylporphyrin derivatives were used as standards for mass spectrometry and to estimate the effect of net charge on the capillary electrophoresis migration time for sulfonated tetrapyrroles. Clean separation of the sulfonated tetraphenylporphyrin derivatives [5,10,15,20-tetrakis(4-sulfonatophenyl)porphyrin (TPPS4), 5,10,15-tris(4-sulfonatophenyl)-20-phenylporphyrin (TPPS3) and 5,10-bis(4-sulfonatophenyl)-15,20-diphenylporphyrin (TPPS2a)] was observed by capillary electrophoresis.

Incorporation of polyoxotungstate complexes in silica spheres and in situ formation of tungsten trioxide nanoparticles

In this paper, we demonstrated a new convenient route for in situ fabrication of well separated small sized WO(3) nanoparticles in silica spheres, through a predeposition of surfactant encapsulated polyoxotungates as tungsten source, and followed by a calcination process. In a typical procedure, selected polyoxotungates with different charges were enwrapped with dioctadecyldimethylammonium cations through electrostatic interaction. Elemental analysis, thermogravimetric analysis, and spectral characterization confirmed the formation of prepared complexes with the anticipated chemical structure. The complexes were then phase-transferred into aqueous solution that predissolved surfactant cetyltrimethylammonium bromide, and finally incorporated into silica spheres through a joint sol-gel reaction with tetraethyl orthosilicate in a well dispersed state under the protection of organic layer for polyoxotungates from the alkaline reaction condition. Transmission electron microscopic images illustrated the well dispersed WO(3) nanoparticles in the size range of ca. 2.2 nm in the silica spheres after the calcination at 465 °C. The sizes of both the silica spheres and WO(3) nanoparticles could be adjusted independently through changing the doping content to a large extent. Meanwhile, the doped polyoxotungate complexes acted as the template for the mesoporous structure in silica spheres after the calcination. Along with the increase of doping content and surfactant, the mesopore size changed little (2.0-2.9 nm), but the specific surface areas increased quite a lot. Importantly, the WO(3)-nanoparticle-doped silica spheres displayed an interesting photovoltaic property, which is favorable for the funtionalization of these nanomaterials.

Phase I clinical trial of the use of zinc phthalocyanine tetrasulfonate as a photosensitizer for photodynamic therapy in dogs

OBJECTIVE

To determine the threshold for acute toxicosis of parenterally administered zinc phthalocyanine tetrasulfonate (ZnPcS(4)), a candidate second-generation photosensitizer, in mice and evaluate the compound's safety in a phase I clinical trial of ZnPcS(4)-based photodynamic therapy (PDT) in pet dogs with naturally occurring tumors.

ANIMALS

Male Swiss-Webster mice and client-owned dogs with naturally occurring neoplasms.

PROCEDURES

For the study of acute toxicosis, mice were given graded doses of ZnPcS(4). To determine safety, a rapid-titration phase I clinical trial of ZnPcS(4)-based PDT in tumor-bearing dogs was conducted.

RESULTS

In mice, administration of >or= 100 mg of ZnPcS(4)/kg resulted in renal tubular necrosis 24 hours after IP injection. In tumor-bearing dogs, ZnPcS(4) doses <or= 4 mg/kg induced no signs of toxicosis and resulted in partial to complete tumor responses in 10 of 12 dogs 4 weeks after PDT. Tumor remission was observed with ZnPcS(4) doses as low as 0.25 mg/kg.

CONCLUSIONS AND CLINICAL RELEVANCE

A conservative starting dose of ZnPcS(4) was arrived at on the basis of mouse toxicosis findings. Zinc phthalocyanine tetrasulfonate-based PDT was tolerated well by all dogs and warrants further study. The identification of the maximum tolerated dose through traditional phase I clinical trials may be unnecessary for evaluating novel PDT protocols.

Catalytic therapy of cancer with porphyrins and ascorbate

Catalytic therapy (CT) is a cancer treatment modality based on the generation of reactive oxygen species (ROS) using a combination of substrate molecules and a catalyst. The most frequently used substrate and catalyst pair is ascorbate/Co phthalocyanine (PcCo). In the present study, porphyrins containing transition metal ions as catalysts in place of PcCo were studied. Porphyrins that are expected to be as efficient as phthalocyanines, but may have fewer side effects, were analyzed. ROS production through the combined use of ascorbate and porphyrins decreased the number of breast cancer tumor cells by 20-40% after a single in vitro treatment, as compared to control cells. Treatment with ascorbate in conjunction with porphyrins stimulated apoptosis and disrupted the cell cycle. These treatments enhanced apoptosis by 20-40% when compared to treatments with ascorbate and porphyrins. In addition, the number of cells accumulating in the sub G0/G1 stage of the cell cycle increased from 3- to 10-fold, potentially reflecting that the treatment was highly effective in inducing DNA damage in the tumor cells, suggesting that porphyrins may be beneficial as a CT catalyst in the treatment of cancer.

Avaliação da atividade fotodinâmica de porfirinas para uso em terapia fotodinâmica através da fotoxidação de triptofano

Neste trabalho investigou-se a atividade fotodinâmica de octaetilporfirina (OEP), octaetilporfirina de vanadil (VOOEP) e meso-tetramesitilporfirina (m-TMP). Este estudo foi realizado através da determinação da constante da velocidade de fotoxidação (k f) do aminoácido triptofano (Trp). A participação do oxigênio singlete nesta fotoxidação foi determinada através da adição de azida de sódio e água deuterada no meio de reação. Os valores de k f/10-4s-1 para a fotoxidação de Trp demonstraram que OEP (2,80 ± 0.05) é mais eficiente do que m-TMP (1,62 ± 0,07) e VOOEP (0,81 ± 0,08). Os valores de k f foram menores na presença de azida de sódio e maiores na presença de água deuterada, sugerindo que o oxigênio singlete é o responsável pela atividade fotodinâmica de OEP, VOOEP e m-TMP. Estes resultados sugerem também que as diferenças na atividade fotodinâmica entre as porfirinas podem ser associadas com as diferenças na estrutura molecular das mesmas. A presença do grupo vanadil (V=O) interfere claramente na atividade fotodinâmica de OEP causando considerável redução na sua eficiência.

Femtosecond Transient Absorption, Raman, and Electrochemistry Studies of Tetrasulfonated Copper Phthalocyanine in Water Solutions

Ultrafast time-resolved electronic spectra of the primary events induced in the copper tetrasulfonated phthalocyanine Cu(tsPc)4-) in aqueous solution has been measured by femtosecond pump-probe transient absorption spectroscopy. The primary events initiated by the absorption of a photon occurring within the femtosecond time scale are discussed on the basis of the electron transfer mechanism between the adjacent phthalocyanine rings proposed recently in our laboratory. The femtosecond transient absorption results are compared with the low temperature emission spectra obtained with Raman spectroscopy and the voltammetric curves.

Two-photon absorption of copper tetrasulfophthalocyanine induces phototoxicity towards Jurkat cells in vitro

The feasibility to induce oxygen-independent tumour cell kill by two-photon excitation of copper tetrasulfophthalocyanine (CuPcS4) was studied in Jurkat cells in vitro. Following incubation with CuPcS4 cells were transferred to a closed cuvette and irradiated with 532 nm pulsed-laser or 680 nm continuous-laser light to evaluate the effect of either two- or one-photon excitation, respectively. Cell survival was measured using MTT and Trypan Blue exclusion tests. Cell viability decreased 10-20% following two-photon excitation while one-photon illumination did not affect cell survival. These data confirm that two-photon excitation of CuPcS4 to the upper excited triplet state results in the formation of toxic species suggesting its potential use as a sensitizer for the photodynamic treatment of poorly oxygenated tumours.

Synthesis and Cellular Studies of Nonaggregated Water-Soluble Phthalocyanines

Water-soluble phthalocyanines are promising photosensitizers for application in cancer therapy and in the photoinactivation of viruses. The water-soluble zinc(II) phthalocyanines 5 and 6 were synthesized by converting the corresponding ester derivative 4 into the sodium carboxylate and carboxylic acid species. Compound 5 can be solubilized in water as a monomeric species, as demonstrated by UV/vis and fluorescence spectroscopy. These compounds were characterized by analytical and spectroscopic methods and, in the case of 4, by X-ray crystallography. The water-soluble phthalocyanines were found to have low dark cytotoxicity toward V79 hamster fibroblasts and human HEp2 cells, to be phototoxic at low light and drug doses, to be taken up by cells in culture, and to localize intracellularly, mainly in the cell lysosomes. Conjugation of the anionic phthalocyanines with positively charged LipoGen liposomes resulted in effective delivery of these compounds into the nuclei of cells. It is concluded that these highly water-soluble phthalocyanines are promising sensitizers for the photodynamic therapy of tumors.

Ultrafast studies of the excited-state dynamics of copper and nickel phthalocyanine tetrasulfonates: potential sensitizers for the two-photon photodynamic therapy of tumors

In order to evaluate the potential of copper and nickel phthalocyanine tetrasulfonates as sensitizers for two-photon photodynamic therapy, we conducted kinetic femtosecond measurements of transient absorption and bleaching of their excited state dynamics in aqueous solution. Samples were pumped with 620 nm and 310 nm laser light, which allowed us to study relaxation processes from both the first and second singlet (or doublet for the copper phthalocyanine) excited states. A second excitation from the first excited triplet state, approximately 685 and 105 ps after the first excitation for copper and nickel phthalocyanine tetrasulfonate respectively, was the most efficient way to bring the molecules to an upper triplet state. Presumably this highest triplet state can inflict molecular damage on adjacent biomolecules int eh absence of oxygen, resulting in the desired cytotoxic cellular response. Transient absorption spectra at different fixed delays indicate that optimum efficiency would require that the second photon has a wavelength of approximately 750 nm.

Photosensitizer binding to lipid bilayers as a precondition for the photoinactivation of membrane channels

The photodynamic activity of sulfonated aluminum phthalocyanines (AlPcS(n), 1 </= n </= 4) was found to correlate with their affinity for membrane lipids. Adsorbing to the surface of large unilamellar vesicles (LUVs), aluminum phthalocyanine disulfonate induced the highest changes in their electrophoretic mobility. AlPcS(2) was also most efficient in mediating photoinactivation of gramicidin channels, as revealed by measurements of the electric current across planar lipid bilayers. The increase in the degree of sulfonation of phthalocyanine progressively reduced its affinity for the lipid bilayer as well as its potency of sensitizing gramicidin channel photoinactivation. The portion of photoinactivated gramicidin channels, alpha, increased with rising photosensitizer concentration up to some optimum. The concentration at which alpha was at half-maximum amounted to 80 nM, 30 nM, 200 nM, and 2 microM for AlPcS(1), AlPcS(2), AlPcS(3), and AlPcS(4), respectively. At high concentrations alpha was found to decrease, which was attributed to quenching of reactive oxygen species and self-quenching of the photosensitizer triplet state by its ground state. Fluoride anions were observed to inhibit both AlPcS(n) (2 </= n </= 4) binding to LUVs and sensitized photoinactivation of gramicidin channels. It is concluded that photosensitizer binding to membrane lipids is a prerequisite for the photodynamic inactivation of gramicidin channels.