Investigation ofIn vitroPDT Activities andIn vivoBiopotential of Zinc Phthalocyanines Using131I Radioisotope

Photosensitizers for Photodynamic Therapy of Brain Cancers-A Review

On average, there are about 300,000 new cases of brain cancer each year. Studies have shown that brain and central nervous system tumors are among the top ten causes of death. Due to the extent of this problem and the percentage of patients suffering from brain tumors, innovative therapeutic treatment methods are constantly being sought. One such innovative therapeutic method is photodynamic therapy (PDT). Photodynamic therapy is an alternative and unique technique widely used in dermatology and other fields of medicine for the treatment of oncological and nononcological lesions. Photodynamic therapy consists of the destruction of cancer cells and inducing inflammatory changes by using laser light of a specific wavelength in combination with the application of a photosensitizer. The most commonly used photosensitizers include 5-aminolevulinic acid for the enzymatic generation of protoporphyrin IX, Temoporfin-THPC, Photofrin, Hypericin and Talaporfin. This paper reviews the photosensitizers commonly used in photodynamic therapy for brain tumors. An overview of all three generations of photosensitizers is presented. Along with an indication of the limitations of the treatment of brain tumors, intraoperative photodynamic therapy and its possibilities are described as an alternative therapeutic method.

Non-canonical anti-cancer, anti-metastatic, anti-angiogenic and immunomodulatory PDT potentials of water soluble phthalocyanine derivatives with imidazole groups and their intracellular mechanism of action

Cancer is currently a leading health issue globally. Chemotherapy is a prominent treatment method but due to undesired side effects t, there has been a need for novel less toxic approaches. Photodynamic therapy may be listed among the alternatives for efficient and potentially less detrimental applications of cancer therapy. Canonical photodynamic therapy (PDT) approach requires a light source with a specific wavelength of light, a non-toxic photosensitizer and molecular oxygen. PDT creates the desired effect by the photochemical reaction created through interaction of these components to create reactive oxygen species that will act on the cancer cells to enable anti-cancer activities. In our study we focus on non-canonical PDT application. In this approach we are not only aiming to eliminate cancer cells in the environment but also test the anti-metastatic, anti-angiogenic and possible immunomodulatory activities of the novel photosensitizers. Moreover, in our approach, we studied the intracellular pathways that are crucial for carcinogenesis, cell cycle, apoptosis, angiogenesis, metastasis and immune function to decipher the mechanism of the action for each compound. Reactive oxygen species based explanation was not valid in our study, hence it brings out a non canonical approach to PDT applications. Our results suggests that Phthalocyanine derivatives with imidazole groups can be effectively used against lung, colon, breast and prostate cancer while differentially effecting metastasis, angiogenesis, cell cycle, apoptosis and immune system cells' activities. Based on the results, PDT application of these phthalocyanine derivatives can be an effective treatment option to replace chemotherapy to minimize the potential side effects.

Imaging and detection of cell apoptosis byIn vitrophotodynamic therapy applications of zinc (II) phthalocyanine on human melanoma cancer

This study aims to investigate the photodynamic therapy (PDT) effects on MeWo (human melanoma cells) and HaCaT (normal human keratinocyte cells) by light stimulation of different concentrations of Zinc (II)-tetra-tert-butyl-phthalocyaninato (ZnPc). MTT viability assay data indicated that a 25 μM concentration of ZnPc is cytotoxic to the melanoma cancer cells while this concentration of ZnPc is not cytotoxic for the HaCaT cell line. Moreover, the results showed that photoactivated ZnPc at 12.5 μM concentration reduced the cell viability of the MeWo cell line to about 50 %. At this photosensitizing concentration, the efficacy of light doses of 20, 30, 40, and 50 J/cm² was evaluated against MeWo and HaCaT cells. ZnPc at a concentration of 12.5 μM activated with a light dose of 50 J/cm² was the most efficient for the killing of MeWo cells. In conclusion, the 12.5 μM of ZnPc with the treatment light dose of 50 J/cm² from a RED light source was adequate to destroy MeWo cells by the ROS-induced apoptosis mechanism. It also exhibited low killing effects on healthy HaCaT cells. These findings are supported by the results of apoptosis with the Annexin V & Dead Cell Kit and fluorescence imaging.

Facile construction of a hyperbranched poly(acrylamide) bearing tetraphenylethene units: a novel fluorescence probe with a highly selective and sensitive response to Zn2+

Thermo-responsive hyperbranched copoly(bis(N,N-ethyl acrylamide)/(N,N-methylene bisacrylamide)) (HPEAM-MBA) was synthesized by using reversible addition–fragmentation chain-transfer polymerization (RAFT). Interestingly, the zinc ion (Zn²⁺) was found to have a crucial influence on the lowest critical solution temperature (LCST) of the thermo-responsive polymer. The tetraphenylethylene (TPE) unit was then introduced onto the backbone of the as-prepared thermo-responsive polymer, which endows a Zn²⁺-responsive “turn-off” effect on the fluorescence properties. The TPE-bearing polymer shows a highly specific response over other metal ions and the “turn-off” response can even be tracked as the concentration of Zn²⁺ reduces to 2 × 10⁻⁵ M. The decrement of fluorescence intensity was linearly dependent on the concentration of Zn²⁺ in the range of 4–18 μmol L⁻¹. The flexible, versatile and feasible approach, as well as the excellent detection performance, may generate a new type of Zn²⁺ probe without the tedious synthesis of the moiety bearing Zn²⁺ recognition units.

A novel fluorescent HPEAM-TPEAH, possessing a highly selective and sensitive response to Zn²⁺, was synthesized using RAFT.

Phototoxicity of Liposomal Zn- and Al-phthalocyanine Against Cervical and Oral Squamous Cell Carcinoma Cells In Vitro

Background

Photodynamic therapy (PDT) utilizes light to activate a photosensitizer in the presence of oxygen, and leads to local photodamage by the generation of highly reactive oxygen species (ROS). Liposomal delivery of photosensitizers is adaptable to the treatment of cancers. We examined the phototoxicity of free or liposome-embedded phthalocyanine photosensitizers using HeLa cervical carcinoma and HSC-3 oral squamous cell carcinoma cells.

Material/Methods

Liposomes were composed of palmitoyloleoyphosphatidylcholine (POPC): phosphatidylglycerol (PG), and contained either zinc phthalocyanine (ZnPc) or aluminum phthalocyanine chloride (AlPc). Free or liposomal ZnPc and AlPc were incubated with cells for 24 h at 37°C. Cells incubated with ZnPc were exposed to broadband visible light (350–800 nm; light dose 43.2 J/cm²), whereas cells treated with AlPc were exposed to light at 690 nm (light dose 3.6 J/cm²). The effect of folate receptor-targeted liposomal ZnPc was evaluated with HeLa cells. Cytotoxicity was analyzed by the Alamar Blue assay.

Results

Cell viability, expressed as a percentage of control cells, was calculated according to the formula [(A570–A600) of test cells]×100/[(A570–A600) of control cells]. The relative percentage changes then defined the phototoxic efficacy of the experimental conditions. In HeLa cells, 1 μM free ZnPc and AlPc, reduced cell viability to 52.7±2.1 and 15.4±8.0%, respectively. Liposomal phthalocyanines, at 0.1, 0.5, and 1.0 μM, reduced the viability to 68.0±8.6, 15.1±9.9 and 0% (ZnPc), and to 25.8±8.2, 0 and 0% (AlPc), respectively. In HSC-3 cells, 1 μM free ZnPc and AlPc, reduced cell viability to 22.1±2.8 and 56.6±8.6%, respectively. With 1 μM liposomal ZnPc and AlPc, the viability was reduced to 0 and 21.3±0.3%, respectively.

Conclusions

The embedding of phthalocyanines in liposomes enhanced their phototoxicity and this effect was dependent on cell type.

Intracellular uptake and fluorescence imaging potential in tumor cell of zinc phthalocyanine

A near IR absorbing phthalocyanine bearing four binaphtyl group has been synthesized in order to investigate its cytotoxicity and intracellular uptake of sensitizer on MCF-7 (human breast cancer), MDAH (ovarian cancer), HeLa (human epitheloid cervix carcinoma), EMT-6 (mouse breast cancer) and WI-38 (human fibroblast lung) cell lines. ZnPc showed four time higher intracellular uptake in carcinoma cells (MCF-7) than normal (WI-38) cell lines. With the aim of studying in detail the biodistribution feature and tumor nuclear imaging capacity, ZnPc was also labeled with I-131. The efficiency of radiolabeled compound was 95±4.6%. In addition, ZnPc reveals to be very efficient singlet oxygen generators (ΦΔ=0.612 in DMSO) and promising PS for PDT application. In vitro fluorescence imaging study with MCF-7 cells showed that ZnPc localized in cytoplasm of the cells. This results showed that synthesized ZnPc is promising candidate for dual fluorescence/nuclear imaging breast cancer and shows potential PS for PDT application.