Amphiphilic zinc phthalocyanine photosensitizers: synthesis, photophysicochemical properties and in vitro studies for photodynamic therapy

The chemical and electrochemical stimuli viologen substituted phthalocyanine with tunable optical features1

In this study, viologen-tetrasubstituted Zn(II) phthalocyanines (PcV1 and PcV2) were designed and synthesized to achieve the tunable optical features via redox-active viologen groups. Several parameters relevant to the evaluation of the tunable optical features have been investigated: UV-Vis, cyclic voltammetry (CV), EPR, square wave voltammetry (SWV), and theoretical analyses. The results showed that upon reductions and oxidations of viologen groups either chemically or electrochemically, the optical features of PcV1 and PcV2 change drastically with switchable processes. These outcomes indicate that achieving control over optical features of large organic chromophores such as Pc with our rational design can be used for the design of new complex organic electronic materials.

A hypoxia responsive silicon phthalocyanine containing naphthquinone axial ligands for photodynamic therapy activity

A liposome loaded‑silicon (IV) phthalocyanine (SiPc) containing naphthoquinone axial ligands as hypoxia-responsive a prodrug-like moieties (Prodrug-SiPc), is herein reported. With the help of computational methods, this study assessed the photophysical, photochemical and electrochemical redox properties of the Prodrug-SiPc to elucidate the relationship between material structure and properties. The attachment of the axial quinoid moieties endowed the Prodrug-SiPc with Type I/II photochemical and prodrug-like properties. Following liposomal encapsulation, the therapeutic efficacy of Prodrug-SiPc-liposomes was investigated against Michigan Cancer Foundation-7 (MCF-7) and Henrietta Lacks (Hela) cancer cells as in vitro cancer models and revealed that the as-synthesized Prodrug-SiPc-liposomes are potential photodynamic therapy (PDT) drug candidates. The Prodrug-SiPc-liposome takes full advantage of the hypoxic microenvironment of tumors - a side effect PDT - to trigger therapy, resulting in significantly enhanced efficacy compared to typical PDT. This work highlights the importance of multiple characteristics in designing new and effective photosensitizer candidates.

Novel tetrakis-phthalocyanines bearing pyrimidine derivative: crystal XRD analysis, enzyme inhibition, molecular docking, and anticancer effects

In this study, the novel 4-(4-Aminopyrimidin-2-ylthio) phthalonitrile (1) as starting material was synthesized and its 3D structure was verified by the single crystal X-ray diffraction experiment. Then, its peripherally tetra-substituted phthalocyanines (2,3) and the methylated derivatives (2a,3a) containing pyrimidine derivative were synthesized. All these newly synthesized compounds were characterized with various spectroscopic methods such as UV-Vis, FT-IR, ¹H-NMR, ¹³C-NMR and MALDI-TOF MS by obtaining satisfactory results. In addition, these novel phthalocyanines effectively inhibited acetylcholinesterase enzyme, with K_i values in the range of 10.43 ± 2.38 to 41.70 ± 9.32 µM. For the related enzyme, the IC₅₀ values were obtained in the range of 11.68 to 44.28 µM. For α-glycosidase enzyme the most effective K_i values of (3a) and (2) were with K_i values of 92.87 ± 10.70 and 95.18 ± 17.83 µM, respectively. Indeed, the most potent phthalocyanines against both enzymes were recorded for the purpose of investigating interaction modes of these complexes in the active site of the target enzyme. The cytotoxicity potential of these phthalocyanines against human breast, colon, and prostate cancers demonstrated that these compounds had normal cytotoxic effects.Communicated by Ramaswamy H. Sarma.

Photophysical Properties of Linked Zinc Phthalocyanine to Acryloyl Chloride:N-vinylpyrrolidone Copolymer

This paper focuses on the linking of zinc phthalocyanine (ZnPc) to N-vinylpyrrolidone (N-VP): acryloyl chloride (ClAC) copolymer. The synthesis of binary N-VP:ClAC copolymer was performed by the radical polymerization method and then grafted to ZnPc by the Friedel Crafts acylation reaction. We have developed a water-soluble ZnPc:ClAC:N-VP photosensitizer with a narrow absorption band at 970 nm, fluorescence at λ_em = 825 nm and the decay fluorescence profile with 3-decay relatively longer times of 1.2 µs, 4.6 µs, and 37 µs. The concentration-dependent dark cytotoxicity investigated in normal fibroblasts (NHDF), malignant melanoma (MeWo), adenocarcinoma (HeLa), and hepatocellular carcinoma (HepG2) cell lines incubated to increased concentrations of ZnPc:ClAC:N-VP (up to 40 μM) for 24 h in the dark show low cytotoxicity. Maximum cell viability in HeLa and HepG2 tumor cell lines was observed.

Positively charged styryl pyridine substituted Zn(II) phthalocyanines for photodynamic therapy and photoantimicrobial chemotherapy: effect of the number of charges

Cationic Zn phthalocyanine complexes were synthesized using Knoevenagel reaction starting from a Zn(ii) tetrakis(2-formylphenoxy)phthalocyanine (1) to form Zn(ii) tetrakis(1-butyl-4-(4-(tetraphenoxy)styryl)pyridin-1-ium) phthalocyanine (2) and Zn(ii) tetrakis(4-(4-(tetraphenoxy)styryl)-1-(4-(triphenylphosphonio)butyl)pyridin-1-ium)phthalocyanine (3). The photophysicochemical behaviours of the Pc complexes were assessed. The cationic complexes display high water-solubility and gave moderate singlet oxygen quantum yield in water. The cationic Pcs demonstrate good cellular uptake and photodynamic activity against MCF-7 cells with IC50 values of 8.2 and 4.9 μM for 2 and 3, respectively. The cationic Pcs also demonstrate high photoantimicrobial activity against Escherichia coli with log reductions of 5.3 and 6.0 for 2 and 3, respectively.

Hybrid Complexes of Photosensitizers with Luminescent Nanoparticles: Design of the Structure

Increasing the efficiency of the photodynamic action of the dyes used in photodynamic therapy is crucial in the field of modern biomedicine. There are two main approaches used to increase the efficiency of photosensitizers. The first one is targeted delivery to the object of photodynamic action, while the second one is increasing the absorption capacity of the molecule. Both approaches can be implemented by producing dye-nanoparticle conjugates. In this review, we focus on the features of the latter approach, when nanoparticles act as a light-harvesting agent and nonradiatively transfer the electronic excitation energy to a photosensitizer molecule. We will consider the hybrid photosensitizer-quantum dot complexes with energy transfer occurring according to the inductive-resonance mechanism as an example. The principle consisting in optimizing the design of hybrid complexes is proposed after an analysis of the published data; the parameters affecting the efficiency of energy transfer and the generation of reactive oxygen species in such systems are described.

Symmetrically Substituted Zn and Al Phthalocyanines and Polymers for Photodynamic Therapy Application

N4 macrocyclic complexes of Al and Zn phthalocyanines with symmetrical imine and imidazole moiety at the periphery were synthesized. The synthesized ligands, complexes, and polymers were purified and characterized to study the structure of the molecule. These synthesized complexes were used for photodynamic therapy application as the diamagnetic Zn and Al have the ability to produce and stabilize singlet oxygen species. The synthesized N4 molecules of aluminum iminomethoxy phenyl phthalocyanine and aluminum ethyl phenyl benzimidazolephthalocyanine showed better activity against MCF-7 cells. These results suggest that this assay may be used as an early biomarker of clinical response.

Silicon Tetrapyrazinoporphyrazine Derivatives-Incorporated Carbohydrate-Based Block Copolymer Micelles for Photodynamic Therapy

Developing nonaggregated photosensitizers (PSs) for efficient photodynamic therapy (PDT) using polymeric micelles (PMs) has been challenging. In this study, axially substituted nonaggregated silicon tetrapyrazinoporphyrazine (SiTPyzPz) derivatives in carbohydrate-based block glycopolymer-based PMs were designed and used as PSs for PDT. To achieve the nonaggregated PSs, SiTPyzPz was axially substituted with trihexylsiloxy (THS) groups to form SiTPyzPz-THS, which exhibited highly monomeric behaviors in organic solvents. Moreover, three block copolymers were prepared via reversible addition-fragmentation chain transfer (RAFT) polymerization. Each copolymer comprised hydrophobic polystyrene blocks and loadable SiTPyzPz-THS, and one or two consisted of two possible hydrophilic blocks, polyethylene glycol or poly(glucosylethyl methacrylate). The self-assembly of SiTPyzPz-THS and the block copolymers in aqueous solvents induced the formation of spherical PMs with core-shell or core-shell-corona structures. The SiTPyzPz-THS in the PMs exhibited monomeric state, intense fluorescence emission, and outstanding singlet oxygen generation; moreover, it did not form aggregates. During the in vitro test, which was performed to investigate the PDT efficiency, the PMs, which consisted of poly(glucosylethyl methacrylate) shells, exhibited high photocytotoxicity and cellular internalization ability. Consequently, the PM systems of nonaggregated PSs and carbohydrate-based block copolymers could become very promising materials for PDT owing to their photophysicochemical properties and considerable selectivity against cancer cells.

Synthesis of nonperipherally tetra-[5-(diethylamino)-2-formylphenoxy] substituted metallophthalocyanines and their electrochemistry

3-[5-(diethylamino)-2-formylphenoxy]phthalonitrile ( n-TY-CN ), metallophthalocyanines n-TY-Co , n-TY-Cu , and n-TY-Mn bearing [5-(diethylamino)-2-formylphenoxy] groups at nonperipheral positions were prepared for the first time. These compounds were characterized with IR, NMR (only for n-TY-CN ), mass and UV-vis (except n-TY-CN ) spectroscopy. Voltammetric characterizations of n-TY-Co , n-TY-Cu , and n-TY-Mn revealed that while n-TY-Co , n-TY-Cu , and n-TY-Mn showed characteristic Pc ring and/or metal-based reduction reaction, n-TY-Co , n-TY-Cu , and n-TY-Mn were coated on the working electrode during the oxidation processes owing to the cationic electropolymerizations of the [5-(diethylamino)-2-formylphenoxy] substituents.

Synthesis, characterization, photophysics, and photochemistry of peripherally substituted tetrakis(quinolinylethylenephenoxy)-substituted zinc(ii) phthalocyanines

Quinoline substituted zinc phthalocyanine derivatives were synthesized and characterized, and their photophysical and photochemical properties were investigated.

Synthesis and electrochemical properties of copper(II), manganese(III) phthalocyanines bearing chalcone groups at peripheral or nonperipheral positions

In this study, new chalcone compound 1 , new phthalonitrile derivatives 2 and 3, new copper(II), manganese(III) phthalocyanines bearing chalcone groups at peripheral or nonperipheral positions were synthesized. Electrochemistry of tetra-(4-{(2 E )-3-[2-fluoro-4-(trifluoromethyl)phenyl]prop-2-enoyl}phenoxy) substituted Co(II)Pc and Mn(III)Pcs were studied with cyclic voltammetry (CV) to determine the redox properties of the phthalocyanines. According to the results, while the CuPcs 2a and 3a showed two Pc based reduction reactions and one Pc based oxidation reaction, MnPcs 2b and 3b gave two metal-based reduction reactions. All the redox processes are shifted toward positive potentials as a result of the increased electron-withdrawing ability of the trifluoromethyl substituents.

Targeted photoimmunotherapy based on photosensitizer-antibody conjugates for multiple myeloma treatment

Despite the high in vitro efficacy of photodynamic therapeutics, lack of tumor targeting significantly reduces their in vivo efficacy and thus limits their clinical use. Photoimmunotherapy (PIT) is a new synthetic strategy to target and treat cancer by photodynamic therapy (PDT). In this study, we describe design and synthesis of a third-generation photosensitizer comprising a PEGylated-phthalocyanine star-polymer photosensitizer that covalently bound to a myeloma tumor-selective antibody (MAb) via the carbodiimide chemistry. The free photosensitizer demonstrated a minimum dark toxicity when tested in mammalian myeloma cell line (SP2/OR); and a moderate phototoxicity after irradiation with non thermal laser red light as a result of light-induced production of cytotoxic singlet oxygen species. Covalent attachment of the photosensitizer (Pc) to the MAb resulted in a significantly enhanced phototoxicity. This is mainly ascribed to the fact that internalization enhances phototoxicity of Pc-MAb bioconjugates. The radioactivated photoimmuno-conjugates ¹³¹I(PcMAb) demonstrated the highest phototoxicity to myeloma cells. The suggested bioconjugates are promising candidates as multiple therapeutic models for in vivo treatment of myeloma.

Assessing Amphiphilic ABAB Zn(II) Phthalocyanines with Enhanced Photosensitization Abilities in In Vitro Photodynamic Therapy Studies Against Cancer

We have previously demonstrated that singlet oxygen photosensitization abilities of Zn(II) phthalocyanines (Zn(II)Pcs) are enhanced through α-functionalization with bulky fluorinated substituents (i.e., bis(trifluoromethyl)phenyl units) at facing positions of ABAB Zn(II)Pcs, where A and B refer to differently functionalized isoindoles. In this work, we have prepared the Zn(II)Pc ABAB 1 endowed with hydrophilic triethylene glycol monomethyl ether (i.e., at the A isoindoles) to provide solubility in aqueous media, together with its A₃B and A₄ counterparts, and compared their ability to behave as photosensitizers for photodynamic therapy. All photophysical data, aggregation studies and preliminary in vitro biological assays in cell cultures of SCC-13 (squamous cell carcinoma) and HeLa (cervical cancer cells), have proved ABAB 1 as the best photosensitizer of the series.

Functional chalcone-substituted tetrakis-metallophthalocyanines: Synthesis and spectroscopic characterization

In this study, a new phthalonitrile derivative, ( E)-4-(3-(3-(3-methoxyphenyl)acryloyl)phenoxy)phthalonitrile, and four peripherally ( E)-4-(3-(3-(3-methoxyphenyl)acryloyl)phenoxy) tetrasubstituted new Ni(II), Zn(II), Co(II), and Cu(II) phthalocyanine derivatives are synthesized and characterized. ( E)-4-(3-(3-(3-Methoxyphenyl)acryloyl)phenoxy)phthalonitrile is synthesized by heating ( E)-1-(3-hydroxyphenyl)-3-(3-methoxyphenyl)prop-2-en-1-one and 4-nitrophthalonitrile in the presence of K2CO3 in dry DMF at 60°C for 96 h. The metallophthalocyanines are prepared by cyclotetramerization of ( E)-4-(3-(3-(3-methoxyphenyl)acryloyl)phenoxy)phthalonitrile with NiCl2, Zn(CH3COO)2, CoCl2, and CuCl2 in n-pentanol in the presence of 1,8-diazabicyclo[5.4.0]undec-7-ene. Characterization of the new compounds is performed by means of IR, 1H NMR, 13C NMR, and mass and UV-Vis spectroscopy techniques.

Photophysical Properties of Upconverting Nanoparticle-Phthalocyanine Complexes

Interaction between upconverting nanoparticles and aluminum octacarboxyphthalocyanine was studied. The efficiency of non-radiative energy transfer from the nanoparticles to phthalocyanine increased with the number of phthalocyanine molecules adsorbed on the nanoparticle, but only up to a certain limit. Further increase in the phthalocyanine concentration resulted in a decrease of its sensitized fluorescence due to the dimerization of dye molecules on the nanoparticle surface. When subjected to infrared irradiation, phthalocyanine molecules in the hybrid complex generated singlet oxygen. The observed effects are of interest in regard to the targeted search for new components of efficient third-generation hybrid photosensitizers.

Phthalocyanines with bromobenzenesulfanyl substituents at non-peripheral position: Preparation, photophysical and photochemical properties

Electron-donating bromobenzenesulfanyl-group-substituted phthalonitrile derivative (1) and its novel non-peripherally tetra-substituted metal-free, indium and zinc phthalocyanine complexes (2–4) have been prepared for the first time. The chemical structures of this new phthalonitrile and its phthalocyanine derivatives were characterized by UV-vis, FT-IR, NMR, and MALDI-TOF mass spectrometry. The introduction of this electron-donating sulfanyl type of non-peripheral substituent accounts for a remarkable red shift of the phthalocyanine Q band to approximately 730 nm. Photophysical and photochemical properties of the novel functional complexes were also examined as photosensitizers for PDT applications.

Selective Detection of Trinitrophenol by Amphiphilic Dimethylaminopyridine-Appended Zn(II)phthalocyanines at the Near-Infrared Region

Novel amphiphilic Zn(II)phthalocyanines (ZnPcs) peripherally substituted with four and eight dimethylaminopyridinium units (ZnPc1 and ZnPc2) were synthesized by cyclotetramerization of the corresponding phthalonitriles. The effect of aggregation and photophysical (fluorescence quantum yields and lifetimes) and photochemical (singlet oxygen generation and photodegradation under light irradiation) properties was investigated. The chemosensing ability of ZnPcs toward explosive nitroaromatic compounds was explored in aqueous medium. This study demonstrates that ZnPc1 and ZnPc2 show fluorescence quenching behavior upon interaction with different nitro analytes and show unprecedented selectivity toward 2,4,6-trinitrophenol with a limit of detection (LOD) of 0.7-1.1 ppm with a high quenching rate constant (K _sv) of 1.6-2.02 × 10⁵. The near-infrared (NIR) fluorescence in thin films was quenched efficiently because of the photoinduced electron-transfer process through strong intermolecular π-π and electrostatic interactions. The sensing process is highly reversible and free from the interference of other commonly encountered nitro analytes. Further, experiments were performed to demonstrate the use of ZnPcs as efficient heterogeneous photocatalysts in the reduction of nitro explosives. The smart dual performance of multicharged ZnPcs in aqueous media quantifies them as attractive candidates in developing sensor materials at the NIR region and to possibly convert the toxic explosives into useful scaffolds. These results provide an interesting perspective toward elaboration of stable fluorescent systems for the selective sensing behavior of nitro explosives and their facile heterogeneous catalytic behavior in the reduction reactions.

Synthesis and Encapsulation of a New Zinc Phthalocyanine Photosensitizer into Polymeric Nanoparticles to Enhance Cell Uptake and Phototoxicity

Efforts to enhance the utility of photodynamic therapy as a non-invasive method for treating certain cancers have often involved the design of dye sensitizers with increased singlet oxygen efficiency. More recently, however, sensitizers with greater selectivity for tumor cells than surrounding tissue have been targeted. The present study provides an approach to the modification of the known photosensitizer zinc phthalocyanine (ZnPc), to enhance its solubility and delivery to cancer cells. Targeting a photosensitizer to the site of action improves the efficacy of the sensitizer in photodynamic therapy. In this work we used PLGA-b-PEG to encapsulate a new zinc phthalocyanine derivative, 2(3), 9(10), 16(17), 23(24)-tetrakis-(4’-methyl-benzyloxy) phthalocyanine zinc(II) (ZnPcBCH3), to enhance uptake into A549 cells, a human lung cancer cell line. ZnPcBCH3 exhibited the same photochemical properties as the parent compound ZnPc but gave increased solubility in organic solvents, which allowed for efficient encapsulation. In addition, the encapsulated dye showed a near 500-fold increase in phototoxicity for A549 cancer cells compared to free dye.

Unveiling Ga(III) phthalocyanine-a different photosensitizer in neuroblastoma cellular model

Phthalocyanines (Pc) and their metallated derivatives are strongly considered for photodynamic therapy (PDT) possessing unique properties as possible new photosensitizers (PS). We have used toxicological assessments, real-time monitoring of cellular impedance, and imagistic measurements for assessing the in vitro dark toxicity and PDT efficacy of Ga(III)-Pc in SHSy5Y neuroblastoma cells. We have established the non-toxic concentration range of Ga(III)-Pc, a compound which shows a high intracellular accumulation, with perinuclear distribution in confocal microscopy. By choosing Ga(III)Pc non-toxic dose, we performed in vitro experimental PDT hampering cellular proliferation. Our proposed Ga(III)-Pc could complete a future PS panel for neuroblastoma alternate therapy.

A CdSe/ZnS quantum dot-based platform for the delivery of aluminum phthalocyanines to bacterial cells

Enhancement of optical properties of photosensitizers by additional light-harvesting antennas is promising for the improvement of the photodynamic therapy. However, large number of parameters determine interactions of nanoparticles and photosensitizers in complex and, thus the photodynamic efficacy of the hybrid structure. In order to achieve high efficiency of energetic coupling and photodynamic activity of such complexes it is important to know the location of the photosensitizer molecule on the nanoparticle, because it affects the spectral properties of the photosensitizer and the stability of the hybrid complex in vitro/in vivo. In this work complexes of polycationic aluminum phthalocyanines and CdSe/ZnS quantum dots were obtained. We used quantum dots which outer shell consists of polymer with carboxyl groups and provides water solubility and the negative charge of the nanoparticle. We found that phthalocyanine molecules could penetrate deeply into the polymer shell of quantum dot, leading thereby to significant changes in the spectral and photodynamic properties of phthalocyanines. We also showed that noncovalent interactions between phthalocyanine and quantum dot provide possibility for a release of the phthalocyanine from the hybrid complex and its binding to both Gram-positive and Gram-negative bacterial cells. Also, detailed characterization of the nanoparticle core and shell sizes was carried out.

Group 10 metal–thiocatecholate capped magnesium phthalocyanines – coupling chromophore and electron donor/acceptor entities and its impact on sulfur induced red-shifts

Four thiocatecholate groups at magnesium phthalocyanine can coordinate transition metals, strongly red-shifting the Q band and promoting charge-transfer to peripheral groups.

Crosstalk between p38 MAPK and caspase-9 regulates mitochondria-mediated apoptosis induced by tetra-α-(4-carboxyphenoxy) phthalocyanine zinc photodynamic therapy in LoVo cells

Photodynamic therapy (PDT) is considered to be an advancing antitumor technology. PDT using hydrophilic/lipophilic tetra-α-(4-carboxyphenoxy) phthalocyanine zinc (TαPcZn-PDT) has exhibited antitumor activity in Bel-7402 hepatocellular cancer cells. However, the manner in which p38 MAPK and caspase-9 are involved in the regulation of mitochondria-mediated apoptosis in the TαPcZn-PDT-treated LoVo human colon carcinoma cells remains unclear. Therefore, in the present study, a siRNA targeting p38 MAPK (siRNA-p38 MAPK) and the caspase-9 specific inhibitor z-LEHD-fmk were used to examine the crosstalk between p38 MAPK and caspase-9 during mitochondria-mediated apoptosis in the TαPcZn-PDT-treated LoVo cells. The findings revealed that the TαPcZn-PDT treatment of LoVo cells resulted in the induction of apoptosis, the formation of p38 MAPK/caspase-9 complexes, the activation of p38 MAPK, caspase-9, caspase-3 and Bid, the downregulation of Bcl-2, the reduction of mitochondrial membrane potential (ΔΨm), the upregulation of Bax and the release of apoptosis-inducing factor (AIF) and cytochrome c (Cyto c). By contrast, siRNA-p38 MAPK or z-LEHD-fmk both attenuated the effects of TαPcZn-PDT in the LoVo cells. Furthermore, the results revealed that siRNA-p38 MAPK had more significant inhibitory effects on apoptosis and mitochondria compared with the effects of z-LEHD-fmk in TαPcZn-PDT-treated LoVo cells. These findings indicated that p38 MAPK plays the major regulatory role in the crosstalk between p38 MAPK and caspase-9 and that direct interaction between p38 MAPK and caspase-9 may regulate mitochondria-mediated apoptosis in the TαPcZn-PDT-treated LoVo cells.

Synthesis, characterization and in vitro and in vivo photodynamic activities of a gallium(iii) tris(ethoxycarbonyl)corrole

A gallium(iii) tris(ethoxycarbonyl)corrole is a highly effective photosensitizer against A549 cancer cells via p38 MAPK signaling cascade pathways.

Dual functionality of phosphonic-acid-appended phthalocyanines: inhibitors of urokinase plasminogen activator and anticancer photodynamic agents

Phthalocyanines (Pcs) bearing phosphonic acid groups at the periphery exhibit a potential photodynamic effect to induce phototoxicity on human bladder cancer epithelial cells (UM-UC-3). In vitro photophysical and biological studies show high intrinsic ability to inhibit the activity of urokinase plasminogen activator (uPA) and matrix metalloproteinase-9 (MMP-9).

Iontophoresis Improved Growth Reduction of Invasive Squamous Cell Carcinoma in Topical Photodynamic Therapy

This study examined the potential of iontophoresis in topical photodynamic therapy (PDT) of human invasive squamous cells carcinomas (SCC). SCC was induced in nude BALB/c mice by subcutaneous injection of A431 cells. Tumor penetration and distribution of the photosensitizer tetrasulfonated zinc phthalocyanine (ZnPcS4) was investigated after 10 and 30 min of in vivo iontophoresis of a gel containing ZnPcS4. PDT was performed immediately after iontophoresis using laser at 660 nm with a dose of irradiation of 100 J/cm(2) and irradiance of 48 mW/cm(2) while tumor growth was measured for 30 days. Iontophoresis increased ZnPcS4 penetration into tumors by 6-fold after 30 min when compared with passive delivery. Confocal microscopy analysis showed that ZnPcS4 was homogeneous distributed within deep regions of the tumor after iontophoresis. Irradiation of the tumors immediately after iontophoresis showed reduction in tumor size by more than 2-fold when compared to non-treated tumors. Iontophoretic-PDT treated tumors presented large areas of necrosis. The study concluded that iontophoretic delivery of photosensitizers could be a valuable strategy for topical PDT of invasive SCC.

Investigation of the photophysical and photochemical properties of peripherally tetra-substituted water-soluble zwitterionic and cationic zinc(ii) phthalocyanines

4-{4-[N-((3-Dimethylamino)propyl)amide]phenoxy} substituted zinc(ii) phthalocyanine (2) and its water-soluble sulfobetaine (3), betaine (4) and N-oxide (5) containing zwitterionic and cationic (6) derivatives were synthesized for the first time in this study.

Developments in PDT Sensitizers for Increased Selectivity and Singlet Oxygen Production

Photodynamic therapy (PDT) is a minimally-invasive procedure that has been clinically approved for treating certain types of cancers. This procedure takes advantage of the cytotoxic activity of singlet oxygen (¹O₂) and other reactive oxygen species (ROS) produced by visible and NIR light irradiation of dye sensitizers following their accumulation in malignant cells. The main two concerns associated with certain clinically-used PDT sensitizers that have been influencing research in this arena are low selectivity toward malignant cells and low levels of ¹O₂ production in aqueous media. Solving the selectivity issue would compensate for photosensitizer concerns such as dark toxicity and aggregation in aqueous media. One main approach to enhancing dye selectivity involves taking advantage of key methods used in pharmaceutical drug delivery. This approach lies at the heart of the recent developments in PDT research and is a point of emphasis in the present review. Of particular interest has been the development of polymeric micelles as nanoparticles for delivering hydrophobic (lipophilic) and amphiphilic photosensitizers to the target cells. This review also covers methods employed to increase ¹O₂ production efficiency, including the design of two-photon absorbing sensitizers and triplet forming cyclometalated Ir(III) complexes.

Electropolymerizable peripherally tetra-{2-[3-(diethylamino)phenoxy]ethoxy} substituted as well as axially (4-phenylpiperazin-1-yl)propanoxy-disubstituted silicon phthalocyanines and their electrochemistry

A novel type of peripherally tetra-substituted as well as axially disubstituted silicon(iv) phthalocyanine containing electropolymerizable ligands was designed and synthesized for the first time.