silicon and phthalocyanine

Near infrared photoimmunotherapy (NIR-PIT) is a new cancer therapy based on the photo-induced ligand release reaction of a silicon-phthalocyanine derivative, IRDye700DX (IR700), that causes rapid cell death. Following exposure to an antibody-IR700-conjugate, cells exposed to NIR light within minutes undergo rapid swelling, blebbing, and finally, bursting. The photo-induced ligand release reaction also induces immediate loss of IR700 fluorescence due to dimerization or aggregation of the antibody-IR700 conjugate allowing for real time monitoring of NIR-PIT therapy.

Topics: Cell Line, Tumor; Immunotherapy; Ligands; Phototherapy; Silicon; Xenograft Model Antitumor Assays

Photodynamic therapy (PDT) has drawn a great scientific attention to cancer treatment over the last decades. However, the bottleneck for the PDT is to find good photosensitizers (PSs) with greater water solubility, no aggregation, and fast discharge from the body. Therefore, there are still a big scientific desire for the synthesizing new rational PSs for treatment of cancer by PDT technique. In favor of improving the competence of PDT, an axially bis[4-(diphenylamino-1,1'-biphenyl-4-ol)] substituted silicon(IV) phthalocyanine (3) was converted to its water-soluble quaternized derivative (3Q). Their structures were fully characterized by single-crystal X-ray diffraction, elemental analysis, and different spectroscopic methods such as FT-IR, UV-Vis, MALDI-TOF, and 

Topics: Indoles; Isoindoles; Models, Molecular; Molecular Conformation; Photosensitizing Agents; Protein Binding; Quantum Theory; Serum Albumin, Bovine; Silicon; Solubility; Water

To develop a highly efficient photosensitizer for photodynamic therapy (PDT), we have designed and synthesized a phthalocyanine-lactose conjugate (Pc-Lac) through axial modification of silicon(IV) phthalocyanine with lactose moieties. With the lactose substituents, Pc-Lac is highly hydrophilic and non-aggregated with efficient reactive oxygen species (ROS) generation in aqueous media. With these desirable properties, Pc-Lac shows high photocytotoxicity and cellular uptake toward HepG2 cells. In addition, in vivo fluorescence imaging shows that Pc-Lac could selectively remain at tumor site, leading to its enhanced photodynamic efficacy against H22 tumor-bearing mice. Therefore, Pc-Lac shows a great potential as a highly efficient molecular photosensitizer for PDT.

Topics: Animals; Antineoplastic Agents; Cell Proliferation; Cell Survival; Coordination Complexes; Dose-Response Relationship, Drug; Drug Screening Assays, Antitumor; Hep G2 Cells; Humans; Indoles; Isoindoles; Lactose; Liver Neoplasms, Experimental; Mice; Molecular Structure; Optical Imaging; Photochemotherapy; Photosensitizing Agents; Silicon; Structure-Activity Relationship

Recently several scientific-technological advances in the health area have developed. Among them, we can highlight research addressing nanoscience and nanotechnology focusing on the development of formulations for the cancer treatment. This work describes the synthesis and characterization of bovine serum albumin (BSA) polyelectrolytic nanoparticles for controlled release using silicon dihydroxide phthalocyanine [SiPc (OH)

Topics: Drug Delivery Systems; Isoindoles; Nanoparticles; Particle Size; Photochemotherapy; Polyelectrolytes; Serum Albumin, Bovine; Silicon

Because of their unique properties, including an ultrathin thickness (3-4 nm), ultrahigh resistivity, fluidity and self-assembly ability, lipid bilayers can be readily functionalized and have been used in various applications such as bio-sensors and bio-devices. In this study, we introduced a planar organic molecule: copper (II) 2,9,16,23-tetra-tert-butyl-29H,31H-phthalocyanine (CuPc) to dope lipid membranes. The CuPc/lipid hybrid membrane forms at the water/air interface by self-assembly. In this membrane, the hydrophobic CuPc molecules are located between the hydrophobic tails of lipid molecules, forming a lipid/CuPc/lipid sandwich structure. Interestingly, an air-stable hybrid lipid bilayer can be readily formed by transferring the hybrid membrane onto a Si substrate. We report a straightforward method for incorporating nanomaterials into a lipid bilayer system, which represents a new methodology for the fabrication of biosensors and biodevices.

Topics: Air; Copper; Hydrophobic and Hydrophilic Interactions; Indoles; Isoindoles; Lipid Bilayers; Organic Chemicals; Silicon; Spectrometry, X-Ray Emission; Water

The development of antimicrobial photodynamic therapy (aPDT) is highly dependent on the development of suitable photosensitizers (PSs); ideally, affinity of a PS towards bacterial cells should be much higher than that towards mammalian cells. A cationic charge on a PS may lead to its selective binding to bacteria mediated through electrostatic interaction; however, the photodynamic outcome is highly dependent on the lipophilicity of the PS. Herein, we report the aPDT effect of silicon(IV) phthalocyanine derivatives bearing four positive charges and methyl, phenyl, or naphthyl substituents at the periphery of the macrocycle. We show that through modulation of lipophilicity, it is possible to find a therapeutic window in which bacteria, but not mammalian cells, are effectively killed. The photobiological activity of these PSs was significantly lower when they were deployed as host-guest complexes with cucurbit[7]uril (CB[7]). CB[7] blocks the hydrophobic part of the PS and reduces its lipophilicity, indicating that a hydrophobic interaction with the outer membrane of bacterial cells is essential for aPDT activity. The efficacies of the obtained PSs have been evaluated by using different uropathogenic E. coli isolates and human kidney epithelial carcinoma cells.

Topics: Anti-Bacterial Agents; Coordination Complexes; Epithelial Cells; Humans; Hydrophobic and Hydrophilic Interactions; Indoles; Isoindoles; Light; Molecular Structure; Photochemotherapy; Photosensitizing Agents; Silicon; Static Electricity; Structure-Activity Relationship; Surface Properties; Uropathogenic Escherichia coli

Photodynamic therapy (PDT) has emerged as an effective and minimally invasive cancer treatment modality. In the present study, two novel phthalocyanines, tetra‑triethyleneoxysulfonyl substituted zinc phthalocyanine (ZnPc) and dihydroxy‑2,9(10),16(17),23(24)‑tetrakis(4,7,10‑trioxaundecan‑1‑sulfonyl) silicon phthalocyanine (Pc32), were investigated as photosensitizers (PS) for PDT of cholangiocarcinoma (CC). ZnPc showed a pronounced dose‑dependent and predominantly cytoplasmic accumulation in EGI‑1 and TFK‑1 CC cell lines. Pc32 also accumulated in the CC cells, but this was less pronounced. Without photoactivation, the PS did not exhibit any antiproliferative or cytotoxic effects. Upon photoactivation, ZnPc induced the formation of reactive oxygen species (ROS) and immediate phototoxicity, leading to a dose‑dependent decrease in cell proliferation, and an induction of mitochondria‑driven apoptosis and cell cycle arrest of EGI‑1 and TFK‑1 cells. Although photoactivated Pc32 also induced ROS formation in the two cell lines, the extent was less marked, compared with that induced by ZnPc‑PDT, and pronounced antipoliferative effects occurred only in the less differentiated EGI‑1 cells, whereas the more differentiated TFK‑1 cells did not show sustained growth inhibition upon Pc32‑PDT induction. In vivo examinations on the antiangiogenic potency of the novel PS were performed using chorioallantoic membrane (CAM) assays, which revealed reduced angiogenic sprouting with a concomitant increase in nonperfused regions and degeneration of the vascular network of the CAM following induction with ZnPc‑PDT only. The study demonstrated the pronounced antiproliferative and antiangiogenic potency of ZnPc as a novel PS for PDT, meriting further elucidation as a promising PS for the photodynamic treatment of CC.

Topics: Angiogenesis Inhibitors; Animals; Apoptosis; Cell Cycle; Cell Death; Cell Line, Tumor; Cell Proliferation; Chickens; Cholangiocarcinoma; Chorioallantoic Membrane; Humans; Indoles; Isoindoles; Photochemotherapy; Photosensitizing Agents; Reactive Oxygen Species; Silicon; Zinc

A series of novel symmetric or unsymmetric silicon (IV) phthalocyanines axially substituted with cyclic Arg-Gly-Asp (cRGD) ligands through different ethylene glycol chains have been synthesized by a facile and mild "click" reaction. All the compounds show efficient photosensitizing activities in N,N-dimethylformamide, and are essentially non-aggregated in RPMI 1640 medium with 0.05% Cremophor EL. Owing to the presence of two cRGD ligands, the conjugate 6b exhibits highest selectivity toward α

Topics: Animals; Cell Proliferation; Dose-Response Relationship, Drug; Humans; Indoles; Integrins; Isoindoles; Mice; Mice, Inbred Strains; Molecular Structure; Neoplasms, Experimental; Peptides, Cyclic; Photochemotherapy; Photosensitizing Agents; Reactive Oxygen Species; Silicon; Structure-Activity Relationship; Tumor Cells, Cultured

Herein, we report novel hyaluronic acid formulated nanoparticles containing a platinum(II) conjugated silicon(IV) phthalocyanine (SiPc-Pt-HA) for tumor targeted red light photodynamic therapy and chemotherapy. The SiPc-Pt-HA conjugate showed specific uptake, photo-enhanced cytotoxicity (~1500 fold) and mitochondrial accumulation in breast cancer over normal cells.

Topics: Antineoplastic Agents; Apoptosis; Cell Line, Tumor; HEK293 Cells; Humans; Hyaluronan Receptors; Hyaluronic Acid; Indoles; Isoindoles; Light; Mitochondria; Nanoparticles; Photochemotherapy; Photosensitizing Agents; Platinum; Silicon

In order to improve the efficacy of photodynamic therapy (PDT), biotin was axially conjugated with silicon(IV) phthalocyanine (SiPc) skeleton to develop a new tumor-targeting photosensitizer SiPc-biotin. The target compound SiPc-biotin showed much higher binding affinity toward BR-positive (biotin receptor overexpressed) HeLa human cervical carcinoma cells than its precursor SiPc-pip. However, when the biotin receptors of HeLa cells were blocked by free biotin, >50% uptake of SiPc-biotin was suppressed, demonstrating that SiPc-biotin could selectively accumulate in BR-positive cancer cells via the BR-mediated internalization. The confocal fluorescence images further confirmed the target binding ability of SiPc-biotin. As a consequence of specificity of SiPc-biotin toward BR-positive HeLa cells, the photodynamic effect was also largely dependent on the BR expression level of HeLa cells. The photodynamic activities of SiPc-biotin against HeLa cells were dramatically reduced when the biotin receptors were blocked by the free biotin (IC

Topics: Biological Transport; Biotin; HeLa Cells; Humans; Indoles; Isoindoles; Photochemotherapy; Photosensitizing Agents; Silicon

Combining the merits of delivery vectors with drug molecules is one of the key directions for development of efficient cancer monitoring and treatment techniques. In this work, a novel type of silicon based composite nanoparticles (NPs) with incorporated hydrophobic phthalocyanine molecules (Pc) was synthesized via a facile one-pot method. The as-synthesized Pc@Si NPs, with a small size of 4.2 ± 0.8 nm, have excellent dispersibility in water and good biocompatibility with cells, in addition to favorable photoluminescence and robust photostability even in cells. Moreover, the Pc@Si NPs show significant in vitro cancer cell killing and in vivo tumor inhibiting abilities upon near-infrared light exposure, due to the photodynamic therapy (PDT) effect of Pc. This work develops an efficient fluorescent PDT drug carrier; moreover, the facile one-pot synthesis strategy may be used generally to prepare silicon-based composite NPs incorporated with diverse hydrophobic drugs/diagnostic molecules for a wide range of biomedical applications.

Topics: Cell Line, Tumor; Cell Survival; Diagnostic Imaging; Endocytosis; Fluorescence; Humans; Indoles; Isoindoles; Nanoparticles; Neoplasms; Photochemotherapy; Quantum Dots; Silicon

Silicon(iv) phthalocyanines ( and ) bearing two calixarene groups as axial ligands were synthesized. Surprisingly, both phthalocyanines were obtained as two different isomers ( and ) depending on the distance between calixarene benzene groups and the phthalocyanine ring. DFT and TD-DFT computations were performed to model plausible structures of these isomers and to simulate electronic absorption spectra. These isomers converted into each other depending on the polarity of the used solvent, temperature and light irradiation. The photophysical and photochemical properties of each isomer were investigated in dimethylsulfoxide (DMSO) for the determination of photodynamic therapy (PDT) activities of these compounds. The more blue-shifted isomers ( and ) showed higher fluorescence quantum yields and singlet oxygen generation compared to more red-shifted counterparts ( and ). This behavior is extremely important for developing activatable photosensitizers for cancer treatment by PDT. Although these photosensitizers produce lower singlet oxygen in normal cells, they produce higher singlet oxygen (six times higher for ) in cancer cells since these photosensitizers converted to more blue-shifted isomers by using light irradiation.

Topics: Calixarenes; Indoles; Isoindoles; Photochemotherapy; Photosensitizing Agents; Silicon

Molecular conformation is an important issue related to the self-assembly architecture and property. The self-assembly of silicon(IV) phthalocyanines covalently linked to the 5-N-cytidine or 4-carboxyphenoxy moiety at the axial positions, namely, SiPc(NC)2 and SiPc(CP)2, respectively, has been studied by means of scanning tunneling microscopy (STM) at the solid-liquid interface. The intermolecular axial hydrogen bonding in combination with the stabilizing role of the TCDB template brings about supramolecular self-assembled structures of silicon(IV) phthalocyanines in an edge-on orientation. Two pyridine compounds, 4,4'-bipyridine (BPY) and 1,2-di(4-pyridyl)ethylene (DPE), can tune the supramolecular structure, leading to interestingly axial self-assemblies of SiPc(CP)2 with BPY and DPE in an edge-on manner by hydrogen bonding. The results indicate that the axial substituents and the axial ligands can regulate and precisely control the conformation and arrangement of the phthalocyanine moiety on the graphite surface.

Topics: Carbon; Ethylenes; Graphite; Indoles; Isoindoles; Models, Molecular; Molecular Conformation; Pyridines; Silicon; Surface Properties

The use of light-triggered photolysis provides a powerful tool for unique syntheses and for applications that require remote operation such as drug delivery or molecular switches. Here, we describe the photochemistry of a recently developed alkylsilicon phthalocyanine Pc 227, which undergoes an exchange of the alkyl ligand for a ligand derived from the solvent when the axial Si-C bond is photolyzed in a solvent with low-energy visible light. In this work with methanol as the solvent, we investigate the formation of the methoxy analogue of the therapeutic drug Pc 4, (termed Pc 233) upon irradiation. Using steady-state spectroscopy and characterization of the photoproducts, the competing pathways between direct ligand exchange on the central silicon atom and delocalization of the radical produced by homolysis on the phthalocyanine ring is observed. The delocalized radical intermediate is quite long-lived. At long times this intermediate decomposes without significant formation of Pc 233. The results of this investigation provide insights into recent work utilizing Pc 227 for drug delivery applications and for future work on the use of phthalocyanines as long-wavelength phototriggers.

Topics: Carbon; Indoles; Isoindoles; Kinetics; Light; Methanol; Methylene Blue; Photolysis; Silicon; Singlet Oxygen; Solvents; Spectrum Analysis

We review our achievements in exploring the high resolution imaging of scanning tunneling microscopy (STM) on the surface and adsorbates in a ultra-high vacuum system, by modifying the STM tip or introducing a decoupled layer onto the substrate. With an ultra-sharp tip, the highest resolution of Si(1 1 1)-7 × 7 reconstruction can be achieved, in which all the rest atoms and adatoms are observed simultaneously with high contrast. Further functionalization of STM tips can realize selective imaging of inherent molecular states. The electronic states of perylene and metal-phthalocyanine molecules are resolved with special decorated tips on metal substrates at low temperature. Moreover, we present two kinds of buffer layer: an organic molecular layer and epitaxially grown graphene to decouple the molecular electronic structure from the influence of the underlying metallic substrate and allow the direct imaging of the intrinsic orbitals of the adsorbed molecules. Theoretical calculations and STM simulations, based on first-principle density function theory, are performed in order to understand and verify the mechanism of high-resolution images. We propose that our results provide impactful routes to pursue the goal of higher resolution, more detailed information and extensive properties for future STM applications.

Topics: Electrons; Graphite; Indoles; Isoindoles; Microscopy, Scanning Tunneling; Models, Molecular; Molecular Structure; Organometallic Compounds; Oxygen; Silicon; Silver; Surface Properties

We explore the possible cellular cytotoxic activity of an amphiphilic silicon(IV) phthalocyanine with axially ligated rhodamine B under ambient light experimental environment as well as its in vivo antitumour potential using Hep3B hepatoma cell model. After loading into the Hep3B hepatoma cells, induction of cellular cytotoxicity and cell cycle arrest were detected. Strong growth inhibition of tumour xenograft together with significant tumour necrosis and limited toxicological effects exerted on the nude mice could be identified.

Topics: Animals; Antineoplastic Agents; Cell Line, Tumor; Humans; Indoles; Isoindoles; Liver Neoplasms; Mice; Mice, Nude; Random Allocation; Rhodamines; Silicon; Xenograft Model Antitumor Assays

A series of novel silicon(IV) phthalocyanines conjugated axially with different nucleoside moieties (uridine, 5-methyluridine, cytidine, and 5-N-cytidine derivatives) have been synthesized and evaluated for their photodynamic activities. The uridine-containing compound 1 exhibits the highest photocytotoxicity against HepG2 human hepatocarcinoma cells with an IC50 value as low as 6 nM, which can be attributed to its high cellular uptake and non-aggregated nature in the biological media. This compound shows high affinity toward the mitochondria of HepG2 cells and causes cell death mainly through apoptosis upon illumination. The result indicates that 1 is a highly promising photosensitizer for photodynamic therapy.

Topics: Apoptosis; Coordination Complexes; Hep G2 Cells; Humans; Indoles; Isoindoles; Microscopy, Confocal; Neoplasms; Nucleosides; Photochemotherapy; Photosensitizing Agents; Silicon

A novel bis(ferrocenyl chalcone) silicon(IV) phthalocyanine has been prepared in which the disulfide linker can be cleaved by dithiothreitol. The separation of the ferrocenyl quencher and the phthalocyanine core greatly enhances the fluorescence emission, singlet oxygen production and in vitro photocytotoxicity.

Topics: Cell Survival; Chalcone; Disulfides; Ferrous Compounds; Humans; Indoles; Isoindoles; MCF-7 Cells; Metallocenes; Microscopy, Confocal; Photosensitizing Agents; Silicon; Singlet Oxygen

Semiconducting thin films were grown on quartz substrates and crystalline silicon wafers, using dilithium phthalocyanine and the organic ligands 2,6-dihydroxyanthraquinone and 2,6-diaminoanthraquinone as the starting compounds. The films, thus obtained, were characterized by Fourier Transform infrared (FTIR), fast atomic bombardment (FAB+) mass and ultraviolet-visible (UV-Vis) spectroscopies. The surface morphology of these films was analyzed by means of atomic force microscopy (AFM) and scanning electron microscopy (SEM). It was found that the temperature-dependent electric current in all cases showed a semiconductor behavior with conductivities on the order of 10⁻⁶·S cm⁻¹, whereas the highest value corresponded to the thin film based upon the bidentate amine. The Tauc and Cody optical band gap values of thin films were calculated from the absorption coefficients and were found to be around 1.5 eV, with another strong band between 2.3 and 2.43 eV, arising from non-direct transitions. The curvature in the Tauc plot influencing the determination of the optical gap, the Tauc optical gap corresponding to the thicker film is smaller. The dependence of the Cody optical gap on the film thickness was negligible.

Topics: Absorption; Anthraquinones; Electric Conductivity; Indoles; Isoindoles; Mass Spectrometry; Microscopy, Atomic Force; Microscopy, Electron, Scanning; Optical Phenomena; Quartz; Semiconductors; Silicon; Spectroscopy, Fourier Transform Infrared; Surface Properties; Temperature

We have applied phthalocyaninatosilicon (SiPc) covalently linked to one or two tetramethyl-1-piperidinyloxyl (TEMPO) radicals as fluorescence probes for detecting ascorbic acid in biological systems.

Topics: Ascorbic Acid; Cyclic N-Oxides; Female; Fluorescence; HeLa Cells; Humans; Indoles; Isoindoles; Liposomes; Microscopy, Fluorescence; Molecular Imaging; Silicon; Spectrometry, Fluorescence; Uterine Cervical Neoplasms

A series of unsymmetrical silicon(IV) phthalocyanines with a permethylated β-cyclodextrin unit and a sugar or a diamino moiety as the axial substituents have been prepared. These compounds are highly photocytotoxic with IC(50) values as low as 21 nM, which is ca. sevenfold lower than those of the symmetrical bis(cyclodextrin) analogue.

Topics: Animals; beta-Cyclodextrins; HT29 Cells; Humans; Indoles; Isoindoles; Mice; Organometallic Compounds; Photochemotherapy; Photosensitizing Agents; Silicon

Water-soluble phthalocyanine complexes of silicon (SiPc1) and germanium (GePc1) were synthesized. The absorbance of SiPc1 in water was with minor aggregation while GePc1 strongly aggregated in water. The fluorescence data in water showed low quantum yields of 0.073 (SiPc1) and 0.01 (GePc1) and similar lifetimes of 4.07 ns and 4.27 ns. The uptake of SiPc1 into Candida albicans cells was two orders of magnitude lower as compared to GePc1 and for both was dependent on the cell density. Fungal cells in suspension were completely inactivated after SiPc1 (1.8 μM) at soft light radiation (50 J cm(-2), 60 mW cm(-2)). The fungal biofilm formed on denture acrylic resin was inactivated with 3 log after fractionated light irradiation.

Topics: Biofilms; Candida albicans; Geranium; Indoles; Isoindoles; Microscopy, Confocal; Photochemotherapy; Photosensitizing Agents; Silicon; Solubility; Spectrometry, Fluorescence; Spectrophotometry, Infrared

The combination of a red light PDT agent and a Pt(ii)-based chemotherapeutic drug at the molecular level maintains the intrinsic functions of each unit; the conjugated complexes exhibit remarkable photocytoxicity and demonstrate potential to serve as agents for DNA-targeting PDT as well as red light photochemotherapy.

Topics: Antineoplastic Agents; Antineoplastic Combined Chemotherapy Protocols; Cisplatin; Female; HeLa Cells; Humans; Indoles; Isoindoles; Light; Microscopy, Confocal; Molecular Structure; Photochemotherapy; Radiation-Sensitizing Agents; Silicon; Staining and Labeling; Uterine Cervical Neoplasms

Two novel silicon(IV) phthalocyanines substituted axially with two BODIPY or mono-styryl BODIPY moieties have been synthesised, which exhibit predominantly a photo-induced energy or electron-transfer process in toluene depending on the axial substituents.

Topics: Boron Compounds; Electrons; Fluorescent Dyes; Indoles; Isoindoles; Molecular Structure; Photochemistry; Radiation-Sensitizing Agents; Silicon; Toluene

A series of symmetrical cationic phthalocyanines (Pcs) with either Zn(II) or Si(IV) metal ions and two bulky axial ligands on the silicon complexes was synthesized in high yields. The photophysical (absorption, emission, fluorescence, and singlet oxygen quantum yields) and cellular (uptake, toxicity, and subcellular localization) properties of this series of Pcs were investigated. The Si(IV)-Pcs exist mainly as monomers in aqueous media and have higher fluorescent quantum yields in protic solvents (methanol and water) than the Zn(II)-Pcs. The presence of eight short PEG groups at the periphery of a Zn(II)-Pc significantly increases its solubility in protic solvents, but a centrally chelated silicon ion and associated bulky axial ligands were more efficient in preventing aggregation of the Pc macrocycles. The singlet oxygen quantum yields for this series of Pcs in DMSO are in the range 0.09-0.15. All Pcs were readily taken up by human HEp2 cells, and the extent of their accumulation within cells depends on their hydrophobic character. Intracellularly, all Pcs localized preferentially within the cell lysosomes. The Zn(II)-Pc 11 and Si(IV)-Pcs 12 and 14 were found to be the most phototoxic (IC50 = 2.2 microM at a 1 J cm(-2) light dose) of this series of compounds.

Topics: Cations; Cell Line, Tumor; Humans; Hydrophobic and Hydrophilic Interactions; Indoles; Isoindoles; Ligands; Lysosomes; Molecular Structure; Photochemotherapy; Photosensitizing Agents; Polyethylene Glycols; Pyridines; Silicon; Solubility; Water; Zinc

The electronic structure of the organic semiconductor copper-phthalocyanine (CuPc) has been determined by a combination of conventional and resonant photoemission, near-edge x-ray absorption, as well as by the first-principles calculations. The experimentally obtained electronic valence band structure of CuPc is in very good agreement with the calculated density of states results, allowing the derivation of detailed site specific information.

Topics: Algorithms; Chemistry, Organic; Copper; Electronics; Equipment Design; Indoles; Isoindoles; Light; Molecular Conformation; Molecular Structure; Organometallic Compounds; Photons; Semiconductors; Silicon; Software; Spectrophotometry

A series of silicon(IV) phthalocyanines with two axial isopropylidene-protected galactose moieties and one, two, or eight chloro group(s) on the periphery of the macrocycle have been synthesised and spectroscopically characterised. The photophysical properties and in vitro photodynamic activities of these compounds have been studied and compared with those of the nonchlorinated analogue. All the compounds, with the exception of the octachlorinated counterpart which has a limited solubility, are essentially nonaggregated in N,N-dimethylformamide. The fluorescence quantum yield decreases and the singlet oxygen quantum yield increases as the number of chloro substituent increases, which is in accord with the heavy-atom effect. The non-, mono-, and dichlorinated phthalocyanines formulated with Cremophor EL are all photodynamically active against HT29 human colon adenocarcinoma and HepG2 human hepatocarcinoma cells with IC(50) values ranging from 0.03 to 1.05 microM. The photocytotoxicity as well as the efficiency to generate intracellular reactive oxygen species decrease along this series because of the increase in aggregation tendency upon chloro substitution. The nonchlorinated analogue exhibits the highest potency and can target the lysosomes of HT29 cells, whereas the monochlorinated counterpart is not localised in the lysosomes.

Topics: Cell Line, Tumor; Chlorine; Colorectal Neoplasms; Dimethylformamide; Fluorescence; Formamides; Galactose; HT29 Cells; Humans; Indoles; Isoindoles; Organosilicon Compounds; Photosensitizing Agents; Silicon; Singlet Oxygen; Spectrum Analysis; Structure-Activity Relationship

Heteroporphyrin and -phthalocyanine arrays represent an attractive class of light harvesters and charge-separation systems exhibiting an easy route of synthesis and high chemical stability. In the present work, we report the results of photophysical investigations of two novel non-sandwich-type porphyrin-phthalocyanine heterotriads, in which two meso-tetraphenylporphyrin rings (H2TPP or ZnTPP) are linked to the central silicon atom of a silicon(IV) phthalocyanine core. It was found that the photophysical properties of the triads (H2Tr and ZnTr) in N,N-dimethylformamide (DMF) and toluene are strongly affected by two different types of interaction between the porphyrin (P) and the phthalocyanine (Pc) parts, namely excitation energy transfer (EET) and photoinduced charge transfer. The first process results in appearance of the Pc fluorescence when the P-part is initially excited, and plays a dominant role in fast depopulation of the first excited singlet state of the P moiety. If the first excited singlet state of the Pc-part is populated (either directly or via EET), it undergoes fast depopulation by hole transfer (HT) to the charge-separated (CS) state. In polar DMF, the CS state is the lowest excited state, and the charge recombination occurs directly to the ground state. Using transient absorption spectroscopy, the lifetime of the CS state was estimated to be 30 and 20 ps for H2Tr and ZnTr, respectively. In nonpolar toluene, the energy gap between the first excited singlet state of the Pc-part and the CS state is very small, and back HT occurs in both triads, resulting in appearance of "delayed fluorescence" of the Pc-part with a decay time similar to the lifetime of the CS state (190 and 280 ps for H2Tr and ZnTr, respectively). Since the energy of the CS state of ZnTr in toluene is lower than that of H2Tr, the probability of back HT for ZnTr is lower. This was clearly proved by decay-associated fluorescence spectral measurements.

Topics: Electrochemistry; Electron Transport; Energy Transfer; Heterocyclic Compounds; Indoles; Isoindoles; Molecular Structure; Porphyrins; Silicon; Solvents; Spectrophotometry, Atomic; Spectrophotometry, Ultraviolet; Zinc

The interactions of four novel silicon(IV) phthalocyanines (SiPc), namely SiPc[OC(3)H(5)(NMe(2))(2)](2) (1), SiPc[OC(3)H(5)(NMe(2))(2)](OMe) (2), {SiPc[OC(3)H(5)(NMe(3))(2)](2)}I(4) (3), and {SiPc[OC(3)H(5)(NMe(3))(2)](OMe)}I(2) (4) with human serum albumin (HSA), bovine serum albumin (BSA), and maleylated bovine serum albumin (mBSA) were studied by fluorescence spectroscopy. The fluorescence emission of the serum albumins was effectively quenched by these phthalocyanines mainly through a static quenching mechanism. The higher Stern-Volmer quenching constants for the unsymmetrically substituted phthalocyanines 2 and 4 suggested that they have a stronger interaction with these proteins than the symmetrically substituted analogues 1 and 3. A series of non-covalent BSA or mBSA conjugates of these phthalocyanines were also prepared and evaluated for their in vitro photodynamic activity against HepG2 human hepatocarcinoma cells. The bioconjugation could enhance the photocytotoxicity of 1 and 4 by up to eight folds, but the effects on 2 and 3 were negligible. The results could be partly explained by two counter-balancing effects, namely the enhanced uptake and increased aggregation tendency of phthalocyanine due to BSA conjugation. As shown by absorption spectroscopy, the tetracationic phthalocyanine 3 was significantly aggregated in the protein cavity and its photocytotoxicity remained the lowest among the four photosensitizers.

Topics: Carcinoma, Hepatocellular; Cell Line, Tumor; Humans; Indoles; Isoindoles; Liver Neoplasms; Photosensitizing Agents; Serum Albumin, Bovine; Silicon; Spectrometry, Fluorescence

Three newly elucidated crystal structures of group IV phthalocyaninato complexes are reported, along with data for two further SiPc carboxylate complexes. In one of these crystal structures, bis(undecylcarboxylate)Sn(IV) phthalocyanine, the tin ion is seven coordinate, which is a unique finding for this atom in phthalocyanine ring coordination. Comparison of these structures with other group IV phthalocyaninato and related structures reveals differences, illustrating features significant in the chemistries of Si(IV) and Sn(IV) ions. These differences are thought to originate from their differing sizes and polarizabilities. The structures show that the Sn(IV) ion can only occupy an in-plane location in the phthalocyaninato ring where it elongates toward the two axial ligands. When the axial ligands do not facilitate this elongation cis coordination is preferred and the Sn(IV) ion sits above the phthalocyaninato ring plane. In contrast, the Si(IV) structures, with smaller, harder (i.e., less polarizable) Si(IV) ions, are six coordinate with the Si(IV) ion in the phthalocyaninato ring plane in a distorted octahedral symmetry. The electronic spectra and cyclic voltammetry of some of the Si compounds indicate that on the electrode the oxidized/reduced species behave as though they are in a solid film, rather than a soluble freely diffusing species.

Topics: Crystallography, X-Ray; Electrochemistry; Indoles; Isoindoles; Magnetic Resonance Spectroscopy; Mass Spectrometry; Molecular Structure; Organotin Compounds; Photosensitizing Agents; Silicon

Photodynamic therapy (PDT) of cancer is a modality that relies upon the irradiation of tumors with visible light following selective uptake of a photosensitizer by the tumor tissue. There is considerable emphasis to define new photosensitizers suitable for PDT of cancer. In this study we evaluated six phthalocyanines (Pc) for their photodynamic effects utilizing rat hepatic microsomes and human erythrocyte ghosts as model membrane sources. Of the newly synthesized Pc, two showed significant destruction of cytochrome P-450 and monooxygenase activities, and enhancement of lipid peroxidation, when added to microsomal suspension followed by irradiation with approximately 675 nm light. These two Pc named SiPc IV (HOSiPcOSi[CH3]2[CH2]3N[CH3]2) and SiPc V (HOSiPc-OSi[CH3]2[CH2]3N[CH3]3+I-) showed dose-dependent photodestruction of cytochrome P-450 and monooxygenase activities in liver microsomes, and photoenhancement of lipid peroxidation, lipid hydroperoxide formation and lipid fluorescence in microsomes and erythrocyte ghosts. Compared to chloroaluminum phthalocyanine tetrasulfonate, SiPc IV and SiPc V produced far more pronounced photodynamic effects. Sodium azide, histidine, and 2,5-dimethylfuran, the quenchers of singlet oxygen, afforded highly significant protection against SiPc IV- and SiPc V-mediated photodynamic effects. However, to a lesser extent, the quenchers of superoxide anion, hydrogen peroxide and hydroxyl radical also showed some protective effects. These results suggest that SiPc IV and SiPc V may be promising photosensitizers for the PDT of cancer.

Topics: Animals; Cytochrome P-450 Enzyme System; Erythrocyte Membrane; Humans; Indoles; Isoindoles; Light; Lipid Peroxidation; Male; Membrane Lipids; Microsomes, Liver; Photochemotherapy; Radiation-Sensitizing Agents; Rats; Rats, Sprague-Dawley; Silicon; Structure-Activity Relationship