Ayşe G. Gürek

Water-soluble phthalocyanines mediated photodynamic effect on mesothelioma cells

The new peripherally 2-mercaptopyridine tetrasubstituted zinc phthalocyanine (2) and its quaternized derivative (3) have been synthesized and characterized by elemental analysis, IR, 1H NMR spectroscopy, electronic spectroscopy and mass spectra. The quaternized compound (3) shows excellent solubility in water, which makes it a potential photosensitizer for use in photodynamic therapy (PDT) of cancer. Fluorescence and singlet oxygen quantum yield measurements were conducted on 2-mercaptopyridine appended zinc phthalocyanines in dimethylsulphoxide (DMSO) for both the non-ionic (2) and quaternized (3) derivatives, and in aqueous media for the water-soluble complex 3. General trends are described for fluorescence and singlet oxygen quantum yields of these compounds. In this study, the cells were incubated with a novel water-soluble zinc phthalocyanine derivative (3) and thereafter the cells were illuminated using broad-band incoherent light source of various energy levels. Cytotoxicity of PDT on two pleural malign mesothelioma cell lines was determined by colorimetric proliferation assay. In addition, after PDT treatment, determination of activity matrix metalloproteinases (MMPs) were evaluated using gelatine zymography.

A novel glucose sensor using lutetium phthalocyanine as redox mediator in reduced graphene oxide conducting polymer multifunctional hydrogel

Herein, we report a scalable synthesis of multifunctional conducting polyacrylic acid (PAA) hydrogel (MFH) integrated with reduced grapheme oxide (rGO), vinyl substituted polyaniline (VS-PANI) and lutetium Phthalocyanine (LuPc2) as three dimensional robust matrix for glucose oxidase (GOx) immobilization (PAA-rGO/VS-PANI/LuPc2/GOx-MFH). We have integrated the multicomponents such as PAA with rGO, and VS-PANI through free radical polymerization using methylene bis-acrylamide, and ammonium persulphate as the cross linker and initiator. The LuPc2 was then doped to form multifunctional hydrogel (PAA-rGO/VS-PANI/LuPc2-MFH). Finally, biosensor was fabricated by immobilizing GOx into PAA-rGO/VS-PANI/LuPc2-MFH and subsequently used for electrochemical detection of glucose. The PAA-rGO/VS-PANI/LuPc2/GOx-MFH biosensor exhibited high sensitivity (15.31μAmM-1cm-2) for the detection of glucose over a concentration range of 2-12mM with a low detection limit of 25µm. The PAA-rGO/VS-PANI/LuPc2-MFH biosensor showed a fast response time (1s) to the addition of glucose with high storage stability of 3 months. The real sample analysis reveals that PAA-rGO/VS-PANI/LuPc2/GOx-MFH could be effectively used as an electrochemical biosensor in industrial as well clinical diagnosis.

Investigations and application in piezoelectric phenol sensor of Langmuir–Schäfer films of a copper phthalocyanine derivative functionalized with bulky substituents

An octa-substituted copper phthalocyanine was dissolved in chloroform and spread on ultrapure water subphase in a Langmuir trough. The floating films were characterized at the air-water interface by the Langmuir isotherm, Brewster angle microscopy, and UV-Vis reflection spectroscopy and transferred by Langmuir-Schäfer technique on a silicon substrate, and thickness, refractive index, and extinction coefficient of the phthalocyanine derivative thin film were calculated by means of spectroscopic ellipsometry. A different number of layers were deposited using Langmuir-Schäfer method onto QCM crystals, and the active layers were tested as sensors for the detection of phenols in aqueous solution. The piezoelectric sensor response, totally reversible, is influenced by the number of transferred layers and by the nature of the substituent; on the contrary, the pK(a) value of the injected analytes slightly affects the device performances. Repeatability of the sensor responses was tested, and the frequency variation appears unchanged at least for 100 days.

Synthesis, photophysical and photochemical studies of novel liquid crystalline phthalocyanines

Ni(II) and Zn(II) phthalocyanines carrying four or eight branched oligo(ethyleneoxy)-thia groups on peripheral positions have been synthesized from new phthalonitrile derivatives. The new compounds have been characterized by elemental analysis, IR, NMR, mass spectra and electronic spectroscopy. The aggregation behaviors of the phthalocyanine complexes were studied in different solvents and concentrations. General trends are described for photodegradation, singlet oxygen and fluorescence quantum yields, and fluorescence lifetimes of these compounds in dimethylsulfoxide (DMSO). The effects of the substitution on the photophysical and photochemical parameters of the nickel(II) (3a and 4a) and zinc(II) phthalocyanines (4b) are also reported. The octasubstituted zinc(II) complex (3b) is not stable for these measurements. Preliminary investigation of the photophysical and photochemical properties of phthalocyanine complexes are very useful for further PDT applications. The mesogenic properties of these new materials were studied by differential scanning calorimetry (DSC), optical polarized microscopy and X-ray investigations.

Significant sensitivity and stability enhancement of tetraphenylporphyrin-based optical oxygen sensing material in presence of perfluorochemicals

Emission-based oxygen sensing properties of highly luminescent tetraphenylporphyrin molecules were investigated in polystyrene, ethyl cellulose, poly(1-trimethylsilyl-1-propyne) and poly(isobutylmethacrylate) matrices. The effect of perfluorochemicals (PFCs) on oxygen sensitivity and stability of the sensor materials was also examined. Fluorescence intensity and lifetime measurements of meso-tetraphenylporphyrinato Zn(II) (ZnTPP) and meso-tetraphenylporphyrin (H2TPP) materials were performed in the concentration range of 0–100% pO2. The fluorescence intensity variation of H2TPPvs. oxygen was 86%. H2TPP-based composite also yielded higher Stern–Volmer constant, faster response and regeneration time, excellent long term photostability and larger linear response range with respect to ZnTPP. The detection limit of oxygen for H2TPP was less than 0.5%. When stored in sealed bags protected from sunlight, no decrease in oxygen sensitivity was observed during approximately five months. As far as we know, the gathe...

Liquid crystalline alkylthia-substituted novel phthalocyanines: synthesis and characterization

Methylene-bridged tetra- and octa-alkylthia substituted metal free- and Ni(II) phthalocyanines were synthesized from the corresponding phthalonitrile derivatives in the presence of the anhydrous metal salt (NiCl2) or a strong organic base. The new compounds were fully characterized by elemental analyses, UV-vis, IR, NMR and mass spectra. The mesogenic properties of these materials were studied by differential scanning calorimetry, optical microscopy and X-ray diffraction investigations. X-ray diffraction patterns of the mesophase confirmed that the tetra- and the octa-substituted compounds formed hexagonal columnar mesophases (Colh). The mesogenic properties of these compounds were compared to that of their octa alkythia substituted phthalocyanine derivatives in the literature.

Memory effects in thin film organic transistor characteristics

Bottom gated field effect transistors were fabricated using spun films of peripherically substituted liquid-crystalline lutetium phthalocyanine (Lu(PcR8)2) molecules as active layers and the electrical characteristics were found to be sensitive to the molecular orientations depending upon the post-deposition heat treatment of the films. High conductive states were attributed to the formation of a well ordered crystalline structure when as deposited Lu(PcR8)2 films were annealed at 242 °C. Annealing at 125 °C produced a different crystalline of lower order, giving rise to low conductive states. The existence of these two well-defined conducting states makes Lu(PcR8)2 films suitable for the fabrication of storage-class memory devices.

Asymmetric zinc phthalocyanines substituted with a single carboxyl and triethyleneoxysulfonyl groups: synthesis, characterization and validation for photodynamic therapy

This work describes modular pathway towards the synthesis of new specific unsymmetrically (AB3) zinc phthalocyanines that contains three polyoxy ethylene and monocarboxylic acid groups as photosensitizers. Their photophysical and photochemical properties are studied. General trends are described for quantum yields of fluorescence, photodegradation and singlet oxygen quantum yields of these compounds. Therefore, these novel phthalocyanines could potentially be good photosensitizers for photodynamic therapy.

A glucose biosensor based on novel Lutetium bis-phthalocyanine incorporated silica-polyaniline conducting nanobeads

The facile preparation of highly sensitive electrochemical bioprobe based on lutetium phthalocyanine incorporated silica nanoparticles (SiO2(LuPc2)) grafted with Poly(vinyl alcohol-vinyl acetate) itaconic acid (PANI(PVIA)) doped polyaniline conducting nanobeads (SiO2(LuPc2)PANI(PVIA)-CNB) is reported. The preparation of CNB involves two stages (i) pristine synthesis of LuPc2 incorporated SiO2 and PANI(PVIA); (ii) covalent grafting of PANI(PVIA) onto the surface of SiO2(LuPc2). The morphology and other physico-chemical characteristics of CNB were investigated. The scanning electron microscopy images show that the average particle size of SiO2(LuPc2)PANI(PVIA)-CNB was between 180-220nm. The amperometric measurements showed that the fabricated SiO2(LuPc2)PANI(PVIA)-CNB/GOx biosensor exhibited wide linear range (1-16mM) detection of glucose with a low detection limit of 0.1mM. SiO2(LuPc2)PANI(PVIA)-CNB/GOx biosensor exhibited high sensitivity (38.53µAmM-1cm-2) towards the detection of glucose under optimized conditions. Besides, the real (juice and serum) sample analysis based on a standard addition method and direct detection method showed high precision for measuring glucose at SiO2(LuPc2)PANI(PVIA)-CNB/GOx biosensor. The SiO2(LuPc2)PANI(PVIA)-CNB/GOx biosensor stored under refrigerated condition over a period of 45 days retains ~ 96.4% glucose response current.

Investigation of optical and electrochemical properties as well as metal ion sensitivities of different number of crown ether appended phthalocyanines

We report herein, the synthesis, and spectral and electrochemical characterization of a series of phthalocyaninato zinc complexes where two biomedically potential structures; crown ether and phthalocyanine moities were gathered on the same molecule. The effect of number of crown ether moieties on metal ion binding properties, as well as proton sensitivity were investigated by using electronic absorption and fluorescence emission spectra. Spectral behaviors of the zinc phthalocyanine complexes fused with one crown ether; Zn[Pc(15C5)(C6H13)6] and four crown ether; Zn[Pc(15C5)4] in presence of Na+ and K+ ions were investigated into detail because of host-guest interactions of subjective ions with crown ether moieties, and compared with the crown ether free phthalocyanine; Zn[Pc(C6H13)8].