Tetracarboxyphenyl Porphyrin Research Articles

Construction of Somatostatin-Based Multiphase "Core-Shell" Coacervates as Photodynamic Biomimetic Organelles.

Biomimetic coacervates have recently attracted great interest in biomedical fields, especially for drug delivery and as protocells. However, these membraneless structures are easily coalesced and poorly targetable, limiting their real biomedical applications. Here multiphase "core-shell" coacervate (CSC) constructed by dsDNA and somatostatin (SST), a 14-mer cyclopeptide is designed. The CSC shows enhanced tumor targetability through SST binding to SST receptors on the tumor cells' surface. G4 quadruplex-hemin complex can be embedded in the CSC by interaction with SST, as demonstrated by molecular simulation and isothermal titration calorimetry. The G4-hemin embedded CSC can further recruit photosensitizers such as tetracarboxyphenyl porphyrin to form the CSC-GHT composite for photodynamic therapy (PDT). As photodynamic biomimetic organelles, CSC-GHT can convert oxygen to singlet oxygen (catalyzed by the catalase-mimetic activity of G4-hemin), resulting in enhanced PDT effect, which allows the inhibition of cellular migration in vitro and tumor growth in vivo. Owing to high stability, targetability, and biosafety, the proposed CSC can recruit various cargos from small dyes to large biomacromolecules (up to 430kDa), providing promising theranostic applications.

Porous carbon nanofiber/porphyrin-based metal organic frameworks/TiO2 nanoparticles ternary materials for selective detection and photoreduction of Cr(Ⅵ)

For the heavy metal ion Cr(Ⅵ), which is widely present in wastewater with acute toxicity, mutagenicity and carcinogenicity, we successfully constructed a ternary material of PCNFs/CuMOF/TiO2 for rapid detection and photoreduction of Cr(Ⅵ). The material has obvious advantages: on the one hand, ZIF-8/polyacrylonitrile (PAN) nanofibers and their derived porous carbon nanofibers (PCNFs) were synthesized by electrospinning and high temperature carbonization, which provided a loading platform for CuMOF and TiO2, effectively inhibited the agglomeration of CuMOF and TiO2, and ensured the exposure of active sites. Meanwhile, its excellent conductivity can promote the effective migration of photogenerated carriers in the photocatalytic process. On the other hand, CuMOF constructed with tetra-carboxyphenylporphyrin (TCPP) as the linking arm and Cu(NO3)2·3 H2O as the metal node was directly loaded on the surface of porous carbon nanofibers (PCNFs), and then TiO2 nanoparticles were introduced by hydrothermal method. CuMOF ensures the responsiveness of the composite to visible light. Moreover, the energy level structure of TiO2 matches with CuMOF, which effectively inhibits the recombination of photogenerated electron-hole pairs (e--h+). The results show that the colorimetric detection of Cr(Ⅵ) was achieved by using 3,3′,5,5′-tetramethylbenzidine (TMB) as the sensing probe. The method was highly selective for Cr(Ⅵ) ions with a limit of detection (LOD) of 24.1 nM. Encouragingly, PCNFs/CuMOF/TiO2 was further used as a photocatalyst. The reduction rate of Cr(Ⅵ) under visible light irradiation is 96.1 % in 60 min. The active species trapping experiments confirm the key role of e- photocatalytic reduction, upon which a possible photocatalytic mechanism is proposed. The degradation rate of Cr(Ⅵ) is still 86.4 % after the five times cycle, and the good stability and reproducibility allow it to be used as a potential green photocatalyst for the conversion of Cr(Ⅵ) to Cr(Ⅲ).

Preparation of copper porphyrin photosensitized iron-based MOFs composite photocatalyst and study on CO2 reduction performance

Fe-based MIL-101(Fe) MOFshavea high potential to capture CO2 due to their high porosity, porous structure,and significant interaction with CO2, but the photogenerated electron and hole recombination phenomenon is relatively obvious. Copper tetracarboxyphenyl porphyrin (Cu-TCPP) was incorporated into MIL-101(Fe) as a photosensitive material to forma heterostructure. This enhanced the light absorption capability and the photogenerated electron-hole pairs separation in the composite catalyst. Based on the above factors, the current study reported the synthesis of MIL-101(Fe) by hydrothermal method, and a new composite photocatalyst Cu-TCPP@MIL-101(Fe) was prepared by using Cu-TCPP as a copper source with different mass ratios. Themorphologicaland structural characterizationof the composite catalyst was carried out by XRD, SEM, TEM, BET, and FT-IR, and the CO2 reduction performance of the composite catalyst Cu-TCPP@MIL-101(Fe) was determined by a vacuum CO2 reduction system under simulated sunlight irradiation. The results revealed that MIL-101(Fe) was loaded with Cu-TCPP with the formation of type II heterojunctions that are capable of inhibitingthe electron-hole recombination with improved light absorption capacity, and accelerated reduction rate of CO2. The reduction rateof CO2 into CO was found to be 29 μmol·g−1·h−1.

Supramolecular tetracarboxyphenylporphyrin modified bismuth oxybromide with improved molecular oxygen activation for antibiotics photodegradation

Supramolecular tetracarboxyphenylporphyrin (TCPP) has been employed to tune the photocatalytic performance of BiOBr. Benefiting from the molecular dipole induced by the electron withdrawing group, the built-in electric field can be created in TCPP, which extends the light absorption range of the photocatalyst. Scanning electron microscopy images demonstrated that TCPP has been uniformly dispersed on the BiOBr surface. The results of radical trapping experiments and electron spin resonance spectra reveal that TCPP/BiOBr possesses a greater concentration of reactive radicals. The molecular oxygen activation performance of TCPP/BiOBr can be promoted relative to pure BiOBr and boost the photocatalytic activity for antibiotics degradation, such as tetracycline and ciprofloxacin. This work deepens the insight of structure-activity correlation of porphyrin supramolecular-based catalysts and offers a general approach at the molecular level for activity optimization.

3D Lanthanide Neodymium Porphyrin Metal–Organic Framework for Photocatalytic Oxidation of Styrene

A novel three-dimensional lanthanide porphyrin-based MOF (Nd-PMOFs) was synthesized by using tetracarboxyphenyl porphyrin as the ligand and the lanthanide Nd as the coordination metal. Its specific crystal structure information was obtained by single-crystal diffraction with the space group C2/c and the empirical formula C72H45N6Nd2O15.25. This new Nd porphyrin-based MOF with an organic framework formed by a unique coordination method enables the effective separation of photogenerated electrons and holes under photoluminescence, giving it excellent photocatalytic property which could be verified by the characterization data. The photocatalytic performance was examined by taking tert-butyl hydroperoxide as the oxidant and Nd-PMOFs as the catalyst for photocatalytic oxidation of styrene to benzaldehyde with 91.4% conversion and 81.2% benzaldehyde selectivity under optimal reactions, which surpasses most of the results reported in the literature. Several styrenes with other substituents were screened to explore the general applicability of Nd-PMOF for photocatalysis of styrene, among which Nd-PMOFs also exhibited excellent photocatalytic performance. This work offers the possibility to apply lanthanide organometallic frameworks, which are widely used in fluorescent materials, to photocatalysis. In addition, it also provides a new method for the catalytic generation of benzaldehyde from styrene that is consistent with the needs of modern green development.

A spectroscopic and molecular docking study of interactions of tetracarboxyphenyl porphyrin and chlorin e6 with bovine serum albumin

A spectroscopic and molecular docking study of interactions of tetracarboxyphenyl porphyrin and chlorin e6 with bovine serum albumin

Discoloration of alizarin red on thin films of Fe (III)-tetracarboxyphenyl porphyrin deposited on silicon oxide

Alizarin Red is a water soluble anthraquinone dye used extensively in the textile industry as a staining agent and is considered to be one of the most recalcitrant and durable pollutants. Fenton reaction can be used to destroy a wide variety of organic compounds: a ferrous ion reacts with hydrogen peroxide (H2O2) to form hydroxyl radical (HO•) which is a powerful oxidizing agent. The rate of this reaction could be increased when exposed o UV–vis light, this method is known as photo-assisted Fenton process and constitutes an attractive alternative of advance oxidation process. In this work, we studied the alizarin red dye photocatalytic discoloration through heterogeneous Photo-Fenton process induced by visible light; we used tetra (4-carboxyphenyl) porphyrin iron (III) adsorbed on silicon dioxide thin films. The characterization of the catalyst was carried out by UV-Vis, diffuse reflectance and IR-FT; The tests were carried out at three (3) pH values 1.0, 3.0 and 5.0; finally, the kinetic model described by Langmuir-Hinshelwood was used to obtain kinetic parameters for photo-discoloration process. The results showed that at pH = 1.0 highest alizarin red photo-discoloration percentage was reported; furthermore, after applied the pseudo-first order model, we obtained rate constants (k) for discoloration process that finds the highest k value was 1.1x10-2 min-1. The hydroxyl radicals were detected by chemical trapping through indirect fluorescence of the 2-hydroxyterephthalic acid. Photo-Fenton processes based on heterogeneous catalysis systems solve part of these environmental problems providing an easy separation and recovery of the catalyst from the treated wastewater, wherein it is noncorrosive, and, besides, it is environmentally friendly.

Coupling graphitic carbon nitrides with tetracarboxyphenyl porphyrin molecules through π–π stacking for efficient photocatalysis

Graphitic carbon nitride (g-C3N4) photocatalysts have attracted dramatically growing attention due to their attractive electronic structure, relatively low cost, high physicochemical stability, and earth-abundant features, but their practical applications are hindered by the fast recombination of photogenerated carriers, low conductivity, and lack of absorption towards longer wavelengths. In this work, a simple and effective strategy is demonstrated to highly promote the photocatalytic performance of the g-C3N4 by modifying with tetrakis (4-carboxyphenyl) porphyrin (TCPP) molecules, which can be tightly adsorbed on the g-C3N4 surfaces through π–π stacking. The typical TCPP/g-C3N4 photocatalyst with 0.1% TCPP content shows a highly enhanced photocatalytic degradation rate of 0.0591 min−1 towards Rhodamine B (RhB), which is more than two times higher than the 0.0224 min−1 for the pristine g-C3N4. Detailed investigations elucidate that the highly improved photocatalytic performance is contributed by the broadened visible light absorption and improved electron–hole separation efficiency and carrier migration efficiency induced by coupling TCPP molecules. Besides, RhB molecules prefer to be adsorbed on the TCPP/g-C3N4 surfaces, which is beneficial for the oxidative degradation reaction with the active species near the surfaces. This study may pave a new avenue to prepare highly efficient photocatalysts based on g-C3N4 by coupling conjugated molecules.

Construction of Metal Organic Frameworks with Porphyrin on (110) Single Crystal Surfaces

Introduction These days, the use of photovoltaics such as solar cells have been expanding since they are clean, cost-effective, and carbon-free. The most common solar cells are crystalline silicon solar cells, but the efficiency is relatively low as about 20 %. The silicon absorbs only infrared radiation even though about half of the solar radiation is constituted by visible-light. On the other hand, porphyrin based solar cells show strong absorption in the visible region, so they have been increasing attention recently. Among them, porphyrin based dye sensitized solar cells (DSSCs) composed of semiconductors including TiO2 are investigated enthusiastically. Since DSSCs are the combination of dye which absorbs visible-light and TiO2 which absorbs ultraviolet radiation, they are thought to be effective. Porphyrin has a planar structure which is composed of four pyrrole subunits and has orientation dependent absorption. It absorbs visible-light most effectively irradiated from normal to the ring plane. Thus, it is important to fix the porphyrin ring flatly to the solid substrate surface to maximize the energy conversion efficiency. In order to control the orientation of molecules, metal organic frameworks (MOFs) which are highly crystalline porous coordination polymers can be utilized. MOFs are made from organic ligand and metal ion, and used as frameworks to introduce functional moiety such as porphyrin. MOFs can be fabricated by a layer-by-layer (LbL) fashion on solid substrate keeping the orientation and controlling the thickness and morphology without loss of bulk properties. As a linker between MOFs and substrates, self-assembled monolayers (SAMs) were employed to fix the MOFs on solid surface. The aim of this study is to construct the three-dimensional MOFs with porphyrin on single crystal Au(110) and TiO2(110) surfaces. As linker SAMs, cysteamine (CA) and isonicotinic acid (IA) SAMs were constructed on Au(110) and TiO2(110), respectively. On both the CA SAM / Au(110) and IA SAM / TiO2(110), Cu - TCPP (tetra-carboxyphenyl porphyrin) - 4,4’ bipyridine (bpy) MOF was fabricated by the LbL fashion. Each preparation process was structurally investigated by scanning tunneling microscopy (STM) and x-ray photoelectron spectroscopy (XPS). Experimental After annealing and quenching, Au(110) was immersed in 1 mM CA ethanol solution at room temperature for 1 hour to construct CA SAM on Au(110). The substrate was then successively soaked in 0.2 mM Cu(OAc)2 ethanol solution, 0.1 mM TCPP ethanol solution, and 0.2 mM bpy ethanol solution for 10 minutes, keeping the temperature of 40°C (Cu-TCPP-bpy MOF / CA SAM / Au(110)). After every immersion, the substrate was sonicated with ethanol for 10 min. In the same way, annealed TiO2(110) was soaked in saturated IA ethanol solution at 40°C for 1 day to construct IA SAM on TiO2(110). Subsequently, the substrate was immersed in 0.1 mM Cu(OAc)2 ethanol solution for 3, 5, and 10 minutes for comparison, keeping the temperature 40° (Cu2+ / IA SAM / TiO2(110)). The substrate was sonicated with ethanol for 10 min after every immersion. At each step, the structure and elemental composition were estimated by STM and XPS. Results and discussion In the case of Cu-TCPP-bpy MOF / CA SAM / Au(110), STM and XPS measurements were conducted. STM image reveals that CA SAM was homogeneously fabricated on the Au(110) surface. It was also observed by STM that Cu2+ and TCPP layers were constructed on the CA SAM with the LbL fashion, and bpy orientates vertical to the MOF sheet with porphyrin. Additionally, XP spectra in S2p and N1s indicates that the CA SAM was existed on Au(110), and those in Cu2p and N1s show that Cu2+, TCPP, and bpy were coordinated after each immersion. On the other hand, for Cu2+ / IA SAM / TiO2(110), XPS was performed. From a peak in N1s region, the modification of IA SAM on TiO2(110) was confirmed. Furthermore, the XP spectrum in Cu2p region shows the deposition of Cu2+ on IA SAM after the immersion.

Layer-By-Layer Construction of Three-Dimensional Metal Organic Frameworks with Porphyrin on the Solid Surfaces

Introduction Porphyrins have planar structure and effectively absorb visible-light normal to the ring plane. Thus, they can be applied to artificial photosynthetic devices and photovoltaic cells when the porphyrin ring is flatly adsorbed on the solid substrate [1]. On the other hand, metal-organic frameworks (MOFs), which have a high surface area, flexibility, and designability, are one of the highly promissing materials to construct the highly oriented three-dimensional structures [2]. Thus, it is expected to construct three-dimentional MOFs with porphyrin, in which porphyrin ring is highly oriented, on the solid surfaces, in order to construct artifical photosynthetic devices. We have succeeded to construct the three-dimensional MOFs on the solid surfaces by a layer-by-layer method [3,4] and also to construct self-assembled monolayers (SAMs) with porphyrin [5-10]. Thus, in this study, we tried to construct the three-dimensional MOFs with porphyrin group, in which porphyrin ring is oriented parallel to the solid surfaces, using various SAM modified solid surfaces, such as iso-nicotinic acid (IA) SAM on TiO2(110), mercapto-propionic acid (MPA) SAM on Au(111), acrylic acid (AA) SAM on Si(111), and amino-propyl tri-methoxy silane (APTMS) SAM on glass substrate. At each step to construct these MOFs with tetra-carboxyphenyl porphyrin (TCPP), Zn tetra-phenyl porphyrin (Zn-TPP), and bipyridine (Bipy) by a layer-by-layer fasion, the adsorbed amounts and orientation were evaluated by x-ray photoelectron spectroscopy (XPS), polarization-modulated infrared reflection absorption spectroscopy (PM-IRRAS), attenuated total refection infrared spectroscopy (ATR-IRS), and ultraviolet/visible absorption spectroscopy (UV-vis). Experiment IA SAM on TiO2(110), MPA SAM on Au(111), AA SAM on Si(111), and APTMS SAM on glass were prepared by dipping each substrate into DMF solution with saturated IA at 110 °C for 10 h, ethanol solution with 1 mM MBA, ethanol solution with saturated methoxy acrylate and then hydrolysis of methoxy group to carboxylate, and ethanol solution with saturated ATPMS at 40 °C for 10h, respectively. After these SAM preparations, two-dimentional TCPP MOF sheets, which is prepared on the water surface [11], was transferred onto IA SAM on TiO2(110) and glass substrate. On the MPA SAM on Au(111) and AA SAM on Si(111), the substrates were dipped instead of the ethanol solutions with Zn-TPP and Bipy. At each step, layered structures and orientation were evaluated XPS, PM-IRRAS, ATR-IRS, and UV-vis. Results and discussion As an example, it is explained that IA SAM was confirmed to construct the TiO2(110) surface. When the pre-treated TiO2(110) substrate was dipped into DMF solution with saturated IA at 110 °C for 10 h, XP peaks around 401 eV in the N1s region and 532 eV in the O1s region due to the aniline ring and calboxylate, respectively, were observed. From these XP peaks, we confirmed that the IA SAM is formed on the TiO2(110) surface. After that, two-dimensional porphyrin sheet was transferred onto this SAM modified TiO2(110) surface by a layer-by-layer fasion.

Generation of Dynamic Combinatorial Libraries Using Hydrazone-Functionalized Surface Mimetics.

Dynamic combinatorial chemistry (DCC) represents an approach, whereby traditional supramolecular scaffolds used for protein surface recognition might be exploited to achieve selective high affinity target recognition. Synthesis, in situ screening and amplification under selection pressure allows the generation of ligands, which bear different moieties capable of making multivalent non‐covalent interactions with target proteins. Generic tetracarboxyphenyl porphyrin scaffolds bearing four hydrazide moieties have been used to form dynamic combinatorial libraries (DCLs) using aniline‐catalyzed reversible hydrazone exchange reactions, in 10 % DMSO, 5 mm NH4OAc, at pH 6.75. High resolution mass spectrometry (HRMS) was used to monitor library composition and establish conditions under which equilibria were established.

One-pot synthesis of porphyrin@polypyrrole hybrid and its application as an electrochemical sensor

In this work, hybrid of polypyrrole with meso-(tetracarboxyphenyl)porphyrin (TCPP@ppy) was prepared by a simple one-pot chemical oxidative polymerization method using ammonium persulfate (APS) as the oxidizing agent. Fourier transform infrared spectroscopy (FT-IR) revealed its successful formation with the presence of N–H, CO and other characteristic peaks of polypyrrole and meso-(tetracarboxyphenyl)porphyrin (TCPP) which was also corroborated by ultraviolet–visible (UV–Vis) spectroscopy and X-ray diffraction (XRD) studies with a red shifted Soret band of TCPP and a broad peak at 2θ = 23.9° including distinctive TCPP peaks respectively. This denoted that interaction took place between various components. High-resolution transmission electron microscopy (HR-TEM) micrographs of the hybrid depicted TCPP molecules to be encapsulated by ppy matrix. Cyclic voltammetry studies illustrated high electroactivity for the hybrid and ppy. Electrochemical sensor was developed using TCPP@ppy for the detection of cadmium (II) ions (Cd2+) by differential pulse voltammetry technique, thus exhibiting its application as a metal ion sensor.

Porphyrin conjugated SiC/SiOx nanowires for X-ray-excited photodynamic therapy

The development of innovative nanosystems opens new perspectives for multidisciplinary applications at the frontier between materials science and nanomedicine. Here we present a novel hybrid nanosystem based on cytocompatible inorganic SiC/SiOx core/shell nanowires conjugated via click-chemistry procedures with an organic photosensitizer, a tetracarboxyphenyl porphyrin derivative. We show that this nanosystem is an efficient source of singlet oxygen for cell oxidative stress when irradiated with 6 MV X-Rays at low doses (0.4–2 Gy). The in-vitro clonogenic survival assay on lung adenocarcinoma cells shows that 12 days after irradiation at a dose of 2 Gy, the cell population is reduced by about 75% with respect to control cells. These results demonstrate that our approach is very efficient to enhance radiation therapy effects for cancer treatments.

Distribución del tamaño de partícula de la tetracarboxifenilporfirina de hierro (III) adsorbida sobre dióxido de silicio por dispersión dinámica de luz

La distribución del tamaño de partícula es una propiedad fundamental para caracterizar sistemas de partículas en suspensión. Las porfirinas son sensibilizadores esenciales para diversas aplicaciones fotoquímicas, sin embargo estos sensibilizadores tienden a formar agregados en solución acuosa, afectando sus propiedades fotofísicas, lo que hace necesaria su inmovilización. En este trabajo se estudió la distribución del tamaño de partícula de la tetracarboxifenilporfirina de hierro (III) adsorbida sobre dióxido de silicio por la técnica de dispersión dinámica de luz. La estabilidad del proceso de adsorción depende del valor del pH, es por esto, que se estudió a un pH de 3 y 5. Se encontró un solo tamaño<br />de partícula a pH = 3 indicando la estabilidad de la porfirina sobre la silica, mientras que a pH = 5, dos tipos de partículas fueron encontradas. Los resultados indican que la técnica de dispersión dinámica de luz es adecuada para determinar la estabilidad de estos sistemas.

Impairments of cells and genomic DNA by environmentally transformed engineered nanomaterials

Enormous increase in the production of nanomaterials and their growing applications in the device technology, biotechnology and biomedical areas suggest the need for developing models for predicting the environmental health and safety (EHS) risks posed by such nanomaterials. We hypothesize that CdSe quantum dots (QDs) and ZnO nanoparticles (NPs) encompassed in liposomes or not and transformed by simulated solar UV light can be model systems for studying the environmental toxicity of engineered nanomaterials. In this study, human lung epithelial adenocarcinoma cells (H1650) are exposed to photoirradiated CdSe QDs or ZnO nanopowder included or not in liposomes. The release of cadmium and zinc ions from the nanomaterials exposed to solar simulated UV radiation is detected and quantified by measuring the steady-state and time resolved fluorescence of the metal ion sensor tetracarboxyphenylporphyrin (TCPP) or the commercial Measure iT Pd/Cd sensor. Viability of cells treated with nanomaterials exposed to solar simulated UV radiation for different durations is measured by MTT assay. Enhanced etching of the nanoparticles exposed to solar simulated UV radiation results in the release of toxic levels of heavy metal ions, which considerably lower the viability of H1650 cells is due to the deactivation of DNA repair enzymes as evidenced by the pinching off of nuclear DNA in comet assays and DNA samples in electrophoresis. Results from this study highlight the need to obtain not only quantitative information about the environmental risks posed by engineered nanomaterials but also environment friendly nanomaterials for practical applications.

Thermal treatment of Co(II) tetracarboxyphenyl porphyrin supported on carbon as an electrocatalyst for oxygen reduction

Ultraviolet–visible and fourier transform infrared absorption spectra indicate that polytetraphenylporphyrin Co (II) (PTPPCo) can be obtained by heat-treating 5,10,15,20-tetra (4-carboxyphenyl)-porphyrin Co (II) (TCPPCo) at 400 °C in argon atmosphere. Polytetraphenylporphyrin Co/C is obtained by heat treatment (HT) of TCPPCo, which is adsorbed on Vulcan XC-72 with different Co–N 4 loading, from 400 °C to 1000 °C in argon atmosphere. Catalysts are evaluated for electroreduction performances of oxygen on modified electrodes in sulfuric acid solutions. Results from electroreduction of the catalyst (HT 600 °C and 6 wt% Co–N 4 loading) show the original reduction voltage is 0.81 V versus the reversible hydrogen electrode, and the transfer electron number is 3.83. The morphology, distribution, and surface elemental analysis of the catalysts are characterized by x-ray diffraction spectroscopy and transmission electron microscopy with energy dispersive x-ray. PTPPCo can homogeneously anchor on the carbon support and withstand decomposition upon heat treatment at 600 °C. Since TCPPCo results in polymerization on XC-72, pi (π) bond increases significantly with the decrease in π-electron delocalization energy. Improved capacity in electron gain or loss is observed, and the center of electrocatalysis is clearly exposed. Thus, the activity, stability, and selectivity of the catalyst presented in this paper are proven better than those of other common catalysts.

Structural and Photophysical Properties of Self-Assembled Porphyrin Nanoassemblies Organized by Ethylene Glycol Derivatives

We demonstrate an ability to control the structures and photodynamics of porphyrin-based nanoassemblies via solvent mixture technique. Surfactants such as ethylene glycol (EG) derivatives with different chain lengths are employed to control the sizes and shapes of nanoparticles composed of meso-substituted tetracarboxyphenyl porphyrin [H2P(CO2H)4] in mixed H2O/THF solvent. With increasing the chain lengths, the diameters of H2P(CO2H)4/EG composite nanoparticles systematically increase in the range of 90−350 nm. In contrast with H2P(CO2H)4/EG composite nanoparticles, pristine H2P(CO2H)4 assemblies show long rod-shaped assemblies with micrometer scales. The porphyrin nanoparticles are stable in solution without precipitation for several days. The nanoparticles exhibit the following optical properties: a large bathochromic shift in the absorption spectra and an increase of the fluorescence quenching properties relative to those for the monomer porphyrin solution. The hierarchical clustering of H2P(CO2H)4 molecules within nanoparticles is caused by the hydrogen bonding and π-stacking effects. The efficient fluorescence quenching of H2P(CO2H)4 is mainly due to the effect of singlet−singlet annihilation of H2P(CO2H)4 moieties within nanoassemblies. We further report the quenching processes of the excited triplet states of H2P(CO2H)4 nanoassemblies. Efficient quenching properties of the excited triplet states of H2P(CO2H)4 moieties are observed in the range of lifetime 26−100 ns, which is largely dependent on the sizes of nanoparticles. These quenching processes can be also analyzed by triplet−triplet annihilation theory.

Pyrrole functionalised metalloporphyrins as electrocatalysts for the oxidation of nitric oxide

Pyrrole-functionalised tetracarboxyphenyl porphyrin and trimethoxyphenylcarboxy-phenyl porphyrin containing Ni, Mn and Pd as the central metal ion were used to modify Pt-disk microelectrodes (∅ 50 μm) (by repetitive cyclic voltammetry, dip-dry and pulse-amperometry methods) for the detection of nitric oxide (NO). Electrodes modified with Mn(II) trimethoxyphenylcarboxyphenyl porphyrin using the pulse amperomery approach, were found to be sensitive, stable and fast in response towards the oxidation of NO. Thus, they were used for the detection of NO release from a population of transformed human umbilical vein endothelial cells (T-HUVEC) into a droplet of electrolyte solution following stimulation with vascular endothelial growth factor (VEGF). The electrode surface was covered with an additional layer of Nafion® to prevent interference from anionic molecules such as nitrite.

Monoclonal Antibodies as Tailor-Made Hosts for Porphyrins

Abstract Monoclonal antibodies against tetracarboxyphenylporphyrin(TCPP) were prepared by immunizing Balb/c mice with TCPP bound keyhole limpet hemocyanin covalently and fusing the spleen cells with myeloma cells by using poly(ethylene glycol). The antibodies bind TCPP strongly with the dissociation constants of 10−6 − 2.5 × 10−7 M.