Porphyrin Concentration Research Articles

Extraction and Metalation of Porphyrins in Fluorous Liquids with Carboxylic Acids and Metal Salts

Porphyrins have found application in a remarkable variety of areas such as sensors, ion selective electrodes, photodynamic therapy, and energy-transfer systems. Here, we demonstrate the extraction of 5,10,15,20-tetraphenylporphyrin (TPhP) and 5,10,15,20-tetra(4-pyridyl)porphyrin (TPyP) into a mixture of perfluorohexanes (FC-72) through noncovalent interactions with Krytox (1), a carboxylic acid terminated perfluoropolyether. We found that 1 transfers two protons to the TPhP tetrapyrrole ring to create the porphyrin dication (H2TPhP2+) in FC-72 while up to six protons are transferred to the TPyP pyridyl and tetrapyrrole nitrogens to create a hexavalent cation macrocycle in the fluorous phase. The total charge on TPyP is controlled by adjusting the concentration of 1 in the fluorous phase. In addition, we observed extraction of ZnTPyP from CDCl3 with 1/FC-72, while ZnTPhP is not extracted by 1/FC-72. We prepared the Zn salt of 1 and found that it extracts (from CDCl3) and metalates TPyP but not TPhP. Competitive binding between the porphyrins and an ethanol cosolvent hinders the extraction of both TPhP and TPyP and inhibits the formation of the TPyP hexacation in FC-72. By controlling the concentration of porphyrin, 1, and ethanol, it is possible to reversibly solubilize TPyP in the fluorous phase through noncovalent interactions between the pyridyl moieties and 1 while leaving the tetrapyrrole ring available to interact with metals or other substrates. In addition, both porphyrins and ZnTPyP are easily recovered from the fluorous phase using commercially available fluorous solid-phase extraction cartridges. Understanding noncovalent interactions in fluorous matrices should lead to development of more robust devices for sensing and energy transfer.

Urinary porphyrin excretion in normal children and adolescents

Background Urinary porphyrins are diagnostic of various metabolic disorders and xenobiotic exposures, but comprehensive normative data for urinary porphyrin concentrations in children are currently unavailable. Methods Subjects were participants in a prospective, randomized, controlled clinical trial of dental materials safety, 8 to 12 y at inception, who were followed longitudinally for 7 y after baseline with an extensive battery of neurobehavioral, neurological, renal function and urinary porphyrin assessments. Porphyrins were quantified by HPLC. Linear regression analyses were used to measure associations of porphyrin levels with age and gender. Results Mean concentrations, 95% confidence intervals, and 10th, 50th, and 90th percentiles for all 5 typically excreted urinary porphyrins are presented by year of age and by gender. Unadjusted urinary concentrations (µg/l) of all 5 porphyrins remained relatively constant throughout the age range of 8–18 y for both males and females. In contrast, creatinine-adjusted urinary porphyrin concentrations (µg/g) declined significantly throughout this age range in both genders. Boys had significantly higher pentacarboxyl- and copro-porphyrin levels compared with girls both before and after creatinine adjustment. Conclusions Normative longitudinal data provided herein may facilitate the clinical assessment of pediatric metabolic disorders and may be of particular relevance in evaluating porphyrin changes as a biological indicator of disease or xenobiotic exposures among children and adolescents.

Role of Solvent Trapping Effects in Determining the Structure and Morphology of Ternary Blend Organic Devices

We present results of scanning transmission X-ray microscopy (STXM) measurements of bulk heterojunction organic solar cells built from a ternary blend of poly(3-hexylthiophene) (P3HT), [6,6]-phenyl-C61-butyric acid methyl ester (PCBM), and [2,3,12,13-tetracyano-5,10,15,20-tetrakis(3,5-di-tert-butylphenyl)porphyrinato]copper(II) (Cu(CN)4P) porphyrin. These results show evidence of solvent trapping due to porphyrin in the film. Upon annealing, submicrometer depressions are observed in the ternary blend films, corresponding to the evolution of solvent that is associated with the small porphyrin aggregates that phase segregate in the middle of the depressions. The areal density and size of the depressions change systematically with porphyrin concentration in the ternary blend. The relationship of the observed morphologies to the previously measured device performance is discussed.

Nonlinear optical absorption properties of porphyrins confined in Nafion membrane

The nonlinear absorption (NLA) properties of five different types of porphyrins were studied using the Z-scan technique. The porphyrins under investigation were confined into Nafion column matrix membrane in order to protect them from possible degradation. The results of the experiments have indicated that all the porphyrins tested exhibited interesting NLA properties. The nonlinear absorption coefficients (β’s) were determined at different porphyrin concentrations by comparing the Z-scan data with the theoretical functions.

Acute Intermittent Porphyria as a Cause of Respiratory Failure: Case Report

A 45-year-old man with end-stage renal disease due to polycystic kidney disease was admitted to the hospital because of recurrent abdominal pain, progressive peripheral motor neuron neuropathy, and respiratory failure. The diagnosis of acute intermittent porphyria was confirmed by an elevated porphyrin concentration in the urine and the presence of an R167Q mutation in the porphobilinogen deaminase gene. Use of hydroxyzine, weight loss, and/or a mild upper respiratory viral infection might have been the provoking factor of the acute intermittent porphyria. Treatment with intravenous hemin (3 mg/kg) and a high-carbohydrate diet (3000 kcal/d) had no clinical effect. Tetraplegia and chronic respiratory insufficiency developed, and the patient needed a pacemaker because of a symptomatic sinus bradycardia due to autonomic dysfunction. The patient died 10 months after the first manifestation of acute intermittent porphyria.

Communication via Electron and Energy Transfer between Zinc Oxide Nanoparticles and Organic Adsorbates

Stable ZnO nanoparticles suitable for further surface functionalization were synthesized in the liquid phase from homogeneous ethanolic solutions of the precursors lithium hydroxide and zinc acetate. It was found that the growth of the particles was governed by temperature as well as the presence of the reaction byproduct lithium acetate during the aging process. In particular, the reaction could be almost completely arrested by removal of this byproduct. The “washing” consisted of repeated precipitation of the ZnO particles by addition of alkanes such as heptane, removal of the supernatant, and redispersion in ethanol. Furthermore, the surface of the colloidal ZnO nanoparticles was successfully modified by catechol-anchoring group containing dye molecules, i.e., 5-(N-(3,4-dihydroxyphenethyl)-2-phenoxyacetamide)-10,15,20-(p-tert-butyltriphenyl)porphyrinatozinc (DOPAZ) and 5-(3,4-dihydroxy-N-phenylbenzamide)-10,15,20-tris(4-tert-butylphenyl)porphyrinatozinc (CAMIZ), for the study of photochemical properties. Thermogravimetric analysis proved the stability of the catechol anchor groups. Steady-state absorption spectroscopy as well as steady-state and time-resolved emission studies confirmed the electronic communication between the ZnO nanoparticles in their excited state and both of the porphyrins. More than 96% emission quenching of ZnO can be achieved by addition of the porphyrins, proving that the visible emission of the ZnO is caused by surface states, since only the surface of the particles was altered by the grafting experiments. Moreover, with increasing porphyrin concentrations the lifetimes changed from 46.0 to 15.3 ns. The shortened lifetimes prompt a new deactivation pathway, namely, through the electronic coupling of the porphyrins to the ZnO nanoparticle. Assuming that the decrease in lifetime is entirely due to electron transfer to the porphyrins, a rate constant of 0.35 × 108 s−1 could be determined for this process. When testing the excited state of the porphyrin in comparative assays between ZnO and Al2O3, we conclude a similar electron transfer deactivation.

CO sensor based on polypyrrole functionalized with iron porphyrin

Polypyrrole (PPy) was chemically functionalized with 5,10,15,20-tetraphenyl-21H,23H-porphyrin iron(III) chloride (FeTPPCl) with special interest on noxious carbon monoxide (CO) gas in ppm level. Controlled functionalization of PPy was achieved with incorporation of various concentrations of porphyrin. The resulted semiconducting material was well characterized by different techniques such as UV–vis spectroscopy, FTIR, GFAAS, XRD, and EDAX. The functionalized polypyrrole material on interdigitated electrode was experienced an immediate increase in resistance when exposed to carbon monoxide gas at very low concentration. The CO gas interacted very fast with the FeTPPCl functionalized PPy at room temperature (RT) and then slowly saturated. The response of these materials was not unidirectional, but reverses to the original resistance level when CO was removed from the test chamber. The highest response factor (Δ R/ R 0 × 100) and lowest response time ( t 50) obtained are 12 and 169 s, respectively. An optimum level of doping (1 mol% of FeTPPCl) was established for the highest sensitivity and the detection level is as low as 100 ppm.

Quantitative determination of Zn protoporphyrin IX, heme and protoporphyrin IX in Parma ham by HPLC

We measured the contents of Zn protoporphyrin IX (ZPP), heme and protoporphyrin IX (PPIX) in Parma ham by simultaneous analysis using high-performance liquid chromatography (HPLC). Extraction with ethyl acetate–acetic acid (4:1) was suitable for the quantitative analysis of ZPP. The contents of heme, ZPP and PPIX in Parma ham were 15.0–29.9, 27.7–47.0 and 0.4–1.1 μg/g, respectively, and total content of porphyrin was 43.7–76.6 μg/g. The amount of ZPP in Parma ham was larger than that of heme, and ZPP accounted for 60–70% of all porphyrins.

A Method for Determining the Nitrogen Isotopic Composition of Porphyrins

We describe a new method for analysis of the nitrogen isotopic composition of sedimentary porphyrins. This method involves separation and purification of geoporphyrins from sediment samples using liquid chromatography and HPLC, oxidation of the nitrogen within porphyrin-enriched fractions using a two-step process, and isotopic analysis of the resulting nitrate using the denitrifier method. By analysis of these degradation products of chlorophylls, we are able to measure an isotopic signature that reflects the nitrogen utilized by primary producers. The high sensitivity of the denitrifier method allows measurement of small samples that contain low concentrations of porphyrins. Extraction of only 50 nmol of nitrogen (nmol N) allows the following five analyses to be made (each on approximately 10 nmol N): nitrogen concentration, an assessment of potential contamination by nonporphyrin N, and three replicate isotopic measurements. The measured values of delta15N have an average analytical precision of +/-0.5 per thousand (1sigma) and an average contribution from Rayleigh fractionation of 0.7 per thousand from incomplete oxidation of porphyrin N to nitrate. The overall method will enable high-resolution records of delta15N values to be obtained for geological and ecological applications.

Photocurrent and photoelectrochemical hydrogen production with tin porphyrin and platinum nanowires immobilized with nafion on glassy carbon electrode

Platinum nanowires mixed with Tin meso-tetra (4-pyridyl) porphine dichloride and nafion solution was used to modify the surface of glassy carbon electrode for photocurrent generation and photo-electrochemical hydrogen production. Different concentrations of porphyrin (50 μM, 100 μM, 300 μM and 500 μM) and platinum loading (200 μg/cm 2, 400 μg/cm 2, 600 μg/cm 2 and 800 μg/cm 2) were tested at −150 mV Vs Ag/AgCl in reaction cell containing the modified glassy carbon electrode as working electrode, platinum wire as counter electrode and Ag/AgCl as reference electrode, under illumination to determine the optimum, based on photocurrent production in 50 mM potassium hydrogen phthalate buffer (pH 3) containing 0.1Na 2SO 4 as supporting electrolyte. Optimum photocurrent was obtained at 100 μM tin porphyrin and 600 μg/cm 2 platinum loading. Detectable amount of hydrogen was produced at −350 mV Vs Ag/AgCl under irradiation with visible light.

Interactions of peripheral-type benzodiazepine receptor with diamino acid derivatives of protoporphyrin IX

The aim of this study was to examine and determine binding affinities of the peripheral benzodiazepine receptor (PBR) with diamino acid derivatives of protoporphyrin IX with general structure PP(AA) 2 in a function of environmental pH changes. Fluorescence intensity was used as a measure of protein association constant. Decrease in protein fluorescence, after titration with increasing concentration of porphyrins, gave evidence of interactions between PBR and examined ligands. Experimental data were fitted to theoretical curves, assuming different models of interactions. All examined ligands were best fitted to weak binding model. Increase in environmental acidity resulted in changes in association constants. For all examined derivatives association constants were at least twice higher in pH 5.5 as compared to pH 7.4 and 6.5.

Hormonal regulation and characterisation of the aldehyde oxidase-like gene of hamster Harderian gland

The HG is a compound tubulo-alveolar gland located in the orbital cavity of the majority of vertebrates. In the golden hamster it shows a clear cut sexual dimorphism in both morphological and biochemical parameters such as cell types, protein pattern, lipid metabolism, porphyrin content, steroid hormone receptor expression. In a previous study we found that in primary culture of male hamster Harderian gland (HG), androgens (A) increase the MHG07 (male Harderian gland) expression and this effect is abrogated by both flutamide and cycloheximide. The present study represents a deeper analysis on MHG07 regulation by other members of steroid/thyroid hormone superfamily. Estrogens (E) impair the stimulatory effect of A and after the addition of a pure anti-estrogen, ICI 164,384, the negative effect of E is abrogated. Dexamethasone (Dex), used alone or in combination with A negatively affect the MHG07 expression. Also T 3 increases the expression of MHG07 mRNA. Progesterone (P) does not affect the expression of MHG07 mRNA. The use of cycloheximide abrogates the effect of steroids, suggesting that the latter act through their own receptors. Dose–response experiments show that low steroid concentrations (10 −12 M) are sufficient to affect the MHG07 expression. It is argued that the expression of MHG07 is under a highly coordinate relationship between androgen, estrogen, glucocorticoid, retinoic acid and thyroid hormones.

Interaction of cationic water-soluble meso-tetrakis(4-N-methylpyridiniumyl)porphyrin (TMPyP) with ionic and nonionic micelles: aggregation and binding

The equilibrium of meso-tetrakis(4-N-methylpyridiniumyl)porphyrin (TMPyP) in aqueous solution in the presence of surfactants was studied by optical spectroscopic techniques and SAXS (small angle X-ray scattering). Anionic SDS (sodium dodecyl sulfate), zwitterionic HPS (N-hexadecyl-N,N-dimethyl-3-ammonio-1-propanesulfonate) and nonionic TRITON X-100 (t-octylphenoxypolyethoxyethanol), surfactants were used. TMPyP is characterized by a protonation equilibrium with a pKa around 1.0, associated with the diacid-free base transition, and a second pKa around 12.0 related with the transition between the free base and the monoanion form. Three independent species were observed for TMPyP at pH 6.0 as a function of SDS concentration: free TMPyP, TMPyP-SDS aggregates and porphyrin monomer bound to micelles. For HPS and TRITON X-100, the equilibrium of TMPyP as a function of pH is quite similar to that obtained in pure aqueous solution: no aggregation was observed, suggesting that electrostatic contribution is the major factor in the interaction between TMPyP and surfactants. SAXS data analysis demonstrated a prolate ellipsoidal shape for SDS micelles; no significant changes in shape and size were observed for SDS-TMPyP co-micelles. Moreover, the ionization coefficient, α, decreases with the increase of the porphyrin concentration, suggesting the "screening" of the anionic charge of SDS by the cationic porphyrin. These results are consistent with optical absorption, fluorescence and RLS (resonance light scattering) spectroscopies data, allowing to conclude that neutral surfactants present a smaller interaction with the cationic porphyrin as compared with an ionic surfactant. Therefore, the interaction of TMPyP with the ionic and nonionic surfactants is predominantly due to the electrostatic contribution.

Binding and Glutathione Conjugation of Porphyrinogens by Plant Glutathione Transferases

Overexpression in Escherichia coli of a tau (U) class glutathione transferase (GST) from maize (Zea mays L.), termed ZmGSTU1, caused a reduction in heme levels and an accumulation of porphyrin precursors. This disruption was highly specific, with the expression of the closely related ZmGSTU2 or other maize GSTs having little effect. Expression in E. coli of a series of chimeric ZmGSTU1/ZmGSTU2 proteins identified domains responsible for disrupting porphyrin metabolism. In addition to known heme precursors, expression of ZmGSTU1 led to the accumulation of a novel glutathione conjugate of harderoporphyrin(ogen) (2,7,12,18-tetramethyl-3-vinylporphyrin-8,13,17-tripropionic acid). Using the related protoporphyrinogen as a substrate, conjugation could be shown to occur on one vinyl group and was actively catalyzed by the ZmGSTU. In plant transgenesis studies, the ZmGSTUs did not perturb porphyrin metabolism when expressed in the cytosol of Arabidopsis or tobacco. However, expression of a ZmGSTU1-ZmGSTU2 chimera in the chloroplasts of tobacco resulted in the accumulation of the harderoporphyrin(ogen)-glutathione conjugate observed in the expression studies in bacteria. Our results show that the well known ability of GSTs to act as ligand binding (ligandin) proteins of porphyrins in vitro results in highly specific interactions with porphyrinogen intermediates, which can be demonstrated in both plants and bacteria in vivo.

Effects of Counterion Mobility, Surface Morphology, and Charge Screening on the Electron-Transfer Rates of Porphyrin Monolayers

The standard electron-transfer rate constants (k0) for the oxidation of porphyrin monolayers are reported for a number of solvent/electrolyte systems and electroactive surfaces. The goal is to explain the inverse correlation between the electron-transfer rates and the porphyrin surface concentration (Roth et al., J. Phys. Chem. B 2002, 106, 8639−8648). Each porphyrin is a zinc chelate and contains three meso-mesityl groups and a benzyl alcohol or benzyl thiol for surface attachment. The solvent/electrolyte systems include (i) the organic solvent propylene carbonate containing electrolytes with a common cation and anions of different size/mobility (PF6-, ClO4-, and Cl-) and (ii) neat ionic liquids with a common cation and anions of different size/mobility [(CF3SO2)2N- and (NC)2N-]. The substrates include Si(100), Au(111), and TiN. The k0 values observed using electrolytes with PF6-, ClO4-, and (CF3SO2)2N- counterions are similar to one another, whereas those observed using electrolytes Cl- and (NC)2N- counterions are 2−5 times faster. The faster rates for the latter anions are attributed to their smaller size/higher mobility. The k0 values observed for monolayers on Si(100) and Au(111) are similar to one another; the k0 values for monolayers on TiN are ∼5-fold faster. The faster rates for the TiN substrate are attributed to a rougher surface morphology (as determined via atomic force microscopy measurements) which results in an actual surface concentration that is lower than the concentration based on the geometrical area of a planar substrate. The k0 values determined for mixed monolayers where the electroactive porphyrin is co-deposited with an electroinactive porphyrin are dependent only on the concentration of the redox-active species, not on the total porphyrin concentration. This behavior is consistent with space-charge effects being the principal determinant of the inverse correlation between the electron-transfer rates and the porphyrin surface concentration. The space charge effects can be mitigated, but not eliminated, by using smaller, more mobile counterions and rougher surfaces.

Side-chain-controlled H- and J-aggregation of amphiphilic porphyrins in CTAB micelles

The aggregation behavior of a series of amphiphilic 4-hydroxyphenyl porphyrins with one ( P1), two ( P2) and three ( P3) hexadecyl side chains in cetyltrimethylammonium bromide (CTAB) micelles has been studied by means of UV–vis and fluorescence spectra. It was found that the number of hexadecyl side chains not only controls the H- and J-aggregation of the porphyrins in CTAB micelles, but also influences the aggregation concentration and tendency. With increasing porphyrin concentration, P1 and P2 form H-aggregates in CTAB micelles, while P3 forms J-aggregates. Porphyrins with more hexadecyl side chains tend to form aggregates more easily and at lower concentrations in CTAB micellar solutions.

SERRS of free-base porphyrins on immobilized metal gold and silver nanoparticles

SERRS of three differently charged free-base porphyrins, namely cationic 5,10,15,20-tetrakis(1-methyl-4-pyridyl) porphyrin (TMPyP), anionic 5,10,15,20-tetrakis(4-sulfonatophenyl) porphyrin (TSPP), and neutral 5,10,15,20-tetrakis(tetraphenylporphyrin) (TPP), was measured on SERS-active substrates prepared by immobilization of Ag or Au nanoparticles to silanized glass plates. Au surfaces were suitable for TMPyP and TSPP detection while Ag surfaces for TMPyP and TPP. SERRS spectra exhibited excellent reproducibility, very good stability in time (relative standard deviation lower than 10%) and did not contain any sign of the porphyrin metalation or perturbation of its native structure. Even SERRS spectra of water-insoluble porphyrin (TPP) were obtained without any interference of solvent Raman signal. Estimated limits of detection (LOD) were between 3 × 10 −9 and 8 × 10 −8 M porphyrin concentrations in soaking solution. SERRS on immobilized Ag and Au nanoparticles was found a suitable analytical method for detection of free-base (including water-insoluble) porphyrins, advantagenous considerably with respect to routinely used metal sols.

Effect of exciton rotational relaxation on luminescence decay of low-doped porphyrin side-chain polymers

Effect of rotational motion of porphyrin molecules on the luminescence dynamic of low-doped porphyrin side-chain polymers has been studied by using the theory of exciton rotational diffusion. It is shown that the rotational motion of porphyrin molecules is an important way that induces the nonradiative relaxation of excitons. The more easily porphyrins rotate， the more rapidly energy decays， therefore， the faster the luminescence decay process. In the case of low doping concentration of porphyrins and long interchain distance， the rotational motion of porphyrin molecules is the main reason of fast luminescence decay and low luminescence efficiency. The transient luminescence relaxation processes of two kinds of polymers were fitted with the theoretical expression， the theoretical analysis are in good agreement with the experimental results.

Oxidative Stress in Porphyria and Carriers

We sought to establish a causal relationship between oxidative stress and porphyria in patients and carriers. We reported changes in urinary porphyrin concentrations related to 8-hydroxy-2'-deoxyguanosine. We measured urinary 8-hydroxy-2'-deoxyguanosine concentration in porphyria patients and carriers with multifactorial inheritance as a possible marker of attack. The porphyria types included 10 patients with porphyria cutanea tarda, 5 with variegate porphyria, 8 with hereditary coproporphyria, 7 with congenital erythropoietic porphyria, 5 with erythropoietic protoporphyria, 5 with acute intermittent porphyria, 7 erythropoietic protoporphyria carriers, and 7 acute intermittent porphyria carriers. Urinary porphyrin concentrations in these patients were significantly higher than those in healthy subjects (p<0.001). Urinary 8-hydroxy-2'-deoxyguanosine concentrations were significantly high in dermatopathy porphyria types namely porphyria cutanea tarda (p<0.001), variegate porphyria (p<0.05), hereditary coproporphyria (p<0.05), congenital erythropoietic phyria (p<0.05), and erythropoietic protoporphyria (p<0.001). These results reveal that urinary 8-hydroxy-2'-deoxyguanosine concentration in cutis porphyria types is a good predictor of attack and abatement.

Two-photon absorption cross-sections and time-resolved fluorescence imaging using porphyrin photosensitisers

Three porphyrin systems have been characterised for use in two-photon fluorescence imaging of biological samples. We have determined the two-photon absorption cross sections (sigma(2)) of the di-cation, free-base and metallated forms of hematoporphyrin derivative (HpD), hematoporphyrin IX (Hp9) and a boronated protoporphyrin (BOPP) using the open-aperture Z-scan and the two-photon induced fluorescence (TPIF) techniques at an excitation wavelength of 800 nm. The insertion of either protons or a metal ion into the macrocycle is shown not to significantly influence the sigma(2) of the porphyrins. Two-photon time-resolved fluorescence images of C6 glioma cells transfected with a free-base form of the BOPP have been obtained as a function of the porphyrin concentration. These studies reveal a maximum useful porphyrin concentration for fluorescence imaging purposes of approximately 30 microg mL(-1).