共查询到20条相似文献,搜索用时 15 毫秒
1.
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. 相似文献
2.
Oni J Pailleret A Isik S Diab N Radtke I Blöchl A Jackson M Bedioui F Schuhmann W 《Analytical and bioanalytical chemistry》2004,378(6):1594-1600
In a preliminary study aimed at developing strategies for the simultaneous detection of various biologically important molecules, a procedure is described that allows the electrochemical detection of nitric oxide (NO) released by a population of human umbilical vein endothelial cells (HUVEC) by using an array of electrodes comprising three individually addressable electrodes. Each electrode in the array was modified with a different NO-sensitive electrocatalyst, thereby demonstrating the possibility of modifying the individual electrodes in an array with different sensing chemistries. This study opens a doorway to the development of arrays of electrodes for the simultaneous detection of multiple analytes in a complex environment by suitably tailoring the sensitivity and selectivity of each electrode in the array to a specific analyte in the test medium. 相似文献
3.
Darren Griffith Alberta Bergamo Sara Pin Marta Vadori Helge Müller-Bunz Gianni Sava Celine J. Marmion 《Polyhedron》2007
Herein, we describe the synthesis and characterisation of a novel class of PtII and PtIV pyridinehydroxamic acid (pyhaH) complexes of general formula cis-[PtIICl2(x-pyhaH)2] and cis-[PtIVCl4(x-pyhaH)2], respectively (where x = 3 or 4) in which the pyridinehydroxamic acid is coordinated to the platinum ion via the pyridine nitrogen only leaving the hydroxamic acid free to potentially release cytotoxic nitric oxide (NO). The crystal structure of the PtIV derivative, cis-[PtCl4(4-pyhaH)2] · 2CH3OH is reported. To establish the biological effect of the uncoordinated hydroxamic acid moiety in the PtII compounds synthesised, the corresponding pyridinecarboxylic acid (pycaH) complexes of general formula cis-[PtIICl2(x-pycaH)2] (where x = 3 or 4) and the PtII pyridine (py) complex, cis-[PtIICl2(py)2] were synthesised and served as reference standards. The NO-releasing properties of each of the PtII compounds, the pyhaH and the pycaH ligands were studied. The PtII pyridinehydroxamic acid derivatives were found to induce potent in vitro effects attributable to either NO-release from the hydroxamic acid moiety and/or stimulation of inducible nitric oxide synthase of endothelial cells. 相似文献
4.
Electrochemical sensors based on chemical surface modification are very attractive because they combine high sensitivity of amperometry with new dimensions of selectivity and stability provided by the surface modifier. This review shows a few strategies employed to facilitate the detection, determination and monitoring of nitric oxide using polymer modified electrodes. Conducting and nonconducting polymer films and composite films are considered. The most significant achievements reached in this field, during the last decade, are critically reviewed. The collected data are also presented in three tables. 相似文献
5.
Fei Ma Gang L Wei Fen Zhou Qiu Juan Wang Yi Hua Zhang Qi Zheng Yao~* School of Pharmacy China Pharmaceutical University Nanjing China 《中国化学快报》2009,20(4):420-422
A series of novel 2,4-diamino-pteridines(9a-1)were synthesized and evaluated as inhibitors of inducible nitric oxide synthase (iNOS)in vitro.It was found that 9a,9d,9e,9h,9i and 91 showed potent inhibitory activities similar to that of methotrexate(MTX),while the activities of 9b,9c,9f,9g,9j and 9k ale stronger than MTX. 相似文献
6.
Nidhi Jain 《Tetrahedron letters》2005,46(15):2599-2602
Water soluble iron(III) porphyrins and phosphotungstic acid in an ionic liquid are effective catalysts for the H2O2 mediated oxidation of the CNOH bond in N-hydroxyarginine and other oximes. The carbonyl compounds generated as the oxidation products can be easily isolated from the reaction media. These systems serve as biomimetic models of nitric oxide synthase (NOS) and the catalyst immobilized in an ionic liquid can be easily recycled and reused. 相似文献
7.
Three different methods for the determination of nitric oxide (NO) in solution are described. These are based, respectively, on the use of a horseradish peroxidase (HRP) biosensor or on electrodes modified with films of redox-active transition metal complexes. In the case of the biosensor the enzyme was electrochemically immobilized onto a glassy carbon (GC) electrode. The activity of HRP is inhibited in presence of NO. Thus, the decrease in activity is correlated to the concentration of NO present in solution. The biosensor responds linearly over the range of 2.7×10−6-1.1×10−5 M NO with a detection limit (5% inhibition) of 2.0×10−6 M. In the case of chemically modified electrodes, particular emphasis is placed on materials capable of catalyzing the oxidation of NO. In terms of electrocatalyst, the discussion will centre on electrodeposited films of 6,17-diferrocenyldibenzo[b,i]5,9,14,18-tetraaza[14]annulen]-nickel(II) and indium(III) hexacyanoferrate(III). The resulting sensors exhibited potent and persistent electroacatalytic activity towards the oxidation of NO with low detection limits (1 μM) and good linear relationship between the catalytic current and NO concentrations. In addition, interference due to the presence of nitrate and nitrite have been significantly reduced. According to these results, the described modified electrodes have been used as sensors for the determination of NO generated by decomposition of a typical NO-donor, such as S-nitroso-N-acetyl-d,l-penicillamine (SNAP). A critical comparison of the various methodologies employed is made. 相似文献
8.
A mild and efficient synthesis of substituted thiophene-2-carboxamidines which are potent inhibitors of nitric oxide synthase (NOS) is reported herein. The key step involves reaction of a BOC-protected imidazolyl thiophene-2-carboxamidine reactive intermediate with various primary amines to form BOC-thiophene-2-carboxamidines which could be readily deprotected using TFA to furnish free carboxamidines. The method is very mild and tolerates diverse substituents including sensitive peptide and amino acid fragments. This new methodology represents a substantial improvement to the literature method owing to its simplicity and hassle-free purification procedures. 相似文献
9.
Renata Galvão de Lima Marilia Gama Sauaia Camila Ferezin Iuri Muniz Pepe Nádia Mamede José Lusiane M. Bendhack Zênis Novais da Rocha Roberto Santana da Silva 《Polyhedron》2007
The entrapped [Ru(terpy)(L)NO](PF6)3, where terpy = 2,2′:6′,2″-terpyridine and L = 2,2′-bipyridine (bpy) and 3,4-diiminebenzoic acid (NH · NHq) complexes into sol–gel processed polysiloxane and silicone matrices, shows NO release characteristics when submitted to light irradiation at 355 and 532 nm, as judged by NO measurement using a NO-sensor electrode. The pharmacological properties of doped matrix showed vasodilator characteristics by visible light irradiation, which is of great interest because the target delivery system can avoid the occurrence of side effects possibly by the aquo ruthenium species. All matrices obtained showed to be amorphous materials. The scanning electron micrographs of the matrices showed irregularly shaped particles, with a broad size of 1000 μm for both matrices and homogeneous distribution. 相似文献
10.
Hemoglobin (Hb) and myoglobin (Mb) were immobilized at the didodecyldimethylammonium bromide (DDAB)-modified powder microelectrode (PME) to fabricate Hb-DDAB-PME and Mb-DDAB-PME. Direct electrochemistry of Hb and Mb were achieved on the DDAB-modified PME. The formal potential was −0.224 V for Hb and −0.212 V for Mb (vs. SCE). The apparent surface concentration of Hb and Mb at the electrode surface was 2.83 × 10−8 and 9.94 × 10−8 mol cm−2. The Hb-DDAB-PME and Mb-DDAB-PME were successfully applied for measurement of NO in vitro. The anodic current peaks for NO oxidation at +0.7 V and the cathodic current peaks for NO reduction at −0.85 V on the CV curves were obtained on the modified electrodes. For detection of NO at +0.7 V, the sensitivity is 3.31 mA μM−1 cm−2 for Hb-DDAB-PME and 0.6 mA μM−1 cm−2 for Mb-DDAB-PME. The detection limit is 5 nM for Hb-DDAB-PME and 9 nM for Mb-DDAB-PME. The linear response range is 9-100 and 28-330 nM for Hb- and Mb-modified PME, respectively. For the electrochemical detection of NO at −0.85 V by using Hb-DDAB-PME, the detection sensitivity is 39.56 μA μM−1 cm−2; the detection limit is as low as 0.2 μM; and the linear response range is 1.90-28.08 μM. 相似文献
11.
Groppe M Thanos S Schuhmann W Heiduschka P 《Analytical and bioanalytical chemistry》2003,376(6):797-807
Nitric oxide (NO) plays multiple roles in the nervous system. It is produced as a result of damage or injury of the retina as a part of the central nervous system. Detailed knowledge of the extent and the time course of NO production is of great importance for the understanding of pathological processes and their appropriate medical treatment.Sections of rat retina were stained with antibodies against the three isoforms of NO synthase (NOS) at several time points after a lesion of the optic nerve. No significant changes of NOS expression could be seen at any of the checked time points.For the electrochemical detection of NO production, we modified small platinum electrodes with a NO-sensitive nickel porphyrin by electrochemical polymerisation. Compared to other substances, electrochemically polymerised eugenol was found to be most suitable for protection against interferences. For the measurements, differential pulse amperometry was used. The response to nitric oxide was linear.NO production of adult rat retinas was measured post axotomy after different time points with electrochemical electrodes ex vivo. With non-treated retinas, an NO concentration of approximately 15 M was measured. NO concentration is elevated after an axotomy reaching its highest value of up to 30 M 5 days after the lesion. The NO concentration is decreased below the initial value after 9–14 days post axotomy. 相似文献
12.
Zhong-Quan Liu 《Tetrahedron letters》2005,46(6):1023-1025
Reaction of N-tosyl aziridines with nitric oxide affords the corresponding ring-opened products in regio-, stereoselectivities and excellent yields. 相似文献
13.
The electrocatalytic oxidation of metformin was studied on a nickel oxide nanotubes-carbon microparticles/Nafion nanocomposite, using cyclic voltammetry and chronoamperometry. In the presence of metformin, the anodic peak current of the Ni(II)/Ni(III) transition increased, followed by a decrease in the corresponding cathodic currents. Based on the results, the drug was oxidized on nickel oxide nanotubes via an electrocatalytic mechanism. The catalytic rate constant, the electron transfer coefficient and the diffusion coefficient involved in the electrocatalytic oxidation of the drug were reported. A sensitive and efficient amperometric method was presented for the analysis of the drug, and the corresponding analytical parameters were reported. For metformin, a detection limit of 0.45 μmol L−1 was obtained. The proposed amperometric method was also applied to the analysis of commercial tablets and the results were in good agreement with the declared values. Also, the applicability of the method to the direct assays of the drug in human serum and urine and breast milk was described. 相似文献
14.
Nitric oxide (NO) is one of the simplest odd electron species. Furthermore, it is relatively hydrophobic, which is consistent with its role as a diffusible intracellular messenger or as an immune effector. NO is generated in biological systems and plays important roles as a regulatory molecule. The main problem in NO analysis is its extreme reactivity; in aerated water solution it is transformed into nitrite and nitrate, inactive biological forms. Moreover, it may lose an electron forming the NO+ ion, involved in the synthesis of nitrosothiols (RSNOs). The main problems encountered in the analytical determination of free NO and of RSNOs in biological systems are the low stability and the very low concentration of these compounds. The determination of nitrates and nitrites may also be difficult when their concentration is in the nmolar range. We describe an electrochemical assay for the determination in the same sample of free NO and of its derivatives in nmolar range. Owing to its high sensitivity, the procedure could also be applied to environmental analyses 相似文献
15.
Zhongquan Liu 《Tetrahedron letters》2005,46(7):1095-1097
Reaction of nitric oxide (NO) with p-substituted benzyl triphenylphosphonium chlorides or bromides (Wittig reagents) in CH2Cl2 under argon undergoes electrophilic attack of NO on the carbon center of phosphonium ylides, producing benzonitriles. 相似文献
16.
Bruno L. Oliveira Filipa Mendes Isabel Santos Carlos Cordeiro João D.G. Correia 《Journal of organometallic chemistry》2011,696(5):1057-1065
The visualization of inducible nitric oxide synthase (iNOS) in vivo with specific radioactive probes could provide a valuable insight into the diseases associated with upregulation of this enzyme. Aiming at that goal, we have synthesized a novel family of conjugates bearing a pyrazolyl-diamine chelating unit for stabilization of the fac-[M(CO)3]+ core (M = 99mTc, Re) and pendant guanidino (L1 = guanidine, L2 = N-hydroxyguanidine, L3 = N-methylguanidine, L4 = N-nitroguanidine) or S-methylisothiourea (L5) moieties for iNOS recognition. L1-L5 reacted with fac-[M(CO)3(H2O)]+, yielding complexes of the type fac-[M(CO)3(k3-L)]+ (M = Re/99mTc; 1/1a, L = L1; 2/2a, L = L2; 3/3a, L = L3; 4/4a, L = L4; 5/5a, L = L5), which were fully characterized by the usual analytical methods in chemistry and radiochemistry, including X-ray diffraction analysis in the case of 1. The rhenium complexes 1-5 were prepared as “cold” surrogates of the 99mTc(I) complexes. Enzymatic assays with murine purified iNOS demonstrated that L1, L2, 1 and 2 are poor NO-producing substrates. These assays have also shown that metallation of L4 and L5 (Ki > 1000 μM) gave complexes with increased inhibitory potency (4, Ki = 257 μM; 5, Ki = 183 μM). The organometallic rhenium complexes permeate through LPS-treated RAW 264.7 macrophage cell membranes, interacting specifically with the target enzyme, as confirmed by the partial suppression of NO biosynthesis (ca. 20% in the case of 4 and 5) in this cell model. The analog 99mTc(I)-complexes 1a-5a are stable in vitro, being also able to cross cell membranes, as demonstrated by internalization studies in the same cell model with compound 4a (4h, 37 °C; 33.8% internalization). Despite not being as effective as the α-amino-acid-containing metal-complexes previously described by our group, the results reported herein have shown that similar 99mTc(I)/Re(I) organometallic complexes with pendant amidinic moieties may hold potential for targeting iNOS expression in vivo. 相似文献
17.
18.
Simone Aparecida Cicillini Ana Carolina Lemos Prazias Antonio Claudio Tedesco Osvaldo Antonio Serra Roberto Santana da Silva 《Polyhedron》2009,28(13):2766-2770
The photochemical, photophysical and photobiological studies of a mixture containing cis-[Ru(H-dcbpy−)2(Cl)(NO)] (H2-dcbpy = 4,4′-dicarboxy-2,2′-bipyridine) and Na4[Tb(TsPc)(acac)] (TsPc = tetrasulfonated phthalocyanines; acac = acetylacetone), a system capable of improving photodynamic therapy (PDT), were accomplished. cis-[Ru(H-dcbpy−)2(Cl)(NO)] was obtained from cis-[Ru(H2-dcbpy)2Cl2]·2H2O, whereas Na4[Tb(TsPc)(acac)] was obtained by reacting phthalocyanine with terbium acetylacetonate. The UV–Vis spectrum of cis-[Ru(H-dcbpy−)2(Cl)(NO)] displays a band in the region of 305 nm (λmax in 0.1 mol L−1 HCl)(π–π*) and a shoulder at 323 nm (MLCT), while the UV–Vis spectrum of Na4[Tb(TsPc)(acac)] presents the typical phthalocyanine bands at 342 nm (Soret λmax in H2O) and 642, 682 (Q bands). The cis-[Ru(H-dcbpy−)2(Cl)(NO)] FTIR spectrum displays a band at 1932 cm−1 (Ru–NO+). The cyclic voltammogram of the cis-[Ru(H-dcbpy−)2(Cl)(NO)] complex in aqueous solution presented peaks at E = 0.10 V (NO+/0) and E = −0.50 V (NO0/−) versus Ag/AgCl. The NO concentration and 1O2 quantum yield for light irradiation in the λ > 550 nm region were measured as [NO] = 1.21 ± 0.14 μmol L−1 and øOS = 0.41, respectively. The amount of released NO seems to be dependent on oxygen concentration, once the NO concentration measured in aerated condition was 1.51 ± 0.11 μmol L−1 The photochemical pathway of the cis-[Ru(H-dcbpy−)2(Cl)(NO)]/Na4[Tb(TsPc)(acac)] mixture could be attributed to a photoinduced electron transfer process. The cytotoxic assays of cis-[Ru(H-dcbpy-)2(Cl)(NO)] and of the mixture carried out with B16F10 cells show a decrease in cell viability to 80% in the dark and to 20% under light irradiation. Our results document that the simultaneous production of NO and 1O2 could improve PDT and be useful in cancer treatment. 相似文献
19.
20.
Probe-donor integrated nanocomposites were developed from conjugating silica-coated Mn2+:ZnS quantum dots (QDs) with MoS2 QDs and photosensitive nitric oxide (NO) donors (Fe4S3(NO)7−, RBS). Under excitation with near-infrared (NIR) light at 808 nm, the Mn2+:ZnS@SiO2/MoS2-RBS nanocomposites showed the dual-emissive two-photon excited photoluminescence (TPEPL) that induced RBS photolysis to release NO in situ. NO caused TPEPL quenching of Mn2+:ZnS QDs, but it produced almost no impact on the TPEPL of MoS2 QDs. Hence, the nanocomposites were developed as a novel QDs-based ratiometric TPEPL probe for real-time detection of NO release in situ. The ratiometric TPEPL intensity is nearly linear (R2 = 0.9901) with NO concentration in the range of 0.01∼0.8 μM, which corresponds to the range of NO release time (0∼15 min). The detection limit was calculated to be approximately 4 nM of NO. Experimental results confirmed that this novel ratiometric TPEPL probe possessed high selectivity and sensitivity for the detection of NO against potential competitors, and especially showed high detection performance for NIR-light triggered NO release in tumor intracellular microenvironments. These results would promote the development of versatile probe-donor integrated systems, also providing a facile and efficient strategy to real-time detect the highly controllable drug release in situ, especially in physiological microenvironments. 相似文献