APPLICATION OF AN ULTRAMICROELECTRODE IN HOMOGENEOUS CATALYTIC REACTIONS .4. ELECTROCATALYTIC REDUCTION OF ORGANOHALIDES BY METALLOPORPHYRIN AT ULTRAMICROELECTRODE

The electrocatalytic reduction of 1,2-dibromoethane and tetrabromoethane with CoTPP in DMF solutions containing 0.1 M TBAP was investigated at a Pt ultramicroelectrode. The experimental results indicated that CoTPP obviously exhibited catalytic activity for 1,2-dibromoethane and tetrabromoethane. The rate constants of 1,2-dibromoethane and tetrabromoethane in this system were calculated to be 0.14 x 10(3) and 0.5 x 10(2) M-1 S-1, respectively. The reaction mechanism of 1,2-dibromoethane and tetrabromoethane reduction electrocatalysed by CoTPP in 0.1 M TBAP DMF solution is discussed.

HELIX-INDUCED ASYMMETRIC POLYMERIZATION

Asymmetric polymerization could be induced by an already formed optically active living prepolymer with one-handed screw sense helix conformation. The usually formed anionic active centre on the prepolymer could be changed to cationic, radical and even of Ziegler-Natta type. These living prepolymers with various kinds of active centre were all effective to induce a consequent asymmetric polymerization of a monomer which may be other than that in the prepolymer, to afford an optically active helical chain with the same screw sense as that of the prepolymer. Eight monomers have been used in the work. Optical rotation, circular dichroism and gelpermeation chromatography have been taken to prove the helix-induced asymmetric polymerization.

ELECTROCHEMICAL AND INSITU SPECTROELECTROCHEMICAL STUDY OF (TETRAPHENYLPORPHINATO)MANGANESE (III) PERCHLORATE IN THE PRESENCE OF CHLORIDE ANIONS .1. REDUCTION PROCESSES

The mechanism of electrochemical redox reactions of (tetra-phenylporphinato) managanese(III) perchlorate, (TPP)Mn(III)ClO4, was studied In the presence of chloride anions in dichloroethane solution. It was demonstrated that Mn(II) or Mn (III) centre can be coordinated with only one chloride anion, this result makes an about 100 mV negative shift of half-wave potential of Mn (III)/Mn (II) reduction. An equilibrium constant of 2.2 x 10(4) was determined for the complexation reaction of Cl- and Mn(III) centre.

STUDIES ON ELECTROGENERATION, INSITU ELECTROCHEMISTRY AND SPECTROELECTROCHEMISTRY OF ALKYL COBALT PORPHYRIN

Methyl-, ethyl-, propyl- and n-butyl cobalt porphyrins were electrochemically synthesized and studied byIn-situ cyclic voltammetry and UV-Visible spectro-el ectrochemistry. Rate constants for the alkylations were determined. It was found that the four alkyl saturated tetraphenylchlorin cobalt complexes were formed after electrochemical reduction of the alkyl cobalt porphyrins.

INVESTIGATION OF CETYLPYRIDINIUM BROMIDE ADSORPTION AT A GLASSY-CARBON ELECTRODE SURFACE BY SPECTROELECTROCHEMISTRY WITH A LONG OPTICAL-PATH LENGTH THIN-LAYER CELL

The adsorption of cationic surfactant cetylpyridinium bromide (CPB) on a glassy carbon (GC) electrode surface has been studied by spectroelectrochemistry with a long optical path length thin-layer cell (LOPTLC) for the first time. A fine adsorption isotherm of CPB molecules from an aqueous solution containing 0.10 M KBr has been obtained over the range of (1.00-8.00) x 10(-5) M. From theoretical calculation and experimental data, adsorption of CPB on the GC electrode surface shows four distinct orientations and three large orientation transitions. Compared with the ordinary isotherm, the differential isotherm is more characteristic and would be suitable for the study of orientation transitions of organic compounds. With a theoretical treatment of the adsorption isotherm, four orientations of adsorbed CPB on a GC electrode surface coincide with the Frumkin-Langmuir type. From adsorption parameters the Frumkin-Langmuir equations, the adsorption free energy and, therefore, the equilibrium constants of orientation transitions of the CPB molecule can be obtained.

SYNTHESIS OF A NEW TYPE OF CH3CN-COORDINATED LANTHANIDE COMPOUNDS LN(CH3CN)9(ALCL4)3CH3CN

Acetonitrile is a weakly donating ligand. The cationic compounds of CH_3CN-coordinated transition metal are versatile homogeneous catalysts for the polymerization and isomerization of olefins and cycloolefins. The cationic compound of lanthanide[Eu(CH_3·CN)_3(BF_4)_3]_n was prepared from the oxidation of Eu with NOBF_4 in CH_3CN by Thomas in 1986. It was found that [Eu(CH_3CN)_3(BF_4)_3]_n can catalyze the polymerization of styrene cyclohexadiene and other olefins. However, there is no information about...

The preparation and bioactivity research of agaro-oligosaccharides

Agaro-oligosaccharides were hydrolytically obtained from agar using hydrochloric acid, citric acid, and cationic exchange resin (solid acid). The FT-IR and NMR data showed that the hydrolysate has the structure of agaro-oligomers. Orthogonal matrix method was applied to optimize the preparation conditions based on alpha-naphthylamine end-labeled HPLC analysis method. The optimal way for oligosaccharides with different degree of polymerization (DP) was achieved by using solid acid degradation, which could give high yield and avoid solution neutralization process. Agaro-oligosaccharides with high purity were consequently obtained by activated carbon column isolation. Furthermore, the antioxidant and alpha-glucosidase inhibitory activity of three fractions were also investigated. The result indicated that 8% ethanol-eluted fraction showed highest activity against alpha-glucosidase with IC50 of 8.84 mg/mL, while 25% ethanol-eluted fraction possessed excellent antioxidant ability.

Molecular cloning and expression profile of putative antilipopolysaccharide factor in Chinese shrimp (Fenneropenaeus chinensis)

A new antimicrobial protein gene of the anti-lipopolysaccharide factor family (tentatively named as ALFFc) has been cloned from hemocytes of the Chinese shrimp Fenneropenaeus chinensis by rapid amplification of 3' and 5' complementary DNA ends with polymerase chain reaction. The full-length complementary DNA of ALFFc consists of 600 bp with a 369-bp open reading frame, encoding 123 amino acids. The deduced peptide contains a putative signal peptide of 25 amino acids and mature peptide of 98 amino acids. The molecular mass of the deduced mature peptide is 13799.16 Da. It is highly cationic, with a theoretical pI of 10.3. The deduced amino acid sequence of ALFFc showed 56% homology with sequences of Tachypleus tridentatus and L. polyhemus. The tissue expression profile of this gene was studied by Northern blot, and ALFFc transcripts were mainly detected in hemocytes, gill, and intestine. RNA in situ hybridization showed that ALFFc was constitutively expressed in hemocytes. Capillary electrophoresis reverse transcriptase PCR was used to quantify the variation of messenger RNA transcription level during the artificial infection process with Vibrio anguillarum. Significant enhancement of ALFFc transcription appeared during the first 24 hours in response to Vibrio infection. These results provide useful information for understanding the function of ALFFc in shrimp.

Molecular cloning and expression analysis of Crustin-like gene from Chinese shrimp Fenneropenaeus chinensis

A new member of antimicrobial protein genes of the Crustin family was cloned from haemocytes of the Chinese shrimp Fenneropenaeus chinensis by 3' and 5' RACE. The full-length cDNA of Crustin-like gene contains a 390 bp open reading frame, encoding 130 amino acids. The deduced peptide contains a putative signal peptide of 17 amino acids and mature peptide of 113 amino acids. The molecular mass of the deduced mature peptide is 12.3 ku. It is highly cationic with a theoretical isoelectric point of 8.5. The deduced amino acids sequence of this Crustin showed high homology with those of Penaeus (Litopenaeas) setferus. Northern blotting showed that the cloned Crustin gene was mainly expressed in haemocytes, gill, intestine, and RNA in situ hybridization indicated that the Crustin gene was constitutively expressed exclusively in haemocytes of these tissues. Capillary electrophoresis RT-PCR analysis showed that Crustin was up-regulated dramatically from 12 to 48 h after a brief decrease of mRNA during first 6 h in response to microbe infection. The level of Crustin mRNA began to restore at 72 h post-challenge. This indicated that Crustin gene might play an important role when shrimps are infected by bacterial pathogen.

Nanotoxicologia

Projeto de Pós-Graduação/Dissertação apresentado à Universidade Fernando Pessoa como parte dos requisitos para obtenção do grau de Mestre em Ciências Farmacêuticas

Porfirinas e Terapia Fotodinâmica em Neoplasias

Projeto de Pós-Graduação/Dissertação apresentado à Universidade Fernando Pessoa como parte dos requisitos para obtenção do grau de Mestre em Ciências Farmacêuticas

Studies of rhodium, platinum and palladium derivatives of some arsena-, carba- and telluraboranes

The research described in this thesis involved the synthesis and characterisation of rhodium, platinum and palladium derivatives of arsena-, carba- and telluraboranes.

New phosphorescence based probes and techniques for the analysis of cellular oxygen and respiration

Real time monitoring of oxygenation and respiration is on the cutting edge of bioanalysis, including studies of cell metabolism, bioenergetics, mitochondrial function and drug toxicity. This thesis presents the development and evaluation of new luminescent probes and techniques for intracellular O2 sensing and imaging. A new oxygen consumption rate (OCR) platform based on the commercial microfluidic perfusion channel μ-slides compatible with extra- and intracellular O2 sensitive probes, different cell lines and measurement conditions was developed. The design of semi-closed channels allowed cell treatments, multiplexing with other assays and two-fold higher sensitivity to compare with microtiter plate. We compared three common OCR platforms: hermetically sealed quartz cuvettes for absolute OCRs, partially sealed with mineral oil 96-WPs for relative OCRs, and open 96-WPs for local cell oxygenation. Both 96-WP platforms were calibrated against absolute OCR platform with MEF cell line, phosphorescent O2 probe MitoXpress-Intra and time-resolved fluorescence reader. Found correlations allow tracing of cell respiration over time in a high throughput format with the possibility of cell stimulation and of changing measurement conditions. A new multimodal intracellular O2 probe, based on the phosphorescent reporter dye PtTFPP, fluorescent FRET donor and two-photon antennae PFO and cationic nanoparticles RL-100 was described. This probe, called MM2, possesses high brightness, photo- and chemical stability, low toxicity, efficient cell staining and high-resolution intracellular O2 imaging with 2D and 3D cell cultures in intensity, ratiometric and lifetime-based modalities with luminescence readers and FLIM microscopes. Extended range of O2 sensitive probes was designed and studied in order to optimize their spectral characteristics and intracellular targeting, using different NPs materials, delivery vectors, ratiometric pairs and IR dyes. The presented improvements provide useful tool for high sensitive monitoring and imaging of intracellular O2 in different measurement formats with wide range of physiological applications.

Comparison of the NMR enantiodifferentiation of a chiral ruthenium(II) complex of C2 symmetry using the TRISPHAT anion and a lanthanide shift reagent

The tris[tetrachlorobenzenediolato]phosphate(v) anion (TRISPHAT) is known to be an efficient NMR chiral shift agent for various chiral cationic species. Here we compare the efficiency of TRISPHAT and of a chiral lanthanide shift reagent for the determination of the enantiomeric purity of the chiral building block [Ru(phen)[2]PY[2]][2][+] which possesses C[2] symmetry. We also discuss our results in terms of the geometry of interaction between the Ru(II) complex and the TRISPHAT anion.

On the adsorption of hexaammineruthenium (III) at anionic self-assembled monolayers

The binding of the electroactive hexaammineruthenium (III) complex ions to anionic self-assembled monolayers (SAMs) has been investigated by means of chronocoulometry and ac voltammetry. From chronocoulometric data recorded in 10-2 M LiClO4 containing different [Ru(NH3)6]3+ concentrations, we have established the adsorption isotherm of [Ru(NH3)6]3+ on a compact monolayer of 2-mercaptobenzimidazole-5-sulfonate (MBIS) self-assembled on Au(1 1 1). The data were satisfactorily fitted to the linearized Langmuir adsorption isotherm and a binding constant of 4.0 (±0.4) × 106 M-1 has been determined. The electrostatic binding of [Ru(NH3)6]3+ to a dilute PNA-DNA monolayer formed after hybridization on a PNA-modified gold electrode by self-assembly from a mixed solution of mercaptobutan-1-ol and PNA oligonucleotides has been studied by ac voltammetry. The admittance of the PNA-modified electrode after hybridization with complementary DNA was measured in 0.01 M Tris-HCl buffer containing different [Ru(NH3)6]3+ concentrations. Based on these data, a binding constant of [Ru(NH3)6]3+ to the surface-confined PNA-DNA duplex was derived from the Langmuir isotherm and amounts to 2.9 (±0.3) × 105 M-1. As the interactions between [Ru(NH3)6]3+ and the immobilized PNA-DNA hybrids on the gold surface are essentially electrostatic, the adsorption of the highly charged cationic redox complex at low concentrations to the negatively charged PNA-DNA modified surface is in large competition with other monovalent cations present in the electrolyte at higher concentrations. The influence of competing sodium cations was thus studied by adding different NaCl concentrations in the 0.01 M Tris-HCl electrolyte. © 2008 Elsevier Ltd. All rights reserved.