Synthesis and characterization of the [Ru(3)O(CH(3)COO)(6)(py)(2)(BPE)Ru(bpy)(2)Cl](PF(6))(2) dimer

The polymetallic [Ru(3)O(CH(3)COO)(6)(py)(2)(BPE)Ru( bpy)(2)Cl](PF(6))(2) complex (bpy = 2,2`-bipyridine, BPE = trans- 1,2-bis(4-pyridil) ethylene and py = pyridine) was assembled by the combination of an electroactive [Ru(3)O] moiety with a [ Ru( bpy) 2( BPE) Cl] photoactive centre, and its structure was determined using positive ion electrospray (ESI-MS) and tandem mass (ESI-MS/MS) spectrometry. The [Ru(3)O(CH(3)COO)(6)(py)(2)(BPE)Ru(bpy)(2)Cl] (2+) doubly charged ion of m/z 732 was mass-selected and subject to 15 eV collision-induced dissociation, leading to a specific dissociation pattern, diagnostic of the complex structure. The electronic spectra display broad bands at 409, 491 and 692 nm ascribed to the [Ru(bpy)(2)(BPE)] charge-transfer bands and to the [Ru(3)O] internal cluster transitions. The cyclic voltammetry shows five reversible waves at - 1.07 V, 0.13 V, 1.17 V, 2.91 V and - 1.29 V (vs SHE) assigned to the [Ru(3)O](-1/0/+ 1/+ 2/+3) and to the bpy (0/-1) redox processes; also a wave is observed at 0.96 V, assigned to the Ru (+2/+ 3) pair. Despite the conjugated BPE bridge, the electrochemical and spectroelectrochemical results indicate only a weak coupling through the pi-system, and preliminary photophysical essays showed the compound decomposes under visible light irradiation.

Chitosan as a Bioadhesive Agent Between Porphyrins and Phospholipids in a Biomembrane Model

Porphyrins are currently used in photodynamic therapy as photosensitizers. In this paper we studied the interaction of two charged porphyrins, 5, 10, 15, 20-mesotetrakis(N-metyl-4-pyridyl) porphyrin, (TMPyP/chloride salt) cationic, and 5, 10, 15, 20-meso-tetrakis(sulfonatophenyl) porphyrin, (TPPS(4)/sodium salt) anionic, nanoassembled in phospholipid Langmuir monolayers and Langmuir-Blodgett films. Furthermore, we used chitosan to mediate the interaction between the porphyrins and the model membrane, aiming to understand the role of the polysaccharide in a molecular level. The effect of the interaction of the photosensitizers on the fluidity of the lipid monolayer was investigated by using dilatational surface elasticity. We also used photoluminescence (PL) spectroscopy to identify the porphyrins adsorbed in the phospholipid films. We observed an expansion of the monolayer promoted by the adsorption of the porphyrins into the lipid-air interface which was more pronounced in the case of TMPyP, as a consequence of a strong electrostatic interaction with the anionic monolayer. The chitosan promoted a higher adsorption of the porphyrins on the phospholipid monolayers and enabled the porphyrin to stay in its monomeric form (as confirmed by PL spectroscopy), thus demonstrating that chitosan can be pointed out as a potential photosensitizer delivery system in photodynamic therapy.

Carbene and nitrene rearrangements: A theoretical study of cyclic allenes and carbenes, carbodiimides, and azirines

B3LYP/6-31G(d) calculations of structures, energies, and infrared spectra of several rearrangement products of (hetero)aromatic nitrenes and carbenes are reported. 3-Isoquinolylnitrene 36 ring closes to the azirine 37 prior to ring expansion to the potentially stable but unobserved seven-membered-ring carbodiimide 38 and diazacycloheptatrienylidene C-s-39S. A new, stable cycloheptatrienylidene, C-s-19S, is located on the naphthylcarbene energy surface. 4-Quinolylnitrene undergoes reaction via the azirine 50 in solution, but ring expansion to the stable seven-membered-ring ketenimine 47 under Ar matrix photolysis conditions. There is excellent agreement between calculated infrared spectra of 1,5-diazacyclohepta-1,2,4,6-tetraene 54 (obtained by photolysis of 4-pyridyl azide), 1-azacyclohepta-1,2,4,6-tetraene 5, 1-azacyclohepta-1,3,5,6-tetraene 55, and 1-azacyclohepta-1,3,4,6-tetraene 56 and the available experimental data.

Direct electrochemistry of the Desulfovibrio gigas aldehyde oxidoreductase

Eur. J. Biochem. 271, 1329–1338 (2004)

Alternative chelating agents: Evaluation of the ready biodegradability and complexation properties

The ready biodegradability of four chelating agents, N,N -(S,S)-bis[1-carboxy-2-(imidazol-4-yl)ethyl]ethylenediamine (BCIEE), N - ethylenedi-L-cysteine (EC), N,N -bis (4-imidazolymethyl)ethylenediamine (EMI) and 2,6-pyridine dicarboxylic acid (PDA), was tested according to the OECD guideline for testing of chemicals. PDA proved to be a readily biodegradable substance. However, none of the other three compounds were degraded during the 28 days of the test. Chemical simulations were performed for the four compounds in order to understand their ability to complex with some metal ions (Ca, Cd, Co, Cu, Fe, Mg, Mn, Ni, Pb, Zn) and discuss possible applications of these chelating agents. Two different conditions were simulated: (i) in the presence of the chelating agent and one metal ion, and (ii) in the simultaneous presence of the chelating agent and all metal ions with an excess of Ca. For those compounds that were revealed not to be readily biodegradable (BCIEE, EC and EMI), applications were evaluated where this property was not fundamental or even not required. Chemical simulations pointed out that possible applications for these chelating agents are: food fortification, food process, fertilizers, biocides, soil remediation and treatment of metal poisoning. Additionally, chemical simulations also predicted that PDA is an efficient chelating agent for Ca incrustations removal, detergents and for pulp metal ions removal process.

Disposable immunosensor using a simple method for oriented antibody immobilization for label-free real-time detection of an oxidative stress biomarker implicated in cancer diseases

This work proposes a novel approach for a suitable orientation of antibodies (Ab) on an immunosensing platform, applied here to the determination of 8-hydroxy-2′-deoxyguanosine (8OHdG), a biomarker of oxidative stress that has been associated to chronic diseases, such as cancer. The anti-8OHdG was bound to an amine modified gold support through its Fc region after activation of its carboxylic functions. Non-oriented approaches of Ab binding to the platform were tested in parallel, in order to show that the presented methodology favored Ab/Ag affinity and immunodetection of the antigen. The immunosensor design was evaluated by quartz-crystal microbalance with dissipation, atomic force microscopy, electrochemical impedance spectroscopy (EIS) and square-wave voltammetry. EIS was also a suitable technique to follow the analytical behavior of the device against 8OHdG. The affinity binding between 8OHdG and the antibody immobilized in the gold modified platform increased the charge transfer resistance across the electrochemical set-up. The observed behavior was linear from 0.02 to 7.0 ng/mL of 8OHdG concentrations. The interference from glucose, urea and creatinine was found negligible. An attempt of application to synthetic samples was also successfully conducted. Overall, the presented approach enabled the production of suitably oriented Abs over a gold platform by means of a much simpler process than other oriented-Ab binding approaches described in the literature, as far as we know, and was successful in terms of analytical features and sample application.

Disposable immunosensor with simple antibody orientation for label-free real-time detection of a cancer biomarker

This work proposes a novel approach for a suitable orientation of antibodies (Ab) on an immunosensing platform, applied here to the determination of 8-hydroxy-2’-deoxyguanosine (8OHdG), a biomarker of oxidative stress that has been associated to chronic diseases, such as cancer. The Anti-8OHdG was bound to an amine modified gold support through its Fc region after activation of its carboxylic functions. Non-oriented approaches of Ab binding to the platform were tested in parallel, in order to show that the presented proposal favored Ab/Ag affinity. The immunosensor design was evaluated by Quartz-Crystal microbalance with Dissipation, Atomic Force Microscopy, Electrochemical Impedance Spectroscopy (EIS) and Square-Wave Voltammetry. EIS was also a suitable technique to follow the analytical behavior of the device against 8OHdG. The affinity binding between 8OHdG and the antibody immobilized in the gold modified platform increased the charged transfer resistance across the electrochemical sep-up. The observed behavior was linear from 0.02 to 7.0 ng/mL of 8OHdG concentrations. The interference from Glucose, Urea and Creatinine was found negligible. An attempt of application to synthetic samples was also successfully conducted. Overall, the presented approach enabled the production of suitably oriented Abs over a gold platform by means of a much simpler process than other oriented-Ab binding approaches described in the literature, as far as we know, and was successful in terms of analytical features and sample application.

A label-free DNA aptamer-based impedance biosensor for the detection of E. coli outer membrane proteins

A label-free DNA aptamer-based impedance biosensor for the detection of E. coli outer membrane proteins (OMPs) was developed. Two single stranded DNA sequences were tested as recognition elements and compared. The aptamer capture probes were immobilized, with and without 6-mercapto-1-hexanol (MCH) on a gold electrode. Each step of the modification process was characterized by Faradaic impedance spectroscopy (FIS). A linear relationship between the electron-transfer resistance (Ret) and E. coli OMPs concentration was demonstrated in a dynamic detection range of 1 × 10−7–2 × 10−6 M. Moreover, the aptasensor showed selectivity despite the presence of other possible water contaminates and could be regenerated under low pH condition. The developed biosensor shows great potential to be incorporated in a biochip and used for in situ detection of E. coli OMPs in water samples.

Insights into human carboxylesterase 2 stability and activity in vivo and in vitro

Dissertation to obtain a Master Degree in Biotechnology

Development of a novel aptamer-based multi-sensor device for the detection of osteopontin

Doctoral Dissertation for PhD degree in Chemical and Biological Engineering

Sensitive label-free electron chemical capacitive transducer signal for D-dimer electroanalyses

Supplementary data associated with this article can be found, in the online version, at: http://dx.doi.org/10.1016/j.electacta.2015.09.169.

Estudio de las propiedades dieléctricas y ópticas de películas de sólidos moleculares sobre sustratos de diversa naturaleza

El tema de investigación propuesto en el presente proyecto es el estudio de las propiedades dieléctricas y ópticas de películas de sólidos moleculares formadas a partir de compuestos derivados del bifenilo, con halógenos como sustituyentes. Se analizará el comportamiento de bis (4 cloro fenil) sulfona y 4-4' dicloro benzofenona comparativamente con fenil sulfona y benzofenona. Se continuará con otros compuestos, variando la posición y naturaleza de los sustituyentes. Se utilizarán sustratos de naturaleza metálica como plata y oro, y dióxido de titanio. Se analizarán efectos específicos de la orientación cristalina de la superficie del sustrato. Una de las motivaciones del presente proyecto es la diversidad de aplicaciones prácticas de estas películas en el campo de la contaminación ambiental, la optoelectrónica y la industria farmacéutica. Efectivamente la actividad biológica y toxicidad de compuestos bifenílicos clorados está directamente relacionada con la conformación molecular y la movilidad relativa de los anillos bencénicos entre sí. Por otra parte muchos de estos compuestos presentan respuestas ópticas no lineales lo cual los hace atractivos para su utilización en el diseño de instrumental optoelectrónico. Además el estudio de estos compuesto presenta interés académico en el campo de la Física del Estado Sólido. En la elaboración de modelos teóricos es importante el conocimiento de los mecanismos a través de los cuales las distintas contribuciones de las fuerzas intramoleculares, intermoleculares y de interacción con el sustrato determinan la estructura del sólido molecular. (...) El objetivo general del presente proyecto es lograr controlar la estructura de películas de compuestos derivados del bifenilo variando las condiciones de trabajo. Específicamente se pretende determinar las condiciones experimentales bajo las cuales son energéticamente más estables las diferentes fases que se observan en estos compuestos. A su vez se intentará determinar los cambios en sus propiedades dieléctricas y ópticas y la toxicidad variando diversos parámetros experimentales con fines prácticos. Por otra parte, con el conocimiento del comportamiento de estas películas aportará información para la elaboración de modelos teóricos que expliquen los mecanismos involucrados en la competencia de los diversos tipos de interacciones que determinan las diferentes estructuras.

Incommensuración conformacional en cristales moleculares

Existen sólidos orgánicos en los cuales las interacciones intermoleculares tienen un efecto determinante sobre la conformación de equilibrio y la dinámica molecular. Tal es el caso de los compuestos de la familia de los bifenilos, que presentan en general valores bajos para la energía de torsión fenil-fenil, en algunos casos comparables a los de las interacciones intermoleculares. Esta competencia de interacciones inter. e intramoleculares, al variar con la temperatura, ocasiona transiciones de fase que pueden involucrar la pérdida de la periodicidad del cristal, como ocurre con el bifenilo y el bis(4-clorofenil)sulfone ((ClC6H4)2SO2), abreviado como BCPS). En estos compuestos se producen transiciones a fases inconmensuradas (IC), en las cuales los ángulos interfenilos están modulados espacialmente con una periodicidad irracional respecto de la red cristalina subyacente. Por otra parte, estos mismos factores estéricos y dinámicos internos juegan un rol crucial en el nivel de actividad biológica de una sustancia, a nivel molecular. En los bifenilos clorados se ha demostrado, que la conformación interna de la molécula y la libertad reorientacional de ciertos grupos moleculares (como por ejemplo anillos bencénicos, C-Cl3, etc.) son determinantes en la interacción con las membranas celulares durante el proceso de absorción. La toxicidad de los pesticidas derivados del DDT esta basada en este hecho. Así, el problema de cómo se modifica la conformación interna de la molécula y su dinámica debido a interacciones con su entorno (vecinos próximos en el sólido, membrana celular, etc.) guarda interés tanto desde el punto de vista de la física del sólido (estudio de fases aperiódicas, dinámica molecular) como de la física aplicada (grado de bioactividad). El objetivo general del proyecto es realizar la caracterización, el análisis y la descripción de los mecanismos que originan, en compuestos bifenilos colorados, transiciones a fases conformacionalmente inconmensuradas. Como objetivo específico, se plantea un estudio de compuestos estructuralmente semejantes al BCPS y soluciones sólidas de estos compuestos de BCPS. Se efectuarán de esta forma, perturbaciones del balance entre las interacciones intra e intermoleculares, observándose el efecto sobre los diagramas de fases, con referencia al correspondiente al BCPS.

Sawhorse-type diruthenium tetracarbonyl complexes containing porphyrin-derived ligands as highly selective photosensitizers for female reproductive cancer cells.

Diruthenium tetracarbonyl complexes of the type [Ru2(CO)4(l2-g2-O2CR)2L2] containing a Ru-Ru backbone with four equatorial carbonyl ligands, two carboxylato bridges, and two axial two-electron ligands in a sawhorse-like geometry have been synthesized with porphyrin-derived substituents in the axial ligands [1: R is CH3, L is 5-(4-pyridyl)-10,15,20-triphenyl-21,23H-porphyrin], in the bridging carboxylato ligands [2: RCO2H is 5-(4-carboxyphenyl)-10,15,20-triphenyl-21,23H-porphyrin, L is PPh3; 3: RCO2H is 5-(4-carboxyphenyl)-10,15,20-triphenyl-21,23H-porphyrin, L is 1,3,5-triaza-7-phosphatricyclo [3.3.1.1]decane], or in both positions [4: RCO2H is 5-(4-carboxyphenyl)-10,15,20-triphenyl-21,23H-porphyrin, L is 5-(4-pyridyl)-10,15,20-triphenyl-21,23H-porphyrin]. Compounds 1-3 were assessed on different types of human cancer cells and normal cells. Their uptake by cells was quantified by fluorescence and checked by fluorescence microscopy. These compounds were taken up by human HeLa cervix and A2780 and Ovcar ovarian carcinoma cells but not by normal cells and other cancer cell lines (A549 pulmonary, Me300 melanoma, PC3 and LnCap prostate, KB head and neck, MDAMB231 and MCF7 breast, or HT29 colon cancer cells). The compounds demonstrated no cytotoxicity in the absence of laser irradiation but exhibited good phototoxicities in HeLa and A2780 cells when exposed to laser light at 652 nm, displaying an LD50 between 1.5 and 6.5 J/cm2 in these two cell lines and more than 15 J/cm2 for the others. Thus, these types of porphyric compound present specificity for cancer cell lines of the female reproductive system and not for normal cells; thus being promising new organometallic photosensitizers.

Evaluation of the GlideScope (R) for tracheal intubation in patients with cervical spine immobilization by a semi-rigid collar

Background: In patients with cervical spine injury, a cervical collar may prevent cervical spine movements but renders tracheal intubation with a standard laryngoscope difficult if not impossible. We hypothesized that despite the presence of a semi-rigid cervical collar and with the patient's head taped to the trolley, we would be able to intubate all patients with the GlideScopeR and its dedicated stylet. Methods: 50 adult patients (ASA 1 or 2, BMI ≤35 kg/m2) scheduled for elective surgical procedures requiring tracheal intubation were included. After standardized induction of general anesthesia and neuromuscular blockade, the neck was immobilized with an appropriately sized semi-rigid Philadelphia Patriot® cervical collar, the head was taped to the trolley. Laryngoscopy was attempted using a Macintosh laryngoscope blade 4 and the modified Cormack Lehane grade was noted. Subsequently, laryngoscopy with the GlideScopeR was graded and followed by oro-tracheal intubation. Results: All patients were successfully intubated with the GlideScopeR and its dedicated stylet. The median intubation time was 50 sec [43; 61]. The modified Cormack Lehane grade was 3 or 4 at direct laryngoscopy. It was significantly reduced with the GlideScopeR (p <0.0001), reaching 2a in most of patients. Maximal mouth opening was significantly reduced with the cervical collar applied, 4.5 cm [4.5; 5.0] vs. 2.0 cm [1.8; 2.0] (p <0.0001). Conclusions: The GlideScope® allows oro-tracheal intubation in patients having their cervical spine immobilized by a semi-rigid collar and their head taped to the trolley. It furthermore decreases significantly the modified Cormack Lehane grade.