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1.
Anal Chem ; 95(47): 17311-17317, 2023 Nov 28.
Artículo en Inglés | MEDLINE | ID: mdl-37956247

RESUMEN

Closed bipolar cells (cBPCs) can offer valuable platforms for the development of electrochemical sensors. On the other hand, such systems are more intricate to model and interpret than conventional systems with a single polarizable interface, with the applied potential "splitting" into two polarized interfaces where two coupled charge transfers take place concomitantly. As a result, the voltammetry of cBPCs shows peculiarities that can be misleading if analyzed under the framework of classic electrochemical cells. In this work, rigorous mathematical solutions are deduced for the cyclic voltammetry (CV) of cBPCs, including the current-potential response, the interfacial potentials, and the interfacial redox concentrations. With such theoretical tools, a comprehensive view of the behavior of cBPCs can be gained, and adequate diagnosis criteria are established on the basis of the shape, magnitude, and position of the CV signal as a function of the scan rate and of the experimental conditions in the anodic and cathodic compartments.

2.
J Transl Med ; 21(1): 802, 2023 11 10.
Artículo en Inglés | MEDLINE | ID: mdl-37950242

RESUMEN

BACKGROUND: Wharton's Jelly (WJ) Mesenchymal Stromal Cells (MSC) have emerged as an attractive allogeneic therapy for a number of indications, except for bone-related conditions requiring new tissue formation. This may be explained by the apparent recalcitrance of MSC,WJ to differentiate into the osteogenic lineage in vitro, as opposed to permissive bone marrow (BM)-derived MSCs (MSC,BM) that readily commit to bone cells. Consequently, the actual osteogenic in vivo capacity of MSC,WJ is under discussion. METHODS: We investigated how physiological bone environments affect the osteogenic commitment of recalcitrant MSCs in vitro and in vivo. To this end, MSC of BM and WJ origin were co-cultured and induced for synchronous osteogenic differentiation in vitro using transwells. For in vivo experiments, immunodeficient mice were injected intratibially with a single dose of human MSC and bone formation was evaluated after six weeks. RESULTS: Co-culture of MSC,BM and MSC,WJ resulted in efficient osteogenesis in both cell types after three weeks. However, MSC,WJ failed to commit to bone cells in the absence of MSC,BM's osteogenic stimuli. In vivo studies showed successful bone formation within the medullar cavity of tibias in 62.5% of mice treated with MSC, WJ. By contrast, new formed trabeculae were only observed in 25% of MSC,BM-treated mice. Immunohistochemical staining of human COXIV revealed the persistence of the infused cells at the site of injection. Additionally, cells of human origin were also identified in the brain, heart, spleen, kidney and gonads in some animals treated with engineered MSC,WJ (eMSC,WJ). Importantly, no macroscopic histopathological alterations, ectopic bone formation or any other adverse events were detected in MSC-treated mice. CONCLUSIONS: Our findings demonstrate that in physiological bone microenvironment, osteogenic commitment of MSC,WJ is comparable to that of MSC,BM, and support the use of off-the-shelf allogeneic MSC,WJ products in bone repair and bone regeneration applications.


Asunto(s)
Células Madre Mesenquimatosas , Gelatina de Wharton , Humanos , Animales , Ratones , Osteogénesis , Gelatina de Wharton/metabolismo , Diferenciación Celular , Técnicas de Cocultivo , Células Cultivadas , Proliferación Celular
3.
Glob Health Action ; 16(1): 2190649, 2023 12 31.
Artículo en Inglés | MEDLINE | ID: mdl-36999571

RESUMEN

BACKGROUND: In 2015, the United Nations adopted the 2030 Agenda for Sustainable Development, including the 17 Sustainable Development Goals (SDGs). Higher education institutions have a role in raising awareness and building skills among future professionals for implementing the SDGs. This review describes how the SDGs have been integrated into higher education globally. OBJECTIVES: Determine how have the SDGs been integrated into higher education globally. Describe the differences in the integration of the SDGs in higher education across high-income countries (HICs) and low- and middle-income countries (LMICs). METHODS: Following a scoping review methodology, we searched Medline, Web of Science, Global Health, and Educational Resources Information Center, as well as websites of key institutions including universities, identifying peer-reviewed articles and grey literature published between September 2015 and December 2021. RESULTS: We identified 20 articles and 38 grey literature sources. Since 2018, the number of publications about the topic has been increasing. The SDGs were most frequently included in bachelor-level education and disciplines such as engineering and technology; humanities and social sciences; business, administration, and economics. Methods of integrating the SDGs into higher education included workshops, courses, lectures, and other means. Workshops and courses were the most frequent. The methods of integration varied in high-income countries compared to low- and middle-income countries. High-income countries seemed to follow a more academic approach to the SDGs while low- and middle-income countries integrate the SDGs with the aim to solve real-world problems. CONCLUSION: This study provides examples of progress in integrating the SDGs into higher education. Such progress has been skewed to high-income countries, bachelor-level initiatives, and certain disciplines. To advance the integration of the SDGs, lessons learned from universities globally should be shared broadly, equitable partnerships formed, and students engaged, while simultaneously increasing funding for these processes.


Asunto(s)
Renta , Desarrollo Sostenible , Humanos , Estudiantes , Naciones Unidas , Universidades , Objetivos
4.
J Chem Educ ; 100(2): 697-706, 2023 Feb 14.
Artículo en Inglés | MEDLINE | ID: mdl-36812115

RESUMEN

Theoretical and practical foundations of basic electrochemical concepts of heterogeneous charge transfer reactions that underline electrochemical processes are presented for their detailed study by undergraduate and postgraduate students. Several simple methods for calculating key variables, such as the half-wave potential, limiting current, and those implied in the kinetics of the process, are explained, discussed, and put in practice through simulations making use of an Excel document. The current-potential response of electron transfer processes of any kinetics (i.e., any degree of reversibility) are deduced and compared for electrodes of different size, geometry, and dynamics, namely: static macroelectrodes in chronoamperometry and normal pulse voltammetry, and static ultramicroelectrodes and rotating disc electrodes in steady state voltammetry. In all cases, a universal, normalized current-potential response is obtained in the case of reversible (fast) electrode reactions, whereas this is not possible for nonreversible processes. For this last situation, different widely used protocols for the determination of the kinetic parameters (the mass-transport corrected Tafel analysis and the Koutecký-Levich plot) are deduced, proposing learning activities that highlight the foundations and limitations of such protocols, as well as the influence of the mass transport conditions. Discussions on the implementation of this framework and on the benefits and difficulties found are also presented.

5.
Methods Mol Biol ; 2571: 207-239, 2023.
Artículo en Inglés | MEDLINE | ID: mdl-36152164

RESUMEN

Metabolomics is the latest of the omics sciences. It attempts to measure and characterize metabolites-small chemical compounds <1500 Da-on cells, tissue, or biofluids, which are usually products of biological reactions. As metabolic reactions are closer to the phenotype, metabolomics has emerged as an attractive science for various areas of research, including personalized medicine. However, due to the complexity of data obtained and the absence of curated databases for metabolite identification, data processing is the major bottleneck in this area since most technicians lack the required bioinformatics expertise to process datasets in a reliable and fast manner. The aim of this chapter is to describe the available tools for data processing that makes an inexperienced researcher capable of obtaining reliable results without having to undergo through huge parametrization steps.


Asunto(s)
Metabolómica , Bases de Datos Factuales , Espectrometría de Masas/métodos , Metabolómica/métodos , Fenotipo
6.
Anal Chem ; 94(35): 12152-12158, 2022 09 06.
Artículo en Inglés | MEDLINE | ID: mdl-35994566

RESUMEN

UV-vis spectroelectrochemistry is assessed as a tool for the diagnosis and quantitative in situ investigation of the incidence of comproportionation in multielectron transfer processes. Thus, the sensitivity of the limiting current chronoabsorptometric signals related to the different redox states to the comproportionation kinetics is studied theoretically for different working modes (normal and parallel light beam arrangements) and mass transport regimes (from semi-infinite to thin layer diffusion). The theoretical results are applied to the spectroelectrochemical study of the two-electron reduction of the anthraquinone-2-sulfonate in alkaline aqueous solution, tuning the thermodynamic favorability of the comproportionation reaction through the electrolyte cation. The quantitative analysis of the experimental results reveals the occurrence of comproportionation in the three media examined, showing different kinetics depending on the cationic species in solution.


Asunto(s)
Antraquinonas , Electrones , Cinética , Oxidación-Reducción , Espectrofotometría Ultravioleta/métodos
7.
Arch Esp Urol ; 73(9): 784-793, 2020 Nov.
Artículo en Español | MEDLINE | ID: mdl-33144532

RESUMEN

INTRODUCTION: Open prostatectomy is an efficacious treatment for Benign Prostatic Hyperplasia (BPH), but its complication rates and risk factors for these might vary due to the characteristics of populations and health systems. OBJECTIVE: To determine the frequency of complications and the risk factors for these, in the first three months after open prostatectomy in a hospital in Medellín (Colombia). METHODS: This is a cohort study in which patients undergoing retropubic open prostatectomy were taken. Medical records were reviewed to obtain demographic, preoperative, and intraoperative data. The main outcome was the incidence of complications in the first three postoperative months and this was divided into early (day 1 to 7 post-surgery) and late (day 8 to 90 post-surgery) complications. Risk factors were determined by estimating Relative Risks (RR). RESULTS: 191 patients with a median age of 70 years were included. The frequency of complications was 34.5%,14.6% occurred early and 19.9% late. Risk factors were dyslipidemia (RR: 2.37, 95% CI: 1.25 to 4.47), irrigation time (RR: 1.31, 95% CI: 1.02 to 1.67) and duration of the postsurgical catheter (RR: 1.07, 95% CI: 1.03 to 1.12); general anesthesia was a protective risk factor compared to spinal (RR: 0.47, 95% CI: 0.24 to 0.91). CONCLUSION: The frequency of complications of open prostatectomy with a retropubic approach was within the figures reported in the literature. The risk factors found could be modifiable and considered for the prevention of adverse outcomes. This study provides an updated basis for future comparisons with alternative treatments for BPH.


INTRODUCCIÓN: La prostatectomía abierta es un tratamiento eficaz para la Hiperplasia Prostática Benigna (HPB) pero sus tasas de complicaciones y los factores de riesgo para estas pueden variar por particularidades de las poblaciones y los sistemas de salud. OBJETIVO: Determinar la frecuencia de complicacione sy factores de riesgo en los primeros tres meses postquirúrgicos de la prostatectomía abierta en un hospital de alta complejidad de Medellín (Colombia). MATERIALES Y MÉTODOS: Este es un estudio de cohortes en el cual se tomaron pacientes llevados a prostatectomía abierta retropúbica. Se revisaron las historias clínicas para obtener datos demográficos, prequirúrgicos e intraquirúrgicos. El desenlace principal fue la presentación de complicaciones en los primeros tres meses postquirúrgicos y éste se dividió en complicaciones tempranas (entre el día 1 y 7) y tardías (entre el día 8 y 90). Se determinaron los factores de riesgo mediante la estimación de Riesgos Relativos (RR). RESULTADOS: Se incluyeron 191 pacientes con una mediana de edad de 70 años. La frecuencia de complicaciones fue de 34,5%, 14,6% tempranas y 19,9% tardías. Los factores de riesgo fueron dislipidemia (RR: 2,37, IC95%: 1,25 a 4,47), tiempo de irrigación (RR: 1,31, IC95%: 1,02 a 1,67) y duración de sonda postquirúrgica (RR: 1,07, IC95%: 1,03 a 1,12); la anestesia general fue un factor de riesgo protector en comparación con la raquídea (RR: 0,47, IC95%: 0,24 a 0,91). CONCLUSIONES: La frecuencia de complicaciones de la prostatectomía abierta bajo enfoque retropúbico estuvo dentro de las cifras reportadas en la literatura. Los factores de riesgo encontrados podrían ser modificables  y tenerse en cuenta para la prevención de desenlaces adversos. Con este estudio se sienta una base actualizada para futuras comparaciones con tratamientos alternativos para HPB.


Asunto(s)
Hiperplasia Prostática , Anciano , Estudios de Cohortes , Colombia/epidemiología , Humanos , Hiperplasia , Masculino , Prostatectomía/efectos adversos , Hiperplasia Prostática/cirugía
8.
Anal Chem ; 92(5): 3728-3734, 2020 03 03.
Artículo en Inglés | MEDLINE | ID: mdl-32003209

RESUMEN

Electrochemical reactions can effectively follow nonunity stoichiometries as can be found in the electrochemistry of halides, hydrogen, and metal complexes. The voltammetric response of these systems shows peculiar deviations with respect to the well-described features of the 1:1 stoichiometry. With the aim of specifying such differences, a rigorous and manageable analytical theory is deduced for the complete characterization of reversible electrode processes with complex stoichiometry in cyclic voltammetry (CV) at macroelectrodes. Particularly, the main features of the CV of 2:1, 1:2, 3:1, and 1:3 processes (that is, the peak currents and potentials and the influence of the scan rate and of the species concentration and diffusion coefficients) are given and compared with the 1:1 case in order to propose unambiguous diagnostic criteria of the stoichiometry of the electrode reaction. Also, expressions for the concentration profiles and surface concentrations of the redox species are given.

9.
Anal Chem ; 91(9): 5929-5937, 2019 May 07.
Artículo en Inglés | MEDLINE | ID: mdl-30938142

RESUMEN

The design of devices whose functions span from sensing their environments to converting light into electricity or guiding chemical reactivity at surfaces often hinges around a correct and complete understanding of the factors at play when charges are transferred across an electrified solid-liquid interface. For semiconductor electrodes in particular, published values for charge-transfer kinetic constants are scattered. Furthermore, received wisdom suggests slower charge-transfer kinetics for semiconductors than for metal electrodes. We have used cyclic voltammetry of ferrocene-modified silicon photoanodes and photocathodes as the experimental model system and described a systematic analysis to separate charge-transfer kinetics from diode effects and interactions between adsorbed species. Our results suggest that literature values of charge-transfer kinetic constants at semiconductor electrodes are likely to be underestimates of their actual values. This is revealed by experiments and analytical models showing that the description of the potential distribution across the semiconductor-monolayer-electrolyte interface has been largely oversimplified.

10.
Anal Chem ; 91(9): 6072-6079, 2019 05 07.
Artículo en Inglés | MEDLINE | ID: mdl-30938145

RESUMEN

A powerful, unified, and simplifying mathematical approach for the theoretical treatment of first-order chemical kinetics coupled to interfacial charge transfers at electrodes of arbitrary geometry and size, both uniformly accessible and nonuniformly accessible to the electroactive species, is presented. The general CEC mechanism at spherical and disc electrodes is considered to test the validity and benefits of such an approach, based on the application of the so-called kinetic steady state, that enables the reduction of the multivariable problem of kinetic-diffusive differential equations to a single variable problem of a diffusion-only differential equation. This is solved both analytically and numerically, showing how this approach leads to general, simple, and efficient solutions for the study of the influence of coupled chemical kinetics on the voltammetric response. The voltammetry of the CEC mechanism is analyzed as a function of the kinetics and thermodynamics of the preceding and subsequent chemical reactions and of the electrode size (from macroelectrodes to ultramicroelectrodes) and shape (spherical and disc). Comparison with the responses of the CE, EC, and E mechanisms is included, proposing diagnosis criteria and procedures for quantitative analysis of experimental data.

12.
Gerokomos (Madr., Ed. impr.) ; 29(3): 117-122, sept. 2018. tab
Artículo en Español | IBECS | ID: ibc-175043

RESUMEN

Objetivos: Describir las coberturas vacunales en residentes de tres centros geriátricos de Hospitalet de Llobregat, provincia de Barcelona, así como la presencia de criterios que indiquen la vacunación sistemática y no sistemática. Método: Estudio cuantitativo, descriptivo, transversal a 98 residentes de tres residencias de atención geriátrica en Hospitalet de Llobregat ingresados, al menos, 6 meses antes de la fecha de recogida de datos (agosto de 2016). Se analizan variables sociodemográficas y clínicas (fragilidad, vacunación sistemática y no sistemática, patologías y tratamiento) mediante análisis descriptivo univariante con medidas de distribución de frecuencias y asociación entre los resultados de las variables categóricas mediante el test de c2, utilizando programa SPSS v.22. Resultados: Población con una edad media de 85,4 (±7,2) años, 67,3% mujeres. Un 80,4% presenta criterios de fragilidad. Las patologías más prevalentes son: enfermedad cardiovascular, 52,6%; demencia, 42,2%, y diabetes mellitus, 25,5%. Vacunación sistemática en residentes: 93,8% correctamente vacunados de gripe, 83,7% de antineumocócica 23-valente y 61,2% de tétanos-difteria. El 44,9% presentaba vacunación incompleta; de estos, el 25,8% rechazaba voluntariamente alguna o todas las vacunas. Vacunación no sistemática: correctamente vacunados de antineumocócica 13-valente el 100% de los residentes con insuficiencia renal y el 11,11% de los residentes con neoplasias. Conclusiones: El perfil del residente es una mujer mayor de 85 años, frágil, bien vacunada de antineumocócica 23-valente y gripe y con baja cobertura de tétanos-difteria. Existe un alto porcentaje de vacunación incompleta; el rechazo a la vacunación es uno de los principales motivos. Las vacunas no sistemáticas más susceptibles de administración fueron: vacuna neumocócica 13-valente y hepatitis B. Se observa en las recomendaciones de autoridades y sociedades científicas falta de unanimidad en la indicación de vacunas no sistemáticas


Objectives: Describing the vaccination coverage in residents of three geriatric centers of Hospitalet de Llobregat, Barcelona, as well as the criteria that indicate systematic and non-systematic vaccination. Method: A quantitative, descriptive, cross-sectional study of 98 residents of three geriatric care residences in Hospitalet de Llobregat, who were admitted six months before the date of data collection at least (August 2016). Sociodemographic and clinical variables (fragility, systematic and non - systematic vaccination, pathologies and treatment) are analyzed, using univariate descriptive analysis with frequency distribution measures and association between the results of categorical variables using the c2 test using SPSS v.22. Results: Population with mean age of 85.4 (±7.2) years old, 67.3% women. The 80.41% presented fragility criteria. The most prevalent pathologies are cardiovascular disease (52.6%), dementia (42.2%) and diabetes mellitus (25.5%). Systematic vaccination in residents: 93.8% correctly vaccinated of influenza, 83.7% of pneumococcal 23-valent and 61.2% of tetanus-diphtheria. The 44.9% had incomplete vaccination and 25.8% of them voluntarily rejected some or all vaccines. Non-systematic vaccination: the 100% of residents with renal insufficiency and 11.11% of residents with neoplasias were correctly vaccinated with 13-valent pneumococcal. Conclusions: The resident profile is a woman older than 85 years old, fragile, well vaccinated with 23-valent pneumococcal and influenza and with low tetanus-diphtheria coverage. There is a high percentage of incomplete vaccination, with vaccination rejection being that one of the main reasons. The most susceptible non-systematic vaccines to be administrated were: 13-valent pneumococcal and HBV vaccines. The recommendations of scientific authorities and societies have a lack of unanimity in the indication of non-systematic vaccines


Asunto(s)
Humanos , Masculino , Femenino , Anciano , Anciano de 80 o más Años , Hogares para Ancianos , Casas de Salud , Salud del Anciano Institucionalizado , Anciano Frágil , Programas de Inmunización/métodos , Cobertura de Vacunación , Atención Primaria de Salud , Estudios Transversales/métodos , Epidemiología Descriptiva
13.
Anal Chem ; 90(5): 3402-3408, 2018 03 06.
Artículo en Inglés | MEDLINE | ID: mdl-29397699

RESUMEN

Analytical expressions are obtained for the study of the net current and individual fluxes across macro- and micro-liquid/liquid interfaces in series as those found in ion sensing with solvent polymeric membranes and in ion-transfer batteries. The mathematical solutions deduced are applicable to any voltammetric technique, independently of the lipophilicity and charge number of the target and compensating ions. When supporting electrolytes of semihydrophilic ions are employed, the so-called double transfer voltammograms have a tendency to merge into a single signal, which complicates notably the modeling and analysis of the electrochemical response. The present theoretical results point out that the appearance of one or two voltammetric waves is highly dependent on the size of the interfaces and on the viscosity of the organic solution. Hence, the two latter can be adjusted experimentally in order to "split" the voltammograms and extract information about the ions involved. This has been illustrated in this work with the experimental study in water | 1,2-dichloroethane | water cells of the transfer of the monovalent tetraethylammonium cation compensated by anions of different lipophilicity, and also of the divalent hexachloroplatinate anion.

14.
Anal Chem ; 90(3): 2088-2094, 2018 02 06.
Artículo en Inglés | MEDLINE | ID: mdl-29260554

RESUMEN

A new theory is presented to tackle the study of transfer processes of hydrophilic ions in two polarizable interface systems when the analyte is initially present in both aqueous phases. The treatment is applied to macrointerfaces (linear diffusion) and microholes (highly convergent diffusion), obtaining analytical equations for the current response in any voltammetric technique. The novel equations predict two signals in the current-potential curves that are symmetric when the compositions of the aqueous phases are identical while asymmetries appear otherwise. The theoretical results show good agreement with the experimental behavior of the "double transfer voltammograms" reported by Dryfe et al. in cyclic voltammetry (CV) ( Anal. Chem. 2014 , 86 , 435 - 442 ) as well as with cyclic square wave voltammetry (cSWV) experiments performed in the current work. The theoretical treatment is also extended to the situation where the target ion is lipophilic and initially present in the organic phase. The theory predicts an opposite effect of the lipophilicity of the ion on the shape of the voltammograms, which is validated experimentally via both CV and cSWV. For the above two cases, simple and manageable expressions and diagnosis criteria are derived for the qualitative and quantitative study of ion lipophilicity. The ion-transfer potentials can be easily quantified from the separation between the two signals making use of explicit analytical equations.

16.
Nat Commun ; 8(1): 2066, 2017 12 12.
Artículo en Inglés | MEDLINE | ID: mdl-29233986

RESUMEN

Predicting or manipulating charge-transfer at semiconductor interfaces, from molecular electronics to energy conversion, relies on knowledge generated from a kinetic analysis of the electrode process, as provided by cyclic voltammetry. Scientists and engineers encountering non-ideal shapes and positions in voltammograms are inclined to reject these as flaws. Here we show that non-idealities of redox probes confined at silicon electrodes, namely full width at half maximum <90.6 mV and anti-thermodynamic inverted peak positions, can be reproduced and are not flawed data. These are the manifestation of electrostatic interactions between dynamic molecular charges and the semiconductor's space-charge barrier. We highlight the interplay between dynamic charges and semiconductor by developing a model to decouple effects on barrier from changes to activities of surface-bound molecules. These findings have immediate general implications for a correct kinetic analysis of charge-transfer at semiconductors as well as aiding the study of electrostatics on chemical reactivity.

17.
Talanta ; 174: 29-37, 2017 Nov 01.
Artículo en Inglés | MEDLINE | ID: mdl-28738582

RESUMEN

Nowadays most metabolomic studies involve the analysis of large sets of samples to find a representative metabolite pattern associated to the factor under study. During a sequence of analyses the instrument signals can be subjected to the influence of experimental variability sources. Implementation of quality control (QC) samples to check the contribution of experimental variability is the most common approach in metabolomics. This practice is based on the filtration of molecular entities experiencing a variation coefficient higher than that measured in the QC data set. Although other robust correction algorithms have been proposed, none of them has provided an easy-to-use and easy-to-install tool capable of correcting experimental variability sources. In this research an R-package -the MetaboQC- has been developed to correct intra-day and inter-days variability using QCs analyzed within a pre-set sequence of experiments. MetaboQC has been tested in two data sets to assess the correction effects by comparing the metabolites variability before and after application of the proposed tool. As a result, the number of entities in QCs significantly different between days was reduced from 86% to 19% in the negative ionization mode and from 100% to 13% in the positive ionization mode. Furthermore, principal component analysis allowed detecting the filtration of instrumental variability associated to the injection order.

18.
Phys Chem Chem Phys ; 19(25): 16464-16476, 2017 Jun 28.
Artículo en Inglés | MEDLINE | ID: mdl-28608880

RESUMEN

A very general and simple theoretical solution is presented for the current-potential-time response of reversible multi-electron transfer processes complicated by homogeneous chemical equilibria (the so-called extended square scheme). The expressions presented here are applicable regardless of the number of electrons transferred and coupled chemical processes, and they are particularized for a wide variety of microelectrode geometries. The voltammetric response of very different systems presenting multi-electron transfers is considered for the most widely-used techniques (namely, cyclic voltammetry, square wave voltammetry, differential pulse voltammetry and steady state voltammetry), studying the influence of the microelectrode geometry and the number and thermodynamics of the (electro)chemical steps. Most appropriate techniques and procedures for the determination of the 'interaction' between successive transfers are discussed. Special attention is paid to those situations where homogeneous chemical processes, such as protonation, complexation or ion association, affect the electrochemical behaviour of the system by different stabilization of the oxidation states.

19.
Talanta ; 164: 636-644, 2017 Mar 01.
Artículo en Inglés | MEDLINE | ID: mdl-28107983

RESUMEN

The quantitative characterization of inclusion complexes formed in aqueous phase between organic ions and hydrophilic hosts by ion-transfer voltammetry with solvent polymeric membrane ion sensors is studied, both in a theoretical and experimental way. Simple analytical solutions are presented for the determination of the binding constant of the complex from the variation with the host concentration of the electrochemical signal. These solutions are valid for any voltammetric technique and for solvent polymeric membrane ion sensors comprising one polarisable interface (1PI) and also, for the first time, two polarisable interfaces (2PIs). Suitable experimental conditions and data analysis procedures are discussed and applied to the study of the interactions of a common ionic liquid cation (1-octyl-3-metyl-imidazolium) and an ionisable drug (clomipramine) with two hydrophilic cyclodextrins: α-cyclodextrin and 2-hydroxypropyl-ß-cyclodextrin. The experimental study is performed via square wave voltammetry with 2PIs and 1PI solvent polymeric membranes and in both cases the electrochemical experiments enable the detection of inclusion complexes and the determination of the corresponding binding constant.

20.
Angew Chem Int Ed Engl ; 56(3): 782-785, 2017 01 16.
Artículo en Inglés | MEDLINE | ID: mdl-27933691

RESUMEN

A new electrochemical framework for tracking individual soft particles in solution and monitoring their fusion with polarized liquid-liquid interfaces is reported. The physicochemical principle lies in the interfacial transfer of an ionic probe confined in the particles dispersed in solution and that is released upon their collision and fusion with the fluid interface. As a proof-of-concept, spike-like transients of a stochastic nature are reported in the current-time response of 1,2-dichloroethane(DCE)|water(W) submilli-interfaces after injection of DCE-in-W emulsions. The sign and potential dependence of the spikes reflect the charge and lipophilicity of the ionic load of the droplets. A comparison with dynamic light scattering measurements indicates that each spike is associated with the collision of a single sub-picoliter droplet. This opens a new framework for the study of single fusion events at the micro- and nanoscale and of ion transport across biomimetic soft interfaces.

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