Application of Blind Source Separation Methods to Ion-Selective Electrode Arrays in Flow-Injection Analysis

International audienceAs shown recently, the interference problem typical of ion-selective electrodes can be dealt with via smart arrays adjusted by blind source separation methods. In this letter, we resume this study and show that such an approach can be applied even when faced with a limited number of samples acquired through flow-injection analysis

Adsorption of proteins to thin-films of PDMS and its effect on the adhesion of human endothelial cells

This paper describes a simple and inexpensive procedure to produce thin-films of poly(dimethylsiloxane). Such films were characterized by a variety of techniques (ellipsometry, nuclear magnetic resonance, atomic force microscopy, and goniometry) and used to investigate the adsorption kinetics of three model proteins (fibrinogen, collagen type-I, and bovine serum albumin) under different conditions. The information collected from the protein adsorption studies was then used to investigate the adhesion of human dermal microvascular endothelial cells. The results of these studies suggest that these films can be used to model the surface properties of microdevices fabricated with commercial PDMS. Moreover, the paper provides guidelines to efficiently attach cells in BioMEMS devices.Fil: Chumbimuni Torres, Karin Y.. The University of Texas at San Antonio; Estados UnidosFil: Coronado, Ramon E.. The University of Texas at San Antonio; Estados UnidosFil: Mfuh, Adelphe M.. The University of Texas at San Antonio; Estados UnidosFil: Castro Guerrero, Carlos. The University of Texas at San Antonio; Estados UnidosFil: Silva, María Fernanda. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mendoza. Instituto de Biología Agrícola de Mendoza. Universidad Nacional de Cuyo. Facultad de Ciencias Agrarias. Instituto de Biología Agrícola de Mendoza; ArgentinaFil: Negrete, George R.. The University of Texas at San Antonio; Estados UnidosFil: Bizios, Rena. The University of Texas at San Antonio; Estados UnidosFil: Garcia, Carlos D.. The University of Texas at San Antonio; Estados Unido

Development of ion-selective electrodes: application in detection system of FIA and strategies for the improvement of detection limit

Orientador: Lauro Tatsuo KubotaTese (doutorado) - Universidade Estadual de Campinas, Instituto de QuimicaResumo: O presente trabalho de doutorado descreve o desenvolvimento de eletrodos íon-seletivos para cálcio, potássio, sódio e cloreto em sistema de injeção em fluxo e sua aplicação para determinação simultânea em sucos de frutas, bem como o desenvolvimento de eletrodos íon-seletivos de contato sólido com baixo limite de detecção. A construção dos eletrodos íon-seletivos para os íons cálcio, potássio, sódio e cloreto foi primeiramente realizado em estado estacionário para logo ser incorporada em sistema de injeção em fluxo. A otimização de parâmetros comuns, tais como: pH, tampão, volume de injeção, vazão, entre outros, possibilitaram a realização da determinação simultânea, utilizando um arranjo de eletrodos em série. O sistema FIA potenciométrico proposto foi satisfatório para determinação simultânea destes íons em amostras de sucos, e os resultados quando comparados com os obtidos pelo método de referência foram estatisticamente iguais num nível de confiança de 95%. Em relação ao desenvolvimento de eletrodos íon-seletivos com baixo limite de detecção, quatro eletrodos diferentes foram desenvolvidos para os íons prata, chumbo, cálcio e iodeto com excelente resposta nernstiana e limite de detecção na faixa nanomolar, que foram 2 nmol L para Ag, 1 nmol L para Pb, 4 nmol L para Ca e 10 nmol L para I. Isto foi conseguido pelo uso do polímero condutor, poli(3-octiltiofeno) como interface entre o contato sólido e a membrana polimérica, o copolímero metilmetacrilato-decilmetacrilato. Os eletrodos desenvolvidos mostraram resposta rápida e boa repetibilidade, sendo promissores para sua utilização em determinações em nível de traçoAbstract: The present work describes the development of ion-selective electrodes for calcium, potassium, sodium and chloride to be employed in flow injection analyses and its application for the simultaneous determination in samples, as well as, the development of solid contact ionselective electrodes with detection limit in the nanomolar range. The preparation of ion-selective electrodes for calcium, potassium, sodium and chloride was performed optimizing them in steady-state and then incorporated in simultaneous low injection analyses. The optimization of common parameters, such as: pH, buffer, injection volume, flow, etc., was performed looking for the simultaneous determination, using an array of electrodes in series. The proposed potentiometric FIA system was satisfactory for simultaneous determination of these ions in juice samples, and the results, when compared to the reference method, were statistically the same in the 95% of confidence level. In relation to the development of solid contact ion-selective electrodes with low detection limit, four different electrodes were developed for silver, lead, calcium and iodide, with excellent nernstian response and detection limit in the nanomolar range. The obtained detection limits were 2 nmol L for Ag, 1 nmol L for Pb, 4 nmol L for Ca e 10 nmol L for I. It was possible by using the conducting polymer, poly(3-octylthiophene) as an interface between the solid contact and polymeric membrane, methyl metacrylate decyl metacrylate copolymer. The electrodes presented short response time and good repetibility, being potentially useful for determination in trace levelsDoutoradoQuimica AnaliticaDoutor em Ciência

Desenvolvimento de um eletro ion-seletivo para calcio e sua aplicação em FIA na analise de soro sanguineo

Orientador: Lauro Tatsuo KubotaDissertação (mestrado) - Universidade Estadual de Campinas, Instituto de QuimicaMestrad

Visible Light-Induced Ion-Selective Optodes Based On A Metastable Photoacid For Cation Detection

A new platform of ion-selective optodes is presented here to detect cations under thermodynamic equilibrium via ratiometric analysis. This novel platform utilizes a \u27one of a kind\u27 visible light-induced metastable photoacid as a reference ion indicator to achieve activatable and controllable sensors. These ion-selective optodes were studied in terms of their stability, sensitivity, selectivity, and theoretical aspects

Embedded Peer Coach Pedagogy to Improve Undergraduate Research in STEM Students

This study assesses the effectiveness of student coaches in improving students’ research experience, skills, and confidence in conducting undergraduate research. Research coach pedagogy is based on a model developed at the University of North Carolina (Pukkila, Arnold, Li, & Bickford 2013). In this study faculty recruited and trained peer research coaches from within their disciplines. The study is one-group (23 students) pretest and posttest (14 students) design. During the study, participants taking a first-year composition research course (ENC 1102) were required to meet the research coach twice per month. Results of dependent – t test for paired samples indicate that participants had statistically significantly more research experience, higher research skills, and more confidence in their research ability at the end of the intervention. After controlling for the effect of pre-intervention research experience, participants’ research experience, research skills and their confidence in their research ability was still significantly higher at the post-test as compared to the pre-test. Limitations exist with the internal and external validity of research findings in this study. However, this study supports the efficacy of research coach pedagogy, which could be extended to large introductory STEM classes where the differences before and after the intervention promise to be advantageous

Nanomolar Detection Limits Of Cd\u3csup\u3e2+\u3c/sup\u3e, Ag\u3csup\u3e+\u3c/sup\u3e, And K \u3csup\u3e+\u3c/sup\u3e Using Paper-Strip Ion-Selective Electrodes

Paper-based ion-selective electrodes (ISEs) are simple, flexible, and cost-efficient in comparison to conventional solid-contact ISEs. Yet, paper-based ISEs have poor limits of detection (in the micromolar range) relative to conventional solid-contact ISEs. Here we describe the construction and optimization of ISEs based on commercially available filter paper modified with single-walled carbon nanotubes (SWCNTs), sputtered gold, and conductive polymer poly(3-octylthiophene) to support an ion-selective membrane. The ion-selective membrane presented here is based on the copolymer methyl methacrylate-decyl methacrylate (MMA-DMA). The copolymer MMA-DMA is highly water-repellent and has a low coefficient of diffusion, which makes it particularly suitable for the creation of sensors with high performance in reaching low limits of detection. Three different configurations of the electrodes have been characterized by using contact angle surface analysis, oxygen influence, and testing for the presence of a water layer. Paper-strip ISEs for cadmium, silver, and potassium ions were developed with groundbreaking limits of detection of 1.2, 25.1, and 11.0 nM, respectively. In addition to such low limits of detection, paper-strip ISEs display high selectivity for their ion of interest and high reproducibility. © 2014 American Chemical Society

Recentes avanços e novas perspectivas dos eletrodos íon-seletivos

This paper describes the recent progress in the development of polymeric membranes for ion-selective electrodes. The importance of knowing the mechanism of potential development in membranes for ion-selective electrodes to reach lower detection limits and improve selectivity are discussed. Recent advances and future trends of research on ion-selective electrodes are also reported