Staple-based paper electrochemical platform for celiac disease diagnosis

A staple-based electrochemical platform is proposed for the first time as a simple and low-cost detection system for paper-based devices. The system, that incorporates small and disposable stainless-steel staples as electrodes (modified with carbon ink in the case of the working electrode) is combined with a paper strip and is carefully optimized with ferrocene carboxylic acid. As a proof-of-concept, it was employed for the enzymatic (HRP-based) immunoelectroanalytical detection of human tissue anti-transglutaminase (anti-tTG), biomarker for celiac disease diagnosis. The intensity of the current due to the electrochemical reduction of TMB (HRP substrate) was recorded chronoamperometrically at -0.2 V in different paper areas. A linear relationship between the current measured at 30 s and the logarithm of the concentration of anti-tTG in the range comprised between 3 and 100 U.mL-1 was obtained. Negative and positive controls produced expected values. Results demonstrated that the paper/staple-combined platform is very convenient for the detection of electroactive analytes and other compounds that can be determined indirectly in bioassays.Fil: Nanni, Paula Inés. Universidad de Oviedo; España. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Instituto Superior de Investigaciones Biológicas. Universidad Nacional de Tucumán. Instituto Superior de Investigaciones Biológicas; Argentina. Universidad Nacional de Tucumán. Facultad de Ciencias Exactas y Tecnología. Departamento de Bioingeniería. Laboratorio de Medios e Interfases; ArgentinaFil: Gonzalez Lopez, Andrea. Universidad de Oviedo; EspañaFil: Nuñez Bajo, Estefanía. Universidad de Oviedo; EspañaFil: Madrid, Rossana Elena. Universidad Nacional de Tucumán. Facultad de Ciencias Exactas y Tecnología. Departamento de Bioingeniería. Laboratorio de Medios e Interfases; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Instituto Superior de Investigaciones Biológicas. Universidad Nacional de Tucumán. Instituto Superior de Investigaciones Biológicas; ArgentinaFil: Fernandez Abedul, M. Teresa. Universidad de Oviedo; Españ

Electrochemical Detection for Isothermal Loop-Mediated Amplification of Pneumolysin Gene of Streptococcus pneumoniae Based on the Oxidation of Phenol Red Indicator

A highly sensitive electrochemical methodology for end-point detection of loop-mediated isothermal nucleic acid amplification reactions was developed. It is based on the oxidation process of phenol red (PR), commonly used as a visual indicator. The dependence of its redox process on pH, which changes during amplification, allows performing quantitative measurements. Thus, the change in the oxidation potential of PR during the amplification is used, for the first time, as the analytical signal that correlates with the number of initial DNA copies. As a proof-of-concept, the amplification of the pneumolysin gene from Streptococcus pneumoniae, one of the main pathogens causing community-acquired pneumonia, is performed. Combination of isothermal amplification with electrochemical detection, performed on small-size flexible electrodes, allows easy decentralization. Adaptation to the detection of other pathogens causing infectious diseases would be very useful in the prevention of future epidemics

Coated and uncoated cellophane as materials for microplates and open-channel microfluidics devices

This communication describes the use of uncoated cellophane (regenerated cellulose films) for the fabrication of microplates, and the use of coated cellophane for the fabrication of open-channel microfluidic devices. The microplates based on uncoated cellophane are particularly interesting for applications that require high transparency in the ultraviolet (UV) regime, and offer a low-cost alternative to expensive quartz-well plates. Uncoated cellophane is also resistant to damage by various solvents. The microfluidic devices, based on coated cellophane, can have features with dimensions as small as 500 μm, and complex, non-planar geometries. Electrodes can be printed on the surface of the coated cellophane, and embedded in microfluidic devices, to develop resistive heaters and electroanalytical devices for flow injection analysis, and continuous flow electrochemiluminescence (ECL) applications. These open-channel devices are appropriate for applications where optical transparency (especially in the visible regime), resistance to damage by water, biocompatibility and biodegradability are important. Cellophane microfluidic systems complement existing cellulose-based paper microfluidic systems, and provide an alternative to other materials used in microfluidics, such as synthetic polymers or glass. Cellulose films are plausible materials for uses in integrated microfluidic systems for diagnostics, analyses, cell-culture, and MEMS.Chemistry and Chemical Biolog