A High Sensitivity Micro Format Chemiluminescence Enzyme Inhibition Assay for Determination of Hg(II)

A highly sensitive and specific enzyme inhibition assay based on alcohol oxidase (AlOx) and horseradish peroxidase (HRP) for determination of mercury Hg(II) in water samples has been presented. This article describes the optimization and miniaturization of an enzymatic assay using a chemiluminescence reaction. The analytical performance and detection limit for determination of Hg(II) was optimized in 96 well plates and further extended to 384 well plates with a 10-fold reduction in assay volume. Inhibition of the enzyme activity by dissolved Hg(II) was found to be linear in the range 5–500 pg·mL−1 with 3% CV in inter-batch assay. Due to miniaturization of assay in 384 well plates, Hg(II) was measurable as low as 1 pg·mL−1 within 15 min. About 10-fold more specificity of the developed assay for Hg(II) analysis was confirmed by challenging with interfering divalent metal ions such as cadmium Cd(II) and lead Pb(II). Using the proposed assay we could successfully demonstrate that in a composite mixture of Hg(II), Cd(II) and Pb(II), inhibition by each metal ion is significantly enhanced in the presence of the others. Applicability of the proposed assay for the determination of the Hg(II) in spiked drinking and sea water resulted in recoveries ranging from 100–110.52%

Recent Trends in Monitoring of European Water Framework Directive Priority Substances Using Micro-Sensors: A 2007–2009 Review

This review discusses from a critical perspective the development of new sensors for the measurement of priority pollutants targeted in the E.U. Water Framework Directive. Significant advances are reported in the paper and their advantages and limitations are also discussed. Future perspectives in this area are also pointed out in the conclusions. This review covers publications appeared since December 2006 (the publication date of the Swift report). Among priority substances, sensors for monitoring the four WFD metals represent 81% of published papers. None of analyzed publications present a micro-sensor totally validated in laboratory, ready for tests under real conditions in the field. The researches are mainly focused on the sensing part of the micro-sensors. Nevertheless, the main factor limiting micro-sensor applications in the environment is the ruggedness of the receptor towards environmental conditions. This point constitutes the first technological obstacle to be overcome for any long-term field tests

Hillsdale: Connecting People and Places

This document contains information developed to enhance the efforts of the Hillsdale Vision Group in making Hillsdale a more accessible and pedestrian-friendly community. There are three primary focus areas in the document. A Pedestrian and Bicycle Accessibility Improvement Study. The purpose of this study is to identify potential pedestrian and bicycle routes to the Hillsdale commercial core. It also suggests methods to implement pedestrian and bicycle accessibility, connectivity, and continuity to the surrounding area. A Street Reclassification Report. This report describes the process for street re-classification in the City of Portland and considers the issues which may arise in this process. Down-grading Capital Highway to reduce traffic volumes on this busy artery, thereby fostering a pedestrian and bicycle atmosphere A Business District Access and Circulation Study. This part of the document critically explores current conditions in the Hillsdale commercial area, suggests alternatives to improve some of problems with traffic flow and bicycle/pedestrian access, and strategies to implement this alternatives. Included as an appendix to the document is a Community Outreach Report. This report identifies some strategies to establish a strong base of community participation and input in the planning process. It is provided to strengthen the implementation of the recommendations and alternatives herein

Mercury-Mediated Organic Semiconductor Surface Doping Monitored by Electrolyte-Gated Field-Effect Transistors

Surface doping allows tuning the electronic structure of semiconductors at near-surface regime and is normally accomplished through the deposition of an ultrathin layer on top or below the host material. Surface doping is particularly appealing in organic field-effect transistors (OFETs) where charge transport takes place at the first monolayers close to the dielectric surface. However, due to fabrication restrictions that OFET architecture imparts, this is extremely challenging. Here, it is demonstrated that mercury cations, Hg2+, can be exploited to control doping levels at the top surface of a thin film of a p-type organic semiconductor blended with polystyrene. Electrolyte- or water-gated field-effect transistors, which have its conductive channel at the top surface of the organic thin film, turn out to be a powerful tool for monitoring the process. A positive shift of the threshold voltage is observed in the devices upon Hg2+ exposure. Remarkably, this interaction has been proved to be specific to Hg2+ with respect to other divalent cations and sensitive down to nanomolar concentrations. Hence, this work also opens new perspectives for employing organic electronic transducers in portable sensors for the detection of an extremely harmful water pollutant without the need of using specific receptors.Q.Z. and F.L. contributed equally to this work. The authors thank the ERC-StG 2012-306826 e-GAMES project, the Networking Research Center on Bioengineering, Biomaterials and Nanomedicine (CIBER-BBN), the DGI (Spain) project, FANCY CTQ2016-80030-R, the Generalitat de Catalunya (2014-SGR-17), and the Spanish Ministry of Economy and Competitiveness, through the “Severo Ochoa” Program for Centres of Excellence in R&D (SEV-2015-0496). Q.Z. acknowledges the China Scholarship Council, the National Natural Science Foundation (NSF) of China (Grant No. 11404266). Q.Z. was enrolled in the Materials Science PhD Program of Universitat Autònoma de Barcelona. F.L. gratefully acknowledges the “Juan de la Cierva” program. The research leading to these results has received funding from the People Program (Marie Curie Actions) of the Seventh Framework Program of the European Union (FP7/2007-2013) under REA Grant Agreement No. 600388 (TECNIOSpring program), and from the Agency for Business Competitiveness of the Government of Catalonia, ACCIÓ. The authors thank E. Barrena and A. Pérez for useful discussions.Peer reviewe