A Multiuse Nanopore Platform with Disposable Paper Analytical Device for the Detection of Heavy Meatal Ions (original) (raw)

Preparation of nanopores and their application for the detection of metals

2017

We have prepared nanopores with conical geometries and we have shown the translocation properties of poly(ethylene terephthalate) (PET) membranes. In order to obtain conically shaped nanopores, asymmetric etching procedure was followed. The characterization of PET membranes were performed by electrochemical methods and SEM measurements. The sensing was performed based on resistive-pulse sensing and current-potential (I-V) measurements. Finally, we have reported the resistive-pulse sensing of Ba using single nanoporous membranes and examined the potential dependence of resistive-pulse sensing. Effect of metal ion concentration on the ion current rectification was also shown and it was concluded that a higher Baconcentration can be correlated with rectification ratios.

Development of a Biomolecular Analyzer Based on Ion-conducting Nanopores: The iNAPO Project

2018

Analyzing biologically relevant molecules is an important aspect of medical diagnostics. The iNAPO project aims at developing a device that is able to specifically detect and quantitatively analyze biomolecules. An example is tumor markers that are emitted by the tumor at elevated levels and can be found in body liquids. The analyzer device core consists of a polymer foil containing a nanopore. In analogy to biological nanopores that control e.g. mass transfer into and out of a cell, the biomimetic artificial nanopore allows the passage of ions of an aqueous electrolyte in an electrochemical two - compartment cell from one compartment to the next one under the influence of an electrical field. When the nanopore wall contains certain immobilized molecules that specifically react with the biomolecules to be analyzed, the ionic current is influenced. The difference in th e current can directly be correlated to the presence and the quantity of the biomolecule. As an example, the measure...

Paper-Based Sensor Chip for Heavy Metal Ion Detection by SWSV

Micromachines, 2018

Heavy metal ion pollution problems have had a terrible influence on human health and the environment. Therefore, the monitoring of heavy metal ions is of great practical significance. In this paper, an electrochemical three-electrode system was fabricated and integrated on nitrocellulose membrane (NC) by the use of magnetron sputtering technology, which exhibited a uniform arrangement of porous structure without further film modification. This paper-based sensor chip was used for Cu 2+ detection by square-wave stripping voltammetry (SWSV). Within the ranges of 5-200 µg•L −1 and 200-1000 µg•L −1 , it showed good linearity of 99.58% and 98.87%, respectively. The limit of detection was 2 µg•L −1. On the basis of satisfying the detection requirements (10 µg•L −1), the integrated sensor was small in size and inexpensive in cost. Zn 2+ , Cd 2+ , Pb 2+ and Bi 3+ were also detected by this paper-based sensor chip with good linearity.

Paper-Based Potentiometric Ion Sensing

Analytical Chemistry, 2014

This paper describes the design and fabrication of ion-sensing Electrochemical Paper-based Analytical Devices (EPADs) in which a miniaturized paper reference electrode is integrated with a small ion-selective paper electrode (ISPE) for potentiometric measurements. Ion-sensing EPADs use printed wax barriers to define electrochemical sample and reference zones. Single-layer EPADs for sensing of chloride ions include wax-defined sample and reference zones that each incorporates a Ag/AgCl electrode. In EPADs developed for other electrolytes (potassium, sodium, and calcium ions), a PVC-based ion-selective membrane is added to separate the sample zone from a paper indicator electrode. After the addition of a small volume (less than 10 L) of sample and reference solutions to different zones, ion-sensing EPADs exhibit a linear response, over three orders of magnitude, in ranges of electrolyte concentrations that are most relevant medically, with a slope close to the theoretical value (59.2/z mV). Ion-selective EPADs provide a portable, inexpensive, and disposable way of measuring concentrations of electrolyte ions in aqueous solutions.

Nitrogen-doped carbon dots as fluorescence ON–OFF–ON sensor for parallel detection of copper(ii) and mercury(ii) ions in solutions as well as in filter paper-based microfluidic device

Nanoscale Advances, 2019

Due to improper garbage disposal and rapid industrialization, concentrations of different metal ions are rising to toxic levels in natural water sources. Development of novel, selective and sensitive sensors for different metal ions is in high demand for rapid detection and remediation. Herein, we report nitrogendoped carbon dots (NCDs) with high blue fluorescence, synthesized by a new one-step pyrolytic method using urea and ethylenediaminetetraacetic (EDTA) acid as precursors. The NCDs were used for parallel detection of Hg 2+ and Cu 2+ ions in aqueous medium through a fluorescence ON-OFF-ON process. The minimum detection limit for Hg 2+ and Cu 2+ were 6.2 nM and 2.304 nM, respectively, in aqueous medium, which is close to or below the allowed levels of Hg 2+ and Cu 2+ ions, i.e., 6 ppb and 2 ppm, respectively, in drinking water as per World Health Organisation (WHO). Hg 2+ and Cu 2+ ions were discriminated with vitamin C (ascorbic acid) and trisodium citrate by a fluorescence turn on process. A filter paper based microfluidic device loaded with NCDs, vitamin C and trisodium citrate was developed using candle wax channels on a filter paper as a proof of principle, projecting NCDs as a promising material for parallel detection of multiple metal ions. The device demonstrated herein is capable of detecting Hg 2+ and Cu 2+ ions up to 0.1 mM. This simple, low cost, disposable paper-based device will be very useful for rapid onsite analysis.

Environmentally friendly disposable sensors with microfabricated on-chip planar bismuth electrode for in situ heavy metal ions measurement

Sensors and Actuators B: Chemical, 2008

This paper presents an environmentally friendly disposable heavy metal ion sensor for in situ and online monitoring in the nature and physiological systems. The miniaturized sensor chip consists of a non-toxic microfabricated bismuth (Bi) working electrode that replaces the conventional mercury electrodes, an integrated Ag/AgCl reference electrode, a gold counter electrode, and microfluidic channels. In this work, the electrochemical behavior of the Bi working electrode was characterized in several non-deaerated buffer solutions using cyclic voltammetry. The detection and quantification of Pb (II) and Cd (II) were statically performed using anodic stripping voltammetry inside the microchannels, in the Pb (II) concentration range of 25-400 ppb (R 2 = 0.991) with limit of detection of 8 ppb for 60 s deposition, and in the Cd (II) concentration range of 28-280 ppb (R 2 = 0.986) with limit of detection of 9.3 ppb for 90 s deposition. Particularly, the applications of this sensor chip have been reported with the examples of in situ measurement of Cd (II) concentration in soil pore and ground water and online direct measurement of Cd (II) concentration in cell culture media in its native environment.

The iNAPO Project: Biomimetic Nanopores for a New Generation of Lab-on-Chip Micro Sensors

International Journal of Theoretical and Applied Nanotechnology

In nature, ion conducting nanopores play a vital role for the function of living cells. They undergo gating processes where they open and close upon an external stimulus, such as the presence of a particular biomolecule, the ligand. When the gating process is observed and is quantitatively measured, one can derive data about the presence and the amount of the ligand. Hence, the nanopores can be utilized for specific sensing. However, biological nanopores are embedded in a biological cell membrane that is fragile and unstable with respect to storage and application. The iNAPO (ion conducting nanopores) project aims at combining robust polymer-based nanopores with protein-based biological nanopores, thus combining the selectivity and sensitivity of the latter with the stability and processibility of the first ones. This paper describes the different steps in the fabrication of ion conducting nanopores. It begins with ion irradiation of polymer foils, combined with chemical etching of the ion damage tracks into nanopores. By means of chemical coupling reactions, the nanopore walls are functionalized with particular molecules which react or bioconjugate with the molecules to be analyzed. As an example, a recent result on sensing a physiologically active phosphorus-based anion is shown. By means of a complexation reaction with Zn-di(picolyl)amine, the selective measurement of the concentration of the anion pyrophosphate is demonstrated. In the final step of the project, the nanopores will be incorporated into a Lab-on-Chip system for applications in e.g. medical diagnostics and environmental analysis.

Screen-printed back-to-back electroanalytical sensors: heavy metal ion sensing

The Analyst, 2015

Screen-printed back-to-back microband electroanalytical sensors are applied to the quantification of lead(II) ions for the first time. In this configuration the electrodes are positioned back-to-back with a common electrical connection to the two working electrodes with the counter and reference electrodes for each connected in the same manner as a normal "traditional" screen-printed sensor. Proof-ofconcept is demonstrated for the electroanalytical sensing of lead(II) ions utilising square-wave anodic stripping voltammetry where an increase in the electroanalytical sensitivity is observed by a factor of 5 with the back-to-back microband configuration at a fixed lead(II) ion concentration of 5 µg L −1 utilising a deposition potential and time of −1.2 V and 30 seconds respectively, compared to a conventional (single) microband electrode. The back-to-back microband configuration allows for the sensing of lead(II) ions with a linear range from 5 to 110 µg L −1 with a limit of detection (based on 3σ) corresponding to 3.7 µg L −1 . The back-to-back microband configuration is demonstrated to quantify the levels of lead(II) ions within drinking water corresponding to a level of 2.8 (±0.3) μg L −1 . Independent validation was performed using ICP-OES with the levels of lead(II) ions found to correspond to 2.5 (±0.1) µg L −1 ; the excellent agreement between the two methods validates the electroanalytical procedure for the quantification of lead(II) ions in drinking water. This back-to-back configuration exhibits an excellent validated analytical performance for the determination of lead(II) ions within drinking water at World Health Organisation levels (limited to 10 µg L −1 within drinking water).

Modified Electrodes Used for Electrochemical Detection of Metal Ions in Environmental Analysis

Biosensors, 2015

Heavy metal pollution is one of the most serious environmental problems, and regulations are becoming stricter. Many efforts have been made to develop sensors for monitoring heavy metals in the environment. This review aims at presenting the different label-free strategies used to develop electrochemical sensors for the detection of heavy metals such as lead, cadmium, mercury, arsenic etc. The first part of this review will be dedicated to stripping voltammetry techniques, on unmodified electrodes (mercury, bismuth or noble metals in the bulk form), or electrodes modified at their surface by nanoparticles, nanostructures (CNT, graphene) or other innovative materials such as boron-doped diamond. The second part will be dedicated to chemically modified electrodes especially those with conducting polymers. The last part of this review will focus on bio-modified electrodes. Special attention will be paid to strategies using biomolecules (DNA, peptide or proteins), enzymes or whole cells.

Paper-Based Ion-Selective Potentiometric Sensors

Analytical Chemistry, 2012

A new approach to develop ultra low-cost, robust, rugged, and disposable potentiometric sensors is presented. A suspension of carbon nanotubes in a water−surfactant mixture (carbon nanotubes ink) is applied on conventional filter papers to turn them into conductive papers, which are then used as a substrate to build ion-selective electrodes. The electrodes are made by drop casting a membrane on a small circular area of the conductive paper. In this way, the carbon nanotubes act as both electric conductors and ion-to-electron transducers of the potentiometric signal. Electrodes for sensing K + , NH 4 + , and pH were built and tested using this approach, and the results were compared with classical solid-state ion selective electrodes using carbon nanotubes as transducers and glassy carbon as a substrate. In all cases, the analytical performance (sensitivity, linear ranges, limits of detection, selectivity, etc.) of these disposable paper electrodes was similar to that obtained for the more conventional type of ion-selective-electrodes. This opens new avenues for very low-cost platforms for generation of chemical information.