Multiuse Nanopore Platform with Disposable Paper Analytical Device for the Detection of Heavy Metal Ions

Abstract

The pollution of heavy metal ions within the environmental is a global problem. The rapid and precise removal of these contaminants can be aided by identifying and quantifying the composition of the sample. It is therefore crucial to develop effective portable analytical techniques to determine the levels of heavy metal contamination.Paper-based analytical devices (PADs) offer a low-cost method making them an excellent platform for onsite environmental sensors. Here we demonstrate how a PAD can be integrated into a multi-use Nanopore platform. The PAD was functionalised with different recognition ligands, who's surface charge densities varied in the presence of an analyte. The surface of the PAD was placed in contact with a Nanopore which exhibited Ion Current Rectification (ICR). The extent of ICR, was dependent upon the PAD's surface charge, and the presence of the analyte of interest i.e. the ICR phenomena was exaggerated or diminished indicating the presence of the metal ion in solution.We demonstrate the potential of PAD-ICR using a PAD functionalised with a peptide aptamer specific for nickel ions. Allowing the detection of nickel(II) as low as 0.25 μM even in the presence of other metal ions. After any measurement, the Nanopore surface can be wiped clean, and reused. PAD-ICR can also be adapted as a multiplexed sensor. This is demonstrated using a PAD with three different DNA aptamers for simultaneous and specific detection of nickel, mercury, and lead ions.

The Detection of Trace Metal Contaminants in Organic Products Using Ion Current Rectifying Quartz Nanopipettes

“…32 Similarly, nonimmobilized polyglutamic acid probes have been employed for the detection of Cu 2+ . 33 Other surface functionalization procedures, with larger molecules, have also been reported, including polyelectrolytes for the detection of Cu 2+ , 34 peptide aptamers for the detection of Ni 2+ , 35 and single-stranded DNA for the detection of Hg 2+ . 36 The development of nanopore metal sensors operable in organic solvent is beneficial to the fine chemical industry, where metal catalysts are heavily utilized.…”

“… 32 Similarly, nonimmobilized polyglutamic acid probes have been employed for the detection of Cu 2+ . 33 Other surface functionalization procedures, with larger molecules, have also been reported, including polyelectrolytes for the detection of Cu 2+ , 34 peptide aptamers for the detection of Ni 2+ , 35 and single-stranded DNA for the detection of Hg 2+ . 36 …”

Layer-by-layer assembly of homopolypeptide polyelectrolytes on asymmetric nanochannels for the detection of nickel ions

“…M. Platt et al introduced a novel approach employing paper-based analytical devices within a nanopore setting specifically for Ni 2+ detection. 17 In addition, Rajesh's group developed a fluorescent sensor based on a Schiff base derivative for the selective detection of Ni 2+ ions. 18 Despite these methods representing notable progress in the detection of nickel ions, the detection limits for nickel ions have yet to meet the desired thresholds for certain applications.…”

Aprotic Solvent Accumulation Amplifies Ion Current Rectification in Conical Nanopores

“…An interesting example, reported by Heaton and Platt, is a multiuse nanopore platform whose rectifying behavior is changed by placing a sheet of metal-immobilized paper on top of the nanopore. 15 While aqueous sensors are suitable for environmental 16 − 19 and biological applications, 20 − 22 they have limited use in industrial settings that feature aprotic solvent production processes, such as in pharmaceutical plants. 23 A deeper understanding of the rectifying behavior of nanopores in non-aqueous electrolytes is essential in the development of ICR sensors compatible with organic solvents and will facilitate a wider range of applications than that for which such sensors are currently developed.…”

“…Numerous fundamental studies into the rectifying behavior of nanopores in aqueous electrolytes have been carried out, notably on the effect of variables including the electrolyte concentration and scan rate on the degree and direction of rectification. − Changes in ICR upon interaction with an analyte can be employed practically in sensing applications and are described by Duleba et al in a recent review paper. An interesting example, reported by Heaton and Platt, is a multiuse nanopore platform whose rectifying behavior is changed by placing a sheet of metal-immobilized paper on top of the nanopore . While aqueous sensors are suitable for environmental − and biological applications, − they have limited use in industrial settings that feature aprotic solvent production processes, such as in pharmaceutical plants .…”