A Mercury Ion Electrochemical Sensor Based on Porous Anodized Alumina Membrane Nanochannels Modified with DNA

Abstract

A novel mercury ion (Hg 2+ ) electrochemical sensor was established via chemical modification of porous anodic alumina (PAA) membrane nanochannels with DNA. PAA membrane was prepared by a two-step anodization. Amino groups were introduced to nanochannels by silanization. Special sequence DNA (along with amino group) was modified on PAA membrane nanochannels by the condensation reaction of amino and aldehyde groups. Electrochemical detector was built via sputtered Au nanoparticles on the surface of PAA nanochannels, which could be used as working electrode. The reduction potential of 0 V was applied, where the flux of Fe(CN) 63− was determined by diffusion. The current response has a positive correlation with the concentration of Fe(CN) 6 3− . After DNA immobilized, the negative charge and the steric hindrance of the nanochannels is increased, resulting in the decreasing of the flux of Fe(CN) 6 3− . The detection current is reduced compared with pure PAA membrane nanochannels. When Hg 2+ is present, a stable thymine-Hg 2+ -thymine structure is formed due to the specific reaction between thymine in DNA and Hg 2+ . In this case, the charge density and steric hindrance of the nanochannels are decreased, thereby increasing the flux of Fe(CN) 6 3− and restoring current. The results show that the detection limit is about 0.08 pM with a good linear response (from 1 pM to 100 nM). Meanwhile, the sensor has a good selectivity. The current responses of other metal ions (Mn 2+ , Mg 2+ , Ba 2+ , Co 2+ and Cd 2+ ) are not obvious compared with Hg 2+ . Therefore, this new sensor could be applied for detecting Hg 2+ in the environment.

Bio-inspired Track-Etched Polymeric Nanochannels: Steady-State Biosensors for Detection of Analytes

“…Mercury, present in a variety of different forms (including metallic, inorganic, and organic), is well known as a widespread bio-accumulative pollutant, and ionic mercury (Hg 2+ ) is a neurotoxin that can lead to serious damage to nervous tissues and organs, and also causes toxicity in vivo . ,− Consequently, it is of great importance to develop highly sensitive and selective biosensors for Hg 2+ detection in environmental monitoring, food safety, and clinical therapy. So far, various methods for detecting Hg 2+ have been reported, such as fluorescence sensors, − colorimetric sensors, − surface-enhanced Raman scattering, − and electrochemical sensors. − In 2013, Tian et al developed a biomimetic Hg 2+ -gated nanochannel by functionalizing thymine-rich ssDNA onto the inner surface of a single conical PI nanochannel, and the ssDNA bonded with Hg + to form strong and stable T-Hg + -T complexes . The principle of this device was that the thymine-rich ssDNA would undergo conformational changes in the presence and absence of Hg 2+ , and the sensor showed high sensitivity with a detection limit of 8 nM and high selectivity toward Hg 2+ .…”

Nanochannel-based sensor for the detection of lead ions in traditional Chinese medicine

“…Nowadays, functionalized nanochannel sensors have become one of the representative electrochemical methods, and have been used as a new platform to detect various ions. [20][21][22][23][24] There are two main features in practical applications of functionalized nanochannel sensors: specicity and signal amplication. Firstly, functionalized nanochannel sensors can provide a highly specic surface area, which allows for an increase in the amount of target modication.…”

Review—Track-Etched Nanoporous Polymer Membranes as Sensors: A Review

“…Various routes and methods have been explored so far for the fabrication of synthetic nanopores including ion beam sculpting, 27,28 electron beam sculpting, 29 thermal annealing, 30 micromolding, 31 dielectric breakdown, 32 laser assisted pulling of capillaries 33 and track-etching 34 in versatile materials like silicon nitride, 35 aluminium oxide, 36 boron nitride, 37 graphene, 38 polymers, [39][40][41] quartz 42 and silicon oxide. 43 Track-etching process is especially of interest for us since it allows the fabrication of different nanopore geometries by simply adjusting experimental conditions.…”