Progress in Electrochemical Sensors for Health and Environmental Monitoring

A special issue of Micromachines (ISSN 2072-666X). This special issue belongs to the section "C:Chemistry".

Deadline for manuscript submissions: closed (15 December 2022) | Viewed by 13050

Special Issue Editors

Institute for Micromanufacturing (IfM), Louisiana Tech University, Ruston, LA 71272, USA
Interests: electrochemical sensors; chemical neuroscience; micro-nanofabrication; carbon nanomaterials; electrode development; 3D printing; biosensors; neurodegenerative diseases
Special Issues, Collections and Topics in MDPI journals
Department of Chemistry and Physics, Louisiana State University Shreveport, Shreveport, LA 71115, USA
Interests: electrochemical sensors; carbon nanomaterials; physics of nanomaterials; electrochemical impedance spectroscopy

Special Issue Information

Dear Colleagues,

The trace analysis of toxic chemicals with current analytical methods is generally performed using bulky, sophisticated, and expensive lab-based techniques that often require cumbersome pre-concentration and separation methods, and can require expensive reagents, relying on highly trained technicians to perform the complex multi-step sample preparation and analytical procedures. Furthermore, these methods are impractical for large-scale real-time health and environmental monitoring.

Therefore, there is a critical need for a portable, mass-producible, and rapid sensor technology that is amenable to large scale, on-site detection of a diverse array of toxic and other contaminants (e.g., neurotoxins, heavy metals, pesticides, and biochemical markers) with sufficiently accurate sensor metrics (i.e., sensitivity, selectivity, limit of detection, and linear range). Electrochemical techniques with highly multiplexed electrode arrays and miniature potentiostats offer a viable economical means of detecting different classes of chemicals via direct oxidation or reduction at a modified working electrode. However, challenges remain in designing an affordable eco-friendly electrochemical sensor that can operate reliably in minimally or unprepared real-world samples.

We welcome your contribution to this Special Issue, where we aim to publish state-of-the art research results of electrochemical sensors that focus on innovative electrode and sensor designs, novel transduction mechanisms, new materials, coatings, and processes that could be transformative for monitoring and ameliorating public health and environmental concerns.

Prof. Dr. Prabhu Arumugam
Prof. Dr. Shabnam Siddiqui
Guest Editors

Manuscript Submission Information

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Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Micromachines is an international peer-reviewed open access monthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 2600 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

  • electrochemical
  • sensors
  • nanomaterials
  • toxic chemicals
  • arrays
  • 3D/inkjet/screen printing
  • inks
  • eco-friendly
  • performance in challenging environments
  • multiplexing
  • sustainability
  • real-time detection
  • scalability
  • paper/plastic substrates

Related Special Issue

Published Papers (7 papers)

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Research

14 pages, 2473 KiB  
Article
Electrochemical Redox Cycling Behavior of Gold Nanoring Electrodes Microfabricated on a Silicon Micropillar
by Haocheng Yin, Chao Tan, Shabnam Siddiqui and Prabhu U. Arumugam
Micromachines 2023, 14(4), 726; https://0-doi-org.brum.beds.ac.uk/10.3390/mi14040726 - 24 Mar 2023
Viewed by 1344
Abstract
We report the microfabrication and characterization of concentric gold nanoring electrodes (Au NREs), which were fabricated by patterning two gold nanoelectrodes on the same silicon (Si) micropillar tip. Au NREs of 165 ± 10 nm in width were micropatterned on a 6.5 ± [...] Read more.
We report the microfabrication and characterization of concentric gold nanoring electrodes (Au NREs), which were fabricated by patterning two gold nanoelectrodes on the same silicon (Si) micropillar tip. Au NREs of 165 ± 10 nm in width were micropatterned on a 6.5 ± 0.2 µm diameter 80 ± 0.5 µm height Si micropillar with an intervening ~ 100 nm thick hafnium oxide insulating layer between the two nanoelectrodes. Excellent cylindricality of the micropillar with vertical sidewalls as well as a completely intact layer of a concentric Au NRE including the entire micropillar perimeter has been achieved as observed via scanning electron microscopy and energy dispersive spectroscopy data. The electrochemical behavior of the Au NREs was characterized by steady-state cyclic voltammetry and electrochemical impedance spectroscopy. The applicability of Au NREs to electrochemical sensing was demonstrated by redox cycling with the ferro/ferricyanide redox couple. The redox cycling amplified the currents by 1.63-fold with a collection efficiency of > 90% on a single collection cycle. The proposed micro-nanofabrication approach with further optimization studies shows great promise for the creation and expansion of concentric 3D NRE arrays with controllable width and nanometer spacing for electroanalytical research and applications such as single-cell analysis and advanced biological and neurochemical sensing. Full article
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20 pages, 3552 KiB  
Article
Zwitterionic Polymer Coated and Aptamer Functionalized Flexible Micro-Electrode Arrays for In Vivo Cocaine Sensing and Electrophysiology
by Bingchen Wu, Elisa Castagnola and Xinyan Tracy Cui
Micromachines 2023, 14(2), 323; https://0-doi-org.brum.beds.ac.uk/10.3390/mi14020323 - 27 Jan 2023
Cited by 5 | Viewed by 1942
Abstract
The number of people aged 12 years and older using illicit drugs reached 59.3 million in 2020, among which 5.2 million are cocaine users based on the national data. In order to fully understand cocaine addiction and develop effective therapies, a tool is [...] Read more.
The number of people aged 12 years and older using illicit drugs reached 59.3 million in 2020, among which 5.2 million are cocaine users based on the national data. In order to fully understand cocaine addiction and develop effective therapies, a tool is needed to reliably measure real-time cocaine concentration and neural activity in different regions of the brain with high spatial and temporal resolution. Integrated biochemical sensing devices based upon flexible microelectrode arrays (MEA) have emerged as a powerful tool for such purposes; however, MEAs suffer from undesired biofouling and inflammatory reactions, while those with immobilized biologic sensing elements experience additional failures due to biomolecule degradation. Aptasensors are powerful tools for building highly selective sensors for analytes that have been difficult to detect. In this work, DNA aptamer-based electrochemical cocaine sensors were integrated on flexible MEAs and protected with an antifouling zwitterionic poly (sulfobetaine methacrylate) (PSB) coating, in order to prevent sensors from biofouling and degradation by the host tissue. In vitro experiments showed that without the PSB coating, both adsorption of plasma protein albumin and exposure to DNase-1 enzyme have detrimental effects on sensor performance, decreasing signal amplitude and the sensitivity of the sensors. Albumin adsorption caused a 44.4% sensitivity loss, and DNase-1 exposure for 24 hr resulted in a 57.2% sensitivity reduction. The PSB coating successfully protected sensors from albumin fouling and DNase-1 enzyme digestion. In vivo tests showed that the PSB coated MEA aptasensors can detect repeated cocaine infusions in the brain for 3 hrs after implantation without sensitivity degradation. Additionally, the same MEAs can record electrophysiological signals at different tissue depths simultaneously. This novel flexible MEA with integrated cocaine sensors can serve as a valuable tool for understanding the mechanisms of cocaine addiction, while the PSB coating technology can be generalized to improve all implantable devices suffering from biofouling and inflammatory host responses. Full article
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10 pages, 5443 KiB  
Article
UnpadStat Design: Portable Potentiostat for Electrochemical Sensing Measurements Using Screen Printed Carbon Electrode
by Riyanto Setiyono, Tias Febriana Hanifa Lestari, Anni Anggraeni, Yeni Wahyuni Hartati and Husein Hernadi Bahti
Micromachines 2023, 14(2), 268; https://0-doi-org.brum.beds.ac.uk/10.3390/mi14020268 - 20 Jan 2023
Cited by 4 | Viewed by 1959
Abstract
In this research a portable potentiostat was built for electrochemical sensing measurements with three electrodes, specifically SPCEs. The circuit uses a microcontroller as the main controller to manage all activities, starting from adjusting the input voltage for the SPCEs, setting measurement parameters, measuring [...] Read more.
In this research a portable potentiostat was built for electrochemical sensing measurements with three electrodes, specifically SPCEs. The circuit uses a microcontroller as the main controller to manage all activities, starting from adjusting the input voltage for the SPCEs, setting measurement parameters, measuring the resulting current, displaying graphics on the touch screen, sending data to the computer via the USB port, and connecting to the SD card. Measurements and errors with cyclic voltammetry techniques have been compared with commercial potentiostats. The measurement results on a dummy circuit and commercial SPCEs have an accuracy of more than 90% compared to commercial potentiostats. In addition, measurement data can also be saved to an SD card in .CSV format for further purposes. Full article
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15 pages, 6507 KiB  
Article
Rapid and Sensitive Electrochemical Assay of Cefditoren with MWCNT/Chitosan NCs/Fe2O3 as a Nanosensor
by Nida Aydogdu, Goksu Ozcelikay and Sibel A. Ozkan
Micromachines 2022, 13(8), 1348; https://doi.org/10.3390/mi13081348 - 19 Aug 2022
Cited by 2 | Viewed by 1302
Abstract
In this research, a glassy carbon electrode (GCE) modified by MWCNT/chitosan NCs/Fe2O3 was prepared for the determination of the cephalosporin antibiotic cefditoren (CFT) using adsorptive stripping differential pulse and cyclic voltammetry techniques. The effects of pH, the scan rate, the [...] Read more.
In this research, a glassy carbon electrode (GCE) modified by MWCNT/chitosan NCs/Fe2O3 was prepared for the determination of the cephalosporin antibiotic cefditoren (CFT) using adsorptive stripping differential pulse and cyclic voltammetry techniques. The effects of pH, the scan rate, the deposition potential, the accumulation time, and modification agents on the determination of CFT were analyzed. The results showed that the modified electrode significantly increased the oxidation peak current of CFT. Under optimized conditions, the MWCNT/chitosan NCs/Fe2O3/GCE nanosensor exhibited a linear response between 0.2 µM and 10 µM toward CFT. The limit of detection and quantification were determined to be 1.65 nM and 5.50 nM, respectively. Model drugs (cefdinir, cefpodoxime, cephalexin, and ceftazidime compounds) were used to enlighten the CFT oxidation mechanism. Moreover, the nanosensor was used to analyze CFT in a pharmaceutical dosage form and commercial deproteinated human serum samples. The accuracy of these methods was proven in the recovery studies, with values of 96.98 and 98.62% for the pharmaceutical dosage form and commercial deproteinated human serum sample, respectively. Full article
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14 pages, 6466 KiB  
Article
An Electrochemical Electrode to Detect Theophylline Based on Copper Oxide Nanoparticles Composited with Graphene Oxide
by Vinoda B. Patil, Shweta J. Malode, Sumitra N. Mangasuli, Suresh M. Tuwar, Kunal Mondal and Nagaraj P. Shetti
Micromachines 2022, 13(8), 1166; https://0-doi-org.brum.beds.ac.uk/10.3390/mi13081166 - 23 Jul 2022
Cited by 20 | Viewed by 1770
Abstract
The electrochemical analysis of theophylline (THP) was investigated by fabricating a carbon paste electrode (CPE) modified with graphene oxide (GO) along with copper oxide (CuO) nanoparticles (CuO-GO/CPE). The impact of electro-kinetic parameters such as the heterogeneous rate constant, the scan rate, the accumulation [...] Read more.
The electrochemical analysis of theophylline (THP) was investigated by fabricating a carbon paste electrode (CPE) modified with graphene oxide (GO) along with copper oxide (CuO) nanoparticles (CuO-GO/CPE). The impact of electro-kinetic parameters such as the heterogeneous rate constant, the scan rate, the accumulation time, the pH, the transfer coefficient, and the number of electrons and protons transferred into the electro-oxidation mechanism of THP has been studied utilizing electrochemical methods such as cyclic voltammetry (CV) and differential pulse voltammetry (DPV). The differential pulse voltammetry technique was employed to investigate THP in pharmaceutical and biological samples, confirming the limit of detection (LOD) and quantification (LOQ) of the THP. X-ray diffraction (XRD) and scanning electron microscopy (SEM) analysis were performed to characterize the CuO nanoparticles. The CuO-GO/CPE was more sensitive in THP detection because its electrocatalytic characteristics displayed an enhanced peak current in the 0.2 M supporting electrolyte of pH 6.0, proving the excellent sensing functioning of the modified electrode. Full article
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13 pages, 2787 KiB  
Article
Brain-Implantable Multifunctional Probe for Simultaneous Detection of Glutamate and GABA Neurotransmitters: Optimization and In Vivo Studies
by Sanjeev Billa, Yaswanthi Yanamadala, Imran Hossain, Shabnam Siddiqui, Nicolaie Moldovan, Teresa A. Murray and Prabhu U. Arumugam
Micromachines 2022, 13(7), 1008; https://0-doi-org.brum.beds.ac.uk/10.3390/mi13071008 - 26 Jun 2022
Cited by 6 | Viewed by 2041
Abstract
Imbalances in levels of glutamate (GLU) and gamma-aminobutyric acid (GABA) and their sub-second signaling dynamics occur in several brain disorders including traumatic brain injury, epilepsy, and Alzheimer’s disease. The present work reports on the optimization and in vivo testing of a silicon (Si) [...] Read more.
Imbalances in levels of glutamate (GLU) and gamma-aminobutyric acid (GABA) and their sub-second signaling dynamics occur in several brain disorders including traumatic brain injury, epilepsy, and Alzheimer’s disease. The present work reports on the optimization and in vivo testing of a silicon (Si) multifunctional biosensor probe for sub-second simultaneous real-time detection of GLU and GABA. The Si probe features four surface-functionalized platinum ultramicroelectrodes (UMEs) for detection of GLU and GABA, a sentinel site, and integrated microfluidics for in-situ calibration. Optimal enzyme concentrations, size-exclusion phenylenediamine layer and micro spotting conditions were systematically investigated. The measured GLU sensitivity for the GLU and GABA sites were as high as 219 ± 8 nA μM−1 cm−2 (n = 3). The measured GABA sensitivity was as high as 10 ± 1 nA μM−1 cm−2 (n = 3). Baseline recordings (n = 18) in live rats demonstrated a useful probe life of at least 11 days with GLU and GABA concentrations changing at the levels of 100′s and 1000′s of μM and with expected periodic bursts or fluctuations during walking, teeth grinding and other activities and with a clear difference in the peak amplitude of the sensor fluctuations between rest (low) and activity (higher), or when the rat was surprised (a reaction with no movement). Importantly, the probe could improve methods for large-scale monitoring of neurochemical activity and network function in disease and injury, in live rodent brain. Full article
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9 pages, 2076 KiB  
Communication
A General, Label-Free and Homogeneous Electrochemical Strategy for Probing of Protease Activity and Screening of Inhibitor
by Yunxiao Feng, Gang Liu, Fan Zhang, Jianwen Liu, Ming La and Ning Xia
Micromachines 2022, 13(5), 803; https://0-doi-org.brum.beds.ac.uk/10.3390/mi13050803 - 21 May 2022
Cited by 3 | Viewed by 1513
Abstract
Proteases play a critical role in regulating various physiological processes from protein digestion to wound healing. Monitoring the activity of proteases and screening their inhibitors as potential drug molecules are of great importance for the early diagnosis and treatment of many diseases. In [...] Read more.
Proteases play a critical role in regulating various physiological processes from protein digestion to wound healing. Monitoring the activity of proteases and screening their inhibitors as potential drug molecules are of great importance for the early diagnosis and treatment of many diseases. In this work, we reported a general, label-free and homogeneous electrochemical method for monitoring protease activity based on the peptide–copper interaction. Cleavage of peptide substrate results in the generation of a copper-binding chelator peptide with a histidine residue in the first or third position (His1 or His3) at the N-terminal. The redox potential and current of copper coordinated with the product are different from the free copper or the copper complex with the substrate, thus allowing for the detection of protease activity. Angiotensin-converting enzyme (ACE) and thrombin were determined as the model analytes. The label-free and homogeneous electrochemical method can be used for screening protease inhibitors with high simplicity and sensitivity. Full article
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