Electrochemical Sensing Platform Research Articles

Gold Nanomaterials and their Composites as Electrochemical Sensing Platforms for Nitrite Detection.

Nitrite is one of the abundant toxic components existing in the environment and is likely to have a great potential to affect human health badly. For that reason, it has become crucial to build a reliable nitrite detection method. In recent years, several nitrite monitoring systems have been proposed. Compared with traditional analytical strategies, the electrochemical approach has a bunch of advantages, including low cost, rapid response, easy operation, simplicity, etc. In this case, noble metal nanomaterials, especially Au-based nanomaterials, have attracted attention in electrode modification because of higher catalytic activity, facile mass transfer, and broad active area for determining nitrite. This review is based on the state-of-the-art, which includes a variety of nanomaterials that have been coupled with gold nanoparticles (AuNPs) for the creation of nanocomposites, and the construction as well as development of electrochemical sensors for nitrite detection over the last few years (2016-2022). A background study on synthesizing different morphological AuNPs and nanocomposites has also been introduced. The fabrication methods and sensing capabilities of modified electrodes are given special consideration.

Activated Glassy Carbon Electrode as an Electrochemical Sensing Platform for the Determination of 4-Nitrophenol and Dopamine in Real Samples.

Glassy carbon electrode (GCE) was electrochemically activated using a repetitive cyclic voltammetric technique to develop an activated glassy carbon electrode (AGCE). The developed AGCE was optimized and utilized for the electrochemical assay of 4-nitrophenol (4-NP) and dopamine (DA). Cyclic voltammetry (CV) was employed to investigate the electrochemical behavior of the AGCE. Compared to the bare GCE, the developed AGCE exhibits a significant increase in redox peak currents of 4-NP and DA, which indicates that the AGCE significantly improves the electrocatalytic reduction of 4-NP and oxidation of DA. The electrochemical signature of the activation process could be directly associated with the formation of oxygen-containing surface functional groups (OxSFGs), which are the main reason for the improved electron transfer ability and the enhancement of the electrocatalytic activity of the AGCE. The effects of various parameters on the voltammetric responses of the AGCE toward 4-NP and DA were studied and optimized, including the pH, scan rate, and accumulation time. Differential pulse voltammetry (DPV) was also utilized to investigate the analytical performance of the AGCE sensing platform. The optimized AGCE exhibited linear responses over the concentration ranges of 0.04–65 μM and 65–370 μM toward 4-NP with a lower limit of detection (LOD) of 0.02 μM (S/N = 3). Additionally, the AGCE exhibited a linear responses over the concentration ranges of 0.02–1.0 and 1.0–100 μM toward DA with a lower limit of detection (LOD) of 0.01 μM (S/N = 3). Moreover, the developed AGCE-based 4-NP and DA sensors are distinguished by their high sensitivity, excellent selectivity, and repeatability. The developed sensors were successfully applied for the determination of 4-NP and DA in real samples with satisfactory recovery results.

Preparation of cuprous oxide-supported silver-modified reduced graphene oxide nanocomposites for non-enzymatic electrochemical sensor

Abstract We constructed a non-enzymatic H2O2 sensor based on cuprous oxide-supported silver-modified reduced graphene oxide nanocomposites. It was found that the sensor exhibited good performances for sensing H2O2 with a detection limit of 0.34 μM and a wide detection range of 1–310 μM. The combination of graphene with silver and cuprous oxide improved the sensor’s sensitivity for detecting H2O2, with good repeatability, selectivity, and stability. The synthesis method of this nanocomposite provides a new idea for the green preparation of graphene-based nanocomposites and a new method for the construction of a new electrochemical sensor platform.

A recent advancement on the applications of nanomaterials in electrochemical sensors and biosensors

Industrialization and globalization, both on an international and local scale, have caused large quantities of toxic chemicals to be released into the environment. Thus, developing an environmental pollutant sensor platform that is sensitive, reliable, and cost-effective is extremely important. In current years, considerable progress has been made in the expansion of electrochemical sensors and biosensors to monitor the environment using nanomaterials. A large number of emerging biomarkers are currently in existence in the biological fluids, clinical, pharmaceutical and bionanomaterial-based electrochemical biosensor platforms have drawn much attention. Electrochemical systems have been used to detect biomarkers rapidly, sensitively, and selectively using biomaterials such as biopolymers, nucleic acids, proteins etc. In this current review, several recent trends have been identified in the growth of electrochemical sensor platforms using nanotechnology such as carbon nanomaterials, metal oxide nanomaterials, metal nanoparticles, biomaterials and polymers. The integration strategies, applications, specific properties and future projections of nanostructured materials for emerging progressive sensor platforms are also observed. The objective of this review is to provide a comprehensive overview of nanoparticles in the field of electrochemical sensors and biosensors.

Magnetic Nanoparticle-Based Electrochemical Sensing Platform Using Ferrocene-Labelled Peptide Nucleic Acid for the Early Diagnosis of Colorectal Cancer.

Diagnostic biomarkers based on epigenetic changes such as DNA methylation are promising tools for early cancer diagnosis. However, there are significant difficulties in directly and specifically detecting methylated DNA regions. Here, we report an electrochemical sensing system based on magnetic nanoparticles that enable a quantitative and selective analysis of the methylated septin9 (mSEPT9) gene, which is considered a diagnostic marker in early stage colorectal cancer (CRC). Methylation levels of SEPT9 in CRC samples were successfully followed by the selective recognition ability of a related peptide nucleic acid (PNA) after hybridization with DNA fragments in human patients’ serums and plasma (n = 10). Moreover, this system was also adapted into a point-of-care (POC) device for a one-step detection platform. The detection of mSEPT9 demonstrated a limit of detection (LOD) value of 0.37% and interference-free measurement in the presence of branched-chain amino acid transaminase 1 (BCAT1) and SRY box transcription factor 21 antisense divergent transcript 1 (SOX21-AS1). The currently proposed functional platform has substantial prospects in translational applications of early CRC detection.

Electrochemical Sensing Platform Based on Functionalized Multi-Walled Carbon Nanotubes and Metal Oxide for the Detection and Degradation Studies of Orange II Dye.

Textile industry effluents are heavily contaminated with dyes. The discharge of these toxic dyes into waterbodies poses a serious threat to aquatic flora and fauna. The ultimate entrance of these toxins from thereon into the food chain affects the primary and secondary consumers. Therefore, the adoption of a sustainable solution for protection against the detrimental effects associated with adulterated water is an immediate need of the hour. To address the severity of the issue, the present work aims to design an electrochemical sensing platform by modifying the glassy carbon electrode (GCE) with zinc oxide nanoparticles and amino group-functionalized multi-walled carbon nanotubes (NH2-fMWCNTs) for the detection of Orange II, which is a toxic azo dye. Zinc oxide nanoparticles facilitate electron transfer between the transducer and the analyte. While, the positively charged NH2-fMWCNTs in acidic medium help in preconcentration of negatively charged analyte molecules at the electrode/electrolyte interface. The modification of the GCE catalyzed the oxidation of Orange II, as evidenced by the negative shift of the oxidation potential and enhancement in peak current intensity. Square wave voltammetry was used to optimize various experimental conditions, such as the supporting electrolyte, pH of the electrolyte, deposition potential, and deposition time for the best performance of the designed sensor. Under the optimized conditions, the detection limit and quantification of the designed sensor were found to be 0.57 and 1.92 nM, respectively. The catalytic degradation studies of Orange II was shown to be facilitated by titanium dioxide, which acted as a photocatalyst. The addition of hydrogen peroxide further promoted the extent and rate of degradation of dye. The breakdown of Orange II was probed by the designed sensing platform electrochemically and also by UV–visible spectroscopy. The dye degraded up to 92% by following pseudo-first-order kinetics.

Non-enzymatic Electrochemical Sensing of 3-Hydroxybutyric Acid by Incorporating Manganese Oxide Modified Electrode and Nitroprusside Electrolyte

The development of 3-hydroxybutyric acid (3-HB) biosensors via electrochemical method is commonly based on the use of enzymes that usually display inherent instability. Here, a novel non-enzymatic 3-HB electrochemical sensor platform by incorporating manganese oxide nanoparticles (Mn2O3 NPs) modified screen printed carbon electrode (SPCE) and sodium nitroprusside (SNP) electrolyte was reported for the first time. The mechanism of this sensor based on the formation of electroactive SNP-HB species with assistance of Mn2O3 catalyst. By the enhanced electroactivity of the complex, 3-HB can be quantitatively measured based on the increased peak current and shifted peak potential in cyclic voltammograms of SNP reduction. SNP concentration and Mn2O3 loading were optimized for maximum current response. The sensitivity of as-prepared sensor system was examined under different pH values (6.4–7.4) in the range of 0–10 mM 3-HB. The highest sensitivity of 39.07 μA·mM−1·cm−2 and 5.84 mV·mM−1 with LOD of 0.5 mM was achieved at pH 7.4 of electrolyte solution. The proposed sensor provided favorable stability and selectivity against various interferents. In addition, the ability to quantitatively detect 3-HB in artificial urine was also demonstrated, suggesting that our sensor can be a promising candidate for practical applications.

A Highly Sensitive Electrochemical Sensing Platform Based on P-doped Fe/Fe3O4@C for the Detection of 4-Nitrophenol

4-Nitrophenol (4-NP) is a typical organic pollutant, thus it is urgent to detect it in environmental samples. This study rationally designed a novel electrode material of P-doping Fe/Fe3O4@C (P-Fe/Fe3O4@C) prepared with MIL-88 as precursor. P2h-Fe/Fe3O4@C-700 was synthesized by calcining MIL-88 at 700 °C, followed by annealing process with NaH2PO2 for 2 h. The P2h-Fe/Fe3O4@C-700 modified glassy carbon electrode (P2h-Fe/Fe3O4@C-700/GCE) showed a high electrocatalytic activity toward 4-NP reduction due to its active metal center, fine-tuned electronic structure by P-doping, as well as good electrical conductivity. It exhibited excellent sensing behaviors in 4-NP detection with rather high sensitivities of 1415.43 μA·mM−1·cm−2 and 424.63 μA·mM−1·cm−2 in the 4-NP concentration of 5 to 100 μM and 100 to 1200 μM, respectively, with a low detection limit of 0.462 μM. The P2h-Fe/Fe3O4@C-700/GCE still had good selectivity for 4-NP detection in the presence of common interferences. In addition, it was found that the current response towards 4-NP at P2h-Fe/Fe3O4@C-700/GCE retained more than 97% of its initial value after one week, indicating a good long-term stability. Furthermore, the P2h-Fe/Fe3O4@C-700/GCE exhibited a good reproducibility. The constructed P2h-Fe/Fe3O4@C-700/GCE achieved practical uses for the sensing of 4-NP in tap water with satisfactory recoveries.

Covalent Organic Frameworks-TpPa-1 as an Emerging Platform for Electrochemical Sensing.

Covalent organic frameworks (COFs) are a new type of metal-free porous architecture with a well-designed pore structure and high stability. Here an efficient electrochemical sensing platform was demonstrated based on COFs TpPa-1 constructed by 1,3,5-triformylphloroglucinol (Tp) with p-phenylenediamine (Pa-1), which possesses abundant nitrogen and oxo-functionalities. COFs TpPa-1 exhibited good water dispersibility and strong adsorption affinities for Pd2+ and thus was used as loading support to modify Pd2+. The Pd2+-modified COFs TpPa-1 electrode (Pd2+/COFs) showed high electrocatalytic activity for both hydrazine oxidation reaction and nitrophenol reduction reaction. In addition, TpPa-1-derived nitrogen-doped carbon presented high activity for the electro-oxidation of reduced glutathione (GSH), and sensitive electrochemical detection of GSH was achieved. The presented COFs TpPa-1 can be utilized as a precursor as well as support for anchoring electro-active molecules and nanoparticles, which will be useful for electrochemical sensing and electrocatalysis.

E.P.A.S.S: Electroanalytical Pillbox Assessment Sensor System, A Case Study Using Metformin Hydrochloride.

Adulteration of medications is an emerging and significant threat to human health and well-being, even though adulterants are still often not considered seriously in clinical or forensic toxicology. Screening of drug adulterations is a major challenge and concern for regulatory authorities worldwide. Metformin hydrochloride, an important drug to treat diabetes, is found to be adulterated worldwide and a major reason to worry about the health and safety procedure. We have demonstrated a first-of-a-kind electrochemical biomedical device utilizing exfoliated graphene oxide (GO)─Nafion-modified customized gold screen-printed electrodes (spiral electrochemical notification-coupled electrode, SENCE), driven by electrochemical adsorptive stripping voltammetry, to identify the trace level adulteration in metformin. The GO-Nafion-SPE interface has been characterized by powder X-ray diffraction, X-ray photoelectron spectroscopy, scanning electron microscopy, energy-dispersive X-ray analysis, and Fourier transform infrared. Custom-made screen-printed SENCEs have been functionalized with GO nanoparticles (transducer) to obtain a fingerprint signal response of metformin using differential pulse voltammetry. A linear calibrated dose response has been obtained with n = 3 repetitions with a low limit of detection of 10 ppm for metformin. We have used the sensing response as a function of adulteration, and it is extensively supported by rigorous statistical analysis along with the help of the machine learning tool. This is a first-of-its-kind IoT-enabled electrochemical sensor and analysis platform that can detect drug adulteration as a low, medium, and high output.

MIP-based electrochemical sensor for direct detection of hepatitis C virus via E2 envelope protein

Hepatitis C is the most common liver disease caused by Hepatitis C virus (HCV), and can evolve into serious health problems e.g. cirrhosis and hepatocellular carcinoma. Nowadays, the initial stage of the disease cannot be practically diagnosed, representing thus an extremely important problem of modern public health care. This study is aimed at the development of a sensor for direct detection of HCV. The sensor utilizes a synthetic recognition element prepared by the technology of molecular imprinting and representing a molecularly imprinted polymer (MIP) having molecular recognition sites of HCV envelope protein E2 (E2-MIP). E2-MIP integrated into an electrochemical sensor platform allows quantitative evaluation of binding of free E2 protein as well as HCV-mimetic particles (HCV-MPs) in human plasma with LOD value of 4.6 × 10−4 ng/mL (for HCV-MPs). The developed electrochemical HCV sensor represents a simple, fast and inexpensive alternative for the existing methods of HCV detection and paves the way for the point-of care diagnostics of Hepatitis C.

Wireless Wearable Electrochemical Sensing Platform with Zero-Power Osmotic Sweat Extraction for Continuous Lactate Monitoring.

Wearable and wireless monitoring of biomarkers such as lactate in sweat can provide a deeper understanding of a subject's metabolic stressors, cardiovascular health, and physiological response to exercise. However, the state-of-the-art wearable and wireless electrochemical systems rely on active sweat released either via high-exertion exercise, electrical stimulation (such as iontophoresis requiring electrical power), or chemical stimulation (such as by delivering pilocarpine or carbachol inside skin), to extract sweat under low-perspiring conditions such as at rest. Here, we present a continuous sweat lactate monitoring platform combining a hydrogel for osmotic sweat extraction, with a paper microfluidic channel for facilitating sweat transport and management, a screen-printed electrochemical lactate sensor, and a custom-built wireless wearable potentiostat system. Osmosis enables zero-electrical power sweat extraction at rest, while continuous evaporation at the end of a paper channel allows long-term sensing from fresh sweat. The positioning of the lactate sensors provides near-instantaneous sensing at low sweat volume, and the custom-designed potentiostat supports continuous monitoring with ultra-low power consumption. For a proof of concept, the prototype system was evaluated for continuous measurement of sweat lactate across a range of physiological activities with changing lactate concentrations and sweat rates: for 2 h at the resting state, 1 h during medium-intensity exercise, and 30 min during high-intensity exercise. Overall, this wearable system holds the potential of providing comprehensive and long-term continuous analysis of sweat lactate trends in the human body during rest and under exercising conditions.

(Digital Presentation) Simultaneous and Real-Time Electrochemical Detection of Multiple Biomarkers in a Microfluidic Chip

Dysregulations in metabolic and physiological cellular processes are generally accompanied by changes in concentration profiles of multiple biomarkers. Measuring dynamic changes in concentrations of several affected biomarkers can enhance our comprehension of the underlying disease pathophysiology and/or mechanisms of cytotoxicity. Most analytical detection techniques require samples to be obtained at pre-defined times for offline analysis. However, the inadequate temporal resolution of these methods can lead to key biological events that occur at shorter timescales, being overlooked. Electrochemical biosensors are relatively simple, cost-effective detection techniques that have been used extensively for continuous analyte monitoring, and more recently, for sensing multiple analytes. We describe the design and functionality of a novel electrochemical detection platform, comprising a screen-printed Pt electrode array, a microfluidic chip, and an automated pump and valve system, capable of quantitatively detecting up to eight analytes. As a proof of concept, we show the simultaneous, sensitive, and selective amperometric detection of four essential biomarkers- glucose, lactate, glutamate, and acetylcholine, in real time. We also demonstrate the biological application of this platform by continuously monitoring exocytotic glutamate release from human induced pluripotent stem cell-derived neuronal cultures over time. Excessive accumulation of glutamate in the synaptic cleft leads to prolonged stimulation of glutamate receptors on neurons, triggering a cascade of neurotoxic events that ultimately results in loss of neuronal function and cell death. The results suggest that our multianalyte electrochemical sensor platform can be coupled with more complex biological systems such as in vitro organotypic models, for the accurate monitoring of biomarker changes during adverse events like acute neurotoxicity and microbial infection.

Electrochemical Sensing Platform Based on The Modified Carbon-Ceramic Electrode Using Multiwalled Carbon Nanotubes (MWCNTs) Through The Sol-Gel Process: Application in Sensitive Determination of Morin as A Common Flavonoids

Morin is one of the most common flavonoids which found in nature, plants and vegetable-derived foods and Brazilian yellow tree is a source for its extraction. Because of hydroxyl group existence, Morin represents better antioxidant properties and have great significance in bio electrochemistry-based investigations. In this research work, an electrochemical-based sensing platform was designed based on a modified carbon-ceramic electrode (CCE) through a sol-gel process with carbon nanotubes for the investigation of the electrochemical behavior of Morin. Various electrochemical techniques have been used for the analytical investigation of the proposed sensing platform including cyclic voltammetry (CV), differential pulse voltammetry (DPV), and anodic stripping voltammetry (ASV) methods. Furthermore, the morphological investigation was efficiently performed for the demonstration of electrode surface characteristics. The obtained results showed that the anodic peak currents increased linearly in a concentration range of 0.7– 3 µM, where detection limit is equal to 0.27 µM for DPV, and the linear range is considered to be 0.6-4 µM where there is a lower detection limit of 0.3 µM for ASV. Such a biosensing assay can also prove a great potential for the determination of Morin in dry tea.

Plasma Functionalized Carbon Interfaces for Biosensor Application: Toward the Real-Time Detection of Escherichia coli O157:H7.

Nonthermal plasma, a nondestructive, fast, and highly reproducible surface functionalization technique, was used to introduce desired functional groups onto the surface of carbon powder. The primary benefit is that it is highly scalable, with a high throughput, making it easily adaptable to bulk production. The plasma functionalized carbon powder was later used to create highly specific and low-cost electrochemical biosensors. The functional groups on the carbon surface were confirmed using NH3-temperature-programmed desorption (TPD) and X-ray photoelectron spectroscopy (XPS) analysis. In addition, for biosensing applications, a novel, cost-effective, robust, and scalable electrochemical sensor platform comprising in-house-fabricated carbon paste electrodes and a miniaturized E-cell was developed. Biotin–Streptavidin was chosen as a model ligand–analyte combination to demonstrate its applicability toward biosensor application, and then, the specific identification of the target Escherchia coliO157:H7 was accomplished using an anti-E. coliO157:H7 antibody-modified electrode. The proposed biosensing platform detected E. coliO157:H7 in a broad linear range of (1 × 10–1–1 × 106) CFU/mL, with a limit of detection (LOD) of 0.1 CFU/mL. In addition, the developed plasma functionalized carbon paste electrodes demonstrated high specificity for the target E. coliO157:H7 spiked in pond water, making them ideal for real-time bacterial detection.

Electrochemical DNA Scaffold-Based Sensing Platform for Multiple Modes of Protein Assay and a Keypad Lock System

Development of a flexible, easy-to-use, and well-controllable DNA-based sensing platform would provide enormous opportunities to boost molecular diagnosis and signal transduction or information processing. Herein, a duplex DNA scaffold containing a bulge was deployed for the fabrication of a simple and general DNA-based electrochemical sensing platform. It could be harnessed for different signal output behaviors (one signal-off and two signal-on modes) toward a single-step analysis of the target protein. The detection limit toward the target protein could reach about 0.1 nM. Also, it could be used as a streamlined electrochemical workflow for the successive monitoring of protein binding. Furthermore, such an electrochemical sensing platform could be explored for the operation of the concatenated AND logic gates as a molecular keypad lock system. The current sensing platform based on only one duplex DNA scaffold presented features such as simple biosensor design and fabrication, flexible operation for different signal outputs, sensitive and selective protein detection, and expandable logic operation. It thus would pave a broad road toward the development of high-performance biosensors or logic devices to be applied for molecular diagnosis or computing.

Ultraselective, ultrasensitive, point-of-care electrochemical sensor for detection of Hg(II) ions with electrospun-InZnO nanofibers

Mercury is one of the top three most hazardous substances (Agency for Toxic Substances and Disease Registry). It is among one of the highly toxic water pollutants causing damage to the brain, lungs, nervous system, and many other vital human organs. Hence, detecting Hg(II) at the lowest concentration (picomolar-femtomolar) is highly desirable to avoid adverse health effects. This article outlines an insightful electrochemical sensor platform for ultraselective sensing of Hg(II) with Self Assembled Monolayers (SAM) of mercaptosuccinic acid (MSA) cross-linked pyridinedicarboxylic acid (PDCA) on top of indium doped ZnO nanofibers (InZnO-NF). The sensor achieves a limit of detection (LOD) 3.13 fM. To improve charge transport properties, indium-doping is used. The MSA-PDCA combination with multifunctional strategy has excellent selectivity towards targeted Hg(II) ions because of its highest stability constant and strong coordinate covalent bond of carboxyl groups (–COOH) with Hg(II). The interaction of Hg(II) ions with InZnO/MSA-PDCA is observed in terms of a change of charge transfer resistance (Rct), which is used as a primary sensing parameter and directly proportional to the mass of targeted Hg(II) ions. The proposed portable electrochemical sensor is the first of its kind capable of ultrasensitive detection of Hg(II) ions in the femtomolar range and useful as a Point-of-care testing platform.

Electrochemical Sensing Platform Based on Graphene Oxide‐chitosan for Simultaneous Determination of some Antihypertensive Drugs

AbstractThe development of selective and simple methods for the determination of different analytes is of great interest. This is the first time to show the applicability of graphene oxide‐chitosan (GO‐CS) nanocomposite for designing an electrochemical nanosensor for determination of Amlodipine, Valsartan, and Hydrochlorothiazide, simultaneously. Differential pulse voltammetrics current of AML, HCT, and VAL increased linearly in the ranges of 0.1–110, 0.1–110, and 1–230 μM with LOD of 5.5×10−2, 3.5×10−2 and 8.6×10−2 μM, respectively. Finally, GO‐CS/GCE was used for the detection of these drugs in commercial tablets and compared with the reference method (HPLC).

Graphitic Carbon Nitride Decorated with Iron Oxide Nanoparticles as a Novel High-Performance Biomimetic Electrochemical Sensing Platform for Paracetamol Detection

Graphitic Carbon Nitride Decorated with Iron Oxide Nanoparticles as a Novel High-Performance Biomimetic Electrochemical Sensing Platform for Paracetamol Detection

Metal Nanocomposites Based Electrochemical Sensor Platform for Few Emerging Biomarkers

:Design of high-performance electrochemical sensor and biosensor platforms has attracted much devotion for the sensitive and selective detection of emergent biomarkers. Electrochemical sensor offers numerous advantageous features include cost-effective and ease of miniaturization, rapid and online monitoring, simultaneous detection ability, etc., which have captivated the potential interdisciplinary research. In this review, the advances and challenges towards the electrochemical detection of emergent biomarkers such as hydrogen peroxide, nitric oxide, β-nicotinamide adenine acetaminophen, dinucleotide (NADH) in biofluids are highlighted based on the recent research outcomes. In fact, the effective utility and benefits of transition metal nanocomposites without the utilization of biological materials, including enzymes, antibodies, etc. as electrode materials towards the detection of selected biomarkers in practical biofluids, monitoring early-stage and diagnosis of disease related biomarkers, are also described. These promising metal nanomaterials based electrochemical sensor platforms concrete the tactic for a new generation of sensing devices.