Electrochemical Sensor Research Articles

Recent advances in electrochemical detection of common azo dyes.

Food forensics is an emerging field and the initial part of this review showcases the toxic effects and the instrumental methods applied for the detection of the most commonly used azo dyes. Electrochemical detection has a lot of advantages and hence the significance of the most important techniques used in the electrochemical detection is discussed. The major part of this review highlights the surface modified electrodes, utilized for the detection of the most important azo dyes to achieve low detection limit (LOD). A thorough literature study was conducted using scopus, science direct and other scientific databases using specific keywords such as toxic azo dyes, electrochemical detection, modified electrodes, LOD etc. The recent references in this field have been included. From the published literature, it is observed that with the growing interests in the field of electrochemical techniques, a lot of importance have been given in the area of modifying the working electrodes. The results unambiguously show that the modified electrodes outperform bare electrodes and offer a lower LOD value. According to the literature reports it can be concluded that, compared to other detection methods, electrochemical techniques are much dependable and reproducible. The fabrication of the electrode material with the appropriate modifications is the main factor that influences the sensitivity. Electrochemical sensors can be designed to be more sensitive, more reliable, and less expensive. These sensors can be effectively used by toxicologists to detect trace amounts of harmful dyes in food samples.

Recent Advances in Electrochemical Biosensors Targeting Stress Markers.

When the body experiences a change in its internal environment due to factors such as mood (euphoria, stress) and illness, it releases biomarkers in large quantities. These biomarkers are used for detecting a disease at its early stages. This involves the detection of insufficient quantities of biocomponents, which can be done by using nanomaterials, conventional materials, and biotechnology; thus, scientists can increase the sensitivity of electrochemical sensors. According to studies conducted in this area, electrochemical sensors have shown promise as a diagnostic tool due to their ability to identify and pinpoint illness biomarkers. The present review article was compiled to gather the latest information on electrochemical biosensors targeting stress markers. The authors searched scholarly databases like ScienceDirect, Pubmed, Medline, and Scopus for information on electrochemical biosensors targeting stress markers. In this article, we looked at the recent developments in electrochemical sensors for stress monitoring. Because of advances in nanomaterial and biomolecule processes, electrochemical biosensors have been developed with the sensitivity to detect several biomarkers in real-time in therapeutically relevant materials. This biomarker sensor strategy can analyze various biofluids (sweat, plasma, urine, and saliva).

Carbon Nanocomposites-based Electrochemical Sensors and Biosensors for Biomedical Diagnostics.

Detection of emergent biomolecules or biomarkers remains crucial for early diagnosis in advancing healthcare monitoring and biomedicine. The possibility for rapid detection, real-time monitoring, high sensitivity, low detection limit, good selectivity, and low cost is central, among other significant issues for advancing point-of-care diagnosis. Carbon-based nanocomposites have been employed as sensing materials for various biomarkers due to their high surface-to-volume ratio, high electrical conductivity, chemical stability, and biocompatibility. The carbon nanomaterials, such as carbon nanotubes (CNTs), graphene (GR), carbon quantum dots (CQDs), carbon fibres (CFs), and their nanocomposites have broadly integrated with numerous sensing electrode materials for the detection of biomarkers under various experimental settings. The present review includes the recent advances in the development of carbon nanomaterials-based electrochemical sensors and biosensors for biomedical applications. The preparation, electrode preparation, effective utilization of carbon-derived nanomaterials, and their sensing performances towards numerous biomarkers have been highlighted. The state-of-the-merit, challenges, and prospects for designing carbon nanocomposites-based electrochemical sensor/biosensor platforms for biomedical diagnostics have also been described.

Electrochemical Sensors for Detection of Phytomolecules: A Mechanistic Approach.

High demand and ongoing technological advancements have created a market for sensors that is both varied and rapidly evolving. Bioactive compounds are separated systematically to conduct an in-depth investigation, allowing for the profiling or fingerprinting of different Plantae kingdoms. The profiling field is significant in elucidating the complex interplay of plant traits, attributes, and environmental factors. Flexible technology advancements have enabled the creation of highly sensitive sensors for the non-destructive detection of molecules. Additionally, very specialized integrated systems that will allow multiplexed detection by integrating many hybrid approaches have been developed, but these systems are highly laborious and expensive. Electrochemical sensors, on the other hand, are a viable option because of their ability to accomplish exact compound detection via efficient signal transduction. However, this has not been investigated because of some obstacles to learning minimum metabolites' fundamentals and nonredox properties. This article reviews the electrochemical basis of plants, contrasting it with more conventional techniques and offering both positive and negative perspectives on the topic. Because few studies have been devoted to the concept of merging the domains, we've expanded the scope of this work by including pertinent non-phytochemical reports for better report comparison.

Aptasensor based on gold nanostructure-decorated 2D Cu metal-organic framework nanosheets for highly sensitive and specific electrochemical lipopolysaccharide detection.

Detecting lipopolysaccharide (LPS) using electrochemical methods is significant because of theirexceptional sensitivity, simplicity, and user-friendliness. Two-dimensional metal-organic framework (2D-MOF) that merges the benefits of MOF and 2D nanostructure has exhibited remarkable performance in constructing electrochemical sensors, notably surpassing traditional 3D-MOFs. In this study, Cu[tetrakis(4-carboxylphenyl)porphyrin] (Cu-TCPP) and Cu(tetrahydroxyquinone) (Cu-THQ) 2D nanosheets were synthesized and applied on a glassy carbon electrode (GCE). The 2D-MOF nanosheets, which serve as supporting layers, exhibit improved electron transfer and electronic conductivity characteristics. Subsequently, the modified electrode was subjected to electrodeposition with Au nanostructures, resulting in the formation of Au/Cu-TCPP/GCE and Au/Cu-THQ/GCE. Notably, the Au/Cu-THQ/GCE demonstrated superior electrochemical activity because of the 2D morphology, redox ligand, dense Cu sites, and improved deposition of flower-like Au nanostructure based on Cu-THQ. The electron transfer specific surface area was increased by the improved deposition of Au nanostructures, which facilitates enriched binding of LPS aptamer and significantly improved thedetection performance of Apt/Au/Cu-THQ/GCE electrochemical aptasensor. The limit of detection for LPS reached 0.15fg/mL with a linear range of 1fg/mL - 100pg/mL. Theproposed aptasensor demonstrated the ability to detect LPS in serum samples with satisfactory accuracy, indicating significant potential for clinical diagnosis.

A novel aptamer-antibody sandwich electrochemical sensor for detecting ADAR1 in complex biological samples

Human adenosine deaminase acting on RNA1 (ADAR1) is an adenosine-to-inosine (A-to-I) RNA-editing enzyme involved in various types of cancer progression. ADAR1 has emerged as a novel prognostic biomarker for cancer. This study describes the application of a newly identified 70-nt DNA aptamer (Apt38483) against ADAR1 to develop a portable and simple electrochemical biosensor platform for the rapid and sensitive detection of ADAR1 in cell lysates. We selected an ADAR1-specific DNA aptamer from a randomized 70-nt single-stranded DNA library using a competitive in vitro selection method. ADAR1 in the cell lysate was sandwiched onto a bare carbon working electrode of an electro-chemically printed chip between the ADAR1 antibody and gold nanoparticles (40 nm) conjugated with Apt38483, followed by electrochemical analysis using differential pulse voltammetry (DPV) for sensor demonstration. A highly sensitive change in current was observed for as little as 0.53 nM ADAR1 in human embryonic kidney cell lysate. Thus, the merging of a novel DNA aptamer probe for ADAR1 with an electrochemical transduction method enabled the development of a simple, low-cost, and rapid method for the direct measurement of ADAR1 in cell lysates and indicated great potential for the development of an ADAR1 analysis platform, which would be useful in cancer prognosis.

Breathable Wearable Smartsensors Deriving from Interface Self-Assembled Film for Tracking l-Cysteine.

The advent of wearable sensors heralds a transformation in the continuous, noninvasive analysis of biomarkers critical for disease diagnosis and fitness management. Yet, their advancement is hindered by the functional challenges affiliated with their active sensing analysis layer. Predominantly due to suboptimal intrinsic material properties and inconsistent dispersion leading to aggregation, thus compromising sensor repeatability and performance. Herein, an innovative approach to the functionalization of wearable electrochemical sensors was introduced, specifically addressing these limitations. The method involves a proton-induced self-assembly technique at the organic-water (O/W) interface, facilitating the generation of biomarker-responsive films. This research offers flexible, breathable sensor capable of real-time precision tracking l-cysteine (l-Cys) precision tracking. Utilizing an activation mechanism for Prussian blue nanoparticles by hydrogen peroxide, the catalytic core exhibits a specific response to l-Cys. The implications of this study refine the fabrication of film-based analysis electrodes for wearable sensing applications and the broader utilization of two-dimensional materials in functional-specific response films. Findings illuminate the feasibility of this novel strategy for precise biomarker tracking and extend to pave the way for constructing high-performance electrocatalytic analytical interfaces.

Cu-Co Bimetallic Catalyst-based Electrochemical Sensing Platform for Determination of Bisoprolol in Clinical Samples.

Bisoprolol (BIS) is a selective beta-blocker. It has been successfully used to treat hypertension and angina pectoris. An overdose of BIS can lead to serious complications. An overdose is a medical emergency that requires immediate medical attention to overcome the adverse effects of the overdose. Hence, sensitive, reliable, and cost-effective methods are required for the determination of BIS. In this work, a new electrochemical sensing platform based on a bimetallic catalyst was developed for the determination of BIS. The Cu-Co nanocatalyst was easily synthesized by galvanic displacement onto a carbon paste electrode (CPE). Then, field emission scanning electron microscopy (FESEM), energy dispersive spectroscopy (EDS), and cyclic voltammetry (CV) were utilized for the characterization of the Cu-Co catalyst. The galvanic displacement of Cu metal significantly affected the electro-catalytic behavior of the Cu-Co catalyst and the Cu-Co/CPE electrode displayed a very sensitive and accurate response towards BIS. Under optimized conditions, the response was linear in the 3 to 120 μM concentration range, sensitivity of 631.1 μA mM-1 and a detection limit of as low as 0.4 μM using cyclic voltammetry. The simple proposed method was also successfully employed in the analysis of BIS in biological and pharmaceutical samples. The advantages of Cu-Co/CPE are its fast and simple manufacturing and the possibility of a repeated surface regeneration of the sensing platform, as well as its application for the detection of BIS in tablets and biological samples, making Cu-Co significant promise for use in clinical diagnostics. Besides, the synthesized catalysts showed excellent reusability and stability. The presence of Cu metal due to galvanic displacement increased the sensitivity. These findings suggest that the new nanocatalyst has potential applications in sensors and electronics.

A Simultaneous Calibration and Detection Strategy for Electrochemical Sensing with High Accuracy in Complex Water.

The electrochemical sensors loaded with nanomaterials have exhibited a great sensitivity. Nonetheless, the field detection for complex waterbodies can be affected by cross-sensitivity, environmental conditions such as temperature and pH value, as well as the relatively low reproducibility and stability of nanomaterials. In this paper, a simultaneous calibration and detection (SCD) strategy is proposed to introduce a simultaneous and precise calibration during field electrochemical detection, which is composed of a linear regression algorithm and a compact electrochemical sensor containing a series of identical sensing cells. This design can significantly mitigate cross-sensitivity in complex water and the inconsistency of sensing materials. Applied in the NO2- detection for practical waterbodies, the SCD strategy has exhibited a relative error of no more than 9.6% for the measurement compared to the results obtained by the standard Griess method and higher accuracy than the normal electrochemical method. The SCD strategy is independent of sensing materials, indicating that it can be widely applied to various detections by just switching the corresponding sensing material.

Reduced Graphene Oxide-Modified Electrodes via Fused Deposition Modeling 3D Printing for Hydrogen Peroxide Sensor

Abstract 3D printed electrochemical electrode processes have garnered significant interest due to their promising applications. However, broader implementation remains constrained due to challenges in material selection, complex fabrication processes, and reproducibility issues. Fused Deposition Modeling (FDM) 3D Printing presents a simplified alternative, enabling swift and cost-effective production of electrochemical sensors. This paper introduces a novel manufacturing approach that uses a dual-printer setup for printing sensor electrodes and subsequent surface modification with reduced graphene oxide (rGO) casting. The electrode surfaces, both before and after rGO drop casting, are comprehensively characterized, including physical morphology, chemical composition, and electrochemical performance. As a result, the electrode, after surface modification with rGO, exhibits a sensitivity increase exceeding fortyfold compared to the pristine printed surface, as demonstrated through hydrogen peroxide (H2O2) amperometric measurements. This outcome opens up new avenues and prospects for the manufacturing of 3D printed electrochemical sensors.

Novel application of carbon nanotube electrodes for electrochemical detection of amino acids in athlete’s biological samples

Understanding different physiological processes and spotting any health problems, especially in athletes, depend on tracking the quantities of amino acids in biological samples. This study looked at the creation of a unique electrochemical sensor for the sensitive and targeted identification of the necessary amino acid methionine in biological materials. Based on a modified glassy carbon electrode (GCE) surface, the sensor incorporated a tungsten disulfide (WS2) and carbon nanotube (CNT) nanocomposite. The improved electrical conductivity and catalytic activity of this material combination towards methionine oxidation led to its selection. The sensor that was created showed remarkable selectivity for methionine over other amino acids, along with a wide linear range of 5–1475 μM and a low detection limit of 10 nM. A relative standard deviation of 3.62 % was obtained across ten consecutive measurements, confirming the sensor's repeatability. The practical use of the CNTs-WS2/GCE sensor was verified by the detection of MTN in human blood serum, urine, and food samples. The recovery values ranged from 93.00 % to 99.40 %, and the relative standard deviation was less than 4.71 %. Based on these findings, we believe that our new CNTs-WS2/GCE sensor holds great potential for quick and precise methionine identification in biological samples from athletes.

A novel nanosheets assembled Co2P2O7 microrods for ultrasensitive electrochemical detection of As(III) ions

Arsenic pollution is common in seafood, grains, fruits, vegetables and groundwater. Long-term intake of arsenic-contaminated food or water may lead to various health problems. In this study, a novel nanosheets assembled Co2P2O7 microrod was prepared via a simple one-step hydrothermal method for the electrochemical detection of As(III). The Co2P2O7 microrods showed superior electric conductivity, good dispersion and a unique layered structure, which provided numerous electroactive sites to bind with As(III) and promoted the direct oxidization of As(III) to As(V) on the modified electrode surface. The proposed electrochemical sensor showed a high sensitivity of 4.174 µA/µg L−1 and a wide linear range of 0 ∼ 30 µg L−1 for As(III) detection via differential pulse voltammetry method in 0.1 M HAc-NaAc buffer (pH 5.0). Additionally, it exhibited good repeatability, reproducibility, stability and selectivity for As(III) detection. Moreover, the proposed sensor exhibited satisfactory applicability in hairtail samples.

Rapid and reliable determination of sulfide and sulfite in food by a multianalyte electrochemical sensor based on nanoporous gold

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Keggin type Polyoxometalate-based metal-organic frameworks with electrocatalytive activity as effective multifunctional amperometric sensors for metal ions and ascorbic acid

Polyoxometalates (POMs) based metal-organic frameworks (POMOFs) integrate the merits of POMs with excellent redox properties and MOFs with highly ordered porous crystalline structures, which show potential electrochemical applications relying on the synergistic catalytic effect. Here, two new Keggin-type POMOFs [Cd(btbu)2(H2O)2(PMo12O40)] (CUST-636), [Cd(btbu)2(H2O)(SiW12O40)0.5](CUST-638) are synthesized using flexible ligand of 1,4-bis(1,2,4-triazol-1-yl)butane (abbreviated as btbu) as a ligand by hydrothermal method. PXRD, IR, and TG analysis were carried out on CUST-636 and CUST-638. Then, they were prepared into electrode materials (referred to as 636-GCE and 638-GCE), to explore the electrocatalytic properties. 636-GCE and 638-GCE show good electrocatalytic redox performance against KBrO3, KNO2, K2Cr2O7 and AA. Furthermore, detection of trace Cr(VI) was conducted using electrochemical sensors 636-GCE and 638-GCE. The low detection limits (LODs) of CUST-636 and CUST-638 were 0.32 and 0.45 μM, respectively, which were lower concentrations of Cr(VI) in drinking water than the maximum allowable concentration specified by the World Health Organization (WHO).

A flexible non-enzymatic hydrogel-assisted electrochemical sensor: Wireless, sensitive, and selective uric acid detection for home monitoring

A smartphone-enabled, wireless, and battery-free electrochemical sensor equipped with electroactive poly (3,4-ethylenedioxythiophene):poly(styrenesulfonate)/polyvinyl alcohol (PEDOT:PSS/PVA) hydrogel composites, was developed for the non-enzymatic assessment of uric acid (UA) concentrations in human serum and wound exudate. The sensor was constructed with the aid of simple and sustainable modification techniques, such as drop-casting and crosslinking via a green freezing–thawing protocol. Gold nanoparticles (AuNPs) and the PEDOT:PSS/PVA electroactive hydrogel were employed to increase the surface area of the sensor and sample interactions, which improved the sensitivity and specificity for UA detection in the clinical range of 10–1,000 µM, with a detection limit of 0.05 mg/dL in addition to biocompatibility (L-929 cell viability > 90 %). In human serum and wound exudate samples, the prepared sensor demonstrated a good correlation for UA detection when compared to ISO15189 accredited medical laboratory measurements (Pearson correlation coefficient (r) = 0.97 and r = 0.98, respectively). The UA sensor was integrated with the flexible near field communication (NFC) circuit, and demonstrated the feasibility of measuring UA in human serum and wound exudate with results that were consistent with uricase enzymatic determination (p-value > 0.05). The sensor’s wearability was demonstrated by a recovery rate of 101–109 % UA detection when bending on the IV training arm. This NFC UA sensing device can serve as a good alternative platform for self–UA monitoring, along with the potential for developing a smart wound dressing for wound management.

Electrochemical detection of poly(3-hydroxybutyrate) production from Burkholderia glumae MA13 using a molecularly imprinted polymer-reduced graphene oxide modified electrode.

Thedevelopment and application of an electrochemical sensor is reported fordetection of poly(3-hydroxybutyrate) (P3HB) - a bioplastic derived from agro-industrial residues. To overcome the challenges of molecular imprinting of macromolecules such as P3HB, this study employed methanolysis reaction to break down the P3HB biopolymer chains into methyl 3-hydroxybutyrate (M3HB) monomers. Thereafter, M3HB were employed as the target molecules in the construction of molecularly imprinted sensors. The electrochemical device was then prepared by electropolymerizing a molecularly imprinted poly (indole-3-acetic acid) thin film on a glassy carbon electrode surface modified with reduced graphene oxide (GCE/rGO-MIP) in the presence of M3HB. Electrochemical impedance spectroscopy (EIS), cyclic voltammetry (CV), scanning electron microscopy with field emission gun (SEM-FEG), Raman spectroscopy, attenuated total reflection Fourier-transform infrared (ATR-FTIR) and X-ray Photoelectron Spectroscopy (XPS) were employed to characterize the electrode surface. Under ideal conditions, the MIP sensor exhibited a wide linear working range of 0.1 - 10nM and a detection limit of 0.3pM (n = 3). The sensor showed good repeatability, selectivity, and stability over time. For the sensor application, the bioproduction of P3HB was carried out in a bioreactor containing the Burkholderia glumae MA13 strain and sugarcane byproducts as a supplementary carbon source. The analyses were validated through recovery assays, yielding recovery values between 102 and 104%. These results indicate that this MIP sensor can present advantages in the monitoring of P3HB during the bioconversion process.

One-step green synthesis of flower-like non-precious metal (Cu, Ni, Fe or Zn) doped ZIF-67 and its application as non-enzymatic electrochemical glucose sensors

Co ions and imidazolate ligands can be self-assembled into a novel metal-organic frameworks (MOFs) with zeolite-like topological structures, which is named as ZIF-67. Flower-like ZIF-67 can be precisely prepared by one-step green synthesis method under specific experimental conditions, and has excellent enzyme-like electrocatalytic activity toward glucose. Non-precious metal (Cu, Ni, Fe or Zn) can be doped into flower-like ZIF-67 while maintaining zeolite-like topological structures, which may also be an important way to enhance the electrocatalytic performances of ZIF-67. In this study, flower-like non-precious metal (Cu, Ni, Fe or Zn) doped ZIF-67 was contrastively researched by physical characterizations and electrochemical techniques, and was employed as electrocatalysts for non-enzymatic electrochemical glucose sensors. Flower-like non-precious metal (Cu, Ni, Fe or Zn) doped ZIF-67 all exhibits perfect electrocatalytic activities toward glucose, among them the performance of Fe(5 %)-ZIF-67 is the most outstanding.

Enhanced modified poly-tyrosine voltammetric sensor for the quantification detection of salivary pepsin

Pepsin as an aspartic acid protease member and one of the three foremost proteolytic enzymes in the digestive system is essential to be detected. An electrochemically polymerized tyrosine film on carbon paste electrode (pTyr/CPE) has been synthesized by electro-polymerization donating an affordable electrochemical sensor to sense salivary pepsin as a diagnostic technique for gastroesophageal reflux disease (GRD) due to saliva collection is non-invasive and relatively comfortable. The pTyr/CPE was applied for Voltammetric sensing of pepsin and its quantification in phosphate buffer solution of pH 2.0 (PBS). Scanning electron microscopy (SEM) was conducted to learn the surface morphology. Cyclic voltammetry (CV), differential pulse voltammetry (DPVs), chronoamperometry (CA), and electrochemical impedance spectroscopy (EIS) were developed to realize the electrocatalytic activity of the sensor. The pTyr/CPE proceeded as a sensitive detector to pepsin with two linear ranges from 1 to 20 & 20 to 100 ng/mL donating two limits of detection as 0.5 & 0.09 ng/mL, respectively, and high selectivity toward pepsin, as well as stability and fast response of 1.5 s. Consequently, it is guessed that the pTyr/CPE sensor could be supportive for the initial diagnosis of GRD through the detection of pepsin in saliva. Finally, we quantified the pepsin levels in saliva samples of LPR patients (n = 2), showing that the results were agreeable with those from the electrochemical sensor.

Electrochemical sensor based on mesoporous g-C3N4/N-CNO/gold nanoparticles for measuring oxycodone

Oxycodone, often used as an analgesic, is a potent opioid. While its effectiveness has been proven in the control of moderate to acute pain, excessive use of oxycodone imposes heart failure, heart palpitations, reduction of red blood cells, bone pain, and even death. Therefore, monitoring the oxycodone concentration in blood is vital for emergency care. For this purpose, a novel electrochemical sensor was designed based on a glassy carbon electrode modified with mesoporous g-C3N4 (M-C3N4), carbon nano-onions doped with nitrogen (N-CNO), and gold nanoparticles. At first, the SEM and XRD techniques were employed to characterize prepared M-C3N4 and N-CNO samples. The electro-oxidation behavior of the oxycodone was evaluated by cyclic and differential pulse voltammetric methods. Based on the influence of the potential scanning rate and solution pH on the voltammetric response of oxycodone oxidation, a redox mechanism was proposed. A 16 nM detection limit was acquired for the oxycodone analysis with a linear response in the 0.05–150 µM range. This sensor showed a remarkable ability for oxycodone detection in plasma samples. The long-term stability, superior selectivity, and reproducibility of this sensor prove its ability to measure oxycodone accurately and precisely in authentic spices.

Enhanced Stability and Detection Range of Microbial Electrochemical Biotoxicity Sensor by Polydopamine Encapsulation

Enhanced Stability and Detection Range of Microbial Electrochemical Biotoxicity Sensor by Polydopamine Encapsulation