Selective Electrochemical Detection Research Articles

Integrating theoretical and experimental insights into nanoporous gold electrochemistry for enhanced baicalein sensing performance

We introduce an innovative electrochemical sensing method for the sensitive detection of Baicalein (BAI), emphasizing a simple surface modification process. The study encompasses both practical and theoretical investigations into the electrochemical behavior of nanoporous gold. Our theoretical analysis, based on advanced quantum-mechanical calculations, demonstrates that the adsorption of BAI molecule on gold-based substrates is energetically favorable, with adsorption energy increasing from an unmodified surface to a more porous substrate. BAI physisorbs on unmodified regions in a horizontal alignment, while it chemisorbs more strongly on nanoporous regions by penetrating the pores. On less modified surfaces, interaction energy predominates, whereas on heavily modified surfaces, distortion energies become more significant due to increased substrate reactivity. These results align with physicochemical characterizations, which reveal that nanoscale modifications, induced by different anodization times, explain the variations in electrode performance. Experimentally, cyclic voltammetry (CV) and differential pulse voltammetry (DPV) were employed using both a gold electrode (GE) and a nanoporous gold electrode (NPGE). The GE was subjected to surface treatment by immersion in H2SO4 and potential control at ca. +2.0 V for 40 seconds, resulting in a nanoporous configuration. Following optimizations, Adsorptive Stripping Voltammetry (AdSV) was used to determine BAI. The method achieved detection (LOD) and quantification (LOQ) limits of 0.015 µmol L-1 and 0.045 µmol L-1, respectively (Edeposition=-0.25 V; tdeposition=50 s). Additionally, the standard addition method was applied to the NPGE for recovering BAI from spiked synthetic human plasma and urine, with success rates ranging from 93.4% to 106%. This approach exhibited excellent stability, precision, and accuracy, with minimal interference from other substances. Moreover, the theoretical findings provided deeper insights into the selective electrochemical detection of BAI on nanoporous gold surfaces, offering new perspectives on this field.

Modifying metal ion ratios in nickel-aluminum layered double hydroxide/reduced graphene oxide composites for selective electrochemical detection of antibiotics

Modifying metal ion ratios in nickel-aluminum layered double hydroxide/reduced graphene oxide composites for selective electrochemical detection of antibiotics

Fabrication of MnSnO2 intercalated TA-rGO modified sensor for selective electrochemical detection of chloramphenicol in real samples

Chloramphenicol (CAP), a potent antibiotic capable of inhibiting protein synthesis, presents significant challenges related to long-term dosing and its persistent leaching into the environment, raising concerns about environmental contamination and resistance development. To address this issue, we developed a reliable, low-cost, and biocompatible nanocomposite material comprising tannic acid (TA)-reduced graphene oxide (rGO) intercalated into manganese-doped tin oxide nanoparticles (MnSnO₂ NPs). The structural formation and catalytic activity of the MnSnO₂ NPs/TA-rGO nanocomposite were characterized using field emission-scanning electron microscopy (FE-SEM), high-resolution transmission electron microscopy (HR-TEM), X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FT-IR), Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), and electrochemical techniques. This material exhibits robust interfacial interactions and synergistic effects, resulting in an admirable electrocatalytic reduction response for CAP sensing. The presence of co-interference molecules improved the selectivity performance of the MnSnO2 NPs/TA-rGO-modified glassy carbon electrode. The fabricated exhibited a two linear determination range (0.011–103.43 μmol L−1 and 103.43–1924.16 μmol L−1), with a detection limit (LOD) is 6.7 nmol L−1 and limit of quantification (LOQ) is 12.3 nmol L−1. Furthermore, this sensor demonstrated good sensitivity, admirable reproducibility, repeatability, and storage stability. Finally, the practicability of the fabricated MnSnO2 NPs/TA-rGO glassy carbon electrode sensor was evaluated by analyzing the CAP content in milk, honey, eye drops, biofluids (human serum and urine), and river water, and satisfactory recovery rates of 95.4 %–100.3 % were noted.

Surface functionalization of graphene electrode using flavin AuNps for a realtime sensing of asparagine

Asparagine (ASN) is one of the major non-essential amino acids and helps to breakdown the toxic ammonia within the cell. The electrochemical detection of asparagine was performed by the surface functionalized screen-printed carbon (MSPEC) and screen-printed graphene electrodes (MSPEG) through flavin (Quercetin) based gold nanoparticles (AuNps). Cyclic voltammetry (CV) and Differential Pulse Voltammetry (DPV) were performed through MSPEC and MSPEG at single drop of analyte via DROPSENS. SEM and Electrochemical Impedance (EIS) examined for the surface characteristics, enhancement, and functionality of electrodes modified with flavin AuNps. The surface functionalized electrodes revealed excellent electrochemical sensor with high stability, selectivity, repeatability, and have a low limit detection of 0.001 nM. Also, sensors progression was found to occur through adsorption-controlled phenomena. The oxidation peak potential for asparagine in CV and DPV was well-expressed by the MSPEC and MSPEG, with potentials of +0.0881 V and +0.3141 V, respectively. Hence the flavin based AuNps is a new sensing platform for the consistent asparagine real-time sensor and the selective electrochemical detection of asparagine with an exceptionally low detection limit at one drop.

Construction of Cu2Y2O5/g-C3N4 Novel Composite for the Sensitive and Selective Trace-Level Electrochemical Detection of Sulfamethazine in Food and Water Samples.

The most frequently used sulfonamide is sulfamethazine (SMZ) because it is often found in foods made from livestock, which is hazardous for individuals. Here, we have developed an easy, quick, selective, and sensitive analytical technique to efficiently detect SMZ. Recently, transition metal oxides have attracted many researchers for their excellent performance as a promising sensor for SMZ analysis because of their superior redox activity, electrocatalytic activity, electroactive sites, and electron transfer properties. Further, Cu-based oxides have a resilient electrical conductivity; however, to boost it to an extreme extent, a composite including two-dimensional (2D) graphitic carbon nitride (g-C3N4) nanosheets needs to be constructed and ready as a composite (denoted as g-C3N4/Cu2Y2O5). Moreover, several techniques, including X-ray diffraction analysis, scanning electron microscopy analysis, energy-dispersive X-ray spectroscopy, Fourier transform infrared spectroscopy, and Raman spectroscopy were employed to analyze the composites. The electrochemical measurements have revealed that the constructed g-C3N4/Cu2Y2O5 composites exhibit great electrochemical activity. Nevertheless, the sensor achieved outstanding repeatability and reproducibility alongside a low limit of detection (LOD) of 0.23 µM, a long linear range of 2 to 276 µM, and an electrode sensitivity of 8.86 µA µM-1 cm-2. Finally, the proposed GCE/g-C3N4/Cu2Y2O5 electrode proved highly effective for detection of SMZ in food samples, with acceptable recoveries. The GCE/g-C3N4/Cu2Y2O5 electrode has been successfully applied to SMZ detection in food and water samples.

Exploring the synchronized effect of MWCNT/X-manganate (X-Cu, Zn) nanocomposite for the sensitive and selective electrochemical detection of Hg(II) and Pb(II) in water.

The presence of heavy metal ions in the environment is a long-lasting problem that requires the simultaneous detection of Hg(II) and Pb(II) which is both vital and challenging. This present study examines a simplified and effective approach for synthesizing multi-walled carbon nanotube-copper manganese oxide (MWCNT-CuMn2O4) and multi-walled carbon nanotube-zinc manganese oxide (MWCNT-ZnMn2O4) nanocomposites for electrochemical detection of heavy metal ions. The nanocomposites MWCNT-CuMn2O4 and MWCNT-ZnMn2O4 exceptional electrochemical performance was evaluated using Square Wave Anodic Stripping Voltammetry (SWASV). The fabricated MWCNT-ZnMn2O4 demonstrated lower values of Electrochemical Impedance Spectroscopy (EIS) with charge transfer resistance (Rct) of approximately 34.13 Ω. Remarkably, the MWCNT-ZnMn2O4 electrochemical sensor exhibited the widest linear ranges of 0.5-10μM with sensitive detection limits (0.011μM for Hg(II) and 0.014μM for Pb(II)). Interestingly, the MWCNT-ZnMn2O4 sensor showed excellent capability in detecting Hg(II) and Pb(II) in real water samples with a recovery percentage of 94.1% and 91.3%. Overall, the MWCNT-ZnMn2O4 modified GCE showcased superior selectivity, sensitivity, reproducibility, stability, and repeatability.

2D sheet structure of zinc molybdate decorated on MXene for highly selective and sensitive electrochemical detection of the arsenic drug Roxarsone in water samples

Water contamination is a serious environmental issue posing a significant global challenge. Roxarsone (ROX), a widely used anticoccidial drug is excreted in urine and feces, potentially disrupting natural habitats. Therefore, rapid and cost-effective ROX detection is essential. In this study, we developed a 2D sheet structure of zinc molybdate decorated on MXene (ZnMoO4/MXene) for detecting ROX using electrochemical methods. The materials were characterized using appropriate spectrophotometric and voltammetric techniques. The ZnMoO4/MXene hybrid exhibited excellent electrocatalytic performance due to its rapid electron transfer rate and higher electrical conductivity. The ZnMoO4/MXene-modified GCE (ZnMoO4/MXene/GCE) showed a broad linear range with high sensitivity (10.413 μA μМ−1 cm−2) and appreciable limit of detection (LOD) as low as 0.0081 μM. It also demonstrated significant anti-interference capabilities, excellent storage stability, and remarkable reproducibility. Furthermore, the feasibility of utilizing ZnMoO4/MXene/GCE for monitoring ROX in water samples was confirmed, achieving satisfactory recoveries.

Electrochemical detection of salicylic acid in fruit products with ternary ZnO/CuO/Y2O3 nanocomposites embedded PEDOT:PSS by differential pulse voltammetry

In this approach, a novel electrochemical sensor for the determination of salicylic acid (SA) in fruit juices was developed using a nanocomposite (NC) of ZnO/CuO/Y2O3 coated on a glassy carbon electrode (GCE). The ternary metal oxide NCs were synthesized via a facile hydrothermal method and thoroughly characterized using techniques such as X-ray photoelectron spectroscopy (XPS), X-Ray diffraction analysis (XRD), UV–Vis spectroscopy (UV–Vis), Fourier Transform Infrared Spectroscopy (FTIR), Field emission scanning electron microscopy (FESEM), and Energy-Dispersive X-Ray Spectroscopy (EDS). The NCs were then used to modify a flat-polished GCE surface, with a conducting polymer binder (PEDOT:PSS) used to facilitate the coating. Differential pulse voltammetry (DPV) was employed for the selective electrochemical detection of SA using this NC-modified GCE sensor. The DPV analysis exhibited a linear relationship between the peak current and SA concentration over a wide range of 1.5 ∼ 15.0 μM, indicating a large linear dynamic range. The sensor demonstrated excellent sensitivity, with a value of 5.79 μA μM−1 cm−2, and a low limit of detection of 0.18 ± 0.09 μM for SA. Additionally, the sensor’s performance was evaluated in terms of pH optimization, response time, stability, reproducibility, and repeatability. Importantly, the developed ZnO/CuO/Y2O3 NC-modified GCE sensor was successfully applied to the analysis of real fruit juice samples, showcasing its potential for practical applications in food analysis and quality control.

Hybrid graphene nanoflakes for electrochemical sensing with multianalyte detection capability

This work illustrates the production of highly electrochemically active graphene by liquid phase exfoliation technique for ultrasensitive electrochemical sensors. An airless high-pressure spray technique was designed to exfoliate bulk natural graphite into nm-scaled flakes (referred as HP50). Transmission electron microscopy, Raman and X-ray photoelectron spectroscopy studies reveal that the HP50 sample has a mixed structure composed of amorphous carbon and a few-layer graphene fraction with high amount of edge plane defects. The HP50 flakes are drop cast on glassy carbon electrodes to test the simultaneous and selective electrochemical detection of hydrogen peroxide, ascorbic acid, and dopamine. In cyclic voltammetry measurements, hydrogen peroxide reduces at −0.2 V vs Ag/AgCl (1 M), while ascorbic acid and dopamine oxidize at 0.1 V vs Ag/AgCl (1 M) and 0.3 V vs Ag/AgCl (1 M), respectively. Linear sweep voltammetry demonstrates high sensitivity (164, 739, and 3357 μA mM−1 cm−2) and low limit of detection (15, 1.7, and 2.1 μM) for the three analytes, respectively. Interference studies confirm a high sensitivity and selectivity towards the different chemical species. The HP50-based multianalyte sensors are also tested against different environmental and commercial samples, illustrating their viability in practical applications.

Sensitive and selective electrochemical detection of acetaminophen based on GO-MnO2-modified electrode

Sensitive and selective electrochemical detection of acetaminophen based on GO-MnO2-modified electrode

Integrated microfluidic chip with a MIP-gated organic electrochemical transistor for continuous, selective, and label-free quantification of tumor marker

Early diagnosis of cancer is crucial to effective treatment of the patients and to higher survival rates. Tumor marker detection as an effective and noninvasive cancer diagnosis method has important clinical significance. N1, N12-diacetylspermine (DAS) is a new tumor marker. The development of its detection methods is an urgent need for medical diagnosis and human health monitoring. The conventional detection methods of DAS are labor-intensive and time-consuming approaches. In this work, a novel electrochemical detection platform was established by integrating an organic electrochemical transistor (OECT) with a microfluidic chip and applied for trace measurement of DAS. The sensing unit is a gate electrode in the OECT modified with molecularly imprinted polymers (MIPs), which can be used as an artificial receptor to realize label-free detection. The high specific recognition ability of MIPs films combined with the amplified function of an OECT yielded a highly sensitive and selective electrochemical detection chip. The integrated microfluidic channel controlledthe exact amount of solution to be delivered and provided real-time detection of DAS. The experimental results indicated that changes in channel current was proportional to DAS concentrations from 1 nM to 10 μM, with the detection limits of 0.8 nM. It is the first demonstration of the integration of a microfluidic system with a MIP-gated OECT for real-time tumor marker detection. The study results of this work helped to develop Point-Of-Care (POC) tools for the early diagnosis of lung cancer, colon cancer and breast cancer.

Surface modification prepared porous copper oxide/(Cu-S)n metal-organic framework/reduced graphene oxide hierarchical structure for highly selective electrochemical quercetin detection.

Electrochemical alkalization of (Cu-S)n metal-organic framework (MOF) and graphene oxide ((Cu-S)n MOF/GO) composite yields a new CuO/(Cu-S)n MOF/RGO (reduced GO) composite with porous morphology on screen printed carbon electrode (SPCE) which facilitated the electron transfer properties in electrochemical quercetin (QUE) detection. A selective QUE detection ability has been demonstrated by the constructed electrochemical sensor (CuO/(Cu-S)n MOF/RGO/SPCE), which also has a broad dynamic range of 0.5 to 115µM in pH 3 by differential pulse voltammetry. The detection limit is 0.083µM (S/N = 3). In this study, it was observed that the real samples contained 0.34mgmL-1 and 27.7µgg-1 QUE in wine and onion, respectively.

Covalent organic framework/carbon black/molecularly imprinted polydopamine composites for the selective recognition and electrochemical detection of ciprofloxacin

Covalent organic framework/carbon black/molecularly imprinted polydopamine composites for the selective recognition and electrochemical detection of ciprofloxacin

Highly sensitive and selective electrochemical detection of Aflatoxin B1 in water and Pistachio samples with MOF/MXene composite based sensor

Aflatoxins are poisonous secondary metabolites capable of causing toxicity in several food items and water. The routine monitoring of Aflatoxins has assumed great analytical significance. The electrochemical biosensors are attractive tools to screen the Aflatoxin-laden samples. The present study reports on a new type of electrochemical biosensor, based on an electrode prepared of multifunctional MOF (Metal-organic framework)/MXene composite material. Molybdenum-based 2-dimensional (2D) MOF and Ti3C2 MXene have been mixed to prepare the composite, which is then deposited over a screen-printed electrode (SPE). The anti-Aflatoxin B1 (AFB1) antibodies (Ab) are covalently complexed, and the prepared Ab-MOF/MXene sensor is investigated for its applicability to detect AFB1. Utilizing the electrochemical impedance spectroscopic (EIS) analysis, the Ab-MOF/MXene sensor has allowed the detection of AFB1 from 0.06 to 50 ng/mL with a very low limit of detection, i.e., 8 pg/mL. The sensor performs well with respect to all the major quality parameters, such as long-term stability, specificity in co-presence of interfering species, reproducibility, and repeatability. It is demonstrated successfully to detect AFB1 in the spiked samples of Pistachio.

Highly selective and sensitive Pb2+ detection via sulfur-doped graphitic carbon nitride modified by Bi nanospheres

The present-day human race is facing a series of environmental problems due to sewage discharge, excessive use of chemicals, mineral exploitation and so on, which are closely related to the rapid development of industries. The direct consequence is that the pollution of heavy metal ions is becoming more and more serious. It is very important to develop sensitive and efficient methods for detecting heavy metal ions. In this study, the nanocomposite of sulfur-doped graphitic carbon nitride (SCN) and Bi nanospheres (BiNSs) was prepared by thermal polycondensation reaction to introduce the sulfur into carbon nitride, followed by solvothermal method to realize the decoration of BiNSs. The SCN/BiNSs nanocomposite presents a highly selective and sensitive electrochemical detection capacity for Pb2+, derived from S-Pb strong bonding interaction and Bi-Pb binary alloy formation. The low detection limit of 0.07 μM could be achieved when the current response of Pb2+ was measured in the linear range of 0.1 μM − 4.5 μM by square wave anodic stripping voltammetry. The detection of Pb2+ in actual water specimens led to a recovery rate varied from 88 to 123 %. Further, in the presence of 20-fold interfering ions such as Zn2+, Fe3+, Cd2+, Cu2+, Fe2+ and Ni2+, the SCN/BiNSs-modified electrode still possesses excellent immunity and selectivity. Meanwhile, the remarkable stability, repeatability and reproducibility of the above sensing electrode have also been demonstrated. Our primary results show that the SCN/BiNSs nanocomposite holds great potential for practical application for Pb2+ detection.

Multi-walled carbon nanotube wrapped rare earth tungstate nanosheet composites for selective and rapid detection of sulfadiazine

Multi-walled carbon nanotube wrapped rare earth tungstate nanosheet composites are developed for the ultrasensitive and selective electrochemical detection of sulfa drug, sulfadiazine (SAN) as they exhibit high levels of toxicity towards public health and ecosystem. Here, we synthesized Gadolinium tungstate decorated with multi-walled carbon nanotubes (Gd2WO6/MWCNT) though hydrothermal processing and characterized by XRD, SEM, EDX, TEM, and EIS measurement to investigate the phase purity, morphology, and interfacial property. Gd2WO6 is a double perovskite that has high oxygen surface exchange kinetics and the MWCNT possesses high catalytic capability and a larger surface area contributes to the efficient sensing ability. The Gd2WO6/MWCNT possessed a great electrical conductivity owing to the synergism between the Gd2WO6 and MWCNT. The synergistic effect increases the surface area, ionic and electrical conductivity which increases the current response of SAN. Under optimum conditions, the Gd2WO6/MWCNT/GCE displays a broad linear of 0.01 – 671 µM and a LOD level of 2 nM (S/N ratio: 3) with a sensitivity of 0.371 µA µM cm−1. The analytical applicability of the proposed electrode modifier leads to a promising sensor for SAN detection in human urine and water samples with appreciable results.

Synthesis, characterization, and application of ZnO@SiO2-APTES core-shell composite for selective electrochemical detection of Pb2+ ions

This study focuses on improving the electrochemical performances for the detection of heavy metals such as Pb2+ by using a silica-based nanomaterial. In order to do this, ZnO nanoparticles (core) were used as a seed for the chemical deposition of a SiO2 shell. The nanomaterial was synthesized according to a core-shell configuration and the obtained particles were subsequently functionalized with (3-aminopropyl) triethoxysilane APTES to enhance their electrochemical sensing capabilities. The unique physical and chemical properties of these particles, such as their uniform porosity and their ability to detect Pb2+, were exploited. The resulting composite was characterized by scanning electron microscopy, X-ray diffraction, and infrared spectroscopy to analyze its morphology and chemical composition. An electrochemical characterization was also performed to evaluate the change in electrode properties with a ZnO@SiO2-APTES-modified glassy carbon electrode. The differential pulse voltammetry technique was used to determine the Pb2+ ion concentration. After optimization, the electrochemical sensor based on ZnO@SiO2-APTES showed significant sensitivity and exceptional performance in the detection of Pb2+ with a limit of detection of 0.1 nM. Moreover, the proposed electrochemical sensor was successfully applied in the determination of trace metal ions in real environmental samples.

SnO2–MWCNT and SnO2–rGO Nanocomposites for Selective Electrochemical Detection in a Mixture of Heavy Metal Ions

SnO₂–MWCNT and SnO₂–rGO Nanocomposites for Selective Electrochemical Detection in a Mixture of Heavy Metal Ions

Biofilm monitoring through the detection of cyclic diguanosine-monophosphate with an easy-to-use electrochemical sensor

The identification and monitoring of biofilm is of utmost importance because it ensures the survival of bacteria in a variety of environments, such as nature, medical indwelling devices, hospital surfaces, or the food industry. Here, we describe the novel application of a screen-printed electrode modified with nanomaterials for the in situ detection of bacterial biofilm. This approach enables simple, rapid, and highly sensitive and selective electrochemical detection of cyclic diguanosine-monophosphate (cdGMP). The best electrochemical signal of cdGMP was obtained after testing several electrode materials and screen-printed electrodes modified with different nanomaterials, different electrolyte solutions, pH, and electrochemical technique parameters. Using the anodic peak of the cdGMP on screen-printed electrodes modified with carbon nanotubes (CNT-SPE), the sensor showed excellent sensitivity, with a 25 nM–1 µM linear range, and a limit of detection of 15 nM. The sensor allowed the selective detection of cdGMP, with low interference from other molecules and was successfully applied to real sample analyses (laboratory biofilm produced by various bacterial species over distinct time intervals).

Abstract 5027: Simplified selective electrochemical detection of ctDNA differentiates between cancer progression and regression

Abstract Advanced cancers therapies, including personalized ones, often fail. Rapid evaluation of treatment efficacy is therefore critical to reduce medical and financial side effects and, most importantly, facilitate the implementation of a therapy most appropriate for that individual. Current approaches for evaluating treatment are too slow and expensive to rapidly modify therapy. The previously documented selective affinity of DNA to Au surfaces, albeit cumbersome, unsuitable for point-of-care (PoC) applications and having poor discrimination ability, suggested a solution to this clinically important problem. Methods presented herein potentially solve the problem as first illustrated by a studies of plasma from those with and without cancers. Multiple improvements, most notably optimized buffer conditions dramatically changed and enhanced the difference in adsorption between ctDNA and normal cfDNA drastically improving assay performance. The enhanced sensitivity of this Therascape™ assay was not only able to better detect the difference between healthy and cancer cfDNA but demonstrated potential for the monitoring of cancer treatment efficacy. De-identified clinical samples of the few patients that the Scripps Biorepository and University of Colorado supplied had samples before and after treatment, and were known to have progressed or responded in the interim, were analyzed. This initial group included 6 lymphoma patients and two NSCLC patients (in one case the cfDNA was isolated from urine). One of the patient samples taken before initiating therapy was in the healthy range and considered ineligible for the assay. Ten before and after pairs were then evaluated in a blinded fashion. TheraScape correctly correlated with the change in cancer burden in each pair (10/10 times, p = 0.00016, paired t-test). In some cases the “after” specimen was ~1 month after therapy began. The presentation will include additional patients. The CVs of repeat electrodes were less than 10%, interoperator variability did not increase this. The novel method of detecting cfDNA using disposable electrodes presents a significant advancement in monitoring the efficacy of treatments for advanced cancers, and may be particularly critical for immunotherapy. This approach reduced expenses by 10 to 50 times compared to current reimbursement rates for sequence dependent methods, even more critical is the same day turn around would allow rapid, truly individualized, patient therapy optimization. Citation Format: Matthew Jordan Russo, Kirsten Arnold, Shannon Tunney, Suzin Wright, Floyd Taub, Charles S. Henry. Simplified selective electrochemical detection of ctDNA differentiates between cancer progression and regression [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 5027.