Platform For Electrochemical Detection Research Articles

Monodispersed Au nanoparticles decorated MoS2 nanosheets with enhanced peroxidase-like activity based electrochemical H2O2 sensing for anticancer drug evaluations

BackgroundThe unique size, physical and chemical properties, and ultra-high stability of nanozymes have attracted extensive attentions in sensing, but improvement of catalytic activity of the nanozymes is still an urgent issue. Given the ultra-high simulated enzyme activity of metal nanoparticles and the advantage of multi-enzyme catalysis, an Au-decorated MoS2 nanosheets (MoS2/Au NS) integrating the double peroxidase-like (POD) activity is developed. ResultsBy optimizing and adjusting the density of AuNPs, as well as its morphology and other parameters, a monodisperse and high-density distribution of AuNPs on MoS2 nanosheets was obtained, which can greatly improve the POD-like activity of MoS2/Au NS. Nafion solution was applied to assist the modification of MoS2/Au NS on the electrode surface so as to improved its stability. An electrochemical H2O2 detection platform was constructed by modifying MoS2/Au NS nanozyme on the SPCE using the conductive Nafion solution. And the negatively charged sulfonic acid group can eliminate negatively charged electroactive substances to improve the specificity. Then ascorbic acid was used to stimulate tumor cells to produce H2O2 as therapeutic model, an ultrasensitive chronocoulometry detection for H2O2 in cell lysate was established. The logarithmically of ΔQ and the logarithmically of H2O2 concentration showed a good linear relationship between 1 μM and 500 mM, with a LOD value of 0.3 μM. SignificanceThe developed H2O2 sensor has excellent stability, reproducibility (RSD = 2.3 %, n = 6) and selectivity, realized the quantitative detection of H2O2 in cell lysate. Compared with commercial fluorescence detection kits for H2O2 in cell lysate, it is worth mentioning that the electrochemical H2O2 sensor developed in this study is simpler and faster, with higher sensitivity and lower cost. This provides a potential substitute for disease diagnosis and treatment evaluation based on accurate detection of H2O2.

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.

Enhancing sensitivity towards electrochemical miRNA detection using an affordable paper-based strategy

In the era of liquid biopsy, microRNAs emerge as promising candidates for the early diagnosis and prognosis of cancer, offering valuable insights into the disease’s development. Among all the existing analytical approaches, even if traditional approaches such as the nucleic acid amplification ones have the advantages to be highly sensitive, they cannot be used at the point-of-care, while sensors might be poorly sensitive despite their portability. In order to improve the analytical performance of existing electroanalytical systems, we demonstrate how a simple chromatographic paper-based disk might be useful to rationally improve the sensitivity, depending on the number of preconcentration cycles. A paper-based electrochemical platform for miRNA detection has been developed by modifying a paper-based electrode with a methylene blue (MB)-modified single-stranded sequence (ssDNA) complementary to the chosen miRNA, namely miR-224 that is associated with lung cancer. A detection limit of ca. 0.6 nM has been obtained in spiked human serum samples. To further enhance the sensitivity, an external chromatographic wax-patterned paper-based disk has been adopted to preconcentrate the sample, and this has been demonstrated both in standard and in serum solutions. For each solution, three miR-224 levels have been preconcentrated, obtaining a satisfactory lowering detection limit of ca. 50 pM using a simple and sustainable procedure. This approach opens wide possibilities in the field of analytical and bioanalytical chemistry, being useful not only for electrochemistry but also for other architectures of detection and transduction.

A High-Performance Electrochemical Analysis Platform for Ultrasensitive Detection of HTLV-1 DNA: Integrating Cascade Signal Amplification with λ-Exonuclease-Assisted Target Recycling and Enzyme Catalysis

A High-Performance Electrochemical Analysis Platform for Ultrasensitive Detection of HTLV-1 DNA: Integrating Cascade Signal Amplification with λ-Exonuclease-Assisted Target Recycling and Enzyme Catalysis

Electrochemical detection platform based on graphene-zinc oxide composite nanomaterials for 17β-estradiol determination in milk

This research presents the development of an innovative electrochemical detection platform using a graphene-zinc oxide (G-ZnO) nanocomposite for the quantification of 17β-estradiol in milk. The G-ZnO nanocomposite, synthesized via a facile one-pot method, exhibited a unique wrinkled structure with a high specific surface area of 143 m²/g. Characterization through SEM, TEM, and XRD confirmed the effective integration of ultrafine ZnO nanoparticles onto graphene sheets. The electrochemical performance of the G-ZnO modified glassy carbon electrode was evaluated, revealing a notably low detection limit of 8.3 nM for 17β-estradiol, a significant improvement over traditional sensors. The sensor demonstrated a wide linear range of 0.05–100 μM and exceptional reproducibility with less than 3.5 % RSD over repeated measurements. Recovery studies in spiked milk samples yielded highly accurate results, with recovery percentages ranging from 97.8 % to 104.6 %. These findings underscore the potential of G-ZnO nanocomposites in creating sensitive, efficient, and reliable sensors for healthcare and environmental applications.

Waste hazelnut shell based effective hydrothermal carbon/SnO2 nanoparticles: Towards electrochemical sensing of catechol in green tea, fruit juice, and urine samples

This study focused on the electrochemical detection of catechol (CC), a carcinogenic for humans and a periodic environmental pollutant found in consumed food and beverages and has low degradability and high toxicity in the ecological environment. Also, in this study, for the first time, a new and green electrochemical detection platform was developed for the detection of CC through green carbon material (HZ) recycled from waste hazelnut shells with the hydrothermal carbonization technique (HTC) and SnO2 nanoparticles (NPs). The morphology, surface chemistry, chemical structure, and physicochemical properties of the synthesized green-based functional carbon material and SnO2 NPs were thoroughly investigated and elucidated using different characterization techniques. Thus, a green perspective was contributed to the studies of researchers working on CC detection in designing new types of nanosensors and developing electrode modifications. On GCE with an HZ-SnO2 modification, the effects of pH, the supporting electrolyte, and the scan rate on the electrochemical behavior of CC were investigated. The limit of detection (LOD) of the proposed nanosensor for CC was determined as 8.51 nM and the linearity range was determined as 0.80–80 µM under optimal conditions using adsorptive stripping differential pulse voltammetry (AdsDPV).The developed new type, the green method, has been performed to detect the CC in green tea, fruit juice, and urine samples with sufficient accuracy and precision.

Distinctive profile of monomeric and polymeric anti-SSA/Ro52 immunoglobulin A1 isoforms in saliva of patients with primary Sjögren’s syndrome and Sicca

ObjectivePrimary Sjögren’s syndrome (pSS) is the second most common chronic autoimmune connective tissue disease. Autoantibodies, immunoglobulin (IgG) anti-SSA/Ro, in serum is a key diagnostic feature of pSS. Since pSS is...

Ti3C2Tx/laser-induced graphene-based micro-droplet electrochemical sensing platform for rapid and sensitive detection of benomyl

The design and fabrication of high-performance electrode devices are highly important for the practical application of electrochemical sensors. In this study, flexible three-dimensional porous graphene electrode devices were first facilely fabricated using common laser ablation technique at room temperature. After then, hydrophilic two-dimensional MXene (Ti3C2Tx) nanosheet was decorated on the surface of the laser-induced graphene (LIG), resulting in disposable Ti3C2Tx/LIG electrode devices. After introducing Ti3C2Tx nanosheet, the electrochemical active area, electron transfer ability of LIG electrode device and its adsorption efficiency toward organic pesticide benomyl was significantly boosted. As a result, the fabricated Ti3C2Tx/LIG electrode device exhibited significantly enhanced electrocatalytic activity toward benomyl oxidation. Based on this, a novel and ultra-sensitive electrochemical platform for micro-droplet detection of benomyl was achieved in the range of 10 nM–6000 nM with detection sensitivity of 169.9 μA μM−1 cm−2 and detection limit of 5.8 nM. Considering the low-cost Ti3C2Tx/LIG electrode devices are rarely used for electrochemical analysis, we believed this research work will contribute to exploring the broader application of MXene/LIG electrode devices in the field of electrochemical sensing.

Aptamer-based electrochemical analysis platform for tumor cells and biomarkers detection

Early diagnosis and treatment of cancer can effectively improve patient survival rates and quality of life. One of the best options for early screening strategies is to track tumor cells and their markers. There is also an urgent need to develop accurate, susceptible, rapid, non-invasive, and low-cost detection methods. Among them, standard detection techniques for tumor cells include immunohistochemistry and histopathology, but they are expensive and require professional personnel. Both tumor cells and normal cells can secrete biomarkers, which can be obtained from biological samples (such as blood, urine, serum, etc.). Tumor biomarkers may be significantly elevated or changed in individuals with tumors. Common tumor biomarkers include proteins, nucleic acids, etc. In recent years, aptamer-based electrochemical analysis methods have been widely used in cancer diagnosis. Aptamers are obtained through in vitro screening technology and have high selectivity and affinity, which can improve the sensitivity of electrochemical analysis technology. This article reviews the achievements of aptamer-based electrochemical analysis methods in detecting tumor cells and tumor markers and the challenges and development prospects in cancer diagnosis.

Portable self-powered electrochemical aptasensing platform for ratiometric detection of mycotoxins based on multichannel photofuel cell

Self-powered electrochemical sensors based on photofuel cells have attracted considerable research interest because their unique advantage of not requiring an external electric source, but their application in portable and multiplexed targets assay is limited by the inherent mechanism. In this work, a portable self-powered sensor constructed with multichannel photofuel cells was developed for the ratiometric detection of mycotoxins, namely ochratoxin A (OTA) and patulin (PAT). The spatially resolved CdS/Bi2S3-modified photoanodes and a shared Prussian Blue cathode were integrated on an etched indium-tin oxide slide to fabricate the multichannel photofuel cell. The aptamers of OTA and PAT were covalently bonded to individual photoanode regions to build sensitive interfaces, and the specific recognition of analytes impaired the output performance of constructed PFC. Accordingly, ratiometric sensing of OTA and PAT was achieved by utilizing the output performance of a control PFC as a reference signal. This approach effectively eliminates the impact of light intensity on the accuracy of the detection. Under the optimal conditions, the proposed sensing chip exhibited linear ranges of 2.0–1000 nM and 5.0–500 nM for OTA and PAT, respectively. The detection limits (3 S/N) were determined to be 0.25 nM for OTA and 0.27 nM for PAT. The developed ratiometric sensing method demonstrated good selectivity and stability in the simultaneous detection of OTA and PAT. It was successfully utilized for the analysis of OTA and PAT real samples. This work provides a new perspective for construction of portable and ratiometric self-powered sensing platform.

Metal oxide based carbon nanocomposite as sensing platform for electrochemical detection of cadmium- computational and experimental approach

Cadmium is detected using an electrochemical sensor prepared by fabricating ITO substrate with metal oxide based carbon nanocomposite (SnO2, MnO2, MWCNTs and ionic liquid (IL)). The computational studies showed that the interaction of metal oxide based nanocomposites with cadmium is thermodynamically favorable (adsorption energy of −1.37 and −8.71 eV for SnO2 adsorbed cadmium and MnO2 adsorbed cadmium respectively). Metal oxide shows good conductivity and provide structural stability to the redox process at the surface. The fabricated sensor, SnO2/MWCNTs/IL/ITO and MnO2/MWCNTs/IL/ITO showed good sensitivity towards cadmium by having linearity range of 20–200 and 300–2000 ppb with a limit of detection 3.61 and 41.34 ppb respectively. The sensor showed good reproducibility and repeatability at optimized conditions. The recovery response to check the stability and resistance to interfering ions showed good results which is credited to the chemical stability and selective sites of SnO2/MWCNTs/IL and MnO2/MWCNTs/IL nanocomposite. The sensor showed good performance in real water samples analysis by showing efficient recovery through spike recovery test with a confidence interval above 95 %.

AuNPs-Ultrathin/Graphitic-C3N4 nanosheets as a sensitive platform for electrochemical detection and determination of dopamine

The present work describes developing a selective and sensitive electrochemical sensor using the AuNPs/Graphitic-C3N4 (ug-C3N4) nanocomposites for the voltammetric detection of dopamine. This nanocomposite is obtained by loading gold nanoparticles (AuNPs) onto an ultrathin nano-sheet of graphitic carbon nitride (utg-C3N4). Firstly, the bulk g-C3N4 was produced through a thermal poly-condensation process, and then, the ug-C3N4 nanosheets were obtained by exfoliating the bulk g-C3N4. The nanocomposite of graphitic carbon nitride decorated with AuNPs exhibits highly sensitive electrochemical signals, suggesting successful immobilization of AuNPs/ug-C3N4 onto the electrode surface. Transmission electron microscopy (TEM), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS),Fourier transform infrared spectroscopy (FT-IR), and X-ray diffraction (XRD) are used for the structural and morphological characterization of the AuNPs/utg-C3N4 composite. Differential pulse and cyclic voltammetric methods are used for the application of AuNPs/utg-C3N4 modified electrodes as an electrochemical sensor for the detection of dopamine (DA). The prepared electrode shows two wide linear ranges from 5.00 − 99 nM and 99–––476 nM, with a detection limit of 0.24 nM (S/N = 3) in voltammetric detection of DA. Using the standard addition method, the electrochemical sensor based on AuNPs/utg-C3N4 nanocomposite is successfully applied for detecting and quantifying DA in human urine samples.

Electrochemically Deposited Cu(II)/Cu(I) Oxide Heterostructure as Highly Sensitive Platform for Electrochemical Detection of Glucose and Methanol

Electrochemically Deposited Cu(II)/Cu(I) Oxide Heterostructure as Highly Sensitive Platform for Electrochemical Detection of Glucose and Methanol

Printing surface cuprous oxides featured liquid metal for non-enzymatic electrochemical glucose sensor

Electrochemical glucose sensors that rely on two-dimensional (2D) oxides have attracted significant attention owing to the strong sensing activity of 2D oxides, but their practical application is hindered by the complexity and high cost of fabrication of electrodes and integrated devices. Herein, a convenient and effective fabrication route that includes printing a Ga-based liquid metal (LM) as a current collection electrode, followed by growing electrochemically active 2D oxides directly on the surface of Ga-based LMs under mild conditions, is developed for non-enzyme-based electrochemical sensors. Specifically, 2D annealed Cu-Oxide (ACO) is successfully grown on a printed Ga electrode through a galvanic replacement reaction, resulting in the formation of a mechanically and electrically well-matched interface between the active sensing materials and the current collection substrate. Benefitting from the high quantity of 2D ACO and good charge transfer at the interface, the as-prepared ACO electrode exhibits attractive glucose sensing performance, with a wide linear range (1 μM-10 mM) of effective detection, low detection limit down to 1 μM, and high sensitivity of 0.87 μA·mM-1·cm-2. Our study highlights the potential of using LMs in bio-sensing applications and provides a non-enzyme-based electrochemical biosensor platform for effective glucose detection in diets and clinical diagnostic settings.

A new thiacalix[4]arene-based metal-organic framework as an efficient electrochemical sensor for trace detection of Cd2+ and Pb2+

Heavy metal ions (HMIs) can lead to serious harm to human health and ecological environment. Thus, developing an efficient detection method for HMIs is extremely necessary. Herein, a new thiacalix[4]arene-based metal–organic framework (MOF) [Co2(L1)(TPA)2]·DMA·3CH3OH·H2O (Co-LTPA) (L1 = thiacalix[4]arene-based ligand and H2TPA = terephthalic acid) was successfully synthesized. The electrochemical detection platform (Co-LTPA/GCE) was acquired, and Co-LTPA/GCE featured ultrasensitive detection of HMIs with greatly low limits of detection (LODs) of 0.119 nM for Cd2+ and 0.279 nM for Pb2+ as well as wide linear ranges of 0.08–5.8 μM for Cd2+ and 0.01–6.0 μM for Pb2+. More importantly, the Co-LTPA/GCE sensor was employed to detect foods (milk, honey and orange juice) and water samples (tap water, lake water and drinking water) with satisfactory recoveries, proving the sensor reliability in practical applications. This work provided an example that the functional electrochemical Co-LTPA/GCE sensor was employed for Cd2+ and Pb2+ detection.

Electroactive ferrites nanostructure driven electrochemical platform for selective detection of dopamine

This study proposes a new electrochemical platform based on electroactive vanadium ferrites (VFe2O4) for the highly selective detection of dopamine (DA). VFe2O4 were synthesized with the sol–gel auto-ignition method and characterized by X-ray diffraction (XRD), Scanning electron microscopy (SEM), impedance analyzer, and cyclic voltammetry. The characterization study revealed that the VFe2O4 have a single-cubic structure with agglomerated structure. The VFe2O4 showed the multi-ions-based increment in the dielectric constant. The VFe2O4 sensor was fabricated by drop-casting method on a glassy carbon (VFe2O4-GCE) electrode with the addition of Nafion and applied for electrochemical detection of DA (a common neurotransmitter) in pharmaceutical preparations and biological samples. The results of electrochemical analysis of DA in the concentration range of 0.05 – 12.3 µM by using VFe2O4-GCE showed a linear response (co-efficient of determination R2 = 0.995) with the limit of detection and quantification (LOD/LOQ) as 0.0087 and 0.029 μM, respectively.

Simple and promising paper-based electrochemical platform for serological detection of American tegumentary leishmaniasis.

American tegumentary leishmaniasis (ATL) is an endemic neglected tropical disease (NTD), its conventional treatment is toxic, slow, and invasive. Rapid diagnosis is crucial for the clinical management of suspected patients, so the development and use of low-cost, miniaturised and portable devices could be the key. This work aimed to develop a simple paper-based electrochemical platform for the serological detection of ATL. Platform was fabricated in Whatman N°1 paper, contains a hydrophobic zone generated by wax printing, two pencil graphite electrodes, and uses specific crude extracts (CA) antigens for ATL immuno-determination. The platform performance was analysed by measuring the relative impedance change for different antigen-antibody combinations. Then, 10 serum human samples previously diagnosed by the gold standard (five positive ATL cases and five non-ATL cases) were evaluated. The platform presented a linear response for the charge transfer resistance (ΔRct) and the interface reactance (ΔXc). Also, optimal working conditions were established (1/60 serum dilution and 180 µg/mL CA concentration). Then, the platform permits to distinguish between ATL and non-ATL (p < 0.05) human serum samples. Our platform could allow the diagnosis, management, and monitoring of leishmaniasis while being an extremely simple and environmentally friendly technology.

Improving electrochemical hybridization assays with restriction enzymes.

Nucleic acids in blood are early indicators of disease that could be detected by point-of-care biosensors if sufficiently sensitive and facile sensors existed. Electrochemical hybridization assays are sensitive and specific but are limited to very short nucleic acids. We have developed a restriction enzyme-assisted electrochemical hybridization (REH) assay for improved nucleic acid detection. By incorporating target-specific restriction enzymes, we detect long nucleic acids, with performance dependent on the location of the cut site relative to the electrode surface. Thus, we have further established guidelines for REH design to serve as a generalizable platform for robust electrochemical detection of long nucleic acids.

Increasing Sensitivity and Selectivity for Heavy Metal Sensing through Microfluidic Electrochemical Sensor

Introduction Cadmium usually exists in nature as a compound and under normal environmental conditions, its small content will not affect human health. Nevertheless, with human society's development, heavy metal ions pollution has become substantially serious, and they have serious biological toxicity. Hence, it is important to develop simple, rapid, sensitive, and portable devices for Cd2+ sensing [1].In the present work, we show how paper based microfluidic sensors improve sensitivity and limit of detection (LOD) in comparison to classical screen-printed carbon-based electrode (SPCE). Furthermore, the presented microfluidic electrochemical carbon-based sensor (μCS) do not employ critical metals and rely on graphite foil that is modified by N-doped carbon nanoonions (N-CNOs) N-CNOs. Experimental For the synthesis of N-doped CNOs the Kuznetsov method was employed [2]. The alignment of the component for μCS device is sketched below. After providing the analyte solution through the sponge the electrochemical detection is carried out through accumulation of the metal at the working electrode for varying times and cathodic potentials. The final detection is carried out through square wave anodic stripping voltammetry (SWASV) of the accumulated metal. Results and discussion To realize a sensitive measurement, some experimental conditions including the optimal amount of the employed N-doped CNOs and Nafion in the nanocomposite, deposition time and potential, and the effect of pH of supporting electrolyte were studied. By increasing the deposition time ranging from 0 to 5 min, the SPCE/N-CNOs signal was increased and after that, it remains roughly constant because the WE surface is being saturated and also the amount of analyte in the droplet was reduced due to the presence of a stagnant flow. However, for μCS/N-CNOs by increasing the accumulation time ranging from 0 to 10 min the signal was increased which shows that the electrode surface is still far from being saturated (because of the live flow). A linear concentration range from 1.0 to 100.0 μg L- 1 was achieved using SWASV. Also, the LOD and sensitivity are calculated to be 0.5 μg L- 1 and 1.02 μA µM-1 cm-2, respectively. Additionally, the method was successfully employed for measurements of Cd2+ in different real samples, which demonstrated the excellent applicability of the device for the adsorption and detection of heavy metal ions. Conclusion The μCS/N-CNOs offers several core advantages over SPCE/N-CNOs in terms of cost, simplicity, analysis time, and sensitivity. These unique advantages are due to the combined microfluidic configuration, 3D electrode layout, and a unique modifier. We believe our findings would have significant implications in developing other portable, fast, and cost-effective electrochemical detection platforms, such as clinical diagnosis and security inspection.

Functionalized Graphitic Carbon Nitride Based Aptasensing Platform for Electrochemical Detection of Helicobacter Pylori

Functionalized Graphitic Carbon Nitride Based Aptasensing Platform for Electrochemical Detection of <i>Helicobacter Pylori</i>