Selective Electrochemical Sensor Research Articles

Green synthesis of Au@g-C3N4 nanocomposite using Hyssopus officinalis extract and its sensing application for vortioxetine determination.

Herein, we introduce a stable and green Au@g-C3N4 nanocomposite as a selective electrochemical sensor for vortioxetine (VOR) determination. The electrochemical behavior of VOR on the developed electrode was investigated through cyclic voltammetry (CV), differential pulse voltammetry (DPV), electrochemical impedance spectroscopy (EIS), and chronoamperometry. The Au@g-C3N4 nanocomposite was thoroughly observed by X-ray diffraction (XRD), energy-dispersive X-ray spectroscopy (EDX), Raman spectroscopy, and scanning electron microscopy. The Au@g-C3N4 nanocomposite had a higher conductivity and a narrower band gap than pure g-C3N4, causing higher electrochemical activity for VOR detection. Moreover, Au@g-C3N4 on the glassy carbon electrode (Au@g-C3N4/GCE) monitored a low level of VOR with high efficiency and low interference as an environmentally friendly processing approach. Interestingly, the as-fabricated sensor exhibited an ultrahigh selectivity for recognizing VOR with a detection limit (LOD) of 3.2nM. Furthermore, the developed sensor was applied to determine VOR in pharmaceutical and biological samples, which indicated a high selectivity in the presence of interferences. This study suggests new insights into the phytosynthesis synthesis of nanomaterials with excellent biosensing applications.

ZnO and Au nanoparticles supported highly sensitive and selective electrochemical sensor based on molecularly imprinted polymer for sulfaguanidine and sulfamerazine detection

This study aimed to develop a molecularly imprinted polymer (MIP) sensor using electropolymerization of thiophene acetic acid monomer around template molecules, sulfaguanidine (SGN) and sulfamerazine (SMR), for selective and sensitive detection of both antibiotics. Au nanoparticles were then deposited on the modified electrode surface, and SGN and SMR were extracted from the resulting layer. Surface characterization, changes in the oxidation peak current of both analytes, and investigation of the electrochemical properties of the MIP sensor were examined using scanning electron microscopy, cyclic voltammetry, and differential pulse voltammetry. The developed MIP sensor with Au nanoparticles showed a detection limit of 0.030 µmol L−1 and 0.046 µmol L−1 for SGN and SMR, respectively, with excellent selectivity in the presence of interferents. The sensor was successfully used for SGN and SMR analysis in human fluids, including blood serum and urine, with excellent stability and reproducibility.

Effect of Magnesium Chloride in Supporting Electrolyte for Enhancing Sensitive and Selective Electrochemical Sensor: An Approach for Anti-Rheumatic Sulfasalazine Detection

In this work, an electroanalytical evaluation for voltammetric sensing of the anti-rheumatic sulfasalazine (SSZ) at an unmodified screen-printed graphene electrode (SPGE) is demonstrated. By using the differential pulse (DPV) technique, the SSZ produced a well-defined peak of around −0.3 V (vs Ag AgCl−1) in Britton-Robinson (BR) buffer pH 4. Supporting electrolytes, pH, and salts all significantly impact SSZ reduction. Therefore, their impact on the working solutions was assessed. We discovered that using a mixture of Britton–Robinson (BR) buffer with pH 4 and MgCl2 as a supporting electrolyte can enhance SSZ sensitivity by approximately 1.7 times while simultaneously increasing detection selectivity. Under optimal conditions, the proposed assay demonstrated the ultrasensitive determination of SSZ with a broad linear detection range from 0.01 to 100 μM and a low detection limit of 4.7 nM (S/N = 3). To demonstrate the impact of the proposed method, the sensor has been successfully applied for the quantitative determination of SSZ in pharmaceutical, urine, and artificial serum sample. Therefore, this approach could offer simplicity, and rapidity, and serve as an alternative to the SSZ detection in practical applications.

Rapid and efficient determination of Bisphenol A using reduced graphene oxide wrapped barium/molybdenum oxide nanocomposite

Because of its toxicity and ubiquity in the environment, Bisphenol A (BA) is a prominent endocrine-disrupting compound widely employed in polycarbonate plastics and epoxy resins. BA causes severe health risks for humans. To resolve this, we crafted a selective electrochemical sensor through an efficient electrocatalyst, reduced graphene oxide (RGO) wrapped barium oxide/molybdenum oxide (BMO) nanorod, developed via the hydrothermal method. BMO/RGO nanocomposite was characterized and employed for electrocatalytic performance. BMO displays admirable selectivity, stability, and sensitivity for the determination of BA. Differential pulse voltammetry (DPV) was used for the electrocatalytic study of BMO/RGO nanocomposite for detecting BA. Our proposed sensor displayed a linear enhancement of current when the concentration of BA was increased from 0.01 to 723 μM with a limit of detection (LOD) of 0.004 μM. Furthermore, the proposed sensor is a tool for the rapid and sensitive detection of environmental samples.

Low Overpotential Amperometric Sensor Using Yb2O3.CuO@rGO Nanocomposite for Sensitive Detection of Ascorbic Acid in Real Samples.

The ultimate objective of this research work is to design a sensitive and selective electrochemical sensor for the efficient detection of ascorbic acid (AA), a vital antioxidant found in blood serum that may serve as a biomarker for oxidative stress. To achieve this, we utilized a novel Yb2O3.CuO@rGO nanocomposite (NC) as the active material to modify the glassy carbon working electrode (GCE). The structural properties and morphological characteristics of the Yb2O3.CuO@rGO NC were investigated using various techniques to ensure their suitability for the sensor. The resulting sensor electrode was able to detect a broad range of AA concentrations (0.5-1571 µM) in neutral phosphate buffer solution, with a high sensitivity of 0.4341 µAµM-1cm-2 and a reasonable detection limit of 0.062 µM. The sensor's great sensitivity and selectivity allowed it to accurately determine the levels of AA in human blood serum and commercial vitamin C tablets. It demonstrated high levels of reproducibility, repeatability, and stability, making it a reliable and robust sensor for the measurement of AA at low overpotential. Overall, the Yb2O3.CuO@rGO/GCE sensor showed great potential in detecting AA from real samples.

Highly sensitive and selective electrochemical sensor for the simultaneous determination of tinidazole and chloramphenicol in food samples (egg, honey and milk)

In this study, an environmentally friendly, highly selective, and sensitive electrochemical sensor was developed for the simultaneous determination of tinidazole (TIN) and chloramphenicol (CAP) using a choline chloride-modified glassy carbon electrode (ChCl/GCE). Electrochemical impedance spectroscopy (EIS), cyclic voltammetry (CV), scanning electron microscopy (SEM), and Fourier transform infrared (FT-IR) spectrometry techniques were utilized for electrochemical and morphological characterization. The proposed sensor showed an excellent performance with a wide linear range of 0.010–170 μM and 0.005–300 μM for TIN and CAP, respectively. The limit of detection (LOD) and quantification (LOQ) were 0.90 nM and 3.0 nM for TIN and 0.27 nM and 0.89 nM for CAP, respectively. ChCl/GCE demonstrated remarkable selectivity over potentially interfering species, including antibiotics, organic and inorganic substances, as well as exceptional repeatability, reproducibility, and long-term stability. The sensor was successfully applied to simultaneously determine TIN and CAP in food samples (eggs, honey, and milk) with acceptable recovery values of 93.0–104 % and relative standard deviations (RSD) below 5 %. Therefore, the developed electrochemical sensor is an excellent alternative for simultaneously determining TIN and CAP in food samples.

Copper oxide nanocomposite particles supported on sodium alginate-g-polyallylamine based reduced graphene oxide: An efficient electrochemical sensor for sensitive detection of cadmium ions in water

A highly sensitive and selective electrochemical sensor, sodium alginate-g-polyallylamine/reducedgrapheneoxide/CuO nanocomposite particles (SAGPMRGO@CuO NPs) has been synthesized for the detection of Cd2+ ions in the aqueous environment. The graft copolymer/reduced graphene oxide supported CuO nanocomposite particles are prepared through bioreduction of graphene oxide by a novel synthesized graft copolymer sodium alginate-g-PAAM (SAG-g-PAAM) to reduced graphene oxide (SAGPMRGO) followed by using it as both a reductant and a stabilizing agent to obtain SAGPMRGO@CuO hybrid nanocomposite particles. The graft copolymer is prepared via free radical solution phase graft copolymerization technique. The graphene oxide (GO) is prepared by the oxidation of graphite using modified Hummer's method. The prepared nanocomposite particles are characterized by UV-VIS, FTIR and Raman spectroscopy, powder X-ray diffraction (PXRD), HRTEM-EDS, FESEM, XPS and DLS analysis with zeta potential measurement in colloidal suspension. The prepared graft copolymer is characterized by 1H and 13C NMR spectroscopy, PXRD and FESEM analysis and the SAMPGRGO is characterized by UV-VIS and Raman spectroscopy, PXRD and FESEM analysis. The CuO nanocomposite particles are spindle shaped with an average particle size ranges from 15.6 nm to 32.1 nm and are well polydispersed. Metal ion (Cd2+) sensing is carried out by cyclic voltammetry (CV) and chronoamperometry (CA) analysis under optimum conditions. The limit of detection (LOD) and limit of quantitation (LOQ) is found to be 1.27 nM and 4.24 nM respectively which is lower than some other reported works. The reproducibility and stability properties of the developed sensor are examined where the results are found to be satisfactory. The selective detection of Cd2+ ions in a river water sample is also evaluated with an excellent performance.

Sensitivity enhancement of a Cu (II) metal organic framework-acetylene black-based electrochemical sensor for ultrasensitive detection of imatinib in clinical samples.

Imatinib (IMB), an anticancer drug, is extensively used for chemotherapy to improve the quality of life of cancer patients. The aim of therapeutic drug monitoring (TDM) is to guide and evaluate the medicinal therapy, and then optimize the clinical effect of individual dosing regimens. In this work, a highly sensitive and selective electrochemical sensor based on glassy carbon electrode (GCE) modified with acetylene black (AB) and a Cu (II) metal organic framework (CuMOF) was developed to measure the concentration of IMB. CuMOF with preferable adsorbability and AB with excellent electrical conductivity functioned cooperatively to enhance the analytical determination of IMB. The modified electrodes were characterized using X-rays diffraction (XRD), X-ray photoelectron spectroscopy (XPS), fourier transform infrared (FT-IR), ultraviolet and visible spectrophotometry (UV-vis), electrochemical impedance spectroscopy (EIS), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), brunauer‒emmett‒teller (BET) and barrett‒joyner‒halenda (BJH) techniques. Analytical parameters such as the ratio of CuMOF to AB, dropping volumes, pH, scanning rate and accumulation time were investigated through cyclic voltammetry (CV). Under optimal conditions, the sensor exhibited an excellent electrocatalytic response for IMB detection, and two linear detection ranges were obatined of 2.5nM-1.0μM and 1.0-6.0μM with a detection limit (DL) of 1.7nM (S/N = 3). Finally, the good electroanalytical ability of CuMOF-AB/GCE sensor facilitated the successful determination of IMB in human serum samples. Due to its acceptable selectivity, repeatability and long-term stability, this sensor shows promising application prospects in the detection of IMB in clinical samples.

A Comprehensive Study of Electrocatalytic Degradation of M-Tolylhydrazine with Binary Metal Oxide (Er2O3@NiO) Nanocomposite Modified Glassy Carbon Electrode

Generally, our ecosystem is continuously contaminated as a result of anthropogenic activities that form the basis of our comfort in our routine life. Thus, most scientists are engaged in the development of new technologies that can be used in environmental remediation. Herein, highly calcined binary metal oxide (Er2O3@NiO) semiconductor nanocomposite (NC) was synthesized using a classical wet chemical process with the intention to both detect and degrade the toxic chemicals in an aqueous medium using a novel electrochemical current–potential (I–V) approach for the first time. Optical, morphological, and structural properties of the newly synthesized semiconductor NC were also studied in detail using FT-IR, UV/Vis., FESEM-EDS, XPS, BET, EIS, and XRD techniques. Then, a modified glassy carbon electrode (GCE) based on the newly synthesized semiconductor nanocomposite (Er2O3@NiO-NC/Nafion/GCE) as a selective electrochemical sensor was fabricated with the help of 5% ethanolic-Nafion as the conducting polymer binder in order to both detect and electro-hydrolyze toxic chemicals in an aqueous medium. Comparative study showed that this newly developed Er2O3@NiO-NC/Nafion/GCE was found to be very selective against m-tolyl hydrazine (m-Tolyl HDZN) and to have good affinity in the presence of other interfering toxic chemicals. Analytical parameters were also studied in this approach to optimize the newly designed Er2O3@NiO-NC/Nafion/GCE as an efficient and selective m-Tolyl HDZN sensor. Its limit of detection (LOD) at an SNR of 3 was calculated as 0.066 pM over the linear dynamic range (LDR) of our target analyte concentration (0.1 pM–0.1 mM). The limit of quantification (LOQ) and sensitivity were also calculated as 0.22 pM and 14.50 µAµM−1cm−2, respectively. m-Tolyl HDZN is among the toxic chemicals in our ecosystem that have lethal effects in living beings. Therefore, this newly designed electrochemical sensor based on semiconductor nanostructure material offers, for the first time, a cost-effective technique, in addition to long-term stability, that can be used as an alternative for efficiently probing other toxic chemicals in real samples.

A Modified Electrochemical Sensor Based on N,S-Doped Carbon Dots/Carbon Nanotube-Poly(Amidoamine) Dendrimer Hybrids for Imatinib Mesylate Determination.

Imatinib mesylate, an anticancer drug, is prescribed to treat gastrointestinal stromal tumors and chronic myelogenous leukemia. A hybrid nanocomposite of N,S-doped carbon dots/carbon nanotube-poly(amidoamine) dendrimer (N,S-CDs/CNTD) was successfully synthesized and used as a significant modifier to design a new and highly selective electrochemical sensor for the determination of imatinib mesylate. A rigorous study with electrochemical techniques, such as cyclic voltammetry and differential pulse voltammetry, was performed to elucidate the electrocatalytic properties of the as-prepared nanocomposite and the preparation procedure of the modified glassy carbon electrode (GCE). A higher oxidation peak current was generated for the imatinib mesylate on a N,S-CDs/CNTD/GCE surface compared to the GCE and CNTD/GCE. The N,S-CDs/CNTD/GCE showed a linear relationship between the concentration and oxidation peak current of the imatinib mesylate in 0.01-100 μM, with a detection limit of 3 nM. Finally, the imatinib mesylate's quantification in blood-serum samples was successfully performed. The N,S-CDs/CNTD/GCE's reproducibility and stability were indeed excellent.

Highly selective electrochemical sensor for new generation targeted-anticancer drug Ibrutinib using newly synthesized nanomaterial GO-NH-B(OH)2@AgNPs modified glassy carbon electrode

Ibrutinib (IBR) is a small molecule new generation smart anti-cancer drug that is Bruton's tyrosine kinase (BTK) inhibitor. In this study, the sensitive and selective electrochemical sensor based on a modification of a glassy carbon electrode with a new GO-NH-B(OH)2 (graphene oxide boramidic acid) nanoparticles and Ag nanoparticles (AgNPs) is proposed for IBR determination. GO-NH-B(OH)2@AgNPs/GCE was characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), electrochemical impedance spectroscopy (EIS), and cyclic voltammetry (CV). The performance of the electrode was evaluated with the parameters of electrode surface area (A), heterogeneous rate constant (ket), standard exchange current density (I0). The electrochemical determination of IBR in 0.1 M HNO3 solution was investigated at the surface of GO-NH-B(OH)2@AgNPs/GCE. Under optimized square wave voltammetric (SWV) conditions, peaks current at GO-NH-B(OH)2@AgNPs/GCE showed good linearity with the concentration of IBR in the operating range of 0.025–1.00 μg mL−1 (5.7 × 10−8 – 2.3 × 10−6 M) with a detection limit (LOD) of 0.006 μg mL−1 (1.36 × 10−8 M). Besides its high stability and reproducibility, the response of IBR at GO-NH-B(OH)2@AgNPs/GCE was not influenced by the presence of dopamine, uric acid, and ascorbic acid. The sensor has successfully caught IBR in pharmaceutical and human urine samples.

Real-time detection of 2,4,6-trichlorophenol in environmental samples using Fe3O4 nanospheres decorated graphitic carbon nitride nanosheets

Real-time detection of 2,4,6-chlorophenol (TCP) has gained greater interest due to its widespread distribution and hazardous effects on living organisms. In this study, graphitic carbon nitride nanosheets decorated with Fe3O4 nanospheres (CN@Fe3O4) composite-modified screen-printed carbon electrodes (SPCE) were designed to develop a novel and selective electrochemical sensor for the detection of TCP. For the synthesis of CN nanosheets, the combustion technique was used, while the co-precipitation method was used for the preparation of CN@Fe3O4 composite. The XRD confirmed a high degree of crystalline nature and exceptionally pure phase, with an average size of 38.7 nm for Fe3O4 on CN nanosheets. Under optimal conditions, CN@Fe3O4 modified SPCE outperformed CN and Fe3O4 modified SPCEs in determining TCP. Analytical validations confirmed that the CN@Fe3O4-modified SPCE has a linear range for TCP between 0.04 and 651 μM with a detection limit of 12 nM. A practicality evaluation of the proposed sensor revealed an outstanding TCP recovery rate in various water samples.

Two different molecularly imprinted polymeric coating techniques for creating sensitive and selective electrochemical sensors for the detection of Ribavirin

Herein, we successfully designed two separate imprinting strategies for the selective and sensitive detection of ribavirin (RIB) based on electropolymerization (EP) with para-aminophenyl boronic acid (p-APBA) functional monomer and photopolymerization (PP) with uracil methacrylate (UraM) functional monomers. For this purpose, firstly, poly(Py-co-p-APBA)]/RIB@MIP/GCE was successfully synthesized by co-polymerization of p-APBA monomer with pyrrole (Py) in the presence of RIB on a glassy carbon electrode (GCE) surface via EP process. Secondly, the PP based UraM/RIB@MIP sensor was fabricated by the co-polymerization of UraM and 2-hydroxyethyl methacrylate (HEMA) using polyvinyl pyrrolidone (PVP) as a sacrificial agent. The modifications of electrode surface are assessed at the molecular and electronic levels by quantum chemical calculations. Under optimum experimental conditions, the dynamic linear range of the developed sensors was found as 1.0 × 10−11-5.0 × 10−10 M and 1.0 × 10−12-2.5 × 10−11 M for EP and PP, respectively. The developed electrochemical sensors shows satisfactory recovery for the determination RIB in capsule form and commercial serum samples as 99.55–101.18% and 99.17% and 101.09% for poly(Py-co-p-APBA)/RIB@MIP/GCE and UraM/RIB@MIP/GCE sensors, respectively.

Ultrasensitive and Selective Electrochemical Sensor Based on Yttrium Benzenetricarboxylate Porous Coordination Polymer (Y-BTC) for Detection of Pb2+ from Bio-Analytes

Due to industrialization, the presence of heavy metal ions in various sources of drinking water causes damage to the ecosystem. Determination of heavy metal ions is still arduous due to their toxicity and carcinogenic behavior to humankind. The present investigation deals with the development of a novel ultrasensitive electrochemical sensor for the detection of lead (Pb2+) from pesticide and fruit core. Repetitive laboratory-scale aqueous samples have been tested to validate all sensing parameters, it exhibited highly selective behaviour towards Pb2+. Hydrothermally synthesized Yttrium Benzenetricarboxylate (Y-BTC) has been characterized by means of structural, morphological, electrochemical and spectroscopic characterizations and utilized as a sensing material. Y-BTC Sensor’s differential pulse behavior shows affinity towards Pb2+, a detailed sensing mechanism further illustrated by XPS studies, DLS measurements, deformation studies by photoluminescence spectra, and charge transfer resistance obtained from EIS data. The developed Y-BTC sensor showcased an excellent picomolar detection limit of 1 pM. Reliability of developed sensor was confirmed by evaluation of sensitivity (4.4 μA M−1), selectivity (towards Pb2+), repeatability and reproducibility. The proposed sensor would play a vital role in monitoring human health in the upcoming days.

A Highly Selective Electrochemical Sensor Based on Molecularly Imprinted Copolymer Functionalized with Arginine for the Detection of Chloramphenicol in Honey.

Developing an efficient method for chloramphenicol (CAP) detection is of great significance for food safety. Arginine (Arg) was selected as a functional monomer. Benefiting from its excellent electrochemical performance, which is different from traditional functional monomers, it can be combined with CAP to form a highly selective molecularly imprinted polymer (MIP) material. It overcomes the shortcoming of poor MIP sensitivity faced by traditional functional monomers, and achieves high sensitivity detection without compounding other nanomaterials, greatly reducing the preparation difficulty and cost investment of the sensor. The possible binding sites between CAP and Arg molecules were calculated by molecular electrostatic potential (MEP). A low-cost, non-modified MIP electrochemical sensor was developed for the high-performance detection of CAP. The prepared sensor has a wide linear range from 1 × 10-12 mol L-1 to 5 × 10-4 mol L-1, achieves a very low concentration CAP detection, and the detection limit is 1.36 × 10-13 mol L-1. It also exhibits excellent selectivity, anti-interference, repeatability, and reproducibility. The detection of CAP in actual honey samples was achieved, which has important practical value in food safety.

A Magnetite Composite of Molecularly Imprinted Polymer and Reduced Graphene Oxide for Sensitive and Selective Electrochemical Detection of Catechol in Water and Milk Samples: An Artificial Neural Network (ANN) Application

In the present study, a stable and more selective electrochemical sensor for catechol (CC) detection at magnetic molecularly imprinted polymer modified with green reduced graphene oxide modified glassy carbon electrode (MIP/rGO@Fe3O4/GCE). Two steps have been applied to achieve the imprinting process: (1) adsorption of CC on the surface of the polypyrrole (Ppyr) during the polymerization of pyrrole and (2) the green extraction of the template (CC) from the mass produced. Hence, the present paper doesn’t present the first use of MIP technology for CC identification but, it presents a new extraction process. The MIP/rGO@Fe3O4/GCE was characterized by voltammetry techniques and exhibited a wide linear range from1 50 μM of CC while the detection limits were estimated to be around 4.18 nM CC and limit of quantification in the range of 12.69 nM CC. Furthermore, the prepared MIP-based sensor provided outstanding electroanalytical performances including high selectivity, stability, repeatability, and reproducibility. For the accurate estimation of CC concentrations, an artificial neural network (ANN) was developed based on the findings of the study. The MIP/rGO@Fe3O4/GCE exhibits excellent stability with a very important selectivity and sensitivity. The analytical testing of the modified electrode has been analyzed in water and commercial milk samples and provided adequate recoveries.

Chromium-Benzenedicarboxylates Metal Organic Framework for Supersensitive and Selective Electrochemical Sensor of Toxic Cd2+, Pb2+, and Hg2+ Metal Ions: Study of their Interactive Mechanism

Voltammetric determination of toxic Cd2+, Pb2+, and Hg2+ metal ions using Cr-BDC/GCE (chromium-benzenedicarboxylates/ Glassy Carbon Electrode) electrochemical sensor has been investigated. Cr-BDC (chromium-benzenedicarboxylate ) metal–organic framework was synthesized by using the facile hydrothermal technique and its efficacy investigated using P-XRD, FTIR, RAMAN, AFM, FE-SEM, and BET, while the electrochemical performance was investigated by CV and EIS technique. The determination capability of Cr-BDC/GCE as an electrochemical sensor has been investigated by DPASV technique. Effective Voltammetric parameters such as pH of buffer solution, pre-accumulation potential, and pre-accumulation time have been optimized to enhance the sensitivity, selectivity, LOD, repeatability, reproducibility, and stability of the sensor. The proposed Cr-BDC/GCE electrochemical sensor exhibits a sensitivity of 16.55, 3.45, and 3.33 μA M−1 and LOD of 0.186, 0.116, and 0.124 nM for Cd2+, Pb2+ and Hg2+ ions, respectively. Moreover, the sensor exhibited good selectivity, reproducibility, repeatability and stability. The sensor also exhibited good recovery and low RSD values for actual tap water samples. Interaction mechanism of Heavy Metal Ions with the Cr-BDC/GCE evidenced by CV and FTIR confirms the surface adsorption-controlled reaction. These findings suggest that the Cr-BDC/GCE platform is well-suited to serve as a next-generation electrochemical sensor for detecting alcohol, ketone, hydrocarbons, medicines, etc.

Highly selective and real-time detection of 5-hydroxymethylcytosine in genomic DNA using a carbon nitride-modified gold transducer-based electrochemical sensor

Cancer biomarkers are crucial indicators of cancer status and progression that aid in early detection and more effective treatment of the disease. The loss of 5-hydroxymethylcytosine (5hmC), an oxidation product of 5-methylcytosine (5mC), is a recurrent epigenetic biomarker across various types of cancers. Therefore, accurately quantifying 5hmC holds great potential for various clinical applications. However, distinguishing 5hmC from 5mC using conventional methods is challenging. In this study, we developed a rapid and highly selective electrochemical sensor for label-free detection of 5hmC-enriched DNAs using a graphitic carbon nitride (g-C3N4)-modified gold transducer. Two-dimensional g-C3N4 sheets were synthesized via direct pyrolysis of urea under ambient or nitrogen atmospheres and drop-cast onto the gold electrode. Subsequently, 5hmC-containing DNAs were immobilized onto g-C3N4 via hydrogen bonding between the –OH of 5hmC and the -NH2 of g-C3N4. The developed sensor demonstrated high sensitivity, selectivity, remarkable reproducibility, and stability, with a low oxidation potential (0.23 V) and an extremely low limit of detection (0.316 pM) for 5hmC. The sensor was also tested for its applicability to real samples using primary liver samples from mouse models, in which 5hmC levels were diminished due to either Tet gene knockout or hepatocellular carcinogenesis. The sensor effectively detected reduced genomic 5hmCs in TET-deficient livers and hepatocellular carcinomas compared to controls. Thus, this novel sensing strategy has the potential to develop clinically applicable sensors for early cancer diagnosis and prognosis evaluation by rapidly quantifying genomic 5hmC.

Application of Monoferrocenylsumanenes Derived from Sonogashira Cross-Coupling or Click Chemistry Reactions in Highly Sensitive and Selective Cesium Cation Electrochemical Sensors.

This paper reports the synthesis and characterization of novel monoferrocenylsumanenes obtained by means of the Sonogashira cross-coupling or click chemistry reaction as well as their application in cesium cation electrochemical sensors. A new synthetic protocol based on Sonogashira cross-coupling was developed for the synthesis of monoferrocenylsumanene or ethynylsumanene. The click chemistry reaction was introduced to the sumanene chemistry through the synthesis of 1,2,3-triazole containing monoferrocenylsumanene. The designed synthetic methods for the modification of sumanene at the aromatic position proved to be efficient and proceeded under mild conditions. The synthesized sumanene derivatives were characterized by detailed spectroscopic analyses of the synthesized sumanene derivatives. The supramolecular interactions between cesium cations and the synthesized monoferrocenylsumanenes were spectroscopically and electrochemically investigated. Furthermore, the design of the highly selective and sensitive cesium cation fluorescence and electrochemical sensors comprising the synthesized monoferrocenylsumanenes as receptor compounds was analyzed. The tested cesium cation electrochemical sensors showed excellent limit of detection values in the range of 6.0-9.0 nM. In addition, the interactions between the synthesized monoferrocenylsumanenes and cesium cations were highly selective, which was confirmed by emission spectroscopy, laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS), and cyclic voltammetry.

Nanomaterials-Based Electrochemical Δ9-THC and CBD Sensors for Chronic Pain.

Chronic pain is now included in the designation of chronic diseases, such as cancer, diabetes, and cardiovascular disease, which can impair quality of life and are major causes of death and disability worldwide. Pain can be treated using cannabinoids such as Δ9-tetrahydrocannabinol (Δ9-THC) and cannabidiol (CBD) due to their wide range of therapeutic benefits, particularly as sedatives, analgesics, neuroprotective agents, or anti-cancer medicines. While little is known about the pharmacokinetics of these compounds, there is increasing interest in the scientific understanding of the benefits and clinical applications of cannabinoids. In this review, we study the use of nanomaterial-based electrochemical sensing for detecting Δ9-THC and CBD. We investigate how nanomaterials can be functionalized to obtain highly sensitive and selective electrochemical sensors for detecting Δ9-THC and CBD. Additionally, we discuss the impacts of sensor pretreatment at fixed potentials and physiochemical parameters of the sensing medium, such as pH, on the electrochemical performance of Δ9-THC and CBD sensors. We believe this review will serve as a guideline for developing Δ9-THC and CBD electrochemical sensors for point-of-care applications.