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In this work, MoO2 nanoparticles were synthesized and annealed to form Mo2C nanoparticles. This is the first report of a ratiometric electrochemical sensor (R-ECS) for the detection of acetaminophen (AP), in which Mo2C is used as the sensing agent and ferrocene (FC) is used as an internal reference. FC (100 μM) is added directly to the electrolyte solution for convenient operation. The synthesized materials were fully characterized with respect to composition, morphology and electrochemical performance. The oxidation peak potentials of FC (0.196 V) and AP (0.364 V) can be completely separated by the Mo2C modified glassy carbon electrode, and their ratiometric signals are used for the quantification of AP. It was found that the oxidation peak currents of AP at separated potentials on Mo2C/GCE are linear with concentration in the range of 0.5–600 μM, and the detection limit is 0.029 μM (S/N = 3). Mo2C/GCE exhibited decent repeatability, reproducibility, stability, and selectivity. The sensor was then applied to measure AP in tap water and river water. [ABSTRACT FROM AUTHOR]

Herein, a Mo 2 C/bimetallic zeolitic imidazolate framework-modified glassy carbon electrode (Mo 2 C@BMZIFs/GCE) was established as an electrochemical sensor for the simultaneous sensitive determination of acetaminophen (APAP) and isoniazid (INZ). The apparent morphology, structural composition, and electrochemical properties were comprehensively investigated. The outstanding electrocatalytic activity and conductivity endow the sensor desirable electrochemical performance toward APAP and INZ compared to the bare GCE, such as wide linear range, low detection limit, and high selectivity. Under the optimum conditions, a linear relationship between the oxidation peak current and the concentration of the measured object was obtained, with linear ranges from 0.1 to 300 μM for APAP and from 10 to 3500 μM for INZ. The detection limits for APAP and INZ were 0.03 μM and 1.5 μM, respectively. More importantly, the APAP and INZ oxidation peaks could be completely separated. Moreover, the highly sensitive and stable sensor was applied to detect APAP and INZ in human serum. This work can provide a viable route to rational design and construct electrochemical sensors for drug monitoring and clinical diagnosis. Image 1 • The detection of APAP and INZ by Mo 2 C@BMZIFs/GCE was reported for the first time. • The sensor was facile preparation and cost effectiveness. • The sensor exhibited wide linear range, low detection limit, and high selectivity. • The sensor could put into use for the drug monitoring and clinical diagnosis. [ABSTRACT FROM AUTHOR]

To overcome the problem of incorrect levodopa (LD) dosage in the treatment of Parkinson's disease, a new analytical tool is urgently needed for accurately determining the concentration of LD in human fluids. Herein, an effective and stable sensor based on a Co-single-atomic-site catalyst (Co-SASC)-modified glassy carbon electrode (Co-SASC/GCE) was developed for the determination of LD concentration. The physicochemical characterization of Co-SASC is systematically investigated. It has excellent thermal stability, graphitization degree, and a large specific surface area. Benefiting from its porous structure for kinetically fast catalysis and component advantages for fix a single cobalt atom to improve stability, Co-SASC/GCE exhibits a superior electrochemical response. Under optimal conditions (pH 2.0, coating amount is 10 μg), an ideal linear relationship is achieved between the logarithm of the peak current of the sensor and the logarithm of LD concentration. The linear range is 0.1–200 μM, and the limit of detection (LOD) is 0.033 μM. After a simple pretreatment, LD in human serum is detected by Co-SASC/GCE with excellent stability and selectivity. As such, this work enlarges the existing electrochemical sensor toolbox by offering a reasonable design and synthesis protocol for advanced materials to accurately determine LD in human fluids for the clinical treatment of Parkinson's disease. Image 1 • Co-SASC-modified glassy carbon electrode detection of levodopa was reported. • Co-SASC has excellent catalytic performance for the oxidation of levodopa. • The sensor was facile preparation and cost-effectiveness. • The sensor can put into use for drug monitoring and clinical diagnosis. [ABSTRACT FROM AUTHOR]

A simple and sensitive sensor based on a glassy carbon electrode modified with nitrogen-rich porous carbon (P-NC) has been developed for the detection of acetaminophen (APAP). The nanocomposite P-NC was prepared by the assisted carbonization of the zeolitic imidazolate framework ZIF-8 using poly(vinylpyrrolidone), and its morphology and surface structure were thoroughly characterized. The results revealed that the P-NC prepared has a uniform pore size distribution with a high superficial area. The electrochemical properties of P–NC–modified electrodes were investigated by cyclic voltammetry, electrochemical impedance spectroscopy, and differential pulse voltammetry. It was found that the modified electrode has a high catalytic activity for APAP and exhibits good linearity for the 3–110 μM concentration range with a minimum detection limit of 0.5 μM (S/N = 3). In addition, the constructed sensor exhibits good repeatability, stability, recovery, and selectivity, allowing it to be successfully applied to the detection of APAP in real-world human urine samples. Image 1 • The electrochemical detection of APAP by P-NC/GCE was reported for the first time. • P-NC/GCE features facile preparation, low reagent consumption and cost effectiveness. • The P-NC based electrochemical sensors exhibited excellent analytical performances. • The method has been successfully applied to the detection of acetaminophen in human urine. [ABSTRACT FROM AUTHOR]

The detection of hydroxyl radicals (•OH) in live cells is significant to study its physiological and pathological roles, while it is full of challenge due to the extremely low concentration and short lifetime of •OH. Herein, we have developed a novel electrochemical sensor based on 6-(Ferrocenyl) hexanethiol (6-FcHT) self-assembled nanoporous gold layer (NPGL) modified GE (6-FcHT/NPGL/GE), which can detect the release of •OH from living cells with high sensitivity and selectivity. The superior sensitivity can stem from the unique porous architecture of NPGL, which enlarged electrode surface area and expedited electron transportation during electrochemical reactions. Additionally, NPGL provides more active binding sites for the assembly of capture agent (6-FcHT) of •OH, thus ensuring high selectivity. For comparison, 6-FcHT/GE was applied to detect •OH, and the obtained sensitivity was 0.0305 mA nM−1 and detection limit was 0.133 nM in the linear range of 0.4 nM–70 nM. After modification of NPGL, the sensitivity of 6-FcHT/NPGL/GE to the •OH response was increased to 0.1364 mA nM−1, detection limit was reduced to 0.316 pM and the linear range was extended from 1 pM to 100 nM. It is worth mentioning that a plenty of extra merits has also been validated like reproducibility, repeatability and stability, enabling to direct electrochemical detection of •OH in HepG2 cells. Image 1 • The work on using NPGL coupled to 6-FcHT to build a sensor was first reported. • Modification by coupling NPGL with 6-FcHT realized sensitive and selective assay of •OH. • In situ monitoring •OH released from HepG2 cells was done with the hybrid sensor. • The •OH sensor exhibits an ultralow detection limit of 0.316 pM. • The prepared sensor exhibits outstanding selectivity, reusability and stability. [ABSTRACT FROM AUTHOR]