Search

[Display omitted] • SCCNT were coated by ALD with nanometric NiO films of different thickness. • SCCNT/NiO-based electrochemical sensors displayed high sensitivity to lactic acid. • The developed SCCNT/NiO sensors were suitable for the lactic acid quantification in saliva. NiO-coated stacked-cut carbon nanotubes (NiO/SCCNT) nanocomposites were synthesized via atomic layer deposition (ALD), coating the CNT core walls with a shell of NiO at different thickness varying NiO ALD cycles (0, 50, 200, and 700). The as-prepared core–shell composite nanomaterials were applied as electrode materials for modifying screen-printed carbon electrodes (SPCE) for the non-enzymatic electrochemical detection of lactate (LA). Electrochemical tests performed by CV and EIS demonstrated the reduced charge transfer resistance in NiO(x)/CNT-SPCE compared to pristine CNT-SPCE configuration, and the pronounced dependence of electrochemical behavior on NiO coating thickness. Notably, the NiO/CNT composite with 200 ALD cycles exhibited superior electrochemical properties for the electrooxidation of lactate. The developed sensor showed high sensitivity to LA, (138.44 µA mM−1 cm−2 in the 0–4 mM range). The limit of detection (LOD) values stood at 0.067 mM (considering the signal-to-noise ratio of S/N=3). The sensor showcased several advantages including a conductive supporting carbon material, impressive sensitivity, selectivity, stability, and reproducibility, thereby enabling rapid and precise lactate quantification in salivary real samples. [ABSTRACT FROM AUTHOR]

A novel electrochemical sensor for the determination of nitrites based on the modified screen‐printed electrode (SPCE) by Zn‐bidentate Schiff base complexes (ZnLX2) is presented. ZnLX2 complexes have been synthesized and characterized using several morphological and microstructural techniques such as scanning electron microscopy (SEM), X‐ray powder diffraction (XRD), and fourier transformed‐infrared (FT‐IR) spectroscopy. Cyclic voltammetry (CVs) proved the good electrochemical performances of the ZnLX2/SPCE for nitrite ions determination. The influence of pH, scan rate, nitrite concentration, and interfering ions was investigated. After optimization of the operating parameters, the developed ZnLX2/SPCE sensor displayed two linear relationships between response current and nitrite concentration in the overall range 2–4838 μM and a lower detection limit estimated to be 0.78 μM based on 3σ/m. Finally, the analytical application of the developed sensor was evaluated to quantify nitrite in a real sample of mineral water. Results obtained demonstrate that the ZnLX2/SPCE electrochemical sensor provided an effective tool for the detection of nitrite ions. [ABSTRACT FROM AUTHOR]

In this article, the electrochemical monitoring of phenol (Ph) in water by using a nanostructured MnO2-modified screen-printed carbon electrode (MnO2-SPCE) is reported. MnO2 nanoparticles were synthesized by the redox-precipitation method. Morphological, textural, and microstructural characteristics were investigated by scanning electron microscopy (SEM), X-ray diffraction, Raman, Brunauer–Emmett–Teller (BET) surface area, and pore volume analyses. Electrochemical properties of the modified MnO2-SPCE electrode have been investigated by cyclic voltammetry and linear sweep voltammetry. The detection of Ph in water by the developed sensor was exploited using square wave voltammetry and chronoamperometry. The sensor showed good characteristics, such as simple fabrication, low cost, good sensitivity, stability, reproducibility, and selectivity, against inorganic analytes and other phenolic compounds. The reported results demonstrated the great potential of nanostructured MnO2 in developing high performances electrochemical sensors to be utilized in the field of environmental pollution monitoring. [ABSTRACT FROM AUTHOR]

The rapid growth of research in electrochemistry in the last decade has resulted in a significant advancement in exploiting electrochemical strategies for assessing biological substances. Among these, amino acids are of utmost interest due to their key role in human health. Indeed, an unbalanced amino acid level is the origin of several metabolic and genetic diseases, which has led to a great need for effective and reliable evaluation methods. This review is an effort to summarize and present both challenges and achievements in electrochemical amino acid sensing from the last decade (from 2010 onwards) to show where limitations and advantages stem from. In this review, we place special emphasis on five well-known electroactive amino acids, namely cysteine, tyrosine, tryptophan, methionine and histidine. The recent research and achievements in this area and significant performance metrics of the proposed electrochemical sensors, including the limit of detection, sensitivity, stability, linear dynamic range(s) and applicability in real sample analysis, are summarized and presented in separate sections. More than 400 recent scientific studies were included in this review to portray a rich set of ideas and exemplify the capabilities of the electrochemical strategies to detect these essential biomolecules at trace and even ultra-trace levels. Finally, we discuss, in the last section, the remaining issues and the opportunities to push the boundaries of our knowledge in amino acid electrochemistry even further. [ABSTRACT FROM AUTHOR]