Micro-colloidal catalyst of palladium nanoparticles on polyaniline-coated carbon microspheres for a non-enzymatic hydrogen peroxide sensor

Voltammetric determination of hydrogen peroxide at decorated palladium nanoparticles/poly 1,5-diaminonaphthalene modified carbon-paste electrode

In this work, palladium nanoparticles (PdNPs)/p1,5-DAN/ carbon paste electrode (CPE) and p1,5-DAN/CPE sensors have been developed for determination of hydrogen peroxide. Both sensors showed a highly sensitive and selective electrochemical behaviour, which were derived from a large specific area of poly 1,5 DAN and super excellent electroconductibility of PdNPs. PdNPs/p1,5-DAN/CPE exhibited excellent performance over p1,5-DAN/CPE. Thus, it was used for detecting hydrogen peroxide (H2O2) with linear ranges of 0.1 to 250 µM and 0.2 to 300 µM as well as detection limits (S/N = 3) of 1.0 and 5.0 nM for square wave voltammetry (SWV) and cyclic voltammetry (C.V) techniques, respectively. The modified CPE has good reproducibility, adequate catalytic activity, simple synthesis and stability of peak response during H2O2 oxidation on long run that exceeds many probes. Both reproducibility and stability for H2O2 detection are attributable to the PdNPs immobilized on the surface of p1,5-DAN/CPE. The modified CPE was used for determining H2O2 in real specimens with good stability, sensitivity, and reproducibility.

Highly Sensitive Detection of Hydrogen Peroxide in Cancer Tissue Based on 3D Reduced Graphene Oxide-MXene-Multi-Walled Carbon Nanotubes Electrode

Hydrogen peroxide (H2O2) is a signaling molecule that has the capacity to control a variety of biological processes in organisms. Cancer cells release more H2O2 during abnormal tumor growth. There has been a considerable amount of interest in utilizing H2O2 as a biomarker for the diagnosis of cancer tissue. In this study, an electrochemical sensor for H2O2 was constructed based on 3D reduced graphene oxide (rGO), MXene (Ti3C2), and multi-walled carbon nanotubes (MWCNTs) composite. Three-dimensional (3D) rGO-Ti3C2-MWCNTs sensor showed good linearity for H2O2 in the ranges of 1-60 μM and 60 μM-9.77 mM at a working potential of -0.25 V, with sensitivities of 235.2 µA mM-1 cm-2 and 103.8 µA mM-1 cm-2, respectively, and a detection limit of 0.3 µM (S/N = 3). The sensor exhibited long-term stability, good repeatability, and outstanding immunity to interference. In addition, the modified electrode was employed to detect real-time H2O2 release from cancer cells and cancer tissue ex vivo.

Homogeneous wet-spinning construction of skin-core structured PANI/cellulose conductive fibers for gas sensing and e-textile applications

Fiber-based wearable electronic textiles have broad applications, but non-degradable substrates may contribute to electronic waste. The application of cellulose-based composite fibers as e-textiles is hindered by the lack of fast and effective preparation methods. Here, we fabricated polyaniline (PANI)/cellulose fibers (PC) with a unique skin-core structure through a wet-spinning homogeneous blended system. The conductive network formation was enabled at a mere 1 wt% PANI. Notably, PC15 (15 wt% PANI) shows higher electrical conductivity of 21.50 mS cm-1. Further, PC15 exhibits excellent ammonia sensing performance with a sensitivity of 2.49 %/ppm and a low limit of detection (LOD) of 0.6 ppm. Cellulose-based composite fibers in this work demonstrate good gas sensing and anti-static properties as potential devices for smart e-textiles.

Fabrication of Nitrogen-Doped Reduced Graphene Oxide Modified Screen Printed Carbon Electrode (N-rGO/SPCE) as Hydrogen Peroxide Sensor

In recent years, the electrochemical sensing approach has attracted electrochemists because of its excellent detection process, simplicity, high sensitivity, cost-effectiveness, and high selectivity. In this study, we prepared nitrogen doped reduced graphene oxide (N-rGO) and characterized it using various advanced techniques such as XRD, SEM, EDX, Raman, and XPS. Furthermore, we modified the active surface of a screen printed carbon electrode (SPCE) via the drop-casting of N-rGO. This modified electrode (N-rGO/SPCE) exhibited an excellent detection limit (LOD) of 0.83 µM with a decent sensitivity of 4.34 µAµM-1cm-2 for the detection of hydrogen peroxide (H2O2). In addition, N-rGO/SPCE also showed excellent selectivity, repeatability, and stability for the sensing of H2O2. Real sample investigations were also carried out that showed decent recovery.

Flow Injection Amperometric Measurement of Formalin in Seafood

Formalin is illegally used as an antibacterial and a preservative in seafood products. It is extremely important for public health reasons to be able to simply, rapidly, and accurately detect formalin in fresh seafood. In this work, we developed a flow injection amperometric (FI-Amp) formalin sensor based on a glassy carbon electrode modified with a composite of palladium particles and carbon microspheres (PdPs-CMs/GCE). The CMs were decorated with PdPs via an electroless deposition method. The surface morphology of the CMs and the PdPs-CMs composite was characterized by scanning electron microscopy/energy dispersive X-ray spectroscopy (SEM/EDX). The electrochemical behavior and measurement of formalin at the PdPs-CMs/GCE was evaluated by cyclic voltammetry and amperometry. The modified electrode demonstrated good electrocatalytic performance for the oxidation of formalin. The synthesis method and FI-Amp operating conditions were optimized. Under the optimal conditions, the developed sensor showed a linear range of 0.025 to 15.00 mmol L^-1 and a detection limit of 8 μmol L^-1. Repeatability (RSD < 4.1%, n = 30), reproducibility (RSD = 0.25%, n = 5), stability (RSD = 3.2%, n = 80), and selectivity were good. The fabricated sensor achieved recoveries of formalin in seafood between 96 ± 1 to 105 ± 3 (n = 3).