Prussian Blue Nanocubes‐SnO 2 Quantum Dots‐Reduced Graphene Oxide Ternary Nanocomposite: An Efficient Non‐noble‐metal Electrocatalyst for Non‐enzymatic Detection of H 2 O 2

Crumpled Graphene/Poly (azure I) Modified Electrode for Non-enzymatic Detection of Hydrogen Peroxide Secreted from Tumor Cells

Hydrogen peroxide (H₂O₂), an important representatives of reactive oxygen species, its aberrant expression is related to many diseases, including cancers. Therefore, it is very significant to design a reliable method for the real-time detection of endogenous H₂O₂. Herein, we describe preparing a poly (azure I)/crumpled graphene (cGN) modified electrode by an electro-polymerization method. The results showed that this electrode presented obvious electrocatalytic effect on the reduction of H₂O₂. Amperometric method was employed to monitor H₂O₂, and the amperometric response exhibited a good linear relationship with its concentration in the range of 8.0 × 10^-6 - 1.25 × 10^-3 mol/L; the detection limit reached to 6.7 × 10^-7 mol/L (S/N = 3). Furthermore, this modified also displayed good selectivity, long-term stability and a high anti-interference ability. Excitingly, the established method could be successfully used to detect H₂O₂ in human serum samples, and measured H₂O₂ secreted from living MCF-7 cells. It could have potential use in cancer diagnosis.

Enzyme-free detection of hydrogen peroxide with a hybrid transducing system based on sodium carboxymethyl cellulose, poly(3,4-ethylenedioxythiophene) and prussian blue nanoparticles

Herein, we report a two-layered hybrid catalytic interface composed of carboxymethyl cellulose (CMC), poly (3,4-ethylene dioxythiophene) (PEDOT), Prussian blue (PB) nanoparticles and Nickel-Hexacyanoferrate (Ni-HCF) layer for the enzyme-free detection of hydrogen peroxide (H₂O₂). Whereas the first layer, CMC:PEDOT:PB, is responsible for generating amperometric signals toward H₂O₂, Ni-HCF on CMC:PEDOT:PB layer is playing an active role as an operational stability-enhancer. In the study, where the systematic optimization of the sensor electrode is presented using cyclic voltammetry (CV), amperometry and electrochemical impedance spectroscopy (EIS) technique, the physical and chemical properties of the hybrid composite systems constructed is also supported by scanning electron microscopy (SEM) and Fourier-transform infrared spectroscopy (FTIR) techniques. The amperometric signal generation of the H₂O₂ sensor was linear between 1 and 100 μM (R² = 0.999) with a sensitivity of 416.11 μA mM^-1cm^-2, providing a limit of detection (LOD) of 0.33 μM. The sensing system, which was not affected by the various interfering molecules, creates a successful sensor platform for H₂O₂ measurements in tap water with a high recovery value between 94.0% and 110.5% and relatively small RSD in the range of 0.4-5.2%.