Electrochemical sensor for H2O2 using a glassy carbon electrode modified with a nanocomposite consisting of graphene oxide, cobalt(III) oxide, horseradish peroxidase and nafion

Co3O4/fluoro-copolymer nanocomposite modified boron-doped diamond electrode non-enzymatic sensor for the determination of skeletal muscle relaxant drug cyclobenzaprine in biological fluids

Electrochemical sensors have revolutionized pharmaceutical analysis by providing enhanced speed, selectivity, and cost-effectiveness. This study presents the development of a highly sensitive, non-enzymatic electrochemical sensor for Cyclobenzaprine (CBZ) determination. The sensor features a boron-doped diamond electrode (BDDE) modified with a novel Cobalt Oxide/Nafion-based nanocomposite (Co₃O₄/Nafion), synthesized and optimized for superior performance. The electroactive surface was fabricated by drop-casting a Co₃O₄/Nafion suspension onto the BDDE. Characterization techniques, including X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), energy dispersive X-ray spectroscopy (EDX), Raman spectroscopy, and Fourier transform infrared spectroscopy (FTIR), confirmed the crystallinity, morphology, and functional groups of the nanocomposite. Electrochemical analyses, comprising electrochemical impedance spectroscopy (EIS), square wave voltammetry (SWV), and cyclic voltammetry (CV), demonstrated enhanced charge transfer properties and a one-electron/proton oxidation mechanism for Cyclobenzaprine (CBZ) detection. The sensor demonstrated optimal performance in BR buffer at pH 5.6, with a linear response to CBZ concentrations ranging from 2.49 μg/L to 19.61 μg/L, achieving a LOD of 2.08 μg/L and LOQ of 6.96 μg/L. Practical applicability was established by successfully quantifying CBZ in various biological matrices, including human blood serum (37.8 %), artificial blood serum (35.6 %), artificial sweat (-28.9 %), and urine (-8.9 %), with excellent recovery rates in pharmaceutical formulations (99.75 %) and human blood serum (100.16 %). The sensor exhibited high specificity, unaffected by common interferents such as ions, carbohydrates, and heavy metals. This work introduces, for the first time, a Co₃O₄/Nafion-modified BDDE sensor for CBZ determination, offering rapid, selective, and interference-free analysis with potential applications in therapeutic drug monitoring and pharmaceutical quality control.

Cyanobacterial Phycocyanin-Based Electrochemical Biosensor for the Detection of the Free Radical Hydrogen Peroxide

Cyanobacteria are photosynthetic prokaryotes that inhabit extreme environments by modifying their photosensitive chemoreceptors called cyanobacteriochromes (CBCRs) which are linear tetrapyrrole-linked phycobilin molecules. These light-sensitive phycobilin from Spirulina platensis is recognized as a potential photoreceptor tool in optogenetics for monitoring cellular morphogenesis. We prepared and extracted highly fluorescent cyanobacterial phycocyanin (C-PC) by irradiating the culture with ambient red light. The crude phycocyanin was subjected to ion exchange chromatography, and its purity was monitored using UV-visible, fluorescence, and FT-IR spectroscopy methods. In the conventional method, red light-induced C-PC exhibited strong antioxidant activity against H2O2, with 88.7% in vitro scavenging activity without requiring any other preservatives. Interestingly, this red light-acclimated phycocyanin was applied as a biosensing material for the detection of the free radical hydrogen peroxide (H2O2) using the enzyme horseradish peroxidase (HRP) as a mediator. The modified C-PC-HRP glassy carbon electrode (GCE) can detect H2O2 from 0.1 to 1600 µM. The lowest possible detection limit of the electrode for H2O2 was 19 nM. This electrode was used to detect free radical H2O2 in blood serum samples. The microstructure of the lyophilized PC under SEM showed a flat crystal pattern, which enabled the immobilization of HRP on the electrode surface and electron transfer.

Designing Nanocomposite-Based Electrochemical Biosensors for Diabetes Mellitus Detection: A Review

This review will unveil the development of a new generation of electrochemical sensors utilizing a transition-metal-oxide-based nanocomposite with varying morphology. There has been considerable discussion on the role of transition metal oxide-based nanocomposite, including iron, nickel, copper, cobalt, zinc, platinum, manganese, conducting polymers, and their composites, in electrochemical and biosensing applications. Utilizing these materials to detect glucose and hydrogen peroxide selectively and sensitively with the correct chemical functionalization is possible. These transition metals and their oxide nanoparticles offer a potential method for electrode modification in sensors. Nanotechnology has made it feasible to develop nanostructured materials for glucose and H2O2 biosensor applications. Highly sensitive and selective biosensors with a low detection limit can detect biomolecules at nanomolar to picomolar (10-9 to 10-12 molar) concentrations to assess physiological and metabolic parameters. By mixing carbon-based materials (graphene oxide) with inorganic nanoparticles, nanocomposite biosensor devices with increased sensitivity can be made using semiconducting nanoparticles, quantum dots, organic polymers, and biomolecules.

Electrochemical Enzyme Sensor Based on the Two-Dimensional Metal-Organic Layers Supported Horseradish Peroxidase

Metal-organic frames (MOFs) have recently been used to support redox enzymes for highly sensitive and selective chemical sensors for small biomolecules such as oxygen (O₂), hydrogen peroxide (H₂O₂), etc. However, most MOFs are insulative and their three-dimensional (3D) porous structures hinder the electron transfer pathway between the current collector and the redox enzyme molecules. In order to facilitate electron transfer, here we adopt two-dimensional (2D) metal-organic layers (MOLs) to support the HRP molecules in the detection of H₂O₂. The correlation between the current response and the H₂O₂ concentration presents a linear range from 7.5 μM to 1500 μM with a detection limit of 0.87 μM (S/N = 3). The sensitivity, reproducibility, and stability of the enzyme sensor are promoted due to the facilitated electron transfer.

SnO2QDs Deposited on GO/PPy-Modified Glassy Carbon Electrode for Efficient Electrochemical Hydrogen Peroxide Sensor

In this present work, we demonstrate an efficient electrochemical sensor for the detection of hydrogen peroxide (H₂O₂) using a glassy carbon electrode (GCE) modified with a ternary nanocomposite of tin oxide QDs/GO/PPy (SGP2). An in situ chemical oxidative polymerization method was used to create the SGP2 nanocomposite. FTIR, XRD, HR TEM, CV, DPV, and impedance analysis were used to characterize the nanocomposite. The SGP2 nanocomposite modified GCE can be used to create an effective H₂O₂ electrochemical sensor with high sensitivity and a low detection limit (LOD). With SGP2 modified GCE, the electrochemical detection test for H₂O₂ was carried out using cyclic voltammetry (CV) and amperometric methods. The SGP2 modified GCE shows improved sensing capabilities, resulting in considerable sensitivity of 11.69 µA mM cm^-2 and a very low limit of detection (LOD) of 0.758 µM for a broad linear range of H₂O₂ concentration from 0.1 mM to 0.8 mM with a correlation coefficient R² = 0.9886. Additionally, the performance of the SGP2-modified GCE electrode is on par with or nonetheless superior to that of the other functional materials that have been reported for H₂O₂. As a result, our findings suggest that combining conductive polymer with metal oxide may be a useful method for producing sophisticated and affordable electrochemical sensors.

A high-efficiency cathodic sodium nitroprusside/luminol/H2O2 electrochemiluminescence system in neutral media for the detection of sodium nitroprusside, glucose, and glucose oxidase

Sodium nitroprusside (SNP) is an anti-hypertension drug used in vascular surgery, chronic cardiovascular disease, and in the management of acute myocardial infarction by the spontaneous release of nitric oxide. Herein, for the first time, we extend its application to electrochemiluminescence (ECL). The NO generated from the electrochemical reduction of SNP reacts with H₂O₂ to generate reactive oxygen species, which subsequently reacts with luminol to produce intense ECL. The ECL signal of the new SNP/H₂O₂/luminol system under neutral conditions (pH 7.4) is almost equivalent to the classic luminol/H₂O₂ system at pH 10, making this system highly attractive for bioanalysis that directly or indirectly liberates H₂O₂ under neutral conditions. At the optimum experimental conditions, the ECL intensity increases proportionally with the log of H₂O₂ and SNP concentration over the range from 0.2 μM-1000 μM and 0.08 mM-1.8 mM with the detection limits of 0.078 μM and 0.038 mM, respectively. The RSD for ten analyses of H₂O₂ is 4.25%. Recoveries from 97.2% to 101.7% were obtained for real sample analysis. Since H₂O₂ participates in numerous important enzymatic reactions, the application of this system was further investigated using glucose oxidase (GODx) and glucose as a representative enzyme and substrate, respectively, thus liberating H₂O₂ as a reaction product. The concentrations of glucose and the activity of GODx were directly proportional to the ECL intensities over a range of 5-1000 μM and 0.0025-1 units per mL with the limits of detection of 2.65 μM and 0.0012 units per mL (S/N = 3), respectively.

Study of horseradish peroxidase and hydrogen peroxide bi-analyte sensor with boronate affinity-based molecularly imprinted film

A novel electrochemical horseradish peroxidase (HRP) sensor was developed based on boronate affinity-based electropolymerized polythionine (PTh) molecularly imprinted polymer (MIP) as specific recognition element for HRP on gold nanoparticles (AuNPs) modified glassy carbon electrode, in which PTh acted as the electrochemical probe for the sensor. The sensor was characterized by scanning electron microscopy and electron dispersive spectroscopy. Electrochemical impedance spectroscopy, cyclic voltammetry, and differential pulse voltammetry were exploited for the study of the properties of the MIP sensor. The MIP sensor exhibited excellent linear response over the range of 2.0 × 10−10 mg/mL ∼ 1.0 × 10−7 mg/mL for HRP. In addition, with MIP film as HRP immobilized matrices, the sensor for the detection of H2O2 was developed with the MIP sensor based on the reduction of H2O2 catalyzed by HRP in the presence of electron mediator PTh. The sensor showed linear relationships between the current response and H2O2 concentration from 6.0 × 10−7 to 2.0 × 10−5 mol/L. HRP and H2O2 bi-analyte sensor based on MIP film was successfully developed in this work. The developed method can also be applicable for enzyme and its enzymatic substrate bi-analyte sensor.