Synthesis of copper nanorods for non-enzymatic amperometric sensing of glucose

Glucose and UA sensing based on Cu nanoparticle decorated Nif/GO flexible electrode

A novel, green, and facile approach has been developed to construct an ultrasensitive flexible enzyme-less electrochemical sensor on the basis of chitosan and graphene oxide composites decorated with Cu nanoparticles supported on nickel foam (Nif/Cs/GO@Cu), in which GO functions as the intermediate between Nif and Cu nanoparticles. The Nif/Cs/GO@Cu sensing platform was successfully fabricated by the drop casting method to load Cs/GO onto Nif followed by an additionally electrodeposition to support Cu nanoparticles on Nif/Cs/GO. Impressively, the Nif/Cs/GO@Cu exhibited much higher electrocatalytic activity for glucose and UA oxidation as compared to that of Nif or Nif@Cu. For glucose and UA at about 0.6 V and 0.1 V (vs. Ag/AgCl), linearity could be obtained in the concentration ranges 5 µM-4 mM and 5-345 µM; the sensitivities were 16 and 2.5 µA µM-1 cm-2, and the detection limits 83 nM and 0.3 µM, respectively. The improved performance of the composite electrode was ascribed to the synergistic effect of Cu nanoparticles, Nif and GO, in which GO provides high electron conductivity and large surface area to prevent the agglomeration of Cu nanoparticles; Cu nanoparticles and Nif offer abundant active sites towards analytes oxidation. Additionally, the method was applied to determine both analytes successfully in blood serum samples with excellent recovery and also opens up an attractive route to potential applications of the flexible nickel foam-based electrochemical sensor.

Differential Analysis of Three Copper-Based Nanomaterials with Different Morphologies to Suppress Alternaria alternata and Safety Evaluation

The overuse of copper-based fertilizers and pesticides over the last few decades has resulted in detrimental risks to our environment. Nano-enabled agrichemicals with a high effective utilization ratio have shown great potential for maintaining or minimizing environmental issues in agriculture. Copper-based nanomaterials (Cu-based NMs) serve as a promising alternative to fungicides. Three types of Cu-based NMs with different morphologies were analyzed for their different antifungal effects on Alternaria alternata in this current study. Compared to commercial copper hydroxide water power (Cu(OH)₂ WP), all tested Cu-based NMs, including cuprous oxide nanoparticles (Cu₂O NPs), copper nanorods (Cu NRs) and copper nanowires (Cu NWs), especially Cu₂O NPs and Cu NWs, showed higher antifungal activity against Alternaria alternata. Its EC₅₀ were 104.24 and 89.40 mg L^-1, respectively, achieving comparable activity using a dose approximately 1.6 and 1.9-fold lower. Cu-based NMs could introduce the downregulation of melanin production and soluble protein content. In contrast to trends in antifungal activity, Cu₂O NPs showed the strongest power in regulating melanin production and protein content and similarly exhibited the highest acute toxicity to adult zebrafish compared to other Cu-based NMs. These results demonstrate that Cu-based NMs could offer great potential in plant disease management strategies.

Non-Enzymatic Glucose Sensors Involving Copper: An Electrochemical Perspective

Non-enzymatic glucose sensors based on the use of copper and its oxides have emerged as promising candidates to replace enzymatic glucose sensors owing to their stability, ease of fabrication, and superior sensitivity. This review explains the theories of the mechanism of glucose oxidation on copper transition metal electrodes. It also presents an overview on the development of among the best non-enzymatic copper-based glucose sensors in the past 10 years. A brief description of methods, interesting findings, and important performance parameters are provided to inspire the reader and researcher to create new improvements in sensor design. Finally, several important considerations that pertain to the nano-structuring of the electrode surface is provided.

Shape-controlled Cu2O nanospheres as bifunctional catalysts boosting the oxidations of glucose and hydrazine

Cuprous oxide (Cu2O) nanoparticles hold promise as low-cost catalysts for the oxidations of both glucose and hydrazine (N2H4). The shape-controlled growth of Cu2O crystals can regulate effectively its catalytic activities.

Developing a versatile electrochemical platform with optimized electrode configuration through screen-printing technology toward glucose detection

Rapid on-site detection of glucose has been attracting considerable attention nowadays. Screen-printed electrodes (SPEs) were assessed as ideal detection platforms due to their advantages such as, disposability, portability, ease of miniaturization, and mass production. The topology and shape of electrodes have a crucial impact on their electrical conductivity and electrochemical properties. In this study, a versatile electrochemical platform with optimized three-electrode configuration was developed through screen-printing technology. Three types of SPEs were prepared, and their electrocatalytic properties toward glucose detection were investigated. Based on this platform, both enzyme-based (denoted as GOD/rGO) and non-enzymatic (denoted as Co@MoS2/rGO) bioactive compounds were deposited on the working electrode of the circular SPE through simply drop-casting, respectively. Their morphology was characterized through scanning electron microscopy (SEM). Cycle sweep voltammetry was used to study the electrocatalytic activity of these biosensors. The circular SPE exhibited satisfying electrochemical redox activity and much higher sensitivity towards glucose detection, which rendered it a promising candidate for point-of-care detection.

Insightful Analysis of Phenomena Arising at the Metal|Polymer Interphase of Au-Ti Based Non-Enzymatic Glucose Sensitive Electrodes Covered by Nafion

This paper focuses on the examination of glucose oxidation processes at an electrode material composed of gold nanoparticles embedded in a titanium template. Three different conditions were investigated: the chloride content in the electrolyte, its ionic conductivity and the presence of a Nafion coating. The impact of the provided environment on the oxidation reaction was evaluated by cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). Two models, namely: chemisorption and incipient hydrous oxide/adatom mediator (IHOAM), were applied to explain the complex voltammetric responses of the electrodes exposed to solutions of varied glucose concentrations. Three different phenomena were observed for the studied cases. The first is related to the transition between the dominant mechanism of glucose oxidation from the IHOAM model to the chemisorption model. This happens only in an electrolyte containing chlorides after exceeding a certain amount of glucose. The second effect exhibits a bottleneck nature resulting from the presence of Nafion on the electrode’s surface. In this case, mass transport through the semi-permeable polymer is hampered, due to the blocking of channels and physical internal cross-linking. This leads to a preconcentration of glucose inside the pores resulting in an increase in both the material sensitivity and the linear range of the calibration curve. Lastly, the third effect is manifested in a low concentration of the supporting electrolyte. It is based on the fact that mass transport of hydroxyl ions is governed not only by diffusion, but also by migration. These three effects have a tremendous impact on the glucose oxidation mechanism and reveal its very complex nature.

Tunable hierarchical surfaces of CuO derived from metal–organic frameworks for non-enzymatic glucose sensing

A facile thermal treatment is conducted to prepare nanosphere stacking CuO derived from Cu-MOF, which achieves good glucose sensing performance and is expected to be effective for developing non-enzyme and non-invasive glucose sensors.

Copper Nanoparticle and Nitrogen Doped Graphite Oxide Based Biosensor for the Sensitive Determination of Glucose

Copper nanoparticles with the diameter of 50 ± 20 nm decorated nitrogen doped graphite oxide (NGO) have been prepared through a simple single step carbonization method using copper metal-organic framework (MOF), [Cu₂(BDC)₂(DABCO)] (where BDC is 1,4-benzenedicarboxylate, and DABCO is 1,4-Diazabicyclo[2.2.2]octane) as precursor. The surface morphology, porosity, surface area and elemental composition of CuNPs/NGO were characterized by various techniques. The as-synthesized CuNPs/NGO nanomaterials were coated on commercially available disposable screen-printed carbon electrode for the sensitive determination of glucose. We find that the modified electrode can detect glucose between 1 μM and 1803 μM (linear range) with good sensitivity (2500 μA mM⁻¹ cm⁻²). Our glucose sensor also possesses low limits of detection (0.44 μM) towards glucose determination. The highly selective nature of the fabricated electrode was clearly visible from the selectivity studies. The practicability of CuNPs/NGO modified electrode has been validated in the human serum samples. The storage stability along with better repeatability and reproducibility results additionally substantiate the superior electrocatalytic activity of our constructed sensor towards glucose.

Amperometric nonenzymatic sensing of glucose at very low working potential by using a nanoporous PdAuNi ternary alloy

The authors present a nonenzymatic sensor for glucose that has an exceedingly low working potential which makes the sensor highly selective over other electroactive species. The sensor is based on the use of a glassy carbon electrode (GCE) that was modified with a nanoporous PdAuNi alloy (np-PdAuNi). The PdAuNi alloy nanostructure displays enhanced electrocatalytic activity for glucose oxidation (compared to PdNi alloys). The modified GCE enables amperometric sensing of glucose at a typical working electrode potential of 0.0 V vs. SCE in solutions of pH 13 containing 0.1 M NaCl. Response is linear in the 5 to 100 μM concentration range, with a 1.7 μM detection limit (at an S/N ratio of 3). For higher concentrations deviations from linearity were found. The method is selective and reproducible. The modified electrode was applied to the determination of glucose in human serum. Graphical Abstract Nanoporous PdAuNi alloy with three-dimensional bicontinuous nanosponge architecture was successfully prepared via chemical dealloying. The electrochemical nonenzymatic glucose sensor shows a low working potential, wide linear range, good sensitivity, low detection limit and excellent selectivity.

Electrochemical nonenzymatic sensing of glucose using advanced nanomaterials

An overview (with 376 refs.) is given here on the current state of methods for electrochemical sensing of glucose based on the use of advanced nanomaterials. An introduction into the field covers aspects of enzyme based sensing versus nonenzymatic sensing using nanomaterials. The next chapter cover the most commonly used nanomaterials for use in such sensors, with sections on uses of noble metals, transition metals, metal oxides, metal hydroxides, and metal sulfides, on bimetallic nanoparticles and alloys, and on other composites. A further section treats electrodes based on the use of carbon nanomaterials (with subsections on carbon nanotubes, on graphene, graphene oxide and carbon dots, and on other carbonaceous nanomaterials. The mechanisms for electro-catalysis are also discussed, and several Tables are given where the performance of sensors is being compared. Finally, the review addresses merits and limitations (such as the frequent need for working in strongly etching alkaline solutions and the need for diluting samples because sensors often have analytical ranges that are far below the glucose levels found in blood). We also address market/technology gaps in comparison to commercially available enzymatic sensors. Graphical Abstract Schematic representation of electrochemical nonenzymatic glucose sensing on the nanomaterials modified electrodes. At an applied potential, the nanomaterial-modified electrodes exhibit excellent electrocatalytic activity for direct oxidation of glucose oxidation.

Novel synthesis and characterization of pristine Cu nanoparticles for the non-enzymatic glucose biosensor

Non enzymatic electrochemical glucose sensing was developed based on pristine Cu Nanopartilces (NPs)/Glassy Carbon Electrode (GCE) which can be accomplished by simple green method via ocimum tenuiflorum leaf extract. Then, the affect of leaf extract addition on improving Structural, Optical and electrochemical properties of pristine cu NPs was investigated. The synthesized Cu NPs were characterized with X-ray diffraction (X-ray), Uv-Visible spectroscopy (Uv-Vis), Fourier transformation infrared spectroscopy (FTIR), Particle size distribution (PSA), Scanning electron microscopy (SEM), Energy dispersive X-ray spectroscopy (EDS), Transmission electron microscopy (TEM) for structural optical and morphological studies respectively. The synthesized Cu NPs were coated over glassy carbon electrode (GCE) to study the electrochemical response of glucose by cyclic voltammetry and ampherometer. The results indicates that the modified biosensor shows a remarkable sensitivity (1065.21 μA mM^-1 cm^-2), rapid response time (<3s), wide linear range (1 to 7.2 mM), low detection limit (0.038 μM at S/N = 3). Therefore, the prepared Cu NPs by the Novel Bio-mediated route were exploited to construct a non-enzymatic glucose biosensor for sustainable clinical field applications.

Ternary NiCoP nanosheet array on a Ti mesh: a high-performance electrochemical sensor for glucose detection

NiCoP nanosheet array acts as a high-active catalyst electrode for glucose electro-oxidation in alkaline media. As a non-enzyme electrochemical glucose sensor, it shows a low detection limit of 0.13 μM (S/N = 3) and a high sensitivity of 14 586 μA mM⁻¹ cm⁻².