An electrochemical dopamine sensor based on the ZnO/CuO nanohybrid structures

FEM simulation of palladium thin film coated surface acoustic wave hydrogen sensor for high frequency applications

A higher operating frequency is desirable for Surface Acoustic Wave (SAW) based sensors as they become more sensitive at high frequencies. The acoustic wave gets more confined near the surface at high frequencies and become more sensitive to the external stimulations. This makes SAW devices a suitable device for sensing gaseous state chemicals. SAW devices have become the basic building block of wireless sensor networks with its advantages enabling remote sensing. In this paper, a SAW based Hydrogen sensor is realized through the Finite Element Analysis tool ANSYS. Hydrogen even though has a significant role in many industries, its explosive nature demands constant monitoring. SAW delay line made up of XY-LiNbO3 as substrate with a thin layer of Palladium coated along the delay length as the sensing element is modeled. Palladium with its high affinity for Hydrogen absorbs the same and undergoes changes in properties like density and stiffness. This disturbs the surface wave propagation and in turn, affects the operating frequency which is the sensor response parameter. The frequency shift of 1.91 MHz for Hydrogen concentration of 0.3 a.f. as compared to 0.49 MHz with YZ- LiNbO3. The operating frequency also shifts to a higher range as the acoustic velocity of the substrate increases.

Green synthesis of nonprecious metal-doped copper hydroxide nanoparticles for construction of a dopamine sensor

Background: Copper oxide nanoparticles doped with nonprecious metal species (Ni and Mn) were synthesized. Method: A glassy carbon electrode (GCE) was modified by drop-casting of nanostructure suspensions, constructing Ni:Cu(OH)₂/GCE, Mn:Cu(OH)₂/GCE and Cu(OH)₂/GCE. Results: The voltammetric oxidation of dopamine (DA) by the constructed electrodes confirmed that the electrocatalytic oxidation of DA is a reversible, pH-dependent, diffusion-controlled process; the best response was obtained by Mn:Cu(OH)₂/GCE. A sensitive calibration graph (0.664 μA/μM) was produced for DA in the concentration range of 0.3-10.0 μM, with a detection limit of 79 nM using Mn:Cu(OH)₂/GCE. Conclusion: The Mn:Cu(OH)₂/GCE possessed an accurate response toward DA with an acceptable selectivity, stability and antifouling effect, revealing the applicability of the Mn:Cu(OH)₂/GCE for DA analysis in biological samples.

A facile one-pot green synthesis of gold nanoparticle-graphene-PEDOT:PSS nanocomposite for selective electrochemical detection of dopamine

A facile one-pot and green method was developed to prepare a nanocomposite of gold nanoparticle (AuNP), graphene (GP) and poly(3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS). Graphene was first electro-exfoliated in a polystyrene sulfonate solution, followed by a one-step simultaneous in situ formation of gold nanoparticle and PEDOT. The as-synthesized aqueous dispersion of AuNP-GP-PEDOT:PSS was thereafter used to modify the glassy carbon electrode (GCE). For the first time, the quaternary composite between AuNP, GP, PEDOT and PSS was used for selective determination of dopamine (DA) and uric acid (UA) in the presence of ascorbic acid (AA). In comparison to a bare GCE, the nanocomposite electrode shows considerably higher electrocatalytic activities toward the oxidation of DA and UA due to a synergistic effect between AuNP, GP, PEDOT and PSS. Using differential pulse voltammetry (DPV), selective determination of DA and UA in the presence of AA could be achieved with a peak potential separation of 110 mV between DA and UA. The sensor exhibits wide linear responses for DA and UA in the ranges of 1 nM to 300 μM and 10 μM to 1 mM with detection limits (S/N = 3) of 100 pM and 10 μM, respectively. Furthermore, the proposed sensor was also successfully used to determine DA in a real pharmaceutical injection sample as well as DA and UA in human serum with satisfactory recovery results.

A facile one-pot green synthesis of gold nanoparticle-graphene-PEDOT:PSS nanocomposite was successfully demonstrated.

One-pot synthesis of dendritic Pt3Ni nanoalloys as nonenzymatic electrochemical biosensors with high sensitivity and selectivity for dopamine detection

Preparation of Pt-based nanocatalysts with high catalytic activity and exploration of their novel applications have attracted significant interest in the nanoscale field. Herein, we report a facile synthesis of dendritic Pt₃Ni nanoalloys and their applications for electrochemical nonenzymatic dopamine biosensors. As a result of their unique structure, the dendritic Pt₃Ni nanoalloys show high electrocatalytic activity towards dopamine oxidation. Amperometric dopamine biosensors based on dendritic Pt₃Ni nanoalloy microelectrode exhibit a wide linear detection ranges from 0.5 μM to 250 μM with ultrahigh sensitivity, fast response, and excellent selectivity at a potential of 0.3 V in a 0.1 M phosphate buffered solution (pH = 7.2). The limit of detection on dendritic Pt₃Ni nanoalloy microelectrodes can decrease down to 10 nM, which is the least concentration of dopamine in serum samples with a value of sensitivity up to 4.6 μA mg^-1_Pt cm^-2. This study shows an effective approach for the development of dendritic Pt₃Ni nanoalloys as electrocatalysts for electrochemical nonenzymatic dopamine biosensors.

Simple synthesis of ZnO nanoparticles on N-doped reduced graphene oxide for the electrocatalytic sensing of l-cysteine

A new kind of ZnO nanoparticle/N-doped reduced graphene oxide nanocomposite (ZnONPs/N-rGO) was synthesized through a low temperature, low-cost and one step hydrothermal process.

A copper hexacyanocobaltate nanocubes based dopamine sensor in the presence of ascorbic acid

A highly selective and sensitive dopamine sensor was demonstrated based on copper hexacyanocobaltate nanocubes in the presence of ascorbic acid.