Electrochemical Oxidation and Determination of Glucose Using Cyclic Voltammetry and a One-step Prepared Nanoporous Gold Wire Electrode

Facile fabrication of hierarchically nanostructured gold electrode for bio-electrochemical applications

Nanoporous gold (NPG) is one of the most extensively investigated nanomaterials owing to its tunable pore size, ease of surface modification, and range of applications from catalysis, actuation, and molecular release to the development of electrochemical sensors. In an effort to improve the usefulness of NPG, a simple and robust method for the fabrication of hierarchical and bimodal nanoporous gold electrodes (hb-NPG) containing both macro-and mesopores is reported using electrochemical alloying and dealloying processes to engineer a bicontinuous solid/void morphology. Scanning electron microscopy (color SEM) images depict the hierarchical pore structure created after the multistep synthesis with an ensemble of tiny pores below 100 nm in size located in ligaments spanning larger pores of several hundred nanometers. Smaller-sized pores are exploited for surface modification, and the network of larger pores aids in molecular transport. Cyclic voltammetry (CV) was used to compare the electrochemically active surface area of the hierarchical bimodal structure with that of the regular unimodal NPG with an emphasis on the critical role of both dealloying and annealing in creating the desired structure. The adsorption of different proteins was followed using UV-vis absorbance measurements of solution depletion revealing the high loading capacity of hb-NPG. The surface coverage of lipoic acid on the hb-NPG was analyzed using thermogravimetric analysis (TGA) and reductive desorption. The roughness factor determinations suggest that the fabricated hb-NPG electrode has tremendous potential for biosensor development by changing the scaling relations between volume and surface area which may lead to improved analytical performance. We have chosen to take advantage of the surface architectures of hb-NPG due to the presence of a large specific surface area for functionalization and rapid transport pathways for faster response. It is shown that the hb-NPG electrode has a higher sensitivity for the amperometric detection of glucose than does an NPG electrode of the same geometric surface area.

Enzyme-free glucose sensors with efficient synergistic electro-catalysis based on a ferrocene derivative and two metal nanoparticles

Gold electrodes (GE) were modified by the deposition of copper nanoparticles (CuNPs) and cobalt nanoparticles (CoNPs), followed by drop-casting of the ferrocene derivative FcCO-Glu-Cys-Gly-OH (Fc-ECG), resulting in two enzyme-free electrochemical sensors Fc-ECG/CuNPs/GE and Fc-ECG/CuNPs/GE. The ferrocene-peptide conjugate acts as an effective redox mediator for glucose oxidation, while metal nanoparticles acted as non-biological sites for glucose oxidation. Field emission scanning electron microscopy (FESEM), cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) were carried out for characterization, while differential pulse voltammetry (DPV) was used for glucose quantification. Under optimized conditions, DPV shows a linear relationship between glucose concentration and the peak current. Both sensors showed a surprisingly high sensitivity of 217.27 and 378.70 μA mM⁻¹ cm⁻², respectively. A comparison to other glucose sensors shows a sensitivity that is 25 times higher. The sensors exhibit good reproducibility, stability, and repeatability. In injection experiments, recovery rates were 87.39–107.65% and 100.00–106.88%, respectively.

We exploit the ferrocene–glutathione conjugate Fc-ECG as electron transfer mediator and make use of gold electrodes that were modified with either copper or cobalt nanoparticles to give sensor surfaces that exhibit excellent catalytic activity of glucose oxidation.

High-performance non-enzymatic biofuel cells based on an organic copper complex cathode and a nanoporous gold nanoparticle anode

We developed non-enzymatic biofuel cells based on organic copper complex and nanoporous gold nanoparticle electrocatalysts in a neutral medium.

Recent advances and developments on integrating nanotechnology with chemiluminescence assays

Chemiluminescence (CL) techniques are extensively utilized for detection of analytes due to their high sensitivity, rapidity and selectivity. With the advent of nanotechnology and incorporation of the nanoparticles in the CL system has revolutionized the assays due to their unique optical and mechanical properties. Several CL-based reactions have been developed where these nanoparticle based CL sensors have evolved as excellent prospects for sensing in various analytical applications. This review article addresses the nanoparticles based CL detection system that are recently developed, the mechanisms has been summarized and the role of luminophors have been discussed. This article critically analyzes the optimal conditions for the CL detection along with quantitative assessment of the analytes. We have included the use of semiconductor nanoparticles, metal nanoparticles, graphene based nanostructures, mesoporous nanospheres, layered double hydroxides, clays for CL detection. The scope and application of these nanoscale material based CL system in various branches of science and technology including chemistry, biomedical applications, pharmaceutics, food, environmental and toxicological applications has been critically summarized.