Baiqing Yuan

Sandwich-type electrochemical biosensor for glycoproteins detection based on dual-amplification of boronic acid-gold nanoparticles and dopamine-gold nanoparticles.

Glycoproteins play important roles in a wide variety of biological processes. The change in the concentration levels has been associated with many cancers, as well as other diseases. Thus, rapid, sensitive and selective determination of glycoproteins is much preferred. In this work, we reported a sandwich-type electrochemical biosensor based on dual-amplification of 4-mercaptophenylboronic acid (MBA)-capped gold nanoparticles (MBA-AuNPs) and dopamine (DA)-capped AuNPs (DA-AuNPs). Biological recognition elements such as synthetic receptor and aptamer immobilized onto gold electrodes were used to capture glycoproteins. The captured glycoproteins were then derivatized with MBA-AuNPs through the formation of tight covalent bonds between the boronic acids of MBA-AuNPs and diols of glycoproteins. Electroactive DA-AuNPs were attached by the anchored MBA-AuNPs via the interaction of boronic acids with DA tags, which facilities the amplified voltammetric detection of glycoproteins. With avidin and prostate specific antigen (PSA) as model analytes, we demonstrated the feasibility and sensitivity of the proposed method. The results indicated that sub-picomolar avidin/PSA can be readily measured. We believe that this strategy will be valuable for the electrochemical detection of other glycoproteins.

Amplified voltammetric detection of dopamine using ferrocene-capped gold nanoparticle/streptavidin conjugates

Dopamine (DA) is one of the most important neurotransmitters present in brain tissues and body fluids of mammals. The change in the concentration levels has been associated with various diseases and disorders. Thus, sensitive and selective determination of DA is much preferred. In this work, sandwich-type electrochemical biosensor was developed, in which phenylboronic acid immobilized onto gold electrodes was used to capture DA. The anchored DA was then derivatized with biotin for the attachment of ferrocene-capped gold nanoparticle/streptavidin conjugates. The voltammetric responses were found to be proportional to the concentrations of DA ranging from 0.5 to 50 nM. A detection limit of 0.2 nM was achieved, which is 1~2 orders of magnitude lower than those achievable at various chemically modified electrodes. Analytical merits (e.g., dynamic range, reproducibility, detection level, selectivity and interference) were evaluated. The feasibility of the method for analysis of DA in artificial cerebrospinal fluid and dopamine hydrochloride injection has been demonstrated.

3D porous metal-organic framework as an efficient electrocatalyst for nonenzymatic sensing application

Novel electroactive materials with high surface area and stability have great potential for electrochemical sensor. Herein, we demonstrate the exploitation of a porous Cu-based metal-organic framework (Cu-MOF) with large pore size as nonenzymatic sensors for the electrochemical determination of hydrogen peroxide (H2O2) and glucose. The Cu-MOF shows high stability even in NaOH solution. The as-prepared Cu-MOF modified carbon paste electrode (CPE) presents a well-behaved redox event from electroactive metal centers in the MOF at the physiological pH which can be utilized to catalyze the electroreduction of H2O2. It also exhibited excellent electrocatalytic activity towards the oxidation of glucose in alkaline solution. The results showed that the nonenzymatic sensors based on the Cu-MOF display excellent analytical performances, which make it a promising candidate in electrochemical sensor.

Quick synthesis of zeolitic imidazolate framework microflowers with enhanced supercapacitor and electrocatalytic performances

Novel zeolitic imidazolate framework-67 (ZIF-67) microflowers were synthesized by a quick and simple method without using any template or surfactant. Enhanced specific capacitance (188.7 F g−1 at 1 A g−1) and good cycle stability (remaining at 105% after 3000 cycles) of the ZIF-67 microflowers are observed in aqueous KOH electrolytes, which could be ascribed to the high chemical and thermal stabilities, large BET surface area, and small ion-transport (OH−) resistance of the hierarchical microflowers structure. In addition, the as-prepared ZIF-67 microflowers exhibited good electrocatalytic activity toward the reduction of H2O2. The obtained sensor also presented good reproducibility, high stability and a wide linear range. This work suggests that ZIF materials would be promising candidates for potential applications in supercapacitors and electroanalysis.

Electrochemical determination of glutathione based on an electrodeposited nickel oxide nanoparticles-modified glassy carbon electrode

An electrodeposited nickel oxide nanoparticles (NiONPs)-modified glassy carbon (GC) electrode is presented for the first time and used for electrochemical determination of glutathione (GSH). The NiONPs/GC electrode showed a low oxidation potential toward GSH and a wide linear range for its analysis. Different forms of nickel oxide, electrochemically synthesized in different pH buffer solutions, were investigated for the electrochemical oxidation of GSH. The presented sensor was also applied in the analysis of GSH in the presence of uric acid (UA). In addition, the effects of other interfering species including ascorbic acid (AA), dopamine (DA) and glucose were examined and discussed in detail.

Glassy carbon electrode modified with 7,7,8,8-tetracyanoquinodimethane and graphene oxide triggered a synergistic effect: low-potential amperometric detection of reduced glutathione.

A sensitive electrochemical sensor based on the synergistic effect of 7,7,8,8-tetracyanoquinodimethane (TCNQ) and graphene oxide (GO) for low-potential amperometric detection of reduced glutathione (GSH) in pH 7.2 phosphate buffer solution (PBS) has been reported. This is the first time that the combination of GO and TCNQ have been successfully employed to construct an electrochemical sensor for the detection of glutathione. The surface of the glassy carbon electrode (GCE) was modified by a drop casting using TCNQ and GO. Cyclic voltammetric measurements showed that TCNQ and GO triggered a synergistic effect and exhibited an unexpected electrocatalytic activity towards GSH oxidation, compared to GCE modified with only GO, TCNQ or TCNQ/electrochemically reduced GO. Three oxidation waves for GSH were found at -0.05, 0.1 and 0.5V, respectively. Amperometric techniques were employed to detect GSH sensitively using a GCE modified with TCNQ/GO at -0.05V. The electrochemical sensor showed a wide linear range from 0.25 to 124.3μM and 124.3μM to 1.67mM with a limit of detection of 0.15μM. The electroanalytical sensor was successfully applied towards the detection of GSH in an eye drop solution.

Facile synthesis of ZnCo2O4 mesoporous structures with enhanced electrocatalytic oxygen evolution reaction properties

Recently, as one kind of ternary spinel metal oxide, ZnCo2O4 has attracted extensive attention in the energy storage and conversion field due to it being cost-effective, scalable, and environmentally friendly. Herein, porous ZnCo2O4 micro-spindles and truncated drums were synthesized by a solvent thermal route first and then with an annealing treatment with the precursors. The morphology and structure of ZnCo2O4 were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and high-resolution TEM (HRTEM). It is worth noting that ZnCo2O4 porous micro-spindles show a high surface area of 65.85 m2 g−1 with an average pore diameter of ∼6.34 nm. The as-prepared ZnCo2O4 materials, especially micro-spindles, exhibited good electrocatalytic water-splitting performance with excellent activity and stability. The ZnCo2O4 micro-spindle catalyst exhibits an overpotential of 0.389 V at the benchmark of a current density of 10 mA cm−2. The Tafel slope is 59.54 mV dec−1 and the OER overpotential of the catalyst shows no obvious increase during 7200 s. The high activity, low Tafel slope, and good stability will pave the way for the use of ZnCo2O4 micro-spindles in practical applications.