Dehua Deng

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.

Preparation of electrochemically reduced graphene oxide-modified electrode and its application for determination of p -aminophenol

A simple and eco-friendly electrochemical method to reduce graphene oxide precursor was employed for fabrication of graphene sheets modified glassy carbon electrode, and then, the resulting electrode [electrochemically reduced graphene oxide (ERGO)/glassy carbon electrode (GCE)] was used to determine p-aminophenol. The experimental results demonstrated that the modified electrode exhibited excellent electrocatalytic activity toward the redox of p-aminophenol as evidenced by the significant enhancement of redox peak currents and the decreased peak-to-peak separation in comparison with a bare GCE. A highly sensitive and selective voltammetry determination of p-aminophenol is developed using the ERGO/GCE. This method has been applied for the direct determination of p-aminophenol in artificial wastewater.

A comparative study of different types of reduced graphene oxides as electrochemical sensing platforms for hydroquinone and catechol

We compared the electrochemical performance of various reduced graphene oxides (RGOs), including chemically reduced graphene oxide (CRGO), thermally reduced graphene oxide (TRGO), and electrochemically reduced graphene oxide (ERGO) under different reduction potentials, using aromatic species of hydroquinone and catechol as analytes. Strong adsorption of analytes on RGOs surface is found due to π-π interaction between RGOs and aromatic species. Analytical parameters of electron transfer rate, detection sensitivity, and linear response range were considered. CRGO showed the fastest heterogeneous electron transfer rate and the most wide linear range but among the poorest detection sensitivity. The different restoration extent of graphitic network, such as ERGO prepared under different reduction potentials, will also affect the sensing performance. These results will enhance our understanding of the applicability of RGOs in biosensing.

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.

Simple, Fast and Selective Detection of Adenosine Triphosphate at Physiological pH Using Unmodified Gold Nanoparticles as Colorimetric Probes and Metal Ions as Cross-Linkers

We report a simple, fast and selective colorimetric assay of adenosine triphosphate (ATP) using unmodified gold nanoparticles (AuNPs) as probes and metal ions as cross-linkers. ATP can be assembled onto the surface of AuNPs through interaction between the electron-rich nitrogen atoms and the electron-deficient surface of AuNPs. Accordingly, Cu2+ ions induce a change in the color and UV/Vis absorbance of AuNPs by coordinating to the triphosphate groups and a ring nitrogen of ATP. A detection limit of 50 nM was achieved, which is comparable to or lower than that achievable by the currently used electrochemical, spectroscopic or chromatographic methods. The theoretical simplicity and high selectivity reported herein demonstrated that AuNPs-based colorimetric assay could be applied in a wide variety of fields by rationally designing the surface chemistry of AuNPs. In addition, our results indicate that ATP-modified AuNPs are less stable in Cu2+, Cd2+ or Zn2+-containing solutions due to the formation of the corresponding dimeric metal-ATP complexes.

Anti-adsorption properties of gold nanoparticle/sulfonated graphene composites for simultaneous determination of dihydroxybenzene isomers

In this work, the simultaneous determination of dihydroxybenzene isomers of hydroquinone and catechol at the gold nanoparticle/sulfonated graphene modified electrode was reported. The gold nanoparticle/sulfonated graphene composites were prepared by electrostatic self-assembly of positively charged gold nanoparticles on negatively charged graphene sheets. The application of the composites for the electrocatalysis of hydroquinone and catechol was studied by cyclic voltammetry and differential pulse voltammetry. Compared to the well-known graphene modified electrode, including chemically reduced sulfonated graphene and electrochemically reduced graphene, the composites modified electrode exhibited obvious anti-adsorption properties toward aromatic species of hydroquinone and catechol. The results showed that the isomers could be detected selectively and sensitively at the composites modified electrode with an anodic peak-to-peak separation of about 110 mV. The linear range of hydroquinone and catechol was 5 to 100 μM and the detection limit was 1 μM and 2 μM, respectively. Simultaneous determination of hydroquinone and catechol in tap water samples has been studied. The attractive electrochemical performances and facile preparation methods have made this novel electrode promising for the development of effective dihydroxybenzene sensors.