Nian Hong

An electrochemical DNA sensor without electrode pre-modification.

We present a non-modification electrochemical DNA sensing strategy, which used Potential-Assisted Au-S Deposition and a clamp-like DNA probe. The dual-hairpin probe DNA was tagged with a methylene blue (MB) at the 3 terminal and a thiol at the 5 terminal., Without being hybridized with target DNA, the loop of probe prevented the thiol from reaching the bare gold electrode surface with an applied potential., After hybridization with the target DNA, the probe s loop-stem structure opened through two distinct and sequential events, which led to the formation of a triplex DNA structure. Then the thiol easily contacted with electrode and resulted in potential-assisted Au-S self-assembly. Electrochemical signals of MB were measured by differential pulse voltammetry (DPV) and used for target quantitative detection. This strategy offered a detection limit down to 2.3pM. and an inherently high specificity for detecting even single mismatch.

“Off-On”switching electrochemiluminescence biosensor for mercury(II) detection based on molecular recognition technology

A novel off-On electrogenerated chemiluminescence (ECL) biosensor has been developed for the detection of mercury(II) based on molecular recognition technology. The ECL mercury(II) biosensor comprises two main parts: an ECL substrate and an ECL intensity switch. The ECL substrate was made by modifying the complex of Ruthenium(II) tris-(bipyridine)(Ru(bpy)32+)/Cyclodextrins-Au nanoparticles(CD-AuNps)/Nafion on the surface of glass carbon electrode (GCE), and the ECL intensity switch is the single hairpin DNA probe designed according to the molecular recognition strategy which was functionalized with ferrocene tag at one end and attached to Cyclodextrins (CD) on modified GCE through supramolecular noncovalent interaction. We demonstrated that, in the absence of Hg(II) ion, the probe keeps single hairpin structure and resulted in a quenching of ECL of Ru(bpy)32+. Whereas, in the presence of Hg(II) ion, the probe prefers to form the T-Hg(II)-T complex and lead to an obvious recovery of ECL of Ru(bpy)32+, which provided a sensing platform for the detection of Hg(II) ion. Using this sensing platform, a simple, rapid and selective off-On ECL biosensor for the detection of mercury(II) with a detection limit of 0.1xa0nM has been developed.

Ru(bpy)3 2+ /β-cyclodextrin-Au nanoparticles/nanographene functionalized nanocomposites-based thrombin electrochemiluminescence aptasensor

In this study, a functionalized nanocomposite-based electrochemiluminescence (ECL) sensor for detecting thrombin was developed. First, Ru(bpy)32+/β-cyclodextrin-Au nanoparticles (β-CD-AuNPs)/nanographene (NGP) composites were used to modify the glassy carbon electrode (GCE) surface, and then aptamers (TBA1 and TBA2 with a 1:1xa0M ratio) were labeled with ferrocene (Fc) acting as the probes and were attached to the composite via the host–guest recognition between β-CD and Fc. In the absence of thrombin, the quenching of Fc to [Ru(bpy)3]2+ was maintained, and “signal-off” ECL was observed. However, because of the specific combination of the aptamer probes and thrombin, the configuration of aptamer probes changed and escaped from the electrode surface once thrombin appears, which results in the quenching disappearance, and the ECL signal was changed from “off” to “on.” Meanwhile, the application of nanocomposites amplified the effect of “signal-on.” By this strategy, thrombin was detected with high sensitivity and with a detection limit down to 0.23xa0pM. Moreover, the relatively simple ECL sensor exhibited excellent reproducibility with at least 6xa0cycles of recovering the original signal.

A ZnS-Nanoparticle-Label-Based Electrochemical Codeine Sensor

Codeine (3-methylmorphine) is an opiate that is widely used to treat mild or moderate pain and cough suppression. It is the second predominant alkaloid in opium with a mild sedative effect. In the present study, we describe an electrochemical sensor for codeine detection by using the DNA aptamers against codeine. In the sensing protocol, a dually-labeled DNA aptamer probe was designed to be labeled at one end with HS, and at its another end with dabcyl as an electrochemical tag to produce electrochemical signal via recognization occurrence. One special electrochemical marker was prepared by modifying ZnS nanoparticle with-cyclodextrins (ab. ZnS-CDs), which employed as electrochemical signal provider and would conjunct with the codeine probe modified electrode through the host–guest recognition of CDs to dabcyl. With codeine adding, aptamer folding allows the ZnS-CDs into soultion that caused an increase of current signal. This sensor has the ability to detect 37pM codeine. Our study demonstrates that the biosensor has good specificity and stability. It can be used to detect codeine.