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Hun X.,Key Laboratory of Eco Chemical Engineering | Hun X.,Qingdao University of Science and Technology | Xu Y.,Key Laboratory of Eco Chemical Engineering | Xu Y.,Qingdao University of Science and Technology | Chen C.,Ankang University
Sensors and Actuators, B: Chemical | Year: 2014

A novel chemiluminescent (CL) immunoassay protocol for the sensitive determination of Gibberellic acid (GA) using DNA-based hybridization chain reaction (HCR) is described. The carboxyl terminated magnetic beads (MBs) were modified with GA antibody and the gold nanoparticles (AuNPs) signal probes were labeled with the GA antibody and DNA initiator strands. In the presence of target GA, the sandwiched immunocomplex was formed between the immobilized antibody on the MBs and the signal antibody on the AuNPs. When the two complementary stable species of DNA hairpins, which are G-rich DNA, were added the hybridization events were happened, thereby resulting forming the long nicked double-helix. Numerous double G-rich DNA were formed on the AuNPs, each of which produced a CL signal within the applied CL reaction. The CL signal was obtained via the instantaneous derivatization reaction between a specific CL reagent, 3,4,5-trimethoxyl-phenylglyoxal (TMPG), and the G-rich DNA on immunocomplex. Under optimal conditions, GA can be detected in the concentration ranged from 0.01 ng/mL to 70 ng/mL, and the limit of detection was 0.003 ng/mL. The reproducibility and selectivity of the developed method were also investigated. In addition, the real samples were assayed by using the developed immunoassay, and the recovery was 96.0-102.0%. © 2014 Elsevier B.V. Source


Hun X.,Key Laboratory of Eco Chemical Engineering | Hun X.,Qingdao University of Science and Technology | Hun X.,Jiangnan University | Mei Z.,Key Laboratory of Eco Chemical Engineering | And 4 more authors.
Spectrochimica Acta - Part A: Molecular and Biomolecular Spectroscopy | Year: 2012

A highly sensitive chemiluminescence (CL) method for detection of phytohormone indole-3-acetic acid (IAA) was developed by using G-rich DNA labeled gold nanoparticles (AuNPs) as CL probe coupling the DNA signal amplification technology. The IAA antibody was immobilized on carboxyl terminated magnetic beads (MBs). In the presence of IAA, antibody labeled AuNPs were captured by antibody functionalized MBs. The DNA on AuNPs is released by a ligand exchange process induced by the addition of DTT. The released DNA is then acted as the linker and hybridized with the capture DNA on MBs and probe DNA on AuNPs CL probe. The CL signal is obtained via the instantaneous derivatization reaction between a specific CL reagent, 3,4,5-trimethoxyl-phenylglyoxal (TMPG), and the G-rich DNA on AuNPs CL probe. IAA can be detected in the concentration range from 0.02 ng/mL to 30 ng/mL, and the limit of detection is 0.01 ng/mL. © 2012 Elsevier B.V. All rights reserved. Source


Lin J.,Key Laboratory of Eco Chemical Engineering | Zhang H.,Key Laboratory of Eco Chemical Engineering | Niu S.,Key Laboratory of Eco Chemical Engineering
Microchimica Acta | Year: 2014

We report on an electrochemical immunoassay for simultaneous detection of the tumor markers carcinoembryonic antigen (CEA) and α-fetoprotein (AFP). Gold nanoparticles (AuNPs) were synthesized inside the internal pore walls of mesoporous silica (MPS). Then, Methylene blue (MB) and 6-ferrocenylhexanethiol (FeC), which act as electrochemical substrates, were incorporated into the channels via the formation of Au-S bonds. Finally, monoclonal antibodies against CEA (anti-CEA) and AFP (anti-AFP) were immobilized in the channels of MB-AuNPs-MPS and FeC-AuNPs-MPS, respectively. Suspensions of anti-CEA/MB-AuNPs-MPS and of anti-AFP/FeC-AuNPs-MPS were deposited on two different sites of the ITO electrode. When incubated with samples containing the two analytes, the formation of electrically nonconductive immunoconjugates blocks electron transfer. Simultaneous detection of CEA and AFP was accomplished by monitoring the current change before and after an immunoreaction has occurred. The AuNPs confined inside the channels are promoting the electron transport and thus improve detection limits. The immunoelectrode responds to CEA in the 0.5–50 ng mL−1 concentration range, and to AFP in concentrations between 0.5 and 100 ng mL−1. The detection limits (at an S/N of 3) are 0.1 ng mL−1 in both cases. © 2014, Springer-Verlag Wien. Source


Wan J.,Key Laboratory of Eco Chemical Engineering | Ding J.,Key Laboratory of Eco Chemical Engineering | Wang M.,Key Laboratory of Eco Chemical Engineering
Journal of Cluster Science | Year: 2010

A simple method to fabricate gold nanotube by means of a direct electrodeposition is constructed, utilizing anodic aluminum oxide (AAO) as a template. The performances of gold nanoelectrode have been characterized with cyclic voltammetric technique and scanning electron microscope (SEM). The SEM image of as-prepared gold nanoelectrode shows that the surface of electrode was covered with honeycomb gold tube with average pore diameter 200 nm. Its cyclic voltammetric shows the peak current is 6. 25 times larger than the bare Au electrode, so the new honeycomb gold nanoelectrode was obviously better than conventional gold electrode. Microperoxidase-11 (MP-11) was immobilized on the electrode and characterized with cyclic voltammetric technique. It was demonstrated that the gold nanotube not only could offer a friendly environment to immobilize MP-11, but also enhance the electron transfer ability between protein molecules and the underlying electrodes. © 2010 Springer Science+Business Media, LLC. Source


Xu G.,Key Laboratory of Eco Chemical Engineering | Tang L.,Key Laboratory of Eco Chemical Engineering | Liu H.,Key Laboratory of Eco Chemical Engineering
Ionics | Year: 2013

The electrochemical property of dinuclear copper(II) complex containing mixed ligands of N-hydroxyethylaminoethyl oxamido and 2,2′-bipyridine [Cu2(bpy)2(HAO)2 2+] was studied with cyclic voltammetry. Cu2(bpy)2(HAO)2 2+ had irreversible oxidation peaks in 0. 1 mol/L NaCl solution at the stearic acid-modified carbon paste electrode. Cyclic voltammetry and absorption spectra measurements were used to study the interaction between Cu2(bpy)2(HAO)2 2+ and herring fish sperm DNA. All the experimental results showed that Cu2(bpy)2(HAO)2 2+ interacted with DNA mainly through electrostatic affinity to make tiny difference between Cu2(bpy)2(HAO)2 2+-ssDNA and Cu2(bpy)2(HAO)2 2+-dsDNA. The binding ratio and the binding constant of DNA-Cu2(bpy)2(HAO)2 2+ were calculated as 1:1 and 6. 41 × 104, respectively. The redox peak current of Cu2(bpy)2(HAO)2 2+ decreased markedly after its interaction with DNA. This was used to detect the concentration of DNA quantitatively. © 2012 Springer-Verlag. Source

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