Wenping Deng

Application of ZnO quantum dots dotted carbon nanotube for sensitive electrochemiluminescence immunoassay based on simply electrochemical reduced Pt/Au alloy and a disposable device

We report on a disposable microdevice suitable for sandwich-type electrochemiluminescence (ECL) detection of prostate specific antigen (PSA). The method is making use of ZnO quantum dots dotted carbon nanotube (ZnO@CNT) and simply electrochemical reduced Pt/Au alloy. The latter was selected as immunosensing probe to modify screen-printed carbon electrode, due to its excellent electrical property. For further ultrasensitive, low-potential and stable ECL detection, ZnO@CNT composite was first synthesized using a facile solvothermal method, and employed as signal amplification label. In this work, two working electrodes in one device were used for one determination to obtain more exact results based on screen-print technique. Taking advantage of dual-amplification effects of the Pt/Au and ZnO@CNT, this immunosensor could detect the PSA quantitatively, in the range of 0.001-500 ng mL(-1), with a low detection limit of 0.61 pg mL(-1). The resulting versatile immunosensor possesses high sensitivity, satisfactory reproducibility and regeneration. This simple and specific strategy has vast potential to be used in other biological assays.

A 3D electrochemical immunodevice based on an Au paper electrode and using Au nanoflowers for amplification

A highly sensitive electrochemical (EC) immunosensor combined with a 3D origami device for the detection of cancer antigen 125 (CA 125) was developed based on a novel Au nanoparticle-modified paper working electrode (Au-PWE) as sensor platform and Au nanoflowers (AuNFs) as signal amplification label. The microfluidic origami electrochemical device was fabricated by directly screen-printing electrodes on wax-patterned cellulose paper in bulk. The Au-PWE was fabricated using a seed-mediated growth approach and served as an effective matrix for antibody attachment with good bioactivity and stability. Molybdenum disulfide catalyzed the hydrogen peroxide so that the current peak was presented with differential pulse voltammetry (DPV). On the basis of the considerably amplified DPV signal and sandwich-type format, the proposed method successfully fulfilled the highly sensitive detection of CA 125 with a linear range of 0.001 to 50 ng mL−1 and a detection limit of 0.36 pg mL−1. This facile origami EC immunodevice exhibited high sensitivity, specificity and excellent performance in real human serum assay, and it could be applied in point-of-care testing of other tumor markers in remote regions and developing countries.

A sensitive quenched electrochemiluminescent DNA sensor based on the catalytic activity of gold nanoparticle functionalized MoS2

In this paper, molybdenum disulfide (MoS2) was synthesized through the hydrothermal method, which was further fabricated into gold nanoparticle (AuNP) functionalized MoS2 (MoS2–Au). The prepared MoS2–Au showed an excellent catalytic performance of hydrogen peroxide (H2O2) in the reduction reaction. In addition, the CdS/ZnS quantum dots coated with polyethyleneimine (PEI-CdS/ZnS QDs) with good electrochemiluminescence (ECL) properties were prepared. Finally, the prepared MoS2–Au and PEI-CdS/ZnS QDs were applied in a simple sandwich-type ECL sensor for DNA detection. In the DNA sensor, PEI-CdS/ZnS QDs acted as solid supports for capturing DNA and MoS2–Au was employed as the supporter of reporter DNA. MoS2–Au could quench the ECL signal of the PEI-CdS/ZnS QDs in which Au could facilitate the ECL measure and the quenching ECL intensity could be obtained. The proposed DNA sensor enabled target DNA concentrations to be determined in the 0.05–1000 fM concentration range, with a detection limit of 0.023 fM. The DNA sensor showed a low detection limit, good specificity, high sensitivity and reproducibility. Hence, the use of proposed electrochemiluminescent biosensors could become a promising method for DNA detection.

A sensitive electrochemiluminescent immunosensor based on 3D-flower-like MoS2 microspheres and using AuPt nanoparticles for signal amplification

We herein report the synthesis of MoS2, consisting of three-dimensional flower-like microspheres assembled by bent flakes with a thickness of several nanometers. The diameter of theses spheres was approximately 1.5 μm, and they showed good catalysis of H2O2 and could increase the electrochemiluminescence (ECL) intensity of luminol. The ECL properties of luminol were investigated and a type of luminol composite (MoS2–luminol) was prepared. Glucose oxidase–AuPt nanoparticles (GOx–AuPt) showed excellent catalytic performance for the reduction reaction of glucose. The prepared GOx–AuPt and MoS2–luminol were applied in a sandwich-type ECL immunosensor for prostate-specific antigen (PSA). In the immunosensor, MoS2–luminol acted as a solid support for PSA primary antibody, and GOx–AuPt was employed as a support for PSA secondary antibody. With the addition of glucose, hydrogen peroxide was prepared and the ECL properties of the MoS2–luminol were enhanced. The proposed immunosensor enabled PSA concentrations to be determined in the range of 0.001 ng mL−1 to 100 ng mL−1, with a detection limit of 0.28 pg mL−1. The experimental results indicated that the immunosensor exhibited simple instrumentation, high sensitivity, wide linear range and excellent analytical performance, and could be a promising technique for tumor marker detection.

Highly sensitive hybridization assay using the electrochemiluminescence of an ITO electrode, CdTe quantum dots functionalized with hierarchical nanoporous PtFe nanoparticles, and magnetic graphene nanosheets

AbstractWe report on a disposable microdevice suitable for sandwich-type electrochemiluminescence (ECL) detection of DNA. The method is making use of CdTe quantum dots functionalized with hierarchical nanoporous PtFe (CdTe@PtFe) nanoparticles and with magnetic graphene nanosheets. The latter were selected as carriers for the capture DNA due to their excellent biomagnetic separation capability and electrical properties. The CdTe@PtFe nanoparticles were used to label the signal DNA which resulted in distinctly enhanced ECL owing to the large specific surface area and good electrical conductivity of the PtFe alloy. A DNA sensor was constructed on a disk-shaped indium tin oxide electrode that was fabricated via etching. Under optimal conditions, the biosensor responds linearly to DNA in the 0.02 fM to 5000 fM concentration range, with a detection limit as low as 15 aM. The electrode is regenerable. The method displays excellent specificity, extremely good sensitivity, and is highly reproducible. FigureCdTe quantum dots functionalized hierarchical nanoporous PtFe alloy (CdTe@PtFe) and magnetic graphene nanosheet (MGN) were applied for sensitive sandwich-type electrochemiluminescence DNA detection based on a disposable microdevice. The method displays excellent specificity, extremely good sensitivity, and is highly reproducible.

Using carbon nanotubes-gold nanocomposites to quench energy from pinnate titanium dioxide nanorods array for signal-on photoelectrochemical aptasensing

On the basis of the absorption and emission spectra overlap, an enhanced resonance energy transfer caused by excition-plasmon resonance between carbon nanotubes-gold nanoparticles (CNTs-Au) and pinnate titanium dioxide nanorods array (P-TiO2 NA) was obtained. Three-dimensional single crystalline P-TiO2 were prepared successfully on fluorine-doped tin oxide conducting glass (FTO glass), and its optical absorption properties and photoelectrochemical (PEC) properties were investigated. With the synergy of CNTs-Au as energy acceptor, it resulted in the enhancement of energy transfer between excited P-TiO2 NA and CNTs-Au. Upon the novel sandwichlike structure formed via DNA hybridization, the exciton produced in P-TiO2 NA was annihilated and a damped photocurrent was obtained. With the use of carcinoembryonic antigen (CEA) as a model which bonded to its specific aptamer and destroyed the sandwichlike structure, the energy transfer efficiency was lowered, leading to PEC response augment. Thus a signal-on PEC aptasensor was constructed. Under the optimal conditions, the PEC aptasensor for CEA determination exhibited a linear range from 0.001 to 2.5ngmL(-1) with a detection limit of 0.39pgmL(-1) and was satisfactory for clinical sample detection. Furthermore, the proposed aptasensor shows satisfying performance, such as easy preparation, rapid detection and so on. Moreover, since different aptamer can specifically bind to different target molecules, the designed strategy has an expansive application for the construction of versatile PEC platforms.