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.

A highly sensitive electrochemical immunosensor combined with a 3D origami device for detection of cancer antigen was developed based on a novel Au nanoparticle-modified paper working electrode.

We herein report the synthesis of MoS2which was three-dimensional flower-like microspheres, and then the prepared GOx–AuPt and MoS2–luminol were applied in a sandwich-type ECL immunosensor for prostate-specific antigen detection.

A highly sensitive and selective turn on fluorescent probe P-acid-aldehyde (P-CHO) is developed for the determination of cysteine (Cys) and homocysteine (Hcy). The probe is designed and synthesized by incorporating the specific functional group aldehyde group for thiols into a stable pi-conjugated material 4,4'-(2,5-dimethoxy-1,4-phenylene) bis(ethyne-2,1-diyl) dibenzoic acid (P-acid). The probe fluorescence is quenched through donor photoinduced electron transfer (d-PET) between the fluorophore (P-acid) and the recognition group (aldehyde group). In the presence of thiols, Cys and Hcy can selectively react with aldehyde group of the probe because the inhibition of d-PET between fluorophore and recognition group. Therefore, a turn-on fluorescent sensor was established for the fluorescence recovery.Under the optimized conditions, the fluorescence response of probe is directly proportional to the concentration of Cys in the range of 4-95 nM L-1, with a detection limit 3.0 nM. In addition, the sensing system exhibits good selectively toward Cys and Hcy in the presence of other amino acids. It has been successfully applied for bioimaging of Cys and Hcy in living cells with low cell toxicity. (C) 2016 Elsevier B.V. All rights reserved.

A simple sandwich-type ECL sensor for DNA detection based on MoS2–Au quenching the ECL signal of CdS/ZnS QDs.

A novel fluorescence sensor based on carbon dots–MnO2 nanocomposites was fabricated successfully, which can detect glutathione (GSH) in aqueous solutions succinctly, rapidly and selectively. The carbon dots (CDs), which were synthesized by using organosilane as a coordinating solvent, had a highly luminescent quantum yield. The nanoflower-like MnO2 had an enormous specific surface area, which could react with more CDs. Subsequently, CDs–MnO2 nanocomposites were synthesized through a facile one-step method. As a result of fluorescence resonance energy transfer (FRET) from CDs to the MnO2, the fluorescence of CDs can be quenched by MnO2. However, when GSH was introduced into the system, the quenched fluorescence could be restored because MnO2 was reduced to Mn2+ by GSH, which led to the elimination of FRET. Compared with other electrolytes and biomolecules, we find that the chemical response of the CDs–MnO2 nanocomposites exhibited good selectivity toward GSH. Under the optimal conditions, the proposed immunosensor was successfully performed with a linear range of 0.03–974.1μmolL−1, with a detection limit of 0.015μmolL−1. In addition, the proposed fluorescence sensor has several merits, such as low cost, good selectivity, great biocompatibility and chemical turn-on fluorescence response.

A facile and sensitive electrochemiluminescence (ECL) immunosensor for the detection of human carcinoembryonic antigen (CEA) was designed. The immunosensor used Pt nanoparticles dotted graphene-carbon nanotubes composites (Pt/Gr-CNTs) as a platform and carbon dots functionalized Pt/Fe nanoparticles (Pt/Fe@CDs) as bionanolabels. The Pt/Gr-CNTs was first synthesized using a facile ultrasonic method to modify the working electrode, which increases the surface area to capture a large amount of primary anti-CEA antibodies as well as improving the electronic transmission rate. The bionanolabels Pt/Fe@CDs prepared through ethanediamine linking, showed good ECL signal amplification performance. The reason is that the Pt/Fe@CDs nanocomposites as signal tags can increase CDs loading per immunoreaction in comparison with single CDs. The approach provided a good linear response range from 0.003 to 600 ng mL(-1) with a low detection limit of 0.8 pg mL(-1). The immunosensor showed good specificity, acceptable stability and reproducibility. Satisfactory results were obtained in the determination of CEA in human serum albumin samples. Hence, the proposed ECL immunosensor could become a promising method for tumor marker detection.

We reported here the synthesis of thin MoS2 nanosheets, which showed a good catalysis of H2O2. The MoS2 nanosheets were further synthetized into nano-composite MoS2-Au, and the MoS2-Au was found with a better catalysis property of H2O2 and well electroconductibility. Furthermore, we composed Ag nanospheres (AgNPs), which have good electricity and large surface area. The prepared AgNPs and MoS2-Au were applied in a sandwich-type immunosensor for detecting carcinoembryonic antigen (CEA). In the immunosensor, MoS2-Au acted as the solid support for CEA primary antibody and AgNPs were employed as the supporter of glucose oxidase (GOx) and CEA secondary antibody. With the addition of glucose, the hydrogen peroxide was prepared and the MoS2-Au catalyzed hydrogen peroxide that the current peak was presented with the differential pulse voltammetry (DPV). The proposed immunosensor enabled CEA concentrations to be determined in the range of 1pgmL−1 to 50ngmL−1, with a detection limit of 0.27pgmL−1. The immunosensor showed low detection limit, good specificity, high sensitivity and reproducibility. Satisfactory results were obtained for determination of CEA in human serum albumin samples. This work is to open new avenues in the application of AuNPs dotted MoS2 composite interface for sensitive electrochemical immunoassay. Hence, the proposed electrochemical immunosensor could become a promising method for tumor marker detection.

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.

We report on the synthesis of flower-like 3D titanium dioxide (fl-TiO2) using a hydrothermal method. This material possesses a large specific surface and displays an electrochemiluminescence (ECL) intensity that is much stronger than the one of TiO2 nanoparticles having smooth surfaces. It was used to label the secondary antibody in a sandwich immunoassay. A thin layer of metallic gold (Au) and palladium (Pd) was deposited on an indium tin oxide (ITO) electrode by code-position at a potential of 0.2 V in the respective chloride solutions. The Au/Pd-modified ITO electrode showed good conductivity. An ECL based immunoassay for the prostate specific antigen (PSA) was then worked out by immobilizing the first antibody on the Au/Pd layer on the ITO electrode, then exposing the electrode to a sample containing PSA, then forming the sandwich with the fl-TiO2 labeled secondary antibody, and finally measuring the intensity of ECL at a potential of −1.5 V. This ECL sensor has a response range that extends from 0.001 to 600 ng∙mL−1, a lower detection limit of 0.32 pg∙mL−1, good specificity, acceptable stability and good reproducibility. It gave satisfactory results when used for the determination of PSA in (spiked) diluted solutions of human serum.

We 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.