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We herein report a self-powered and renewable cytosensing device based on ZnO nanodisks(NDs)@g-C 3 N 4 quantum dots. The device features enhanced photoelectrochemical (PEC) activity compared to ZnO NDs or g-C 3 N 4 QDs alone. The enhanced PEC ability is attributed to the synergistic effect of the high visible light sensitivity of g-C 3 N 4 QDs and the staggered band alignment heterojunction structure with suitable band offset, which affords higher photoelectron transfer and separation efficiency. In addition, the hybridization of g-C 3 N 4 QDs further accelerates interfacial electron transfer and blocks recombination between electron donors and photo-generated holes. The device was applied to the detection of CCRF-CEM cells. By conjugation to Sgc8c aptamer, which preferentially interacts with membrane-bound PTK7 on CCRF-CEM membranes, capture of target CCRF-CEM cells resulted in a decrease in apparent power output, which was then exploited for the ultrasensitive detection of the target cells. This decrease in power output can be recovered by simply increasing the temperature to release the cells, thus recycling the cytosensing performance. The device displayed a linear relationship between the change of power output and the logarithm of the cell concentration from 20 to 20,000 cell/mL (R 2 = 0.9837) and a detection limit down to 20 cell/mL, as well as excellent selectivity and reproducibility. Thus, this ZnO NDs@g-C 3 N 4 QDs-based device exhibits high potential for the detection of CCRF-CEM cells.

In this work, a highly-efficient competitive method-based electrochemiluminescence (ECL) immunosensor was proposed based on {[Ru(bpy) 3 ][Cu 2x Ni 2(1-x) (ox) 3 ]} n (Cu/Ni/Ru) as luminophor to efficiently detect aflatoxins B1 (AFB1). Cu/Ni/Ru exhibited excellent ECL behavior. While polyethyleneimine capped silicon dioxide (PEI@SiO 2 ) could decrease the ECL performance of Cu/Ni/Ru due that PEI could destroy the structure of Cu/Ni/Ru via producing the complex between PEI and metal ions (Cu(II)/Ni(II)), inducing the release of Ru(bpy) 3 2+ . Since Au nanoparticles can directly combine with antibody and antigen, the Cu/Ni/Ru and PEI@SiO 2 was functionalized by Au nanoparticles. The quantitative detection of AFB1 was based on the competitive binding between AFB1-bovine serum albumin labeled Au-PEI@SiO 2 (Au-PEI@SiO 2 -AFB1-BSA) and free AFB1 with antibody-AFB1 which immobilized on Au-Cu/Ni/Ru. The ECL signal increased with augmenting the concentrations of the free AFB1 due to less Au-PEI@SiO 2 -AFB1-BSA combining with antibodies. Under optimal conditions, the proposed immunosensor exhibited a wide linear range from 0.01ngmL -1 to 100ngmL -1 with a detection limit of 0.0039ngmL -1 (S/N = 3). The proposed immunosensor also provides a promising approach for ultrasensitive detection of other mycotoxins., (Copyright © 2017 Elsevier B.V. All rights reserved.)

Heart failure (HF) is a burgeoning public health problem trigged by a heart circulation disorder. N-terminal pro-B-type natriuretic peptide (NT-proBNP) has been acknowledged as a prognostic biomarker for cardiac disease. Herein, a sandwich-type electrochemiluminescence (ECL) immunosensor was introduced for sensitive detection of NT-proBNP. Gold nanoparticle modified graphene oxide-Ru(bpy) 3 2+ /Ag 2 C 2 O 4 was used as a luminophore and a desirable platform for immobilization of the captured antibodies. The more stable immobilization of plentiful Ru(bpy) 3 2+ could be implemented by direct covalent bonding chelation with Ag 2 C 2 O 4 . More importantly, significant quenching can be achieved by introducing polydopamine (PDA) coated Fe 3 O 4 onto the electrode via sandwich immunoreactions. The quenching mechanism mainly showed that the excited states of Ru(bpy) 3 2+ could be annihilated by quinone units in PDA via energy transfer. The ECL quenching efficiency was logarithmically related to the concentration of the NT-proBNP in the range from 0.0005 ng/mL to 100.0 ng/mL with a detection limit of 0.28 pg/mL. Furthermore, this specific immunosensor presented good stability and repeatability as well as selectivity, which offers a guiding significance in both fundamental and clinical diagnosis of NT-proBNP.

Herein, we demonstrated the protocol of a visible light induced photoelectrochemical cytoassay on the basis of TiO 2 nanorods/carboxylated g-C 3 N 4 /ox-graphene quantum dots coupling with a biospecific interaction for the ultrasensitive detection of fibroblast-like synoviocyte cells. The nanohybridization assembly of TiO 2 NRs, carboxylated g-C 3 N 4 and ox-GQDs showed good PEC performance through the excellent electrical conductivity as well as the high photon-to-electron conversion efficiency and improved the sensitivity of the cytosensor. To perform the cytoassay, CD95 antibody, a marker of FLS cells, was conjugated onto the TiO 2 NR/carboxylated g-C 3 N 4 /ox-GQD modified electrode to trap the cell target by using EDC/NHS coupling reactions. The concentrations of FLS cells were determined by the decrease in photocurrent intensity resulting from the increase in steric hindrance from FLS cells. This strategy opens a simple perspective for the application of carboxylated g-C 3 N 4 and ox-GQDs as light-harvesting architectures.

The excellent catalytic activity of a novel nanomaterial was introduced to ultrasensitive sandwich-type electrochemical immunosensor applications for detection of carcinoembryonic antigen (CEA). Amino-functionalized multi-walled carbon nanotube (MWCNT-NH 2 ) supported PdPt nanocages were used as catalytic labels of secondary anti-CEA. PdPt nanocages with hollow interiors and porous walls could efficiently enhance electrocatalysis for reduction of H 2 O 2 . Meanwhile, with good dispersion, large specific surface area and amino groups, MWCNT-NH 2 can immobilize a large amount of PdPt nanocages to improve the sensitivity and amplify the signal of the immunosensor. For the immobilization of primary antibodies, 3-aminopropyltriethoxysilane functionalized graphene sheets were used as transducing materials to modify glassy carbon electrodes and to enhance the electron transfer efficiently. Under the optimal conditions, the electrochemical immunosensor exhibited a wide linear range of 0.001-20 ng mL -1 with a low detection limit of 0.2 pg mL -1 for CEA. The proposed sensing strategy enriches electrochemical immunoassays and may have a promising application in bioassay analysis.