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In this work, we reported an efficient platinum nanoparticles functionalized nitrogen doped graphene (PtNPs@NG) nanocomposite for devising novel electrochemical glucose biosensor for the first time. The fabricated PtNPs@NG and biosensor were characterized using transmission electron microscopy, high-resolution transmission electron microscopy, X-ray photoelectron spectroscopy, static water contact angle, UV–vis spectroscopy, electrochemical impedance spectra and cyclic voltammetry, respectively. PtNPs@NG showed large surface area and excellent biocompatibility, and enhanced the direct electron transfer between enzyme molecules and electrode surface. The glucose oxidase (GOx) immobilized on PtNPs@NG nanocomposite retained its bioactivity, and exhibited a surface controlled, quasi-reversible and fast electron transfer process. The constructed glucose biosensor showed wide linear range from 0.005 to 1.1 mM with high sensitivity of 20.31 mA M −1 cm −2 . The detection limit was calculated to be 0.002 mM at signal-to-noise of 3, which showed 20-fold decrease in comparison with single NG-based electrochemical biosensor for glucose. The proposed glucose biosensor also demonstrated excellent selectivity, good reproducibility, acceptable stability, and could be successfully applied in the detection of glucose in serum samples at the applied potential of −0.33 V. This research provided a promising biosensing platform for the development of excellent electrochemical biosensors. [ABSTRACT FROM AUTHOR]

Highlights: [•] An ultrasensitive chemiluminescent (CL) immunoassay strategy was developed. [•] This assay was preformed based on a streptavidin-functionalized MWCNTs platform. [•] The sensitivity displays 7.9-fold increase compared to that without MWCNTs. [•] This method provides a promising approach for ultrasensitive CL immunoassay. [Copyright &y& Elsevier]

Abstract: A streptavidin functionalized capillary immune microreactor was designed for highly efficient flow-through chemiluminescent (CL) immunoassay. The functionalized capillary could be used as both a support for highly efficient immobilization of antibody and a flow cell for flow-through immunoassay. The functionalized inner wall and the capture process were characterized using scanning electron microscopy. Compared to conventional packed tube or thin-layer cell immunoreactor, the proposed microreactor showed remarkable properties such as lower cost, simpler fabrication, better practicality and wider dynamic range for fast CL immunoassay with good reproducibility and stability. Using α-fetoprotein as model analyte, the highly efficient CL flow-through immunoassay system showed a linear range of 3 orders of magnitude from 0.5 to 200ngmL−1 and a low detection limit of 0.1ngmL−1. The capillary immune microreactor could make up the shortcoming of conventional CL immunoreactors and provided a promising alternative for highly efficient flow-injection immunoassay. [Copyright &y& Elsevier]

Abstract: A new method has been established for the determination of dopamine hydrochloride (DPH) using sodium 1,2-naphthoquinone-4-sulfonate (NQS) and tetradecyl benzyl dimethyl ammonium chloride (Zeph). This method is based on the formation of a pink compound from the reaction of DPH, sodium 1,2-naphthoquinone-4-sulfonate and Zeph. The condensation reaction proceeds quantitatively in pH 9.40 buffer solution. The maximum absorption wavelength and the value of ɛ 491 were 491nm, and 7.51×103 lmol−1 cm−1, respectively, when the stoichiometric ratio of the reaction was 1:1:1. Beer′s law was obeyed in the range of 0.16–40mgl−1 of DPH. The data have been filled to a linear regression equation A =0.5781+0.0254 C (mgl−1), with a correlation coefficient of 0.9993. The detection limit is 0.12mgl−1, R.S.D. is 0.64% (40mgl−1, n =11), and average recovery is over 99.7%. This paper further improves the determination of DPH compared to the previous methods. The kinetic property and reaction mechanism have also been discussed. This proposed method has been successfully applied to the determination of DPH in injection and biological samples with satisfactory results. [Copyright &y& Elsevier]

Abstract Quantitative detection of multiple chicken cytokines is a good evaluation of cell-mediated immunity in chickens after disease infection or vaccination. However, current assay methods for chicken cytokines cannot meet the needs of clinical diagnosis due to unsatisfactory sensitivity and low assay throughput. Herein, a sensitive chemiluminescence (CL) imaging immunosensor array has been developed for high-throughput detection of multiple chicken cytokines. The chicken cytokines immunosensor array was prepared by assembling different cytokine capture antibodies onto a disposable silanized glass chip, where horseradish peroxidase and antibody-conjugated gold nanoparticles were used as multienzymatic amplification probe for CL imaging signal amplification. By using a sandwich assay mode, the amplified CL signals from each sensing array cell were collected for quantitation. Using chicken interleukin-4 and chicken interferon-γ as model cytokines, this novel multiplexed and amplified method demonstrated simultaneous measurement of the two chicken cytokines in the linear ranges of 0.008–0.12 ng/mL and 0.005–0.20 ng/mL, respectively, which yields limits of detection down to 2 pg/mL and 3 pg/mL. The CL imaging array method reported here also demonstrated high specificity, good repeatability, and high stability and accuracy, providing a novel multiplex immunoassay strategy for highly sensitive and high-throughput detection of chicken cytokines and further disease diagnosis in poultry. Graphical abstract A novel multiplex immunosensor array for sensitive and high-throughput detection of multiple chicken cytokines is for the first time developed based on highly-sensitive chemiluminescence imaging coupled with a multienzymatic signal amplification probe. Image 1 Highlights • Multiplex immunosensor array for chicken cytokines was proposed for the first time. • Multiple chicken cytokines were simultaneously detected by sensitive CL imaging system. • The multiplex cytokines immunoassay has much better performance compared with current methods. • This work provides a novel strategy for sensitive and high-throughput multiplex immunoassay. [ABSTRACT FROM AUTHOR]

Abstract: A novel visible light sensitized photoelectrochemical sensing platform was constructed based on the perylene-3,4,9,10-tetracarboxylic acid/titanium dioxide (PTCA/TiO2) heterojunction as the photoelectric beacon. PTCA was synthesized via facile steps of hydrolysis and neutralization reaction, and then the PTCA/TiO2 heterojunction was easily prepared by coating PTCA on nano-TiO2 surface. The resulting photoelectric beacon was characterized by transmission electron microscope, scanning electron microscopy, X-ray diffractometry, FTIR spectroscopy, and ultraviolet and visible spectrophotometer. Using parathion-methyl as a model, after a simple hydrolyzation process, p-nitrophenol as the hydrolysate of parathion-methyl could be obtained, the fabricated derivative photoelectrochemical sensor showed good performances with a rapid response, instrument simple and portable, low detection limit (0.08nmolL−1) at a signal-to-noise ratio of 3, and good selectivity against other pesticides and possible interferences. It had been successfully applied to the detection of parathion-methyl in green vegetables and the results agreed well with that by GC–MS. This strategy not only extends the application of PTCA, but also presents a simple, economic and novel methodology for photoelectrochemical sensing. [Copyright &y& Elsevier]