Zhejiang Gongshang University

About: Zhejiang Gongshang University is a education organization based out in Hangzhou, China. It is known for research contribution in the topics: Computer science & Chemistry. The organization has 8258 authors who have published 7670 publications receiving 90296 citations. The organization is also known as: Zhèjiāng Gōngshāng Dàxué.

Amperometric immunoassay for the detection of Salmonella pullorum using a screen - printed carbon electrode modified with gold nanoparticle-coated reduced graphene oxide and immunomagnetic beads

Abstract: The article describes a sandwich electrochemical immunoassay for detecting the food pathogen Salmonella pullorum (S. pullorum). The assay is based on the use of immunomagnetic beads (IMB) and reduced graphene oxide coated with gold nanoparticles (rGO/AuNPs) acting as an electrochemical label. The IMB were prepared via conjugation of antibody against S. pullorum (Ab1) to silica coated magnetic beads (SiO2/Fe3O4) and were used to capture S. pullorum from the sample. The rGO/AuNP were prepared by co-reduction of chloroauric acid and graphene oxide and then linked to secondary antibody (Ab2). This conjugate served as a label in a sandwich immunoassay to produce signals. The electrochemical immunoassay was carried out by immobilizing the rGO/AuNP/Ab2/S/IMB complex on a four channel screen-printed carbon electrode (4-SPCE). The assay involves the following steps: (a) Exposure of the modified 4-SPCE to the sample; (b) Electro-oxidation of the modified 4-SPCE in 0.2 M HCl; and (c) Differential pulse voltammetry (DPV). It is found that the use of the rGO/AuNP leads to strong signal amplification. The DPV signal (at an optimal working potential of +1.25 V vs. Ag/AgCl for 120 s) is linearly related to the logarithm of the concentration of S. pullorum in the range from 102 to 106 CFU⋅mL‾1. The detection limit is as low as 89 CFU⋅mL‾1. This nanoparticle-based immunoassay excels by its low cost and ease of operation, thereby providing a promising tool in clinical analysis.

Toxicity of Cu (II) to the green alga Chlorella vulgaris: a perspective of photosynthesis and oxidant stress

Abstract: The toxic effects of Cu (II) on the freshwater green algae Chlorella vulgaris and its chloroplast were investigated by detecting the responses of photosynthesis and oxidant stress. The results showed that Cu (II) arrested the growth of C. vulgaris and presented in a concentration- and time-dependent trend and the SRichards 2 model fitted the inhibition curve best. The chlorophyll fluorescence parameters, including qP, Y (II), ETR, F v /F m , and F v /F 0, were stimulated at low concentration of Cu (II) but declined at high concentration, indicating the photosystem II (PSII) of C. vulgaris was destroyed by Cu (II). The chloroplasts were extracted, and the Hill reaction activity (HRA) of chloroplast was significantly decreased with the increasing Cu (II) concentration under both illuminating and dark condition, and faster decline speed was observed under dark condition. Activities of superoxide dismutase (SOD) and catalase (CAT) and malondialdehyde (MDA) content were also significantly decreased at high concentration Cu (II), companied with a large number of reactive oxygen species (ROS) production. All these results indicated a severe oxidative stress on algal cells occurred as well as the effect on photosynthesis, thus inhibiting the growth of algae, which providing sights to evaluate the phytotoxicity of Cu (II).