Shuo Wang

Three kinds of lateral flow immunochromatographic assays based on the use of nanoparticle labels for fluorometric determination of zearalenone

AbstractColloidal gold, quantum dots and polystyrene microspheres were used as labels in threexa0kinds of lateral flow immunochromatographic assays (ICAs) for the detection of zearalenone (ZEN) in cereal samples. The assays allow ZEN to be quantified within 20xa0min. The LODs are 10xa0μg·L−1 of ZEN for the colloidal gold-based ICA, and 1xa0μg·L−1 for both the quantum dot and polystyrene microsphere based ICAs. The respective data are 60xa0μg·kg−1, 6xa0μg·kg−1 and 6xa0μg·kg−1, respectively, for spiked samples and cereals. Only minor cross-sensitivity occurred between ZEN and fusarium toxins, and no cross-sensitivity if found for aflatoxinxa0B1, T-2 mycotoxin, ochratoxin A, deoxynivalenol, and fumonisin B1. LODs of the three assays are lower than the maximum limits of ZEN set by most standardization agencies.n Graphical abstractSchematic presentation of three lateral flow immunochromatographic assays (ICAs)xa0based on the use of (a)xa0colloidal gold (CG), (b)xa0fluorescent quantum dots (QD), and (c)xa0polystyrene microspheres (PMs)xa0asxa0signalling labels for the rapid and sensitive determination of zearalenone (ZEN) in cereal samples.

Highly Bright Self-Assembled Copper Nanoclusters: A Novel Photoluminescent Probe for Sensitive Detection of Histamine

In this work, highly photoluminescent (PL) self-assembled copper nanoclusters (Cu NCs) capable of rapid, sensitive, and selective detection of histamine were developed. Cu NCs were synthesized in facile conditions by using 2,3,5,6-tetrafluorothiophenol (TFTP) as both the reducing agent and the protecting ligand, which exhibited intense saffron yellow (590 nm) PL via self-assembled induced emission (SAIE), and the absolute quantum yield (QY) of assembly was as high as 43.0%. The size, electronic states, and morphologies of the assembled nanoribbons were characterized, and the geometric structure and spectral properties of the Cu NCs were investigated by theoretical study. Furthermore, the mechanism of the excellent sensing performance of Cu NCs toward histamine was demonstrated by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), and energy dispersive X-ray analysis (EDX). With this sensing system, the amount of histamine in fish, shrimp, and red wine were analyzed, and experiment results verified the application of the sensor. Importantly, the luminescent test strips based on Cu NCs were fabricated for colorimetric detection of histamine in foods. This proposed technique may provide an alternative to traditional methods for histamine detection.

Fluorometric lateral flow immunochromatographic zearalenone assay by exploiting a quencher system composed of carbon dots and silver nanoparticles

AbstractIt is found that the fluorescence of carbon dots (CD) with an emission peak at 459xa0nm is strongly quenched by silver nanoparticles (AgNPs) with their absorption peak at 430xa0nm. The finding was applied in a fluorescence quenchometric lateral flow immunochromatographic assay for detection of zearalenone (ZEN) with CDs conjugated to ovalbumin (OVA) as donor signal probe and AgNP-Ab as acceptor signal probe. The assay has an LOD of 0.1xa0μg·L−1 for ZEN. This is 10 times better than the respective “turn-off” AgNP-based LFIA. In case of cereal samples and their products, the LODs range from 1 to 2.5xa0μg·kg−1. Only minor cross reactivity is found for fusarium toxins, and no cross-sensitivity for aflatoxin B1, T-2 mycotoxin, ochratoxin A, deoxynivalenol, and fumonisin B1. Thexa0assay represents a simple, sensitive, and rapid tool for determination of ZEN in cereal samples and their products.n Graphical abstractSchematic presentation of fluorescence quenching lateral flow immunochromatographic assay (FLFIA) based on carbon dots (CD) and silver nanoparticle (AgNP) fluorescence resonance energy transfer (FRET) system for the rapid high sensitive detection of zearalenone (ZEN) in cereal samples.

An Ultrasensitive Fluorescence Sensor with Simple Operation for Cu2+ Specific Detection in Drinking Water

Whether short-term or long-term, overexposure to an abnormal amount of copper ion does significant harm to human health. Considering its nonbiodegradability, it is critical to sensitively detect copper ion. Herein, a novel fluorescent strategy with a “turn-on” signal was developed for highly sensitive and specific detection of copper ion (Cu2+). In the present investigation, we found that Cu2+ exhibits excellent peroxidase-like catalytic activity toward oxidizing the nonfluorescent substrate of Amplex Red into the product of resofurin with outstanding fluorescence emission under the aid of H2O2. Thus, an enzyme-free and label-free sensing system was constructed for copper ion detection with quite simple operation. To ensure the detection sensitivity and reproducibility, the amount of H2O2 and incubation time were optimized. The limit of detection can reach as low as 1.0 nM. In addition, the developed assay demonstrated excellent specificity and could be utilized to detect copper ion in water samples including tap water and bottled purified water without standing recovery.