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The simultaneous determination of multiple analytes has been an urgent demand in screening of antibiotic residues in food products of animal origin due to its higher analysis efficiency. Five aminoglycoside antibiotics (AGAs) have been monitored in milk, including gentamicin (GEN), kanamycin (KAN), neomycin (NEO), and streptomycin/dihydrostreptomycin (STR/diSTR). A chemiluminescence microarray immunoassay (CLMIA) based on nitrocellulose membrane had been developed for the detection of multiple AGAs, which the LODs for STR, KAN, NEO, and GEN were 4.74 ng/mL, 4.97 ng/mL, 2.99 ng/mL, and 4.42 ng/mL respectively. To improve the sensitivity of immunoassay, single-well carbon tubes (SWCNTs) were utilized as solid support for loading horseradish peroxidase-labelled goat anti-mouse antibody to obtain the multi-enzyme particles. After the optimization of usage of multi-enzyme particles and antibodies, the enhanced CLMIA was established and evaluated. The LODs were 1.25 ng/mL for STR, 0.64 ng/mL for KAN, 0.38 ng/mL for GEN, and 0.39 ng/mL for NEO, which was improved by threefold, sevenfold, 11-fold, and sevenfold compared with the conventional CLMIA developed. These methods presented higher specificity and repeatability. Finally, the enhanced CLMIA based on CNT-assisted multi-enzyme particles was utilized to analyze twenty-five milk samples from local market and dairy farm, which all the results were below the LOD. The enhanced CLMIA showed the great application potential for the detection of multiple targets simultaneously and provided efficient tool for the screening of pollutants in food., (© 2021. Springer-Verlag GmbH Germany, part of Springer Nature.)

Here, a novel chemiluminescence (CL) immunoassay was fabricated for sensitive determination of tetrabromobisphenol A bis(2-hydroxyethyl) ether (TBBPA-DHEE), one of typical tetrabromobisphenol A derivatives. At the indirectly competitive method, the synthesized PS@hemin@Co 2+ was labelled by secondary antibody (Ab 2 ) instead of common natural enzymes, which showed excellent catalysis towards the decomposition of luminol-H 2 O 2 for producing CL signal. Furthermore, the CL signal was greatly amplified owing to the synergistic catalysis of hemin and Co 2+ in the detection system. Under the optimized conditions, the established method offered (i) low detection limit (LOD, 0.9 μg/L), which was almost 5 times lower than that using a conventional ELISA with the same antibody; (ii) a good linearity (1.6-14.3 μg/L); (iii) satisfactory accuracy and precision (recoveries, 89.67-125.33%; CV, 2.75-8.37%). The proposed CL immunoassay was applied for analysis of environmental samples from various sources collected from Jiangsu and Zhejiang province, China. And the detected concentrations were ranged in 2.4-3.7 μg/L in environmental waters and 1.8-2.4 ng/g (dry weight, dw) in soil samples, indicating great potential for trace TBBPA-DHEE detection from environmental samples., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2020 Elsevier B.V. All rights reserved.)

A simple and signal-amplified, label-free electrochemical impedimetric immunosensor for dibutyl phthalate (DBP), a type of phthalate ester, was developed using gold nanoparticles (AuNPs) induced signal amplification. The approach was based on an indirectly competitive binding system of coating antigen that coated on antigen/chitosan/MWCNTs@GONRs/GCE (modified electrodes), target (DBP) and anti-DBP antibody. Signal amplification was performed via the enlargement of AuNPs through NADH-promoted catalytic precipitation, which caused a marked increase in the electron-transfer resistance and electrostatic repulsion after an AuNP-labeled second antibody conjugated to anti-DBP. Under the optimized conditions, this method displayed: (i) low detection limits (7ng/mL, 10 times lower than the traditional ELISA method using the same antibody); (ii) satisfactory accuracy (recoveries, 86.0-120.4%) and agreement with corresponding ELISA method; (iii) high tolerance to some environmental interferents; and (iv) low cost and low sample consumption (6µL). Our results demonstrate the great potential and high efficiency of this immunosensor in practical applications for the cost-effective and sensitive monitoring of DBP in aquatic environments., (Copyright © 2016 Elsevier B.V. All rights reserved.)

Misusage of tetracycline (TC) antibiotics residue in animal food has posed a significant threat to human health. Therefore, there is an urgent need to develop highly sensitive and robust assays for detecting TC. In the current study, gold and platinum nanoparticles were deposited on carbon nanotubes (CNTs) through the superposition method (Au@Pt/CNTs-s) and one-pot method (Au@Pt/CNTs-o). Au@Pt/CNTs-s displayed higher enzyme-like activity than Au@Pt/CNTs-o, which were utilized for the development of sensitive magnetic immunoassays. Under the optimized conditions, the limits of detection (LODs) of magnetic immunoassays assisted by Au@Pt/CNTs-s and Au@Pt/CNTs-o against TCs could reach 0.74 ng/mL and 1.74 ng/m, respectively, which were improved 6-fold and 2.5-fold in comparison with conventional magnetic immunoassay. In addition, the measurement of TC-family antibiotics was implemented by this assay, and ascribed to the antibody used that could recognize TC, oxytetracycline, chlortetracycline, and doxycycline with high cross-reactivity. Furthermore, the method showed good accuracy (recoveries, 92.1–114.5% for milk; 88.6–92.4% for pork samples), which also were applied for determination of the targets in real samples. This study provides novel insights into the rapid detection of targets based on high-performance nanocatalysts. [ABSTRACT FROM AUTHOR]

Summary: Owing to the increasing incidences of antibiotic residues being found in foods of animal‐origin, rapid and reliable screening methods for detecting these residues are urgently required. This study aimed to develop a robust and ultrasensitive colorimetric immunoassay based on nanohybrids for the rapid screening of kanamycin (KAN) residues in milk. The HAuCl4 solution was directly reduced on the multiwalled carbon nanotubes (MWCNTs) using a one‐step synthesis method to obtain the Au/MWCNTs nanohybrids. The Au/MWCNTs exhibited mimetic peroxidase activity and higher affinities for the TMB and H2O2 compared with horseradish peroxidase and other nanohybrids. A direct competitive enzyme‐linked immunosorbent assay (dcELISA) based on Au/MWCNTs was developed and employed for KAN detection in milk samples under optimised conditions. The dcELISA showed high sensitivity toward KAN residues, with a detection limit of 11.2 pg/mL. Moreover, this novel immunoassay displayed high precision and accuracy in milk samples, with a recovery rate ranging from 94.3 to 124.5% and a coefficient variation from 7.8 to 11.3%. Eight real milk samples were found to contain a KAN concentration in the range of ND–0.26 ng/mL. Therefore, this dcELISA based on the Au/MWCNTs nanohybrid has promising potential for applications in food monitoring and quality control. [ABSTRACT FROM AUTHOR]

Tetrabromobisphenol A bis(2-hydroxyethyl) ether (TBBPA DHEE), as one of the TBBPA derivatives, is frequently applied as a flame retardant. To date, however, little evidence has been gathered regarding its environmental behavior and fate. This is mainly attributed to the lack of an analytical approach available to measure it. Mass spectrometry cannot determine levels of TBBPA DHEE. LC-MS could not ionize TBBPA DHEE to yield enough fragments, while GC-MS could not be applied for the analysis either, due to the thermal degradation of TBBPA DHEE. We here designed a novel hapten, then conjugated it with a carrier protein and produced a type of polyclonal antibody capable of recognizing TBBPA DHEE. Based on this approach, a sensitive and high-throughput indirect competitive enzyme-linked immunosorbent assay (ELISA) was established. The respective detection limit (LOD, based on 90% B/B 0 ) and IC 50 calculated from the standard curve were 0.702 and 9.868 ng/mL for TBBPA DHEE. And the established method showed good tolerance to various matrix interferents. Using our ELISA, we measured the concentrations of these substances from environmental water samples with no pretreatment other than filtration. We found the presence of TBBPA DHEE in environmental water samples collected in Jiangsu province, and the detected concentrations ranging from 1.5 to 7.7 ng/mL. Our proposed method here could be applied to completely and systematically investigate TBBPA DHEE and TBBPA MHEE concentrations in environmental samples. [ABSTRACT FROM AUTHOR]

A novel ratiometric fluorescent immunoassay was developed based on silver nanoparticles (AgNPs) for the sensitive determination of dibutyl phthalate (DBP). In the detection system, AgNPs were labeled on the secondary antibody (AgNPs@Ab2) for signal amplification, which aimed to regulate the H2O2 concentrations. When AgNPs-Ab2 and antigen–primary antibody (Ab1) were linked by specific recognition, the blue fluorescence of Scopoletin (SC) could be effectively quenched by the H2O2 added while the red fluorescence of Amplex Red (AR) was generated. Under the optimized conditions, the calculated detection of limit (LOD, 90% inhibition) reached 0.86 ng/mL with a wide linear range of 2.31–66.84 ng/mL, which was approximately eleven times lower than that by HRP-based traditional ELISA with the same antibody. Meanwhile, it could improve the inherent built-in rectification to the environment by the combination of the dual-output ratiometric fluorescence assays with ELISA, which also enhanced the accuracy and precision (recoveries, 87.20–106.62%; CV, 2.57–6.54%), indicating it can be applied to investigate the concentration of DBP in water samples. [ABSTRACT FROM AUTHOR]

Environmental distribution and concentration of tetrabromobisphenol A bis- (2-hydroxyethyl) ether (TBBPA-DHEE) and tetrabromobisphenol A mono- (hydroxyethyl) ether (TBBPA-MHEE), are obscure due to the lack of available analytical methods. Here two novel immunoassays were established to systematically investigate their distributions in Taizhou, Eastern China. Five monoclonal antibodies against pollutants were generated with two designed haptens through animal immunization. After matched with different coating antigens/antibodies, ELISAs were established (LOD for TBBPA-DHEE, 0.12 ng/mL, based on OVA-M3/mAb-D4G6; LOD for TBBPA-MHEE, 0.79 ng/mL, based on OVA-M3/mAb-D2G6) and applied for investigation of their occurrences at a typical e-waste recycling area after 2-year samples collection, where the total 33 water, 32 soil and 16 biological samples were collected with the highest concentrations of 3.46 ng/mL, 2.76 ng/g (dry weight, dw) and 5.01 ng/g (dw), respectively. Meanwhile, our study also indicated that at the centralizing e-waste recycling sites the serious pollution for both chemicals still existed despite of various efforts. Besides, obvious improvements were observed at an abandoned e-waste recycling region treated and remedied for many years by the local Chinese government. These findings highlight the importance of policy decisions in treatment of pollutants to reduce organic pollutant-related health risks. Image 1 • Two simple ELISAs were developed for respective determination of TBBPA-DHEE and TBBPA-MHEE. • The established method showed satisfactory sensitivity and accuracy. • The systematic investigation at a typical area was performed using our approach. • Serious pollution for both chemicals still existed at the centralizing e-waste recycling sites. • Obvious improvements were observed for the pollutant treatment by the local government. [ABSTRACT FROM AUTHOR]

Because of the advantages of simplicity, cost-effectiveness and visibility, lateral-flow immunoassays (LFAs) have been widely used in the food safety field. However, the low sensitivity of LFAs needs to be solved. Nanozymes have amazing potential for application in biosensors due to their excellent and abundant enzyme-like characteristics. In this study, an Au@Pt nanozyme synthesized by a one-step method showed the higher affinity with TMB/H 2 O 2 and higher catalytic efficiency than that of horseradish peroxidase (HRP). For the detection of streptomycin (STR), a typical aminoglycoside antibiotic, a novel LFA based on Au@Pt as a visual tag and an enhanced LFA based on the enzyme-like activity of Au@Pt by addition of the chromogenic substrate 3-amino-9-ethyl-carbazole (AEC) were established and compared with conventional LFA based on AuNPs. The qualitative limit of detection (LOD) was 1 ng mL−1 for the LFA based on Au@Pt as the visual tag and 0.1 ng mL−1 for the enhanced LFA based on the activity of Au@Pt, in comparison to 8 ng mL−1 for LFA based on AuNPs. Furthermore, the level of streptomycin in milk samples from Zhenjiang City was successfully evaluated by the novel LFA based on Au@Pt nanozyme. These results suggest that LFAs based on nanozymes are a promising and effective tool for food safety. Image 1 • Au@Pt nanozyme with higher peroxidase-like activity was synthesized by a simple one-step method. • Lateral-flow immunoassays based on Au@Pt as tag and enzyme mimic showed higher sensitivity. • Lateral-flow immunoassay based on catalytic activity of Au@Pt was used to detect STR in milk. [ABSTRACT FROM AUTHOR]

[Display omitted] • The conformational locking of ZIF-8 is a good method to improve the AIE fluorescence. • This method gives a good strategy to overcome limitations of FELISA in real samples. • The BPS exposure in beverages shows no considerable risk to human health at present. • This work provides available data support for occurrence and risk assessment of BPS. Dietary intake is an important exposure pathway of environmental bisphenols including bisphenol S (BPS, a typical emerging organic pollutant). However, available data on the occurrence and risk assessment of BPS in food samples are limited due to the lack of high-throughput analytical methods. Herein, based on H 2 O 2 inducing fluorescence turn-off signals, a sensitive and high-throughput fluorescence enzyme-linked immunosorbent assay (FELISA) was developed for BPS investigation in beverages. In this system, the fluorescence of copper nanoclusters in ZIF-8 (CuNCs-CS@ZIF-8) could be quenched with the presence of H 2 O 2 owing to the strong oxidation, being served as signal amplification in FELISA. Meanwhile, the aggregation-induced emission (AIE) fluorescence enhancement of CuNCs-CS through the conformational locking of ZIF-8 provided an effective strategy to overcome the intrinsic limitations of FELISA including high background, serious fluorescence quenching in the detection of real samples. Thus, the integration of AIE building blocks into porous ZIF-8 showed obvious advantages in enhancing the analytical performance of FELISA. Under optimized conditions, satisfactory results with good accuracy were achieved in this proposed FELISA, which was applied for the systematic investigation of BPS in foods and further health risk assessments. The results after 100 beverages analysis displayed an average detection frequency of 55%, and the detected concentration of BPS ranged from below the limit of quantification (LOQ) to 12.08 ng/mL with a mean value of 1.717 ng/mL. Besides, the estimated daily intake (EDI) of BPS was calculated to be 0.05449–4.483 ng/kg-bw/day, in which milk–tea drinks contributed to the majority of BPS daily intake (mean EDI = 4.483 ng/kg-bw/day). And the hazard quotient (HQ) according to EDI values indicated that BPS exposure in beverages might not make a considerable impact on human health. [ABSTRACT FROM AUTHOR]