Europium nanosphere-based fluorescence strip sensor for ultrasensitive and quantitative determination of fumonisin B1

Establishment of an immunoassay for detection of nonylphenols in surfactant oilfield chemicals based on computer-aided design

Nonylphenols (NPs) are confirmed endocrine disruptors that are banned in many countries due to correlations with human cancers. NPs pollution in surfactant oilfield chemicals (OFCs) has become an important environmental safety issue. It is significant to establish a simple, accurate and low-cost method for detection of NPs in OFCs. In this research, computer-aided molecular design technology was utilized to design NPs haptens. High affinity monoclonal antibodies against NPs were obtained using a matrix effect-enhanced screening method, with an IC50 value of 183.01 ng/mL. A colloidal gold immunochromatography assay (ICA) for detection of NPs enabled rapid on-site detection of large volumes of OFCs. Under optimal conditions, the limit of detection was 0.72-1.82 mg/kg, with a detection range of 4.49-191.28 mg/kg. The recovery was 84 %-104 %, with coefficients of variation < 13 %. As confirmed by high-performance liquid chromatography of natural positive OFCs samples, the proposed colloidal gold ICA demonstrated accuracy and reliability, with potential for fast and economical on field test.

Sensitive colorimetric detection of Vibrio vulnificus based on target-induced shielding against the peroxidase-mimicking activity of CeO2@PtRu nanozyme

Vibrio vulnificus infection caused by contaminated aquatic products and seawater can lead to severe disease and high mortality. The development of a rapid and sensitive detection method for Vibrio vulnificus is vital to effectively prevent infection in advance. In this study, CeO2@PtRu with high peroxidase activity was used to construct a colorimetric immunoassay for Vibrio vulnificus detection by conjugating polyclonal antibodies via the biotin-streptavidin system. The developed colorimetric biosensor for Vibrio vulnificus demonstrated rapid operability and good sensitivity with a detection range from 104 CFU/mL to 109 CFU/mL, and the limit of detection (LOD) is 193 CFU/mL. Moreover, the colorimetric biosensor showed excellent specificity and good recoveries from 98.70% to 102.10% with RSD < 7.45% for spiked real samples. This novel CeO2@PtRu-based colorimetric biosensor has great application potential for the sensitive detection of Vibrio vulnificus in seafood.

Designing a size exclusion-based hapten and the development of a quantitative and visual time-resolved fluorescence immunochromatography assay strip for detecting dimethomorph and flumorph in a group-specific manner

Based on the size and surface properties of dimethomorph and flumorph, we used a computer simulation-assisted size exclusion hapten design strategy to develop group-specific monoclonal antibodies that can simultaneously recognize dimethomorph and flumorph. For this, we performed quantitative and visual semi-quantitative time-resolved fluorescence immunochromatography (TRFICA) to simultaneously detect dimethomorph and flumorph in potatoes and apples. In potato samples, the visual limit of detection (vLOD) for dimethomorph and flumorph was 4 ng/mL and 8 ng/mL, respectively, whereas the quantitative limit of detection (qLOD) for dimethomorph and flumorph was 0.26 and 0.33 ng/mL, respectively. The vLOD of dimethomorph and flumorph in apple samples was 8 ng/mL, whereas the qLOD of dimethomorph and flumorph was 0.17 and 0.38 ng/mL, respectively. The average recovery of potato and apple samples ranged from 77.5% to 121.7%, which indicated that the method can be used to rapidly detect dimethomorph and flumorph in food samples.

Quantitative immunochromatographic assay for rapid and cost-effective on-site detection of benzo[a]pyrene in oilfield chemicals

Contamination of oilfield chemicals (OFCs) by benzo[a]pyrene (B[a]P) is increasingly becoming a severe environmental security issue. There is an urgent need to develop a rapid and accurate method for B[a]P detection in OFCs. In this study, B[a]P hapten was designed using computer aided molecular design. A high-affinity, specific, and matrix-insensitive monoclonal antibody (mAb) with IC50 values of 6.77 ng/mL was obtained. Based on this mAb, we developed a rapid gold nanoparticle-based immunochromatographic strip assay (GICA) with double T-line mode for on-site detection of B[a]P in OFCs samples. The GICA exhibited excellent detection performance in OFCs samples with strong acidity, strong alkalinity, and deep color. Under optimal conditions, the proposed method detected B[a]P in OFCs at 0.42-300 mg/kg, and limit of detection was 0.23-1.07 mg/kg. The recovery rate was 88-106% with a coefficient of variation of 1.46-6.35%. Confirmed by natural positive OFCs samples and high-performance liquid chromatography, this GICA is accurate and reliable, with great potential for rapid and cost-effective on-site detection.

An Overview for the Nanoparticles-Based Quantitative Lateral Flow Assay

The development of the lateral flow assay (LFA) has received much attention in both academia and industry because of their broad applications to food safety, environmental monitoring, clinical diagnosis, and so forth. The user friendliness, low cost, and easy operation are the most attractive advantages of the LFA. In recent years, quantitative detection has become another focus of LFA development. Here, the most recent studies of quantitative LFAs are reviewed. First, the principles and corresponding formats of quantitative LFAs are introduced. In the biomaterial and nanomaterial sections, the detection, capture, and signal amplification biomolecules and the optical, fluorescent, luminescent, and magnetic labels used in LFAs are described. The invention of dedicated strip readers has drawn further interest in exploiting the better performance of LFAs. Therefore, next, the development of dedicated reader devices is described and the usefulness and specifications of these devices for LFAs are discussed. Finally, the applications of LFAs in the detection of metal ions, biotoxins, pathogenic microorganisms, veterinary drugs, and pesticides in the fields of food safety and environmental health and the detection of nucleic acids, biomarkers, and viruses in clinical analyses are summarized.

An immunochromatographic sensor for ultrasensitive and direct detection of histamine in fish

To ensure food quality and prevent histamine (HA) toxicity, a rapid and direct method of detecting HA is required. In this work, we prepared a monoclonal antibody (mAb) against HA using a hapten produced by the introduction of a phenyl-containing linker. The novel mAb exhibited high sensitivity against HA as determined by ELISA, with a half-maximal inhibitory concentration of 21.51 ng/mL. A gold nanoparticle-based immunosensor was fabricated for rapid detection of HA in fish samples. After optimizing the immunosensor, a visual limit of detection (LOD) and a calculated LOD were 0.25 mg/kg and 10.48 μg/kg for HA, respectively. Recovery rates from the spiked fish samples ranged from 87.33% to 104.67% with the coefficient of variation below 10.82%. Concurrently, the whole process in testing real sample was completed within 15 min, and all results were well confirmed and comparable by liquid chromatography-mass spectrometry and the commercial test strip. These data revealed that the proposed immunosensor could be used as a monitoring tool for the rapid and direct detection of HA in fish samples.

A fluorescent paper biosensor for the rapid and ultrasensitive detection of zearalenone in corn and wheat

Zearalenone (ZEN) is a kind of estrogen-like mycotoxin which contaminates primary crops and their products under natural conditions and becomes a serious hazard to human health. In this study, we prepared a sensitive and specific anti-ZEN monoclonal antibody (mAb) belonging to the IgG2b subclass, with a 50%-inhibitory concentration of 0.034 ng mL^-1. A lateral flow fluorescence microsphere immunochromatographic test strip (FM-ICTS) for the rapid and ultrasensitive detection of zearalenone in corn and wheat samples was developed based on this mAb. After optimizing experimental parameters, the visual limit of detection (LOD) of the strip assay in both corn and wheat samples was 2.5 ng mL^-1, and the cut-off value was 25 ng mL^-1. The LOD was calculated to be 0.68 ng mL^-1 in corn samples and 0.48 ng mL^-1 in wheat samples. Recovery experiments showed that the test results of the strip were consistent with those of ic-ELISA. As a result, this FM-ICTS assay is reliable, simple and sensitive, and can be used for rapid detection of ZEN in corn and wheat.

Aptamer-based detection of fumonisin B1: A critical review

Mycotoxin contamination is a current issue affecting several crops and processed products worldwide. Among the diverse mycotoxin group, fumonisin B1 (FB1) has become a relevant compound because of its adverse effects in the food chain. Conventional analytical methods previously proposed to quantify FB1 comprise LC-MS, HPLC-FLD and ELISA, while novel approaches integrate different sensing platforms and fluorescently labelled agents in combination with antibodies. Nevertheless, such methods could be expensive, time-consuming and require experience. Aptamers (ssDNA) are promising alternatives to overcome some of the drawbacks of conventional analytical methods, their high affinity through specific aptamer-target binding has been exploited in various designs attaining favorable limits of detection (LOD). So far, two aptamers specific to FB1 have been reported, and their modified and shortened sequences have been explored for a successful target quantification. In this critical review spanning the last eight years, we have conducted a systematic comparison based on principal component analysis of the aptamer-based techniques for FB1, compared with chromatographic, immunological and other analytical methods. We have also conducted an in-silico prediction of the folded structure of both aptamers under their reported conditions. The potential of aptasensors for the future development of highly sensitive FB1 testing methods is emphasized.

An ultrasensitive fluorescent paper sensor for fast screening of berberine

Berberine (BBR) is a highly effective animal feed additive, but it also has adverse side effects on animals and causes potential food safety issues. Based on BBR antibody preparation, fluorescent immunochromatography assay was established for quantitative detection of BBR in feed samples.