Quantifying Aflatoxin B1 in peanut oil using fabricating fluorescence probes based on upconversion nanoparticles

A review of biomolecules conjugated lanthanide up-conversion nanoparticles-based fluorescence probes in food safety and quality monitoring applications

Upconversion nanoparticles (UCNPs) are known to possess unique characteristics, which allow them to overcome a number of issues that plague traditional fluorescence probes. UCNPs have been employed in a variety of applications, but it is arguably in the realm of optical sensors where they have shown the most promise. Biomolecule conjugated UCNPs-based fluorescence probes have been developed to detect and quantify a wide range of analytes, from metal ions to biomolecules, with great specificity and sensitivity. In this review, we have given much emphasis on the recent trends and progress in the preparation strategies of bioconjugated UCNPs and their potential application as fluorescence sensors in the trace level detection of food industry-based toxicants and adulterants. The paper discusses the preparation and functionalisation strategies of commonly used biomolecules over the surface of UCNPs. The use of different sensing strategies namely heterogenous and homogenous assays, underlying fluorescence mechanisms in the detection process of food adulterants are summarized in detail. This review might set a precedent for future multidisciplinary research including the development of novel biomolecules conjugated UCNPs for potential applications in food science and technology.

Inner filter effect-based upconversion nanosensor for rapid detection of thiram pesticides using upconversion nanoparticles and dithizone-cadmium complexes

Herein, we propose a method for detecting thiram based on the fluorescence inner filter effect using upconversion nanoparticles and dithizone-cadmium complexes (DZ-Cd2+). The ultraviolet absorption of DZ-Cd2+ was in the range of 480-600 nm under alkaline conditions, resulting in fluorescence quenching of the nanoparticles at 540 nm. Thiram had a stronger coordination effect with Cd2+ than dithizone; thus, more thiram-cadmium complex (T-Cd2+) formed when thiram was added, leading to fluorescence recovery at 540 nm. The standard thiram curve was found to have a detection limit of 6.75 ng/mL in the linear range of 0.01-1000 µg/mL. In addition, high-performance liquid chromatography results for detecting thiram in apple samples revealed good application performance. The results demonstrate that the developed method has great potential to detect thiram residues in food.

Recent Progress on Techniques in the Detection of Aflatoxin B1 in Edible Oil: A Mini Review

Contamination of agricultural products and foods by aflatoxin B1 (AFB1) is becoming a serious global problem, and the presence of AFB1 in edible oil is frequent and has become inevitable, especially in underdeveloped countries and regions. As AFB1 results from a possible degradation of aflatoxins and the interaction of the resulting toxic compound with food components, it could cause chronic disease or severe cancers, increasing morbidity and mortality. Therefore, rapid and reliable detection methods are essential for checking AFB1 occurrence in foodstuffs to ensure food safety. Recently, new biosensor technologies have become a research hotspot due to their characteristics of speed and accuracy. This review describes various technologies such as chromatographic and spectroscopic techniques, ELISA techniques, and biosensing techniques, along with their advantages and weaknesses, for AFB1 control in edible oil and provides new insight into AFB1 detection for future work. Although compared with other technologies, biosensor technology involves the cross integration of multiple technologies, such as spectral technology and new nano materials, and has great potential, some challenges regarding their stability, cost, etc., need further studies.

A highly sensitive photothermal immunochromatographic sensor for detection of aflatoxin B1 based on Cu2-xSe-Au nanoparticles

In the study, Cu_2-xSe-Au nanoparticles (CSA) with a photothermal conversion efficiency of 60.78 % at 808 nm were applied to the construction of thermal analysis immunochromatographic test strips for the highly sensitive quantitative detection of aflatoxin B₁ (AFB₁) in grain. The CSA was coupled with the AFB₁ antibody to form a photothermal sensor probe by physical adsorption. The constructed immunosensor exhibited high sensitivity and a wide linear range from 0.01 to 10 μg/L in PBS. The detection limits of 0.00842 μg/L based on the thermal analysis was significantly improved by 11.88-fold compared with colorimetric results. No cross-reaction with the other mycotoxins was found except for aflatoxin B₂, aflatoxin M₁, aflatoxin G₁ and aflatoxin G₂. Applied to analysize grain sample, the method achieved the detection of AFB₁ ranging from 0.16 to 160 μg/kg.

Exploring the use of upconversion nanoparticles in chemical and biological sensors: from surface modifications to point-of-care devices

Upconversion nanoparticles (UCNPs) have emerged as promising luminescent nanomaterials due to their unique features that allow the overcoming of several problems associated with conventional fluorescent probes. Although UCNPs have been used in a broad range of applications, it is probably in the field of sensing where they best evidence their potential. UCNP-based sensors have been designed with high sensitivity and selectivity, for detection and quantification of multiple analytes ranging from metal ions to biomolecules. In this review, we deeply explore the use of UCNPs in sensing systems emphasizing the most relevant and recent studies on the topic and explaining how these platforms are constructed. Before diving into UCNP-based sensing platforms it is important to understand the unique characteristics of these nanoparticles, why they are attracting so much attention, and the most significant interactions occurring between UCNPs and additional probes. These points are covered over the first two sections of the article and then we explore the types of fluorescent responses, the possible analytes, and the UCNPs' integration with various material types such as gold nanostructures, quantum dots and dyes. All the topics are supported by analysis of recently reported sensors, focusing on how they are built, the materials' interactions, the involved synthesis and functionalization mechanisms, and the conjugation strategies. Finally, we explore the use of UCNPs in paper-based sensors and how these platforms are paving the way for the development of new point-of-care devices.

Upconversion luminescent nanomaterials: A promising new platform for food safety analysis

Foodborne diseases have become a significant threat to public health worldwide. Development of analytical techniques that enable fast and accurate detection of foodborne pathogens is significant for food science and safety research. Assays based on lanthanide (Ln) ion-doped upconversion nanoparticles (UCNPs) show up as a cutting edge platform in biomedical fields because of the superior physicochemical features of UCNPs, including negligible autofluorescence, large signal-to-noise ratio, minimum photodamage to biological samples, high penetration depth, and attractive optical and chemical features. In recent decades, this novel and promising technology has been gradually introduced to food safety research. Herein, we have reviewed the recent progress of Ln³⁺-doped UCNPs in food safety research with emphasis on the following aspects: 1) the upconversion mechanism and detection principles; 2) the history of UCNPs development in analytical chemistry; 3) the in-depth state-of-the-art synthesis strategies, including synthesis protocols for UCNPs, luminescence, structure, morphology, and surface engineering; 4) applications of UCNPs in foodborne pathogens detection, including mycotoxins, heavy metal ions, pesticide residue, antibiotics, estrogen residue, and pathogenic bacteria; and 5) the challenging and future perspectives of using UCNPs in food safety research. Considering the diversity and complexity of the foodborne harmful substances, developing novel detections and quantification techniques and the rigorous investigations about the effect of the harmful substances on human health should be accelerated.

Lanthanide ion (Ln3+ )-based upconversion sensor for quantification of food contaminants: A review

The food safety issue has gradually become the focus of attention in modern society. The presence of food contaminants poses a threat to human health and there are a number of interesting researches on the detection of food contaminants. Upconversion nanoparticles (UCNPs) are superior to other fluorescence materials, considering the benefits of large anti-Stokes shifts, high chemical stability, non-autofluorescence, good light penetration ability, and low toxicity. These properties render UCNPs promising candidates as luminescent labels in biodetection, which provides opportunities as a sensitive, accurate, and rapid detection method. This paper intended to review the research progress of food contaminants detection by UCNPs-based sensors. We have proposed the key criteria for UCNPs in the detection of food contaminants. Additionally, it highlighted the construction process of the UCNPs-based sensors, which includes the synthesis and modification of UCNPs, selection of the recognition elements, and consideration of the detection principle. Moreover, six kinds of food contaminants detected by UCNPs technology in the past 5 years have been summarized and discussed fairly. Last but not least, it is outlined that UCNPs have great potential to be applied in food safety detection and threw new insight into the challenges ahead.

One-step deep eutectic solvent strategy for efficient analysis of aflatoxins in edible oils

BACKGROUND

Aflatoxins, a kind of carcinogen, have attracted increasing attention due to their toxicity and harmfulness to human health. Traditional methods for aflatoxins analysis usually involve tedious extraction steps with a subsequent derivatization process. Herein, a simple and efficient liquid-phase microextraction method based on deep eutectic solvents (DESs) for direct analysis of aflatoxins was developed.

RESULTS

Adopting DESs as the extractant, we surprisingly found out that DESs could either achieve good extraction performance or play a similar role to the derivatization agent, achieving an enhancement of fluorescence intensity for direct analysis of aflatoxins by high-performance liquid chromatography combined with fluorescent detection. Under optimal conditions obtained by response surface methodology, the method provided satisfactory linear ranges (0.01-0.75 μg kg^-1 for AFB1 and AFG1, 0.003-0.25 μg kg^-1 for AFB2 and AFG2) with good determination coefficients (R²  > 0.9988), a low detection limit (0.0005-0.003 μg kg^-1 ), and good recovery rates (72.05-113.54%).

CONCLUSION

These results highlighted superiorities of the one-step DES strategy for analysis of aflatoxins in edible oils, providing insights for future development of efficient methods in food analysis. © 2020 Society of Chemical Industry.

Functional nanomaterials based immunological detection of aflatoxin B1: a review

Aflatoxin B1 (AFB1) is highly carcinogenic, mutagenic and teratogenic. Accordingly, sensitive, rapid and cost-effective techniques for detection of AFB1 is in urgent demand for food safety and the health of consumers. In this review, we report the current state of immunoassay formats and development, mainly based on nanomaterials for determination of AFB1. Following an introduction of the field, the microplate-, membrane- and microelectrode-based immunoassays are described. The relevant mechanisms, sensitivities, superiorities and deficiencies of each format are discussed. Finally, perspectives on the future development of nanomaterials-based immunoassays for AFB1 are provided.

Nanobody-alkaline phosphatase fusion-mediated phosphate-triggered fluorescence immunoassay for ochratoxin a detection

Ochratoxin A (OTA) is a kind of mycotoxin that seriously harms the health of humans and animals. In this study, a nanobody-alkaline phosphatase fusion-mediated phosphate-triggered fluorescence immunoassay (Nb-AP-mediated PT-FIA) was developed for detecting OTA. Based on the constructed phosphate-triggered fluorescence sensing system for Nb-AP and the optimal working conditions, the Nb-AP-mediated PT-FIA has a half maximal inhibition concentration (IC₅₀) of 0.46 ng/mL, a limit of detection (IC₁₀) of 0.12 ng/mL, and a linear range (IC_20-80) of 0.2-1.26 ng/mL, respectively. The recovery experiment indicated acceptable accuracy and precision of the Nb-AP-mediated PT-FIA, and the results were validated by high performance liquid chromatography with fluorescence detector. Thus this proposed method is applicable to sensitive, rapid, and low-cost detection of OTA and other toxic analytes with low molecular weight in food and environment.

Fluorometric determination of lead(II) by using aptamer-functionalized upconversion nanoparticles and magnetite-modified gold nanoparticles

A fluorescent nanoprobe for Pb(II) has been developed by employing aptamer-functionalized upconversion nanoparticles (UCNPs) and magnetic Fe₃O₄-modified (MNPs) gold nanoparticles (GNPs). First, aptamer-functionalized UCNPs and aptamer-functionalized magnetic GNPs were synthesized to obtained the fluorescent nanoprobe. The particles were combined by adding a complementary ssDNA. In the absence of Pb(II), the UCNPs, MNPs and GNPs are linked via complementary base pairing. This led to a decrease in the green upconversion fluorescence peaking at 547 nm (under 980 nm excitation). In the presence of Pb(II), the dsDNA between UCNPs and MNPs-GNPs is cleaved, and fluorescence recovers. This effect allows Pb(II) to be quantified, with a wide working range of 25-1400 nM and a lower detection limit of 5.7 nM. The nanoprobe gave satisfactory results when analyzing Pb(II) in tea and waste water. Graphical abstractSchematic representation of fluorescent nanoprobe based on fluorescence resonance energy transfer (FRET) between upconversion nanoparticles (UCNPs) and gold nanoparticles (GNPs)-Fe₃O₄ magnetic nanoparticles (MNPs) for detection of Pb²⁺.

Aflatoxins in peanut oil: food safety concerns

Aflatoxins are widely recognised as important natural contaminants of a wide range of foods, including maize and peanuts (groundnuts), which form part of the staple diet in many countries of the developing world, especially in Africa. There is a frequent misconception based on solubility considerations and developed market surveys that aflatoxins do not occur in peanut oil. Thus, the use of peanut oil in human food is frequently overlooked as a source of aflatoxin exposure, yet artisanal oil extraction from contaminated peanuts in local facilities in the developing world results in carryover of these mycotoxins into the oil. Consequently, these peanut oils can have high contamination levels. This review highlights food safety concerns and addresses inter alia the analytical adaptations required to determine the polar aflatoxins in peanut oil. The determination of aflatoxins in peanut oil was first achieved by thin-layer chromatography, which was later mostly superseded by high-performance liquid chromatography (HPLC) with fluorescence detection, or later, by mass spectrometric detection. More recently, a specially modified HPLC method with immunoaffinity column clean-up and fluorescence detection has achieved official method status at AOAC International. In addition, the review deals with toxicology, occurrence and detoxification of contaminated oil. Although various methods have been reported for detoxification of peanut oil, the toxicity of degradation products, the removal of beneficial constituents and the effect on its organoleptic properties need to be considered. This review is intended to draw attention to this often overlooked area of food safety.

A large Raman scattering cross-section molecular embedded SERS aptasensor for ultrasensitive Aflatoxin B1 detection using CS-Fe3O4 for signal enrichment

With growing concern on oil safety problems, developing a simple and sensitive method to detect Aflatoxin B1 (AFB1), a common mycotoxin in peanut oil, is very necessary. In this study, Surface-enhanced Raman Scattering (SERS) aptasensor was developed for ultrasensitive AFB1 detection using the amino-terminal AFB1 aptamer (NH₂-DNA1); and thiol-terminal AFB1 complementary aptamer (SH-DNA2) conjugated magnetic-beads (CS-Fe₃O₄) as enrichment nanoprobe and AuNR@DNTB@Ag nanorods (ADANRs) as reporter nanoprobe respectively. 5,5'-Dithiobis(2-nitrobenzoicacid) (DNTB) with large Raman scattering cross-section and no fluorescence interference was embedded in Au and Ag core/shell nanorods as Raman reporter molecules. CS-Fe₃O₄ possessed excellent biocompatibility and superparamagnetism for rapid signal enrichment. Therefore, NH₂-DNA1-CS-Fe₃O₄ and SH-DNA2-ADANRs were fabricated via the hybrid reaction between aptamers and complementary aptamers. When there is AFB1, AFB1 would competitively combine with the NH₂-DNA1-CS-Fe₃O₄ inducing the dissociation of SH-DNA2-ADANRs from CS-Fe₃O₄ and further decreasing the SERS signal. Based on this developed SERS aptasensor, a low limit of 0.0036ng/mL and an effective linear detection range from 0.01 to 100ng/mL with the correlation coefficient up to 0.986 for AFB1 detection were obtained. Moreover, the specificity of this SERS aptasensor was demonstrated by detecting other two mycotoxins and its accuracy for AFB1 detection in real peanut oil was further confirmed by standard addition recovery test.

An ultrasensitive aptasensor based on fluorescent resonant energy transfer and exonuclease-assisted target recycling for patulin detection

Patulin (PAT) is a type of mycotoxin which can compromise both food quality and human health. Due to its harmful effects, strict monitoring of PAT contents in food systems is necessary. A novel kind of bioassay was proposed for determining PAT based on the fluorescent resonant energy transfer (FRET) strategy. The exonuclease-catalyzed target recycling strategy was employed to improve the sensitivity of the FRET system. The results showed that the linear range extends from 0.01 ng/mL to 100 ng/mL. Furthermore, the average recoveries ranged from 93.33% to 105.21%, confirming the reliability of this method. The total analysis time for our assay developed is about 50 min. Compared to traditional analytical methods, the developed assay is more stable and has a significantly lower detection of limit (0.003 ng/mL). We believe the approach developed in this study would be useful for high-throughput screening of PAT in food industry and government laboratory.

High-performance liquid chromatography ultraviolet-photodiode array detection method for aflatoxin B1 in cattle feed supplements

AIM

The objective of the current study is to determine the concentration of aflatoxin B1 using high-performance liquid chromatography (HPLC) with a photodiode array (PDA) detector.

MATERIALS AND METHODS

Aflatoxin B₁ certified reference grade from Trilogy Analytical Laboratory dissolved acetonitrile (ACN) at 10 µg/mL was using standard assessment. HPLC instruments such as ultraviolet-PDA detector used a Shimadzu LC-6AD pump with DGU-20A5 degasser, communication module-20A, and PDA detector SPD-M20A with FRC-10A fraction collector. The HPLC was set isocratic method at 354 nm with a reverse-phase ODS C18 column (LiChrospher^® 100 RP-18; diameter, 5 µm) under a 20°C controlled column chamber. Rheodyne^® sample loops were performed in 20 µL capacities. The mobile phase was performed at fraction 63:26:11 H₂O: methanol:ACN at pH 6.8. A total of 1 kg of feed contained 10% bread crumbs and 30% concentrated, 40% forage, and 20% soybean dregs were using commercials samples. Samples were extracted by ACN and separated with solid phase extraction ODS 1 mL than elution with mobile phase to collect at drying samples performed. The samples were ready to use after added 1 mL mobile phase than injected into the system of HPLC.

RESULTS

We found that the retention time of aflatoxin B₁ was approximately 10.858 min. Linearity of 0.01-0.08 µg/mL aflatoxin B₁ dissolved in mobile phase was obtained at R²=0.9. These results demonstrate that these methods can be used to analyze aflatoxin B₁ and gain 89-99% recovery. The limit of detection of this assay was obtained at 3.5 × 10^-6 µg/mL.

CONCLUSION

This method was easy to apply and suitable to analyzing at small concentrations of aflatoxin B₁ in formulated product of feed cattle.