Research

12 pages, 2003 KiB

Open AccessArticle

A Molecularly Imprinted Polymer-Based Thermal Sensor for the Selective Detection of Melamine in Milk Samples

by Manlio Caldara, Joseph W. Lowdon, Jeroen Royakkers, Marloes Peeters, Thomas J. Cleij, Hanne Diliën, Kasper Eersels and Bart van Grinsven

Foods 2022, 11(18), 2906; https://doi.org/10.3390/foods11182906 - 19 Sep 2022

Cited by 14 | Viewed by 2775

Abstract

In recent years, melamine-sensing technologies have increasingly gained attention, mainly due to the misuse of the molecule as an adulterant in milk and other foods. Molecularly imprinted polymers (MIPs) are ideal candidates for the recognition of melamine in real-life samples. The prepared MIP [...] Read more.

In recent years, melamine-sensing technologies have increasingly gained attention, mainly due to the misuse of the molecule as an adulterant in milk and other foods. Molecularly imprinted polymers (MIPs) are ideal candidates for the recognition of melamine in real-life samples. The prepared MIP particles were incorporated into a thermally conductive layer via micro-contact deposition and its response towards melamine was analyzed using the heat-transfer method (HTM). The sensor displayed an excellent selectivity when analyzing the thermal response to other chemicals commonly found in foods, and its applicability in food safety was demonstrated after evaluation in untreated milk samples, demonstrating a limit of detection of 6.02 μM. As the EU/US melamine legal limit in milk of 2.5 mg/kg falls within the linear range of the sensor, it can offer an innovative solution for routine screening of milk samples in order to detect adulteration with melamine. The results shown in this work thus demonstrate the great potential of a low-cost thermal platform for the detection of food adulteration in complex matrices. Full article

(This article belongs to the Special Issue Emerging Detection Techniques for Contaminants in Food Science)

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12 pages, 3032 KiB

Open AccessArticle

Sandwich Fluorescence Detection of Foodborne Pathogen Staphylococcus aureus with CD Fluorescence Signal Amplification in Food Samples

by Han Du, Tao Ping, Wei Wu and Qingli Yang

Foods 2022, 11(7), 945; https://doi.org/10.3390/foods11070945 - 25 Mar 2022

Cited by 7 | Viewed by 2132

Abstract

Timely detection of Staphylococcus aureus (S. aureus) is critical because it can multiply to disease−causing levels in a matter of hours. Herein, a simple and sensitive DNA tetrahedral (Td) fluorescence signal amplifier with blue carbon quantum dots (bCDs) was prepared for [...] Read more.

Timely detection of Staphylococcus aureus (S. aureus) is critical because it can multiply to disease−causing levels in a matter of hours. Herein, a simple and sensitive DNA tetrahedral (Td) fluorescence signal amplifier with blue carbon quantum dots (bCDs) was prepared for sandwich detection of S. aureus. bCD was modified at the apex of Td, and an aptamer on Td was used to accurately identify and “adsorb” the amplifier to the surface of S. aureus. Atomic force microscopy (AFM) demonstrates the successful preparation of this signal amplifier. The fluorescence intensity emitted in this strategy increased 4.72 times. The strategy showed a stronger fluorescence intensity change, sensitivity (linear range of 7.22 × 10⁰–1.44 × 10⁹ CFU/mL with a LOD of 4 CFU/mL), and selectivity. The recovery rate in qualified pasteurized milk and drinking water samples was 96.54% to 104.72%. Compared with simple aptamer sandwich detection, these fluorescence signal amplifiers have improved fluorescence detection of S. aureus. Additionally, this fluorescent signal amplification strategy may be applied to the detection of other food pathogens or environmental microorganisms in the future. Full article

(This article belongs to the Special Issue Emerging Detection Techniques for Contaminants in Food Science)

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12 pages, 15825 KiB

Open AccessArticle

Ratiometric Monitoring of Biogenic Amines by a Simple Ammonia-Response Aiegen

by Xujing Guo, Xirui Chen, Rui Chen, Yujie Tu, Tianying Lu, Yuqian Guo, Liang Guo, Yonghua Xiong, Xiaolin Huang and Ben Zhong Tang

Foods 2022, 11(7), 932; https://doi.org/10.3390/foods11070932 - 24 Mar 2022

Cited by 6 | Viewed by 2729

Abstract

Herein, we developed a paper-based smart sensing chip for the real-time, visual, and non-destructive monitoring of food freshness using a ratiometric aggregation-induced emission (AIE) luminogen (i.e., H⁺MQ, protonated 4-(triphenylamine)styryl)quinoxalin-2(1H)-one) as pH sensitive indicators. Upon exposure to amine vapors, the [...] Read more.

Herein, we developed a paper-based smart sensing chip for the real-time, visual, and non-destructive monitoring of food freshness using a ratiometric aggregation-induced emission (AIE) luminogen (i.e., H⁺MQ, protonated 4-(triphenylamine)styryl)quinoxalin-2(1H)-one) as pH sensitive indicators. Upon exposure to amine vapors, the deprotonation of H⁺MQ occurs and triggers its color change from blue to yellow, with the fluorescence redshift from blue to amaranth. Consequently, we successfully achieved the sensitive detection of ammonia vapors by recording the bimodal color and fluorescence changes. Given the high sensitivity of H⁺MQ to ammonia vapor, a paper-based smart sensor chip was prepared by depositing H⁺MQ on the commercial qualitative filter paper through a physical deposition strategy. After being placed inside the sealed containers, the developed H⁺MQ-loaded paper chip was applied to the real-time monitoring of biogenic amine contents according to its color difference and ratio fluorescence change. The detection results were further compared with those obtained by the high-performance liquid chromatography method, which verified the feasibility of the designed paper chip for the food spoilage degree evaluation. Briefly, this work indicates that the designed H⁺MQ-loaded paper chip could be a promising approach for improving food freshness monitoring. Full article

(This article belongs to the Special Issue Emerging Detection Techniques for Contaminants in Food Science)

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13 pages, 2378 KiB

Open AccessArticle

Dual-Enzyme-Based Signal-Amplified Aptasensor for Zearalenone Detection by Using CRISPR-Cas12a and Nt.AlwI

by Xijing Yao, Qingli Yang, Yifei Wang, Chuanlin Bi, Han Du and Wei Wu

Foods 2022, 11(3), 487; https://doi.org/10.3390/foods11030487 - 08 Feb 2022

Cited by 17 | Viewed by 2821

Abstract

Zearalenone (ZEN) is harmful to animals and human beings, so it is very important to develop a rapid and sensitive method for the detection of ZEN. In this paper, we proposed a novel ZEN-monitoring method using two aptamers as recognition elements and EnGen [...] Read more.

Zearalenone (ZEN) is harmful to animals and human beings, so it is very important to develop a rapid and sensitive method for the detection of ZEN. In this paper, we proposed a novel ZEN-monitoring method using two aptamers as recognition elements and EnGen LbaCas12a and Nt.AlwI nicking endonuclease as signal amplifiers. When ZEN was present, it bound to the aptamer Z0 and, Z1 was released into solution. The solution was then separated and the Nt.AlwI enzyme was added in order to form a nicking-enzyme cycle, thereby producing large amounts of the ssDNA Z3 for 30 min. The Z3 formed a CRISPR-Cas12a-Z3 complex with CRISPR-Cas12a, activated the trans-cleavage ability of Cas12a, cleaved the Quenched Reporter for 20 min, and underwent fluorescence recovery. The aptasensor was able to sensitively detect ZEN in the linear range of 1–1000 pg/mL, with a detection limit as low as 0.213 pg/mL. The detection time lasted for 2 h. Additionally, this detection technology can also be used to monitor other hazards. Full article

(This article belongs to the Special Issue Emerging Detection Techniques for Contaminants in Food Science)

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13 pages, 3125 KiB

Open AccessArticle

Anti-Interference Detection of Vibrio parahaemolyticus from Aquatic Food Based on Target-Cyclized RCA with Dynamic Adapter Followed by LAMP

by Boying Zhang, Wenhua Sun, Lingling Ran, Chenru Wang, Jing Wang, Ran An and Xingguo Liang

Foods 2022, 11(3), 352; https://doi.org/10.3390/foods11030352 - 26 Jan 2022

Cited by 6 | Viewed by 2571

Abstract

Vibrio parahaemolyticus (V. parahaemolyticus) is considered the most concerning pathogen for seafood. Like other pathogens in food samples, its gene detection suffers from a problem of background interference when isothermal detection methods are used. The sensitivity and specificity greatly decrease due [...] Read more.

Vibrio parahaemolyticus (V. parahaemolyticus) is considered the most concerning pathogen for seafood. Like other pathogens in food samples, its gene detection suffers from a problem of background interference when isothermal detection methods are used. The sensitivity and specificity greatly decrease due to large amounts of background genome. Here we describe a novel isothermal detection technology based on target-cyclized rolling circle amplification combined with loop-mediated isothermal amplification (tRCA-lamp). By avoiding unexpected ligation, a short dynamic adapter is employed to increase the sensitivity of target cyclization in the presence of the background genome. At the amplification step, highly specific detection is obtained by linear RCA and simplified LAMP (only two primers are used). Furthermore, visual detection is easily realized with hydroxynaphthol blue (HNB). In the oyster samples, the tRCA-lamp approach can detect V. parahaemolyticus with a detection limit of 22 cfu/g with none necessary to enrich the bacteria and remove the host DNA. This method gets rid of the complicated primer design process and can be extended to the detection of other pathogens in food samples. Full article

(This article belongs to the Special Issue Emerging Detection Techniques for Contaminants in Food Science)

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17 pages, 6515 KiB

Open AccessArticle

Development of Pectin-Based Aerogels with Several Excellent Properties for the Adsorption of Pb²⁺

by Risi Wang, Ya Li, Xixiang Shuai, Jun Chen, Ruihong Liang and Chengmei Liu

Foods 2021, 10(12), 3127; https://doi.org/10.3390/foods10123127 - 16 Dec 2021

Cited by 9 | Viewed by 3463

Abstract

Traditional aerogels lack specific functional groups for the adsorption of Pb²⁺, which results in a low adsorption capacity and limits the application scope. Novel porous pectin-based aerogels (PPEAs) were prepared by incorporating polyethylenimine (PEI) using ethylene glycol diglycidyl ether (EGDE) as [...] Read more.

Traditional aerogels lack specific functional groups for the adsorption of Pb²⁺, which results in a low adsorption capacity and limits the application scope. Novel porous pectin-based aerogels (PPEAs) were prepared by incorporating polyethylenimine (PEI) using ethylene glycol diglycidyl ether (EGDE) as a cross-linker for the removal of Pb²⁺ from water. The cross-linking mechanism, morphology, mechanical strength, thermal stability, adsorption properties, and mechanism of the aerogels were investigated. The aerogels possessed several desirable features, such as a large maximum Pb²⁺ adsorption capacity (373.7 mg/g, tested at pH 5.0), ultralight (as low as 63.4 mg/cm³), high mechanical strength (stress above 0.24 MPa at 50% strain), and easy recyclability. Meanwhile, the equilibrium adsorption data was well described by the Langmuir–Freundlich (Sips) model and the kinetic adsorption process was well fitted using the pseudo-second-order model. The donor groups, such as -NH₂, and oxygen-containing functional groups were responsible for the Pb²⁺ adsorption, which was confirmed by the FTIR and XPS analysis. The excellent characteristics mean that PPEAs are highly effective adsorbents in the remediation of lead-containing wastewater. Full article

(This article belongs to the Special Issue Emerging Detection Techniques for Contaminants in Food Science)

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18 pages, 5133 KiB

Open AccessArticle

Rapid Detection of Dimethoate in Soybean Samples by Microfluidic Paper Chips Based on Oil-Soluble CdSe Quantum Dots

by Xinpeng Yan, Zhong Zhang, Runguang Zhang, Tian Yang, Guoying Hao, Li Yuan and Xingbin Yang

Foods 2021, 10(11), 2810; https://doi.org/10.3390/foods10112810 - 15 Nov 2021

Cited by 2 | Viewed by 1969

Abstract

Given the imperative of monitoring organophosphorus pesticides (OPs) residues in the ecosystem, here a novel, facile and sensitive fluorescence sensor is presented for the rapid detection of dimethoate. In this work, surface molecularly imprinted polymer (SMIP) and microfluidic technology had been introduced to [...] Read more.

Given the imperative of monitoring organophosphorus pesticides (OPs) residues in the ecosystem, here a novel, facile and sensitive fluorescence sensor is presented for the rapid detection of dimethoate. In this work, surface molecularly imprinted polymer (SMIP) and microfluidic technology had been introduced to enhance the selectivity and portability of the described methodology. Oil-soluble CdSe quantum dots (QDs) synthesized in a green way were used as fluorescent material for the selective detection of dimethoate on the basis of static quenching and photoinduced electron transfer mechanism. Among many kinds of paper materials, glass fiber paper was used as the novel substrate of paper chip due to low pristine fluorescence and better performance when combining CdSe QDs. In the process of molecular imprinting, the interaction between several functional monomers and dimethoate molecule was investigated and simulated theoretically by software to improve the selectivity of the sensor. Consequently, the fabricated novel detection platform could effectively respond to dimethoate in 10 min with the concentration range of 0.45–80 μmol/L and detection limit of 0.13 μmol/L. The recovery in the spiked experiment soybean sample was in an acceptable range (97.6–104.1%) and the accuracy was verified by gas chromatography-mass spectrometry, which signified the feasibility and potential in food sampling. Full article

(This article belongs to the Special Issue Emerging Detection Techniques for Contaminants in Food Science)

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12 pages, 2033 KiB

Open AccessArticle

Eco-Friendly Fluorescent ELISA Based on Bifunctional Phage for Ultrasensitive Detection of Ochratoxin A in Corn

by Weipeng Tong, Hao Fang, Hanpeng Xiong, Daixian Wei, Yuankui Leng, Xinyu Hu, Xiaolin Huang and Yonghua Xiong

Foods 2021, 10(10), 2429; https://doi.org/10.3390/foods10102429 - 13 Oct 2021

Cited by 13 | Viewed by 2501

Abstract

Conventional enzyme-linked immunosorbent assay (ELISA) is commonly used for Ochratoxin A (OTA) screening, but it is limited by low sensitivity and harmful competing antigens of enzyme-OTA conjugates. Herein, a bifunctional M13 bacteriophage with OTA mimotopes fused on the p3 protein and biotin modified [...] Read more.

Conventional enzyme-linked immunosorbent assay (ELISA) is commonly used for Ochratoxin A (OTA) screening, but it is limited by low sensitivity and harmful competing antigens of enzyme-OTA conjugates. Herein, a bifunctional M13 bacteriophage with OTA mimotopes fused on the p3 protein and biotin modified on major p8 proteins was introduced as an eco-friendly competing antigen and enzyme container for enhanced sensitivity. Mercaptopropionic acid-modified quantum dots (MPA-QDs), which are extremely sensitive to hydrogen peroxide, were chosen as fluorescent signal transducers that could manifest glucose oxidase-induced fluorescence quenching in the presence of glucose. On these bases, a highly sensitive and eco-friendly fluorescent immunoassay for OTA sensing was developed. Under optimized conditions, the proposed method demonstrates a good linear detection of OTA from 4.8 to 625 pg/mL and a limit of detection (LOD) of 5.39 pg/mL. The LOD is approximately 26-fold lower than that of a conventional horse radish peroxidase (HRP) based ELISA and six-fold lower than that of a GOx-OTA conjugate-based fluorescent ELISA. The proposed method also shows great specificity and accepted accuracy for analyzing OTA in real corn samples. The detection results are highly consistent with those obtained using the ultra-performance liquid chromatography-fluorescence detection method, indicating the high reliability of the proposed method for OTA detection. In conclusion, the proposed method is an excellent OTA screening platform over a conventional ELISA and can be easily extended for sensing other analytes by altering specific mimic peptide sequences in phages. Full article

(This article belongs to the Special Issue Emerging Detection Techniques for Contaminants in Food Science)

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9 pages, 2081 KiB

Open AccessArticle

Amplification Refractory Mutation System (ARMS)-PCR for Waxy Sorghum Authentication with Single-Nucleotide Resolution

by Xiaoying Zhu, Minghua Wu, Ruijie Deng, Mohammad Rizwan Khan, Sha Deng, Xi Wang, Rosa Busquets, Wanyu Deng and Aimin Luo

Foods 2021, 10(9), 2218; https://doi.org/10.3390/foods10092218 - 18 Sep 2021

Cited by 1 | Viewed by 2611

Abstract

Waxy sorghum has greater economic value than wild sorghum in relation to their use in food processing and the brewing industry. Thus, the authentication of the waxy sorghum species is an important issue. Herein, a rapid and sensitive Authentication Amplification Refractory Mutation System-PCR [...] Read more.

Waxy sorghum has greater economic value than wild sorghum in relation to their use in food processing and the brewing industry. Thus, the authentication of the waxy sorghum species is an important issue. Herein, a rapid and sensitive Authentication Amplification Refractory Mutation System-PCR (aARMS-PCR) method was employed to identify sorghum species via its ability to resolve single-nucleotide in genes. As a proof of concept, we chose a species of waxy sorghum containing the wx^c mutation which is abundantly used in liquor brewing. The aARMS-PCR can distinguish non-wx^c sorghum from wx^c sorghum to guarantee identification of specific waxy sorghum species. It allowed to detect as low as 1% non-wx^c sorghum in sorghum mixtures, which ar one of the most sensitive tools for food authentication. Due to its ability for resolving genes with single-nucleotide resolution and high sensitivity, aARMS-PCR may have wider applicability in monitoring food adulteration, offering a rapid food authenticity verification in the control of adulteration. Full article

(This article belongs to the Special Issue Emerging Detection Techniques for Contaminants in Food Science)

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14 pages, 4195 KiB

Open AccessArticle

ZrO₂ Nanoparticles and Poly(diallyldimethylammonium chloride)-Doped Graphene Oxide Aerogel-Coated Stainless-Steel Mesh for the Effective Adsorption of Organophosphorus Pesticides

by Xiudan Hou, Rong Ding, Shihai Yan, Haiyan Zhao, Qingli Yang and Wei Wu

Foods 2021, 10(7), 1616; https://doi.org/10.3390/foods10071616 - 13 Jul 2021

Cited by 11 | Viewed by 2403

Abstract

A novel sorbent based on the ZrO₂ nanoparticles and poly(diallyldimethylammonium chloride)-modified graphene oxide aerogel-grafted stainless steel mesh (ZrO₂/PDDA-GOA-SSM) was used for the extraction and detection of organophosphorus pesticides (OPPs). Firstly, the PDDA and GO composite was grafted onto the surface [...] Read more.

A novel sorbent based on the ZrO₂ nanoparticles and poly(diallyldimethylammonium chloride)-modified graphene oxide aerogel-grafted stainless steel mesh (ZrO₂/PDDA-GOA-SSM) was used for the extraction and detection of organophosphorus pesticides (OPPs). Firstly, the PDDA and GO composite was grafted onto the surface of SSM and then freeze-dried to obtain the aerogel, which efficiently reduced the accumulation of graphene nanosheets. It integrated the advanced properties of GOA with a thin coating and the three-dimensional structural geometry of SSM. The modification of ZrO₂ nanoparticles brought a selective adsorption for OPPs due to the combination of the phosphate group as a Lewis base and ZrO₂ nanoparticles with the Lewis acid site. The ZrO₂/PDDA-GOA-SSM was packed into the solid-phase extraction (SPE) cartridge to extract OPPs. According to the investigation of different factors, the extraction recovery was mainly affected by the hydrophilic-hydrophobic properties of analytes. Effective extraction and elution parameters such as sample volume, sample pH, rate of sample loading, eluent, and eluent volume, were also investigated and discussed. Under the optimal conditions, the linearity of phoxim and fenitrothion was in the range of 1.0–200 μg L⁻¹, and the linearity of temephos was in the range of 2.5–200 μg L⁻¹. The limits of detection were ranged from 0.2 to 1.0 μg L⁻¹. This established method was successfully applied to detect OPPs in two vegetables. There was no OPP detected in real samples, and results showed that the matrix effects were in the range of 46.5%–90.1%. This indicates that the ZrO₂/PDDA-GOA-SSM-SPE-HPLC method could effectively extract and detect OPPs in vegetables. Full article

(This article belongs to the Special Issue Emerging Detection Techniques for Contaminants in Food Science)

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11 pages, 1158 KiB

Open AccessArticle

Gold Nanobeads with Enhanced Absorbance for Improved Sensitivity in Competitive Lateral Flow Immunoassays

by Xirui Chen, Xintao Miao, Tongtong Ma, Yuankui Leng, Liangwen Hao, Hong Duan, Jing Yuan, Yu Li, Xiaolin Huang and Yonghua Xiong

Foods 2021, 10(7), 1488; https://doi.org/10.3390/foods10071488 - 27 Jun 2021

Cited by 16 | Viewed by 2503

Abstract

Background: Colloidal gold based lateral flow immunoassay (LFIA) commonly suffers from relatively low detection sensitivity due to the insufficient brightness of conventional gold nanoparticles (AuNPs) with the size of 20–40 nm. Methods: Herein, three kinds of gold nanobeads (GNBs) with the size of [...] Read more.

Background: Colloidal gold based lateral flow immunoassay (LFIA) commonly suffers from relatively low detection sensitivity due to the insufficient brightness of conventional gold nanoparticles (AuNPs) with the size of 20–40 nm. Methods: Herein, three kinds of gold nanobeads (GNBs) with the size of 94 nm, 129 nm, and 237 nm, were synthesized by encapsulating numerous hydrophobic AuNPs (10 nm) into polymer matrix. The synthesized GNBs exhibited the enhanced colorimetric signal intensity compared with 20–40 nm AuNPs. The effects of the size of GNBs on the sensitivity of LFIA with competitive format were assessed. Results: The results showed that the LFIA using 129 nm GNBs as amplified signal probes exhibits the best sensitivity for fumonisin B₁ (FB₁) detection with a cut-off limit (for visual qualitative detection) at 125 ng/mL, a half maximal inhibitory concentration at 11.27 ng/mL, and a detection limit at 1.76 ng/mL for detection of real corn samples, which are 8-, 3.82-, and 2.89-fold better than those of conventional AuNP₄₀-based LFIA, respectively. The developed GNB-LFIA exhibited negligible cross-reactions with other common mycotoxins. In addition, the accuracy, precision, reliability, and practicability were demonstrated by determining real corn samples. Conclusions: All in all, the proposed study provides a promising strategy to enhance the sensitivity of competitive LFIA via using the GNBs as amplified signal probes. Full article

(This article belongs to the Special Issue Emerging Detection Techniques for Contaminants in Food Science)

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