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1.
Food Chem ; 351: 129248, 2021 Jul 30.
Artigo em Inglês | MEDLINE | ID: mdl-33640766

RESUMO

Iron-based metal-organic framework, NH2-MIL-101(Fe), was doped with different dosages of cobalt phthalocyanine nanoparticles (CoPc) to synthesize a series of NH2-MIL-101(Fe)@CoPc nanocomposites. The NH2-MIL-101(Fe)@CoPc nanocomposites were then employed to construct novel impedimetric aptasensors for the detection of ochratoxin A (OTA). Combining the intrinsic advantages of NH2-MIL-101(Fe) (highly porous structure and excellently electrochemical activity) and CoPc (good physiochemical stability and strong bioaffinity), the NH2-MIL-101(Fe)@CoPc nanocomposites show promising properties, which are beneficial for immobilizing OTA-targeted aptamer strands. Amongst, the developed impedimetric aptasensor based on NH2-MIL-101(Fe)@CoPc6:1, prepared using the mass ratio of NH2-MIL-101(Fe):CoPc of 6:1, exhibits the best amplified electrochemical signal and highest sensitivity for detecting OTA. The detection limitation is 0.063 fg·mL-1 within the OTA concentration of 0.0001-100 pg·mL-1, accompanying with high selectivity, good reproducibility and stability, acceptable regenerability, and wide applicability in diverse real samples. Consequently, the proposed sensing strategy can be applied for detecting OTA to cope with food safety.


Assuntos
Técnicas de Química Analítica/instrumentação , Indóis/química , Estruturas Metalorgânicas/química , Nanopartículas/química , Ocratoxinas/análise , Compostos Organometálicos/química , Limite de Detecção , Reprodutibilidade dos Testes
2.
J Chromatogr A ; 1639: 461930, 2021 Feb 22.
Artigo em Inglês | MEDLINE | ID: mdl-33556780

RESUMO

Herein, a facile and practical aptamer-grafted ionic affinity monolith with mixed-mode mechanism was explored as a versatile platform for online specific recognition of polar and non-polar mycotoxins. The mixed-mode mechanism including molecular affinity adsorption (between aptamers and targets), hydrophilic interaction and ionic interaction (between stationary phase and targets) were adopted and provided a better flexibility in adjusting separation selectivity to reduce nonspecific adsorption with respect to the single mode. Preparation and characterization of aptamer-based affinity monoliths were investigated, The characterization of pore size distribution, Brunauer-Emmett-Teller (BET) surface area and the specificity and cross-reaction were also evaluated. As a result, the hydrophilic nature and negative charge on affinity monolith were obtained. Multiple interactions including aptamer affinity binding, hydrophilic interaction (HI) and ion exchange (IE) could be adopted for online selective extraction. Specific recognitions of polar ochratoxin A (OTA), non-polar zearalenone (ZEN) and aflatoxin B1 (AFB1) was fulfilled with LODs as 0.03, 0.05 and 0.05 µg/L, respectively. Applied to real cereals, good recoveries of the fortified OTA, AFB1 and ZEN were achieved as 92.6 ± 1.3% ~ 95.6 ± 1.3% (n=3), 93.9 ± 2.3% ~ 98.2 ± 3.4% (n=3) and 92.7 ± 2.0% ~ 96.9 ± 3.5% (n=3) in corn, wheat and rice, respectively. The results displayed that Apt-MCs with hydrophilic and ionic interaction mixed-mode mechanism were efficient enough and competent for the online recognition of mycotoxins in cereals.


Assuntos
Aptâmeros de Nucleotídeos/química , Micotoxinas/análise , Sistemas On-Line , Acetonitrilos/química , Aflatoxina B1/análise , Calibragem , Cromatografia Líquida de Alta Pressão , Grão Comestível/química , Interações Hidrofóbicas e Hidrofílicas , Íons , Limite de Detecção , Ocratoxinas/análise , Oryza/química , Reprodutibilidade dos Testes , Triticum/química , Zea mays/química , Zearalenona/análise
3.
Food Chem ; 336: 127710, 2021 Jan 30.
Artigo em Inglês | MEDLINE | ID: mdl-32763739

RESUMO

Conventional gold nanoparticle-based lateral flow immunoassay (LFIA) usually suffers a huge challenge in measuring target concentration in food matrices with dark color because of its poor resistance to the background matrix and color interference. To address this issue, we first report a novel bifunctional magneto-gold nanohybrid (MGNH) for the simultaneous magnetic separation and colorimetric target sensing by integrating MGNHs into LFIA. Under optimum conditions, an ultrasensitive detection of ochratoxin A (OTA) in grape juice was achieved with a limit of detection at 0.094 ng mL-1. The average recoveries of this MGNH-LFIA ranged from 92.31% to 108.97% with a coefficient of variation of below 12%. The excellent selectivity of our MGNH-LFIA against OTA was demonstrated. Besides, our MGNH-LFIA is comparable to liquid chromatography coupled with mass spectrometry in terms of accuracy, reproducibility, and practicability. The designed MGNH-LFIA platform is readily extended for improving other small molecule detection in food samples.


Assuntos
Contaminação de Alimentos/análise , Sucos de Frutas e Vegetais/análise , Imunoensaio/métodos , Nanopartículas Metálicas/química , Ocratoxinas/análise , Análise de Alimentos/instrumentação , Análise de Alimentos/métodos , Ouro/química , Imunoensaio/instrumentação , Limite de Detecção , Fenômenos Magnéticos , Ocratoxinas/imunologia , Reprodutibilidade dos Testes , Sensibilidade e Especificidade , Espectrofotometria Ultravioleta , Vitis/química
4.
Food Chem ; 337: 127761, 2021 Feb 01.
Artigo em Inglês | MEDLINE | ID: mdl-32777565

RESUMO

Amino and thiolated aptamers are the main aptamers used to construct label-free electrochemical impedimetric aptasensors. In this study, the modification performance and electrochemical properties of amino aptamers and thiolated aptamers were studied in the construction of label-free impedimetric sensors. The results showed that the initial modification density of amino aptamers was higher than that of thiol aptamers. Aptamers can recognize and bind OTA to generate electrical signals. The higher the density of aptamer modification was, the better the electric signals were. If only considering the initial modification density, amino aptamers were more suitable for the preparation of aptasensors than thiolated aptamers. However, the modification density of the amino aptamer decreased with the prolonged immersion time in 1 mM HCl solution, which suggests that the stability of this sensor was poor. However, the thiolated aptamer maintained relatively constant density and could be reused. Thus, the thiolated aptasensor had a wide range and good reproducibility and stability for the determination of ochratoxin A (OTA). In addition, this study proved that gold nanoparticles play an important role in signal amplification by increasing the effective gold surface to fix more aptamers in the process of sensor preparation.


Assuntos
Aptâmeros de Nucleotídeos/química , Aptâmeros de Nucleotídeos/metabolismo , Técnicas Biossensoriais/métodos , Impedância Elétrica , Eletroquímica , Eletrodos , Ouro/química , Nanopartículas Metálicas/química , Ocratoxinas/análise , Reprodutibilidade dos Testes
5.
Int J Food Microbiol ; 339: 109016, 2021 Feb 02.
Artigo em Inglês | MEDLINE | ID: mdl-33360159

RESUMO

Dry-fermented sausages are prone to be colonised by Penicillium nordicum, which is one of the main ochratoxin A (OTA)-producing species. Its ability to produce this mycotoxin on dry-fermented sausages has been reported. However, the influence of the conditions of a traditional processing of a Spanish dry-fermented sausage and the intrinsic physicochemical parameters of this product such as water activity (aw) and pH on OTA production has not been studied yet. Thus, the aim of this study was to evaluate the influence of traditional processing (interaction of relative humidity (RH) x temperature x ripening days) on the evolution of pH and aw during maturation of dry-fermented sausage "salchichón" and its relationship with OTA synthesis by P. nordicum. The expression of otapks and otanps genes, both involved in the biosynthesis of the mycotoxin, was also assessed. For this, 27 raw sausages were inoculated with P. nordicum and ripened for 26 days in a drying chamber (3 days at 5 °C and 84% RH, 17 days at 12 °C and 84% RH, and 6 days at 12 °C and 80% RH). From results, although it seems that the pH slightly influenced on OTA biosynthesis, the aw had a great impact on this mycotoxin production. In fact, the two highest OTA concentrations found coincided with a dramatic rise of the aw value (0.92 aw) by day 18 of incubation when the RH of the drying chamber was still 84% and at the end of the incubation time when the aw decreased noticeably (0.87 aw). The expression of the otapks and otanps genes correlated with the OTA produced by P. nordicum. Results from this work confirm that the traditional processing of Spanish dry-fermented sausages favours itself OTA synthesis by P. nordicum. Our findings may help in informed decision-making in relation to RH/temperature of drying chambers and shortening of the ripening process. This may be then effectively incorporated into the hygienic production system in the framework of HACCP together with other measures including the use of Penicillium nalgiovense as protective culture or the monitoring of otapks gene expression, and aw during the processing of dry-fermented sausages. All these strategies together may put ochratoxigenic Penicillia at a disadvantage and minimise OTA contamination risks in dry-fermented sausages.


Assuntos
Manipulação de Alimentos/métodos , Microbiologia de Alimentos/métodos , Produtos da Carne/microbiologia , Ocratoxinas/metabolismo , Penicillium/metabolismo , Animais , Dessecação , Fermentação , Perfilação da Expressão Gênica , Genes Bacterianos/genética , Concentração de Íons de Hidrogênio , Produtos da Carne/análise , Ocratoxinas/análise , Penicillium/genética , Suínos , Temperatura , Tempo , Água/metabolismo
6.
Food Chem ; 338: 127827, 2021 Feb 15.
Artigo em Inglês | MEDLINE | ID: mdl-32822900

RESUMO

Ochratoxin A (OTA) is a toxic metabolite that is widely distributed in food products. Herein, we proposed a new fluorescent aptasensor for OTA detection by using cascade strand displacement reaction. The binding of OTA and OTA aptamer on magnetic beads surface inhibited its hybridization with complementary DNA, and subsequently initiated the strand displacement reaction that induced amplified fluorescence signal. By tracing fluorescence response, our method demonstrated an improved detection limit of 0.63 ng/mL, a short assay time of 110 min, and a satisfactory detection specificity by using ochratoxin B, aflatoxin B1, and zearalenone as control toxins. Recovery studies were conducted by spiking OTA in real food samples, including white wine, red wine, cereal drink, coffee beverage and tea beverage, and confirmed desirable accuracy and practical applicability of our method. Therefore, our method may have a great potential use in the food quality control in the future.


Assuntos
Aptâmeros de Nucleotídeos/química , Bebidas/análise , Análise de Alimentos/métodos , Contaminação de Alimentos/análise , Ocratoxinas/análise , Aflatoxina B1/análise , Aptâmeros de Nucleotídeos/genética , DNA Complementar , Fluorescência , Limite de Detecção , Sensibilidade e Especificidade , Vinho/análise
7.
Food Chem ; 338: 128122, 2021 Feb 15.
Artigo em Inglês | MEDLINE | ID: mdl-33091999

RESUMO

a dual DNA tweezers nanomachine was developed for one-step simultaneous detection of aflatoxin B1 (AFB1) and ochratoxin A (OTA) in food samples. The dual DNA tweezers are locked by the aptamers of mycotoxins, resulting the "turn off" of fluorescent signal. In the presence of AFB1 and OTA, the aptamers can bind with their corresponding targets, resulting the "open" of DNA tweezers and the "turn on" of the fluorescent signals. The limits of detections were 3.5 × 10-2 ppb for AFB1 and 0.1 ppb for OTA. Moreover, the applicability of the method was further demonstrated by conducting a limited survey on 5 samples collected from various sources. The recoveries of this method change from 90.0% to 110.0% for simultaneous detection of AFB1 or OTA and the RSDs vary from 4.1% to 9.2%. Detection uncertainties were within 5% (with a 95% confidence level).


Assuntos
Aflatoxina B1/análise , DNA , Análise de Alimentos/métodos , Contaminação de Alimentos/análise , Nanotecnologia/métodos , Ocratoxinas/análise , Limite de Detecção , Pinças Ópticas , Fatores de Tempo
8.
Food Chem ; 345: 128828, 2021 May 30.
Artigo em Inglês | MEDLINE | ID: mdl-33338836

RESUMO

Immunochemical methods are highly deployed in analytical laboratories worldwide for monitoring the incidence of mycotoxins in the food chain. Nevertheless, most conventional immunoassays for ochratoxin A (OTA), including commercial kits, show limitations to robustly determine this mycotoxin in grape-derived products below regulated levels (2 ng/mL). Herein, two rapid tests for sensitive OTA determination in wine and must were developed capitalizing on a collection of bioconjugates from innovative synthetic haptens and monoclonal antibodies with subnanomolar affinity. The ELISA (LOD = 8 pg/mL) showed excellent performance in recovery studies, and it was applied to survey commercial wines and musts for OTA contamination. Concerning LFIA, validation according to the Commission Regulation 519/2014 showed that samples exceeding 2 ng/mL were properly scored as uncompliant. More importantly, illegal samples provided a complete inhibition of the test signal, making this test an easy-to-use, rapid, and convenient screening method for in-house control of OTA in wineries.


Assuntos
Análise de Alimentos/métodos , Imunoensaio/métodos , Ocratoxinas/análise , Vinho/análise , Contaminação de Alimentos/análise , Indicadores e Reagentes/química , Limite de Detecção
9.
Toxicon ; 188: 172-177, 2020 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-33096150

RESUMO

The aim of this study was to determine the degree of mold contamination and mycotoxin levels in commercially available green coffee products and dietary supplements with green coffee extract. The study included 34 samples from green coffee products: raw beans (n = 16), ground coffee (n = 15) and instant coffee (n = 3), as well as 22 samples from dietary supplements in form of capsules (n = 19), tablets (n = 2) and sachets (n = 1). Total mold count was determined with spread-plate method. Anamorphic mold were identified based on their microscopic morphology and the type of sporulation. Concentrations of mycotoxins, ochratoxin A and citrinin, were quantified by means of HPLC-fluorescence detection. Molds, typically Aspergillus spp. and Penicillium spp., were found in 94% of green coffee beans, 100% of ground and instant coffee samples, and 55% of dietary supplement samples. None of the samples contained detectable levels of citrinin. Ochratoxin A (0.4 ng/g) was detected in only one sample of raw green coffee beans, but in up to 40% and 67% of ground and instant coffee samples, respectively. Mean concentrations of ochratoxin A in ground and instant coffee samples were 3.28 ng/g and 4.09 ng/g, respectively, and maximum concentrations amounted to 6.65 ng/g and 7.44 ng/g, respectively. Ochratoxin A (mean concentration 9.60 ng/g, maximum level 31.4 ng/g) was also detected in up to 58% of the supplement capsules, but in none of tablets and sachets.


Assuntos
Citrinina/análise , Suplementos Nutricionais/análise , Contaminação de Alimentos/análise , Ocratoxinas/análise , Extratos Vegetais/análise , Café , Suplementos Nutricionais/microbiologia
10.
Toxicon ; 187: 151-162, 2020 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-32889024

RESUMO

Ochratoxins (OTs) are a group of mycotoxins produced by Aspergillus and Penicillium spp. which are ubiquitous. They infect the crops during pre- and post-harvest conditions and contaminate various food and feed. Among all the OTs produced, ochratoxin A (OTA) poses serious health issues like neurotoxicity and carcinogenesis. The harmful impact of the toxins is observed in both humans and animals. The toxins get accumulated in the organs of animals through the contaminated animal-feed which further contaminate the products derived from them, such as milk and meat-based products. Therefore, sensitive and robust identification, detection, and quantification methods along with efficient management and control measures are crucial. Spectrometric and spectroscopy techniques are quite sensitive and lead to better detection of the toxin in the food products. Control and preventive measures during harvesting, storage and transportation are found to be effective in managing the production of such toxins. This review insight on the occurrence, chemistry, biosynthesis, effects on human health and agriculture, detections, management, and control strategies of ochratoxins.


Assuntos
Ração Animal , Exposição Dietética/estatística & dados numéricos , Contaminação de Alimentos/estatística & dados numéricos , Microbiologia de Alimentos , Ocratoxinas/análise , Animais , Aspergillus , Humanos , Penicillium
11.
Toxicon ; 185: 104-113, 2020 Oct 15.
Artigo em Inglês | MEDLINE | ID: mdl-32653416

RESUMO

Fungi produce mycotoxins in the presence of appropriate temperature, humidity, sufficient nutrients and if the density of the mushroom mass is favorable. Although all mycotoxins are of fungal origin, all toxic compounds produced by fungi are not called mycotoxins. The interest in mycotoxins first started in the 1960s, and today the interest in mycotoxin-induced diseases has increased. To date, 400 mycotoxins have been identified and the most important species producing mycotoxins belongs to Aspergillus, Penicillium, Alternaria and Fusarium genera. Mycotoxins are classified as hepatotoxins, nephrotoxins, neurotoxins, immunotoxins etc. In this review genotoxic and also other health effects of some major mycotoxin groups like Aflatoxins, Ochratoxins, Patulin, Fumonisins, Zearalenone, Trichothecenes and Ergot alkaloids were deeply analyzed.


Assuntos
Mutagênicos/toxicidade , Micotoxinas/toxicidade , Aflatoxinas/toxicidade , Aspergillus , Dano ao DNA , Contaminação de Alimentos , Microbiologia de Alimentos , Fumonisinas/toxicidade , Fungos , Fusarium , Ocratoxinas/análise , Patulina , Tricotecenos/toxicidade , Zearalenona/toxicidade
12.
Mycotoxin Res ; 36(3): 327-337, 2020 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-32621108

RESUMO

The aim of this study was to determine dietary exposure to ochratoxin A (OTA) in Turkish adults. In this study, 500 food samples (50 rice, 50 wheat bread, 50 pasta, 50 raisins, 50 dried figs, 50 pistachios, 50 hazelnuts, 50 almonds, 50 chilli, 25 coffee, and 25 cocoa) collected from Turkey were analysed with a high-performance liquid chromatography (HPLC) method. Moreover, a total of 370 analytical results (110 cereal-based snacks, 95 wine, 35 beer, and 130 chocolate) collected from our previous observations were also used in the evaluation of exposure estimates. OTA was found in 52% of cocoa, 42% of raisins, 40% of coffee, 34% of chilli, 14% of dried figs, 10% of pasta, 8% of pistachios, 6% of wheat bread, 4% of rice, and 4% of hazelnuts. The chronic dietary exposure to OTA for Turkish adults, using lower bound (LB) and upper bound (UB) concentrations, varied from 0.683 to 4.487 ng/kg body weight (b.w.) per week for mean estimate and from 3.976 to 5.760 ng/kg b.w. per week for the 95th percentile (P95) estimate. Cereals and cereal-based products made the largest contribution (75.3-85.7%) to OTA exposure. Both mean and P95 chronic exposure to OTA were greatly below the tolerable weekly intake of 120 ng/kg b.w. per week and thus not a health concern for Turkish adults.


Assuntos
Exposição Dietética/estatística & dados numéricos , Contaminação de Alimentos/análise , Ocratoxinas/análise , Adulto , Cromatografia Líquida de Alta Pressão , Exposição Dietética/efeitos adversos , Feminino , Alimentos/toxicidade , Análise de Alimentos , Humanos , Masculino , Ocratoxinas/sangue , Ocratoxinas/toxicidade , Turquia , Adulto Jovem
13.
Food Chem ; 327: 127011, 2020 Oct 15.
Artigo em Inglês | MEDLINE | ID: mdl-32438263

RESUMO

Wheat is one of the main dietary sources for mycotoxins that can cause adverse health effects in humans. Here we report results of a 3-year survey which compared the effects of flour type (whole-grain vs white), wheat species (common vs spelt), and farming system (organic vs conventional) on mycotoxin concentrations in UK and German wheat flour brands. Wholegrain, conventional and organic flour contained 124, 31 and 9% higher concentrations of T-2/HT-2, DON and ZEA respectively, but concentrations of the three Fusarium mycotoxins assessed were ~10 times lower than the EC-maximum contamination levels (MCL). Thirty one percent of flour samples had Ochratoxin A (OTA) concentrations above the MCL (3 µg/kg), but OTA levels were no affected by wheat species, farming system and flour type. Results suggest that both organic and conventional primary production methods and postharvest quality assurance systems are effective for maintaining Fusarium mycotoxins, but not OTA concentrations, below the MCL.


Assuntos
Agricultura/métodos , Farinha/análise , Contaminação de Alimentos/análise , Micotoxinas/análise , Triticum/química , Fusarium , Alemanha , Humanos , Ocratoxinas/análise , Agricultura Orgânica , Inquéritos e Questionários , Reino Unido , Grãos Integrais/química
14.
Food Chem ; 320: 126607, 2020 Aug 01.
Artigo em Inglês | MEDLINE | ID: mdl-32203832

RESUMO

Colorimetric aptasensors have been intensively studied for the ochratoxin A (OTA) detection, but they mostly exhibit just one-color change, resulting in poor visual resolution and limited use for semi-quantitative analysis. Thus, we designed a high-resolution colorimetric assay on the basis of aptamer structural switching and enzyme-induced metallization of gold nanorods (AuNRs). DNA-alkaline phosphatase (ALP)-immobilized magnetic beads were prepared. The aptamer bounded to OTA to form G-quadruplexes, releasing ALP-labelled complementary DNA (cDNA-ALP). After magnetic separation, cDNA-ALP catalyzed the decomposition of ascorbic acid 2-phosphate to ascorbic acid that reduced Ag+, forming an Ag shell on the surface of AuNRs. This caused a blue-shift of the longitudinal local surface plasmon resonance peak of the AuNRs and a naked eye visible multicolor change. Under optimal conditions, the assay exhibited a 9.0 nM detection limit for OTA, with high specificity. This method is promising for the on-site visual semi-quantitative detection of mycotoxins in foods.


Assuntos
Fosfatase Alcalina/metabolismo , Aptâmeros de Nucleotídeos/química , Colorimetria/métodos , Nanotubos/química , Ocratoxinas/análise , Quadruplex G , Ouro/química , Separação Imunomagnética , Limite de Detecção , Ressonância de Plasmônio de Superfície
15.
Food Chem ; 318: 126496, 2020 Jul 15.
Artigo em Inglês | MEDLINE | ID: mdl-32146309

RESUMO

Beer is one the most consumed alcoholic beverage in the world and its contamination with mycotoxins is of public health concern. This study reports a fast and automated analytical procedure based on a multi-heart-cutting two-dimensional liquid chromatography tandem mass spectrometry method using electrospray ionization for the determination of seven mycotoxins (aflatoxins B1, B2, G2 and G1, ochratoxin A, fumonisins B1 and B2) in beers. The developed method was based on the heart-cutting 2D- HPLC technique in which only the specific portions of the first dimension, in the retention time of analytes, were transferred into the second dimension for the further separation and successive determination. The method uses two different chromatographic columns; in the first dimension, 50 µL of sample was injected on first column, and mycotoxins elution regions were collected in a loop and transferred into the second column for the separation of analytes. Each column operated in gradient elution mode in order to eliminate interfering compounds and improve separation and peak shape. After the optimization, the method has been validated according to EU regulation and finally applied for the analysis of forty beer samples collected from Italian supermarkets. Among all mycotoxins studied, fumonisins B1 was the most widely distributed in analysed beers (>21%) in the range from 0.6 to 12.3 ng mL-1. The automated methodology developed was able to determine accurately and simultaneously seven mycotoxins in beer. This provided a significant reduction of sample handle and, consequently of analysis time.


Assuntos
Cerveja/análise , Cromatografia Líquida de Alta Pressão/métodos , Contaminação de Alimentos/análise , Micotoxinas/química , Espectrometria de Massas em Tandem/métodos , Aflatoxina B1/análise , Fumonisinas/análise , Ocratoxinas/análise
16.
J Agric Food Chem ; 68(14): 4277-4283, 2020 Apr 08.
Artigo em Inglês | MEDLINE | ID: mdl-32182058

RESUMO

Ochratoxin A (OTA), a common mycotoxin, has attracted great concern as many foodstuffs can suffer from OTA contamination; OTA causes harmful effects on human and animals. Rapid and sensitive detection of OTA is demanded in many fields for agricultural product quality, food safety, and health. Aptamer fluorescence polarization/anisotropy (FP/FA) assays integrate advantages of nucleic acid aptamers (e.g., easy preparation, high stability, and low cost) and FP/FA analysis (e.g., high sensitivity, rapidity, simplicity, and robustness). Here, we report the preparation of lissamine rhodamine B labeled OTA and developed competitive aptamer fluorescence anisotropy (FA) assays for OTA with signal-off or signal-on responses by using this fluorescently labeled probe. In the signal-off FA assay, the binding between the fluorescent probe and aptamer gave a large FA signal due to molecular volume increase, and the fluorescent probe was displaced from the aptamer in the presence of OTA target, causing FA to decrease. To further enhance the FA change in the signal-off assay, large-sized streptavidin was conjugated on the aptamer, and this assay allowed for a detection limit of 2.5 nM and a more remarkable FA decrease. Furthermore, we found that the fluorescent probe could interact with Tween 20, which caused the fluorescent probe to show a higher FA value than that of the aptamer-fluorescent probe complex. A signal-on FA assay was achieved in the binding buffer containing 0.1% Tween 20, with a detection limit of 10 nM. Signal-off and signal-on FA methods both were selective and enabled detection of OTA spiked in red wine samples, showing capability for target analysis in complex sample matrix.


Assuntos
Aptâmeros de Nucleotídeos/química , Corantes Fluorescentes/química , Ocratoxinas/análise , Rodaminas/química , Ligação Competitiva , Técnicas Biossensoriais , Polarização de Fluorescência/métodos , Contaminação de Alimentos/prevenção & controle , Humanos , Limite de Detecção , Polissorbatos/química , Sensibilidade e Especificidade , Estreptavidina/química , Vinho/análise
17.
Artigo em Inglês | MEDLINE | ID: mdl-32178381

RESUMO

The growing interest in spicy foods leads to the global demand for spices, particularly dried chili. This study aimed to assay both aflatoxin (AFs) and ochratoxin A (OTA) contamination using an integrative method of morphological identification, molecular detection, and chromatography analysis on dried chili provided from traditional and modern markets in Indonesia. The results showed that total fungal infection ranged from 1-408 × 103 CFU/g. Eighty percent of the chili obtained from both the traditional and the modern markets were infected by Aspergillus spp., in which 50% of the infections were identified as A. parasiticus and A. flavus. A complete set of targeted genes involved in AF production and OTA were detected in two isolates of A. flavus and one isolate of A. carbonarius, respectively. The levels of AFs B1, B2, and OTA in the contaminated dried chilies were in the range of 39.3-139.5 µg/kg, 2.6-33.3 µg/kg, and 23.7-84.6 µg/kg, respectively. In contrast, no AFs G1 and G2 were detected. This study showed that the fungal infection of Indonesian dried chili occurs both in the field and during storage; thus, it is suggested to implement good agricultural and handling processes.


Assuntos
Aflatoxinas , Microbiologia de Alimentos , Alimentos em Conserva , Ocratoxinas , Aflatoxinas/análise , Aspergillus/genética , Aspergillus/isolamento & purificação , Cromatografia Líquida de Alta Pressão , Alimentos em Conserva/análise , Alimentos em Conserva/microbiologia , Indonésia , Ocratoxinas/análise
18.
Food Chem ; 319: 126544, 2020 Jul 30.
Artigo em Inglês | MEDLINE | ID: mdl-32151901

RESUMO

Colorimetric biosensors have been widely applied to mycotoxins testing. However, the colorimetric assay previously reported used a single color to detect one mycotoxin, and there were few reports on the simultaneous detection of multiple mycotoxins. In this work, a colorimetric biosensor for dual mycotoxins detection was developed. A Fe3O4/GO based platform for aflatoxins B1 (AFB1) detection and a Fe3O4@Au based platform for ochratoxin A (OTA) detection were fabricated. The quantification of OTA and AFB1 was respectively achieved by the release of thymolphthalein under alkaline conditions and 3,3',5,5'-tetramethylbenzidine was catalyzed by Au NPs under acidic conditions. Because of different conditions, two sensing methods didn't interfere with each other but could provide a higher detection efficiency. The detection range of AFB1 is 5-250 ng·ml-1 and that of OTA is 0.5-80 ng·ml-1. This biosensor has been successfully applied in real sample detection, which has a broad application prospect in fields of food safety.


Assuntos
Aflatoxina B1/análise , Produtos Agrícolas/química , Contaminação de Alimentos/análise , Ocratoxinas/análise , Técnicas Biossensoriais , Colorimetria
19.
Mikrochim Acta ; 187(3): 167, 2020 02 13.
Artigo em Inglês | MEDLINE | ID: mdl-32055989

RESUMO

A paper based sensor array is presented to discriminate and determine five mycotoxins classified into three categories, namely aflatoxins, ochratoxins and zearalenone. The gold and silver nanoparticles, synthesized by three different reducing or capping agents, were employed as sensing elements of the fabricated device. These nanoparticles were poured onto hydrophilic circular zones embedded on the hydrophobic substrate. The response of the assay is dependent on the aggregation of nanoparticles for interaction with mycotoxins. Due to aggregation, the gold and silver nanoparticles changed to purple and brown, respectively. Color changes provide unique colorimetric signatures conducive to recognizing the type of mycotoxin, identifying its chemical structure, and finding the fungi that produce it. The discrimination ability of the assay was investigated by both supervised (linear discriminate analysis) and unsupervised (principle component analysis and hierarchical cluster analysis) pattern recognition methods. The assay was applied to the point of need determination of aflatoxin B1, aflatoxin G1, aflatoxin M1, ochratoxin A and zearalenone with a detection limit of 2.7, 7.3, 2.1, 3.3 and 7.0 ng.mL-1, respectively. The fabricated device has high potential of simultaneously determining the mycotoxins in pistachio, wheat, coffee and milk with the help of partial least square method. The root mean square errors for prediction of PLS model were 5.7, 5.2, 1.5, 7.2 and 2.9 for aflatoxin B1, aflatoxin G1, aflatoxin M1, ochratoxin A and zearalenone, respectively. Graphical abstractSchematic representation of paper based colorimetric sensor array based on gold and silver nanoparticles for both qualitative and quantitative analysis of aflatoxins, ochratoxin and zearalenone.


Assuntos
Aflatoxinas/análise , Colorimetria/métodos , Ouro/química , Nanopartículas Metálicas/química , Ocratoxinas/análise , Prata/química , Zearalenona/análise , Colorimetria/instrumentação , Humanos , Papel
20.
Food Chem ; 315: 126289, 2020 Jun 15.
Artigo em Inglês | MEDLINE | ID: mdl-32014670

RESUMO

Trace residue of mycotoxins in complex medicinal and edible food matrices has brought huge challenges for the development of ultrasensitive analytical methods. Here, a green electrochemical immunosensor for the ultrasensitive detection of ochratoxin A (OTA) was fabricated by self-assembling a compact 2-mercaptoacetic (TGA) monolayer on the surface of the working Au electrode to form the Au/TGA/bovine serum aibumin (BSA)-OTA/anti-OTA monoclonal antibody composite probes for selective and ultra-sensitive detection of OTA based on indirect competitive principle and differential pulse voltammetry analysis. The electrochemical impedance spectroscopy and cyclic voltammetry methods were introduced to characterize the assemble situation of the TGA-modified Au electrode and optimize some critical parameters for the green electrochemical immunoseonsor. Under the optimal conditions, the developed immunosensor exhibited much lower limit of detection (0.08 ng/mL) in the range of 0.1-1.0 ng/mL for OTA compared with other direct or disposable electrochemical immunosensors. Real application in the spiked malt samples verified high accuracy with no matrix interferences of the proposed immunoseonsor. This is a meaningful study on a self-assembled electrochemical immunoseonsor for ultra-sensitive and rapid detection of OTA in malt samples, which suggested a general simple-to-use sensing platform and prospect as an economical and green tool for ultra-sensitive detection of much more trace-level of toxic small molecules in other complex matrices to ensure their quality and safety.


Assuntos
Ocratoxinas/análise , Poaceae/química , Anticorpos Monoclonais/imunologia , Espectroscopia Dielétrica , Técnicas Eletroquímicas/métodos , Eletrodos , Imunoensaio/métodos
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