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1.
Food Chem ; 307: 125645, 2020 Mar 01.
Artigo em Inglês | MEDLINE | ID: mdl-31644983

RESUMO

A simple electrochemical sensor was developed to determine the concentration of Ca2+ in meat. Graphene was treated with oxygen plasma for 10 s and 30 s comparing with the pristine graphene. Through analyzing morphology and chemical composition, the graphene with the lowest defect density was chosen to mix with bovine serum albumin molecule-functionalized gold nanoparticles. It was interesting that only a few gold nanoparticles were trapped in the graphene with 10 s plasma treatment. Then, under the optimal condition measured, the limit of detection was detected as 3.9 × 10-8 M with a linear relationship from 5 × 10-8 to 3 × 10-4 M. Finally, the proposed electrochemical method was applied to detect Ca2+ in the pork sample with stability and reproducibility verified by parallel detections. Thus, the proposed method demonstrates its potential for effectively detecting Ca2+ in meat and prominently reduces time consumption on operations and pretreatments.


Assuntos
Técnicas Biossensoriais/instrumentação , Cálcio na Dieta/análise , Técnicas Eletroquímicas/métodos , Carne/análise , Nanopartículas Metálicas/química , Técnicas Biossensoriais/métodos , Cálcio na Dieta/metabolismo , Ouro/química , Grafite/química , Limite de Detecção , Reprodutibilidade dos Testes , Troponina C/metabolismo
2.
Food Chem ; 305: 125389, 2020 Feb 01.
Artigo em Inglês | MEDLINE | ID: mdl-31520918

RESUMO

A sensitive analytical method for the monitoring 2-methylimidazole and 4-methylimidazole (2-MI and 4-MI) is desirable due to their carcinogenic property. Here, we propose a highly sensitive method basing on the combination of solid-phase extraction and dispersive liquid-liquid microextraction techniques followed by high-performance liquid chromatography to simultaneously determine 2-MI and 4-MI in beverages. Dansyl chloride was used as a derivatizing reagent. Microextraction parameters were optimized by Plackett-Burman design and response surface methodology. Results show that derivatization led to significant improvements in chromatographic behavior for 2-MI and 4-MI due to increased hydrophobicity. The method shows good linearity (R2 ≥ 0.9985), satisfactory precision (%RSD ≤ 8.3%) and low limit of quantification (20 ng/mL), and was successfully applied to determine 2-MI and 4-MI in carbonated drinks, beers and energy drinks, achieving satisfactory recoveries (85-101%). This method provides a potential for routine analysis of 2-MI and 4-MI at the nanogram per milliliter level in beverages.


Assuntos
Bebidas/análise , Cromatografia Líquida de Alta Pressão/métodos , Imidazóis/análise , Microextração em Fase Líquida/métodos , Extração em Fase Sólida/métodos , Compostos de Dansil , Limite de Detecção
3.
Biosci Biotechnol Biochem ; 84(1): 43-52, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31495297

RESUMO

To date, studies on the application of loop-mediated isothermal amplification (LAMP) in the detection of genetically modified organisms (GMOs) are stably increasing and demonstrates LAMP is a potential and promising method for on spot identification of GMOs. However, little information is known for detection of GM potato events by LAMP. In this report, we developed an optimized and visual LAMP assay with high specificity and sensitivity to rapidly amplify genomic DNA of potato EH92-527-1 within 45 min. The limit of detection of LAMP in our study is 10-fold higher than the conventional PCR. Furthermore, LAMP products can be directly observed via naked eyes by addition of SYBR Green I without gel electrophoresis analysis and PCR-based equipment. Therefore, the LAMP assay developed in this paper provides an efficient, convenient and cost-effective tool for the detection of GM potato EH92-527-1.


Assuntos
DNA de Plantas/genética , Plantas Geneticamente Modificadas/genética , Reação em Cadeia da Polimerase/instrumentação , Reação em Cadeia da Polimerase/métodos , Solanum tuberosum/genética , Sequência de Bases/genética , Percepção de Cores , Primers do DNA/genética , Enzimas de Restrição do DNA/genética , Eletroforese em Gel de Ágar , Corantes Fluorescentes/química , Contaminação de Alimentos/análise , Amplificação de Genes , Limite de Detecção , Compostos Orgânicos/química , Reação em Cadeia da Polimerase/economia , Sensibilidade e Especificidade , Temperatura Ambiente , Tempo
4.
Chemosphere ; 240: 124951, 2020 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-31574445

RESUMO

A high demand exists in human biomonitoring studies for reliable and straightforward methods that generate data faster and simultaneously. Thus, the present study combines microextraction by packed sorbent (MEPS) and liquid chromatography coupled to mass spectrometry (LC-MS/MS) for simultaneous extraction and determination of various classes of endocrine-disrupting chemicals (EDCs), including parabens, benzophenones, bisphenols, and the antimicrobial, triclocarban in human urine samples. Optimized MEPS conditions were: i) MEPS sorbent (C18), ii) pH of sample (3), iii) volume of sample (250 µL), iv) number of draws-eject cycles (5) and (vi) desorption solvent conditions (100 µL of CH3OH:H2O 80:20 v/v). The calibration curves were linear over the selected ranges for all studied compound, with correlation coefficients higher than 0.99. The variation coefficient for precision was lower than 20% at lower concentrations and lower than 15% at the higher concentrations studied. The accuracy ranged from 90% to 118%. The proposed strategy affords several advantages over currently published approaches, including simplicity of operation and reduction of sample and solvent volumes and time for matrix clean-up. Moreover, the analytical performance of each MEPS cartridge remained stable over the analysis of at least 70 samples (RSD < 10%). Thus, the current procedure may be an interesting high-throughput alternative for large routine human biomonitoring studies. Urinary geometric mean concentrations of EDCs obtained in this study were close than those previously reported for Brazilian children.


Assuntos
Compostos Benzidrílicos/urina , Benzofenonas/urina , Carbanilidas/urina , Disruptores Endócrinos/urina , Parabenos/análise , Fenóis/urina , Brasil , Calibragem , Criança , Cromatografia Líquida de Alta Pressão/métodos , Cromatografia Líquida , Humanos , Limite de Detecção , Microextração em Fase Sólida/métodos , Espectrometria de Massas em Tandem/métodos
5.
Food Chem ; 305: 125487, 2020 Feb 01.
Artigo em Inglês | MEDLINE | ID: mdl-31518839

RESUMO

QuEChERS and switchable solvent liquid phase microextraction (SS-LPME) were respectively used as pretreatment and preconcentration tools to allow trace determination of selected organochlorine pesticides and hormones by gas chromatography mass spectrometry (GC-MS). The effects of principal SS-LPME variables and their interactions were evaluated with a Box-Behnken experimental design. The limits of detection obtained by direct GC-MS determination were enhanced by about 33-115 folds under the optimized SS-LPME conditions. The SS-LPME method was applied to tap water, well water, lake water, medical wastewater and tea samples. Satisfactory recovery results were obtained for all but the tea samples using the conventional calibration plot. Matrix matched calibration standards were used to improve the percent recovery of analytes to almost 100% in the tea samples. The combined QuEChERS and SS-LPME method was applied to tomato samples and matrix matching was also used to significantly improve analyte recoveries.


Assuntos
Cromatografia Gasosa-Espectrometria de Massas/métodos , Hormônios/análise , Hidrocarbonetos Clorados/análise , Microextração em Fase Líquida/métodos , Praguicidas/análise , Solventes/química , Ondas Ultrassônicas , Hormônios/isolamento & purificação , Hidrocarbonetos Clorados/isolamento & purificação , Limite de Detecção , Praguicidas/isolamento & purificação , Águas Residuárias/química , Poluentes Químicos da Água/análise , Poluentes Químicos da Água/isolamento & purificação
6.
Food Chem ; 306: 125455, 2020 Feb 15.
Artigo em Inglês | MEDLINE | ID: mdl-31629968

RESUMO

The present research reported a facile strategy for the synthesis of a novel magnetic covalent organic frameworks (Fe3O4@COF(TpDA)) material and applied it as a sorbent for magnetic solid phase extraction of plant growth regulators from fruits and vegetables. The prepared Fe3O4@COF materials showed many attractive features involving large specific surface area (180.2 m2/g) and high saturation magnetization (62.3 emu/g), which enabled it an ideal sorbent for sample pretreatment. The experimental conditions affecting the extraction performance were optimized systematically, including eluent, amount of sorbent, adsorption time and desorption time. The extracted samples were detected by HPLC-DAD. Under the optimized conditions, the proposed method exhibited good linearity (R ≥ 0.9990) and low limits of detection (4.68-7.51 µg/L). Satisfactory recoveries were calculated to be 83.0-105.0%. Finally, the proposed method was successfully applied to determination of plant growth regulators in fruits and vegetables, indicating the potential prospect of the Fe3O4@COF(TpDA) materials in sample pretreatment.


Assuntos
Frutas/química , Estruturas Metalorgânicas/análise , Reguladores de Crescimento de Planta/análise , Verduras/química , Cromatografia Líquida de Alta Pressão/métodos , Limite de Detecção , Magnetismo/métodos , Imãs , Extração em Fase Sólida/métodos
7.
Bioelectrochemistry ; 131: 107352, 2020 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-31494386

RESUMO

The designed synthesis of efficient materials can significantly enhance the performance of electrochemical immunoassay in the detection of diseases, pesticide residues and environmental pollutants. The hollow AgPt@Pt core-shell nanoparticles (AgPt@Pt HNs) have exhibited high catalytic efficiency to the hydrogen peroxide (H2O2) reduction for its high mass activity from their hollow structure. Their limitation of instability can be overcome by loading on polypyrrole nanosheet (PPy NS). Besides, PPy NS exhibits good conductivity, and there exists environmentally-friendly method for its synthetic. Thus, AgPt@Pt HNs loaded on PPy NS (AgPt@Pt HNs/PPy NS) exhibits high catalytic efficiency to the reduction of H2O2 and good stability. Furthermore, the quick electron transfer of AgPt@Pt HNs/PPy NS modified glassy carbon electrode has been evidenced by the finding that the large constant of apparent electron transfer rate has also enlarged the current signal when the amount of electron is invariant. The modified electrode has fabricated a label-free amperometric immunosensor to detect sensitively prostate-specific antigen (PSA) with H2O2 as the electroactive material. The immunosensor in hollow core-shell nanosheet structure exhibiting good detection performance of PSA shows its promising applications in the clinical diagnosis.


Assuntos
Técnicas Biossensoriais , Eletrodos , Ouro/química , Nanopartículas Metálicas/química , Nanoestruturas/química , Platina/química , Polímeros/química , Pirróis/química , Biomarcadores Tumorais/análise , Catálise , Peróxido de Hidrogênio/química , Limite de Detecção , Oxirredução , Antígeno Prostático Específico/análise
8.
Bioelectrochemistry ; 131: 107373, 2020 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-31525638

RESUMO

Smart electrochemical biosensors have emerged as a promising alternative analytical diagnostic tool in recent clinical practice. However, improvement in the biocompatibility and electrical conductivity of the biosensor matrix and the immobilization of various bioactive molecules such as enzymes still remain challenging. The present research reports the synthesis of a biocompatible hydrogel network and its integration with gold nanocubes (AuNCs) for developing a novel biosensor with improved functionality. The interpenetrating hydrogel network consist of biopolymers developed using graft co-polymerization of ß-cyclodextrin (ß-CD) and chitosan (CS). The novelty of this work is in integrating the CS-g-ß-CD hydrogel network with conductive AuNCs for improving hydrogel conductivity, biosensor sensitivity and use of the material for a biocompatible sensor. The present protocol advances the state of the art for the utilization of biopolymeric hydrogels system in synergy with an enzymatic biosensing protocol for exclusively detecting hydrogen peroxide (H2O2). Immobilization of the mitochondrial protein, cytochrome c (cyt c) into the hydrogel nanocomposite matrix was performed via thiol cross-linking. This organic-inorganic hybrid nanocomposite hydrogel matrix exhibited high biocompatibility (RAW 264.7 and N2a cell lines), improved electrical conductivity to attain high sensitivity (1.2 mA mM-1 cm-2) and a low detection limit (15 × 10-9 M) for H2O2.


Assuntos
Materiais Biocompatíveis/química , Técnicas Eletroquímicas/métodos , Ouro/química , Hidrogéis/química , Peróxido de Hidrogênio/análise , Nanoestruturas/química , Limite de Detecção
9.
Bioelectrochemistry ; 131: 107392, 2020 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-31707277

RESUMO

A flexible acetylcholinesterase (AChE) film biosensor, based on a AuNPs-MoS2-reduced graphene oxide/polyimide flexible film (rGO/PI) electrode, has been synthesized for paraoxon detection. In this study, the rGO/PI film acts as the flexible substrate and AuNPs are reduced by monolayer MoS2 under illumination. Transmission electron microscopy revealed that AuNPs are uniformly dispersed on the MoS2-rGO/PI electrode surface with a diameter ~10nm. X-ray photoelectron spectroscopy indicated that a strong binding force exists between reduced AuNPs and monolayer MoS2. The AChE modified AuNPs-MoS2-rGO/PI flexible film biosensor is used to hydrolyze acetylcholine chloride and obtain a large current response at 0.49V by differential pulse voltammetry, demonstrating successful immobilization of AChE. In view of the inhibition of paraoxon on the AChE, under optimal conditions, the AChE/AuNPs-MoS2-rGO/PI film biosensor shows a linear response over a concentration range 0.005-0.150µg/mL, a sensitivity of 4.44 uA/µg/mL, a detection limit of 0.0014µg/mL, acceptable reproducibility and stability to paraoxon. The flexible film biosensor has also proved used for detection of paraoxon in real samples.


Assuntos
Acetilcolinesterase/metabolismo , Técnicas Biossensoriais , Dissulfetos/química , Ouro/química , Grafite/química , Inseticidas/análise , Molibdênio/química , Nanopartículas/química , Paraoxon/análise , Limite de Detecção
10.
Food Chem ; 305: 125486, 2020 Feb 01.
Artigo em Inglês | MEDLINE | ID: mdl-31520920

RESUMO

The formation of 3-methyl-2,4-nonanedione (MND) during red wine aging can contribute to the premature evolution of aroma, characterized by the loss of fresh fruit and development of dried fruit flavors. The identification of two new hydroxy ketones, 2-hydroxy-3-methylnonan-4-one (syn- and anti-ketol diastereoisomers) and 3-hydroxy-3-methyl-2,4-nonanedione (HMND), prompted the investigation of the precursors and pathways through which MND is produced and evolves. An HS-SPME-GC-MS method was optimized for their quantitation in numerous must and wine samples, providing insight into the evolution of MND, HMND, and ketols through alcoholic fermentation and wine aging. Alcoholic fermentation resulted in a significant decrease in MND and HMND and the simultaneous appearance of ketol diastereoisomers. The analysis of 167 dry red wines revealed significant increases in MND and anti-ketol contents through aging and a significant positive correlation between MND and anti-ketols. Additional experiments demonstrated that ketols are precursors to MND during red wine oxidation.


Assuntos
Alcanos/química , Diacetil/análogos & derivados , Sucos de Frutas e Vegetais/análise , Cetonas/análise , Vinho/análise , Alcanos/metabolismo , Diacetil/química , Diacetil/metabolismo , Etanol/química , Cromatografia Gasosa-Espectrometria de Massas , Humanos , Concentração de Íons de Hidrogênio , Cetonas/isolamento & purificação , Limite de Detecção , Microextração em Fase Sólida , Estereoisomerismo , Fatores de Tempo
11.
Food Chem ; 305: 125456, 2020 Feb 01.
Artigo em Inglês | MEDLINE | ID: mdl-31525594

RESUMO

This work developed a new technique and an application of an existing approach to determine sodium in food sauces, involving enthalpimetric reactions in the infrared. Infrared Thermometric Titration (TT-IR) was utilized, with simple analyzers and low-cost measurement instruments for the acquisition of the surface temperature generated in the sodium precipitation reaction and development of software for the acquisition and processing of data using Raspberry Pi. The sodium was also quantified by Thermal Infrared Enthalpimetry (TIE), a recently developed technique. The rapid and simple quantification of sodium by the TT-IR and TIE showed the possibility of a selective reaction for sodium, using aluminum nitrate, potassium and ammonium fluoride in an acid medium, with reduction of the reagents and without the digestion step in the sample preparation. The results acquired through TT-IR and TIE corroborated the Flame Atomic Emission Spectrometry (FAES) with 96 to 103% and 95 to 102%, respectively.


Assuntos
Análise de Alimentos/métodos , Raios Infravermelhos , Sódio/análise , Produtos Vegetais/análise , Compostos de Alumínio/química , Limite de Detecção , Nitratos/química , Sódio/química , Espectrofotometria Atômica , Temperatura Ambiente , Termometria/métodos
12.
Food Chem ; 308: 125590, 2020 Mar 05.
Artigo em Inglês | MEDLINE | ID: mdl-31644970

RESUMO

A novel fluorescent nanoprobe was for the first time developed for the efficient detection of ferrocyanide ions ([Fe(CN)6]4-) based on nitrogen (N), sulfur (S) and chlorine (Cl) co-doped carbon nanoparticles (N,S,Cl-CNPs). The N,S,Cl-CNPs were fabricated through a simple and ultrafast acid-base neutralization method. The sensing mechanism was based on the quenching effect of [Fe(CN)6]4- on the fluorescence emission of N,S,Cl-CNPs via dynamic interaction. The N,S,Cl-CNPs were found to show high selectivity and sensitivity towards [Fe(CN)6]4- detection with two good linear relationships were achieved in the concentration ranges of 0.01-1.0 µg/mL and 1.0-50.0 µg/mL, respectively, and the detection limits are as low as 3.3 and 21.8 ng/mL, respectively. The proposed fluorescence method was successfully applied for [Fe(CN)6]4- analyses in food samples with high accuracy. The results of this study indicate the great application prospects of N,S,Cl-CNPs for [Fe(CN)6]4- detection in complex food matrix.


Assuntos
Carbono/química , Ferrocianetos/análise , Nanopartículas , Cloro/química , Ferrocianetos/química , Fluorescência , Análise de Alimentos , Limite de Detecção , Nitrogênio/química , Espectrometria de Fluorescência/métodos , Enxofre/química
13.
J Sci Food Agric ; 100(2): 811-816, 2020 Jan 30.
Artigo em Inglês | MEDLINE | ID: mdl-31617212

RESUMO

BACKGROUND: Natamycin is often added to pastries, cheeses, and beverages. The residual amount of natamycin should be less than 10 mg kg-1 . The current method for its determination in various foodstuffs is high-performance liquid chromatography (HPLC). Capillary electrophoresis (CE) is a simple, fast, and environmentally friendly method with low reagent consumption and comparable separation performance. However, no reports were found on the determination of natamycin in foods by CE. A CE method to determine natamycin is therefore sought. RESULTS: Natamycin in foods was determined by the capillary zone electrophoresis (CZE) method with ultraviolet-visible (UV) detection. Separation conditions were optimized as 20 mM Na2 HPO4 , pH 9.2, with 25 kV applied voltage, and UV detection at 306 nm. Under optimal conditions, electrophoretic analysis was completed in less than 4 min, with a limit of detection (LOD) of 0.065 µg mL-1 and limit of quantitation (LOQ) of 0.22 µg mL-1 . A good linear relationship (r2 = 0.999) was obtained at the range of 0.1-25 µg mL-1 . A comparison with the HPLC-UV method was also carried out according to the National Standards of the People's Republic of China. CONCLUSION: The results obtained by the CZE and HPLC methods are comparable but the proposed CZE method can help us obtain a shorter detection time at low cost. © 2019 Society of Chemical Industry.


Assuntos
Bebidas/análise , Queijo/análise , Cromatografia Líquida de Alta Pressão/métodos , Eletroforese Capilar/métodos , Conservantes de Alimentos/análise , Natamicina/análise , China , Limite de Detecção
14.
J Sci Food Agric ; 100(2): 874-884, 2020 Jan 30.
Artigo em Inglês | MEDLINE | ID: mdl-31680264

RESUMO

BACKGROUND: The low cost of aminoglycoside (AMG) antibiotics facilitates their excessive use in animal husbandry and the agriculture sector. This scenario has led to the occurrence of residues in the food chain. After several years of AMG use in antibacterial therapy, resistance to streptomycin has begun to appear. Most of the detection methods developed for AMG antibiotics lacks specificity. A broad target specific nanoprobe would be ideal for detecting the entire class of AMGs. A rapid and sensitive method for the detection of AMGs is urgently needed. RESULTS: Gallic acid-coated silver nanoparticles (AgNPs) were demonstrated as a nanoprobe for the colorimetric detection of AMGs (yellow to orange / red). A linear dynamic range of 50-650 pmol L-1 was achieved readily by ratiometric spectrophotometry (A560 /A400 ) with a limit of detection (LOD) as low as 36 pmol L-1 . The amine-groups of the AMGs function as molecular linkers, so that electrostatic coupling interactions between neighboring particles drive the formation of AgNP aggregates. The assay can also be applied for the determination of streptomycin residues in serum and milk samples. CONCLUSION: This study revealed the potential of an AgNP probe for the rapid and cost-effective detection of low-molecular-weight target analytes, such as the AMGs. A ligand-induced aggregation of AgNPs coated with gallic acid was reported to be a rapid and sensitive assay for AMGs. Analysis of streptomycin was demonstrated with excellent picomolar-level sensitivity. Thus, the validated method can find practical applications in the ultrasensitive detection of AMGs in complex and diagnostic settings. © 2019 Society of Chemical Industry.


Assuntos
Antibacterianos/análise , Colorimetria/métodos , Resíduos de Drogas/análise , Leite/química , Soro/química , Estreptomicina/análise , Água/química , Animais , Antibacterianos/farmacologia , Bovinos , Colorimetria/instrumentação , Limite de Detecção , Nanopartículas Metálicas/química , Prata/química
15.
Food Chem ; 307: 125526, 2020 Mar 01.
Artigo em Inglês | MEDLINE | ID: mdl-31648172

RESUMO

Effective management of mycotoxins rely on stringent regulation and routine surveillance of food/feed commodities via efficient analysis, hence the continuous need for improved methods. The present study developed, optimized and validated a modified pressurized hot water extraction (PHWE) method for the simultaneous extraction of multi-mycotoxins from maize and subsequent quantification on LC-MS/MS. The PHWE system was modified using ethanol (EtOH) as a cosolvent, while a numerical modelling approach, the central composite design (CCD), was adopted for the optimization of the extraction conditions. Using the optimized method, it was possible to effectively extract and quantify 15 different mycotoxins from maize in a single step with satisfactory linearities (0.986-0.999), recoveries (14-124%) and other associated method validation parameters. Further efficacious application of the method to real samples re-affirmed the prospects of PHWE as a suitable, cost-effective and greener alternative to traditional methods of mycotoxin extraction.


Assuntos
Micotoxinas/análise , Água/química , Zea mays/metabolismo , Cromatografia Líquida de Alta Pressão , Temperatura Alta , Limite de Detecção , Micotoxinas/isolamento & purificação , Pressão , Reprodutibilidade dos Testes , Espectrometria de Massas em Tandem
16.
Food Chem ; 307: 125527, 2020 Mar 01.
Artigo em Inglês | MEDLINE | ID: mdl-31648179

RESUMO

We report on a sensitive and fast quantitative MALDI-MS/MS method used to assess saffron authenticity by direct analysis through the determination of picrocrocin as the saffron authenticity marker, and using curcumin as the non-isotopic isobaric internal standard. The internal standard curcumin yielded good linearity (R2 = 0.994), and with confidence intervals at 95% for intercept. The detectable maximum adulteration percentage (99.0%) was estimated interpolating the limit of detection (LOD) for the isobaric internal standard in linear regression. The LOD was 47.63 ppm, and LOQ was 56.53 ppm. Good accuracy and precision were obtained for all concentrations. The capability of the MS approach to monitor analytes in a specific, selective fashion was used to obtain a semi-quantitative adulteration percentage and to establish the adulterant by additional experiments. The detection of gardecin and its derivatives in commercial samples indicated that Gardenia jasminoides Ellis was used as the adulterant.


Assuntos
Crocus/química , Cicloexenos/análise , Glucosídeos/análise , Espectrometria de Massas por Ionização e Dessorção a Laser Assistida por Matriz/métodos , Terpenos/análise , Calibragem , Curcumina/química , Cicloexenos/normas , Glucosídeos/normas , Limite de Detecção , Modelos Lineares , Espectrometria de Massas por Ionização e Dessorção a Laser Assistida por Matriz/normas , Terpenos/normas
17.
Food Chem ; 307: 125528, 2020 Mar 01.
Artigo em Inglês | MEDLINE | ID: mdl-31648181

RESUMO

Simple, rapid, convenient, and economical surface enhanced Raman scattering (SERS) substrate is developed for on-site evaluation of Aflatoxin B1 (AFB1) in food matrix using handheld Raman Spectrometer. Self-assembly of gold nanobipyramids (Au NBPs) into the nanoholes of anodic aluminum oxide (AAO) template/pattern using 'drop-dry' approach provides a reliable pathway for the rapid fabrication of highly active and uniform SERS substrate. It shows enhanced and reproducible SERS signals towards the probe molecule, 4-aminothiophenol (4-ATP) with a relative standard deviation (RSD) of less than 10% and an average enhancement factor (EF) of 1 × 108. For practical application, the proposed method is demonstrated for the detection of aflatoxin B1 (AFB1) in peanut extracts. The results show that the AFB1 in peanut extracts can be identified within 1 min, with a limit of detection of 0.5 µg/L. Compared with conventional ELISA based AFB1 analysis, our method is much more efficient (1 min versus >30 min).


Assuntos
Aflatoxina B1/análise , Arachis/química , Nanoestruturas/química , Extratos Vegetais/química , Análise Espectral Raman/métodos , Óxido de Alumínio/química , Arachis/metabolismo , Ouro/química , Limite de Detecção
18.
J Agric Food Chem ; 67(46): 12936-12944, 2019 Nov 20.
Artigo em Inglês | MEDLINE | ID: mdl-31670953

RESUMO

An ultrasensitive bio-barcode competitive immunoassay method based on droplet digital polymerase chain reaction (ddPCR) was developed for the determination of triazophos. Gold nanoparticles (AuNPs) were coated with monoclonal antibodies (mAbs) and complementary double-stranded DNA (dsDNA), which included bio-barcode DNA and thiol-capped DNA. Magnetic nanoparticle (MNP) probes were constructed by modifying the MNPs with ovalbumin-hapten conjugates (OVA-hapten). The target pesticide and OVA-hapten on the surface of the MNP probes competed with the AuNP probes simultaneously, and then the bio-barcode DNA was released for quantification by ddPCR. The concentration of released DNA was inversely proportional to the concentration of pesticide to be tested. Under the optimum conditions, the competitive immunoassay exhibited a wide linear range of 0.01-20 ng/mL and a low detection limit of 0.002 ng/mL. Spike recovery tests were carried out using apple, rice, cabbage, and cucumber samples to verify the feasibility of the method. The recovery and relative standard deviations (RSDs) of the technique ranged from 76.9 to 94.4% and from 10.8 to 19.9%, respectively. To further validate the results, a linear correlation analysis was performed between the proposed method and liquid chromatography-tandem mass spectrometry (LC-MS/MS). Consequently, the bio-barcode immunoassay based on nanoparticles and ddPCR, an ultrasensitive method, showed great potential for the determination of target pesticides in real samples.


Assuntos
Imunoensaio/métodos , Inseticidas/análise , Organotiofosfatos/análise , Reação em Cadeia da Polimerase/métodos , Triazóis/análise , DNA/genética , Ouro/química , Imunoensaio/instrumentação , Limite de Detecção , Magnetismo/métodos , Nanopartículas Metálicas/química
19.
Zhongguo Xue Xi Chong Bing Fang Zhi Za Zhi ; 31(5): 468-473, 2019 Oct 16.
Artigo em Chinês | MEDLINE | ID: mdl-31713373

RESUMO

OBJECTIVE: To establish a recombinase aided isothermal amplification (RAA) assay for detection of Clonorchis sinensis. METHODS: The 18S ribosomal RNA (18S rRNA) sequence of C. sinensis was used as the target sequence, and specific primers and probes were designed, synthesized and screened to establish a rapid fluorescent RAA assay for the detection of C. sinensis. Then, the sensitivity of the fluorescent RAA assay was evaluated using the recombinant plasmids containing various copy numbers of DNA fragments and C. sinensis genomic DNA at various concentrations, and the specificity of the fluorescent RAA as say was evaluated using the genomic DNA of Ascaris lumbricoides, Echinococcus granulosus, Schistosoma japonicum, Ancylostoma duodenale and S. mansoni as templates. DNA samples were extracted from the feces containing C. sinensis eggs and freshwater fish containing metacercaria for the fluorescent RAA assay, and the performance for detection of C. sinensis-infected samples was preliminarily assessed in the field. RESULTS: A fluorescent RAA assay for detection of C. sinensis was successfully established, which was feasible for specific amplification of C. sinensis genomic DNA at 39 °C within 20 min. The lowest detection limit was 10 copies/µL if the recombinant plasmid containing various copy numbers of DNA fragments was used as a template, and the lowest detection limit was 3 pg/µL if the C. sinensis genomic DNA at various concentrations served as a template. All detections were negative if the genomic DNA of A. lumbricoides, E. granulosus, S. japonicum, A. duodenale, and S. mansoni was used as templates. In addition, the fluorescent RAA assay showed a high performance for the detection of C. sinensis-infected samples in the field, which successfully detected C. sinensis-infected human and rat fecal samples and Pseudorasbora parva samples. CONCLUSIONS: A fluorescent RAA assay is successfully established, which is simple, rapid, sensitivity and specific for detection of C. sinensis.


Assuntos
Clonorquíase , Clonorchis sinensis , Técnicas de Amplificação de Ácido Nucleico , Ácidos Nucleicos , Animais , Clonorquíase/diagnóstico , Clonorchis sinensis/genética , Primers do DNA , Fezes/parasitologia , Humanos , Limite de Detecção , Parasitologia/métodos , Ratos , Recombinases/metabolismo , Sensibilidade e Especificidade
20.
Chem Commun (Camb) ; 55(92): 13932-13935, 2019 Nov 14.
Artigo em Inglês | MEDLINE | ID: mdl-31686058

RESUMO

In this work, a bipedal DNA walker was employed to mediate an efficient enzyme-free exponential isothermal DNA signal amplification. On the basis of the bipedal DNA walker mediated enzyme-free exponential isothermal signal amplification, an electrochemiluminescence (ECL) biosensor was constructed for sensitive and rapid detection of microRNA (miRNA) with a limit of detection down to 0.24 fM and requiring less than 40 min.


Assuntos
Técnicas Biossensoriais/métodos , DNA/química , MicroRNAs/análise , Linhagem Celular Tumoral , Complexos de Coordenação/química , DNA/metabolismo , Humanos , Limite de Detecção , Medições Luminescentes , Nanopartículas Metálicas/química , Hibridização de Ácido Nucleico , Rutênio/química , Titânio/química
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