RESUMO
A disposable visual microfluidic immunosensor is described for the determination of foodborne pathogens using immunomagnetic separation, enzymatic catalysis and distance indication. Specifically, a sensor was designed to detect Salmonella typhimurium as a model pathogen. Magnetic nanoparticles (MNPs) were modified with the anti-Salmonella monoclonal antibodies and then used to enrich S. typhimurium from the sample. This is followed by conjugation to polystyrene microspheres modified with anti-Salmonella polyclonal antibodies and catalase to form the MNP-bacteria-polystyrene-catalase sandwich. The catalase on the complexes catalyzes the decomposition of hydrogen peroxide to produce oxygen after passing a micromixer. The generated oxygen gas increases the pressure in the chip and pushes the indicating red dye solution to travel along the channel towards the unsealed outlet. The travel distance of the red dye can be visually read and related to the amount of S. typhimurium using the calibration scale. The sensor can detect as low as 150 CFU·mL-1 within 2 h. Graphical abstractSchematic representation of the distance-based microfluidic immunosensor for visual detection of foodborne bacteria using immunomagnetic nanoparticles for bacteria separation, catalase for decomposition of hydrogen peroxide to form oxygen which causes a pressure increase, and red dyed particles movement for distance indication.
Assuntos
Contaminação de Alimentos/análise , Imunoensaio/métodos , Técnicas Analíticas Microfluídicas/métodos , Salmonella typhimurium/isolamento & purificação , Animais , Anticorpos Imobilizados/imunologia , Anticorpos Monoclonais/imunologia , Catalase/química , Galinhas/microbiologia , Peróxido de Hidrogênio/química , Separação Imunomagnética/métodos , Dispositivos Lab-On-A-Chip , Limite de Detecção , Nanopartículas de Magnetita/química , Técnicas Analíticas Microfluídicas/instrumentação , Microesferas , Poliestirenos/química , Salmonella typhimurium/imunologiaRESUMO
In this work, magnetic nanofluid based on a deep eutectic solvent that constricts through a simple and easy route, and subsequently applied for the preconcentration and microextraction of chloramphenicol (CAP) as a hazardous drug from milk and chicken samples via syringe-to-syringe microextraction prior to its determination by high-performance liquid chromatography-ultraviolet (HPLC-UV). In addition, the optimum conditions of effective factors were searched by the central composite design (CCD), and subsequently, at their optimum value, the figures of merit were evaluated. Also, the suggested method illustrated a low limit of detection (0.2 ng mL-1), a low limit of quantitation (0.67 ng mL-1), and a good linear range with an R2 of 0.996. The CAP relative recoveries in milk and chicken samples were 90.3%-95.1%, with relative standard deviations lower than 4.2%. The current enhancement technique is simple, easy, and rapid, which makes it suitable for quantification of CAP by HPLC-UV at trace levels in complicated materials with reliable and reproducible results.
Assuntos
Galinhas , Microextração em Fase Líquida , Animais , Solventes , Cromatografia Líquida de Alta Pressão , Solventes Eutéticos Profundos , Leite , Fenômenos Magnéticos , Microextração em Fase Líquida/métodos , Limite de DetecçãoRESUMO
In this study, we produced a sensitive and specific monoclonal antibody (mAb) against diclazuril based on a new hapten. The mAb, which belongs to the IgG2 subclass, had a 50%-inhibitory concentration of 0.36â¯ng/mL. A cross reactivity test revealed that the mAb had good specificity for diclazuril. A gold nanoparticle-based lateral-flow strip was assembled for the rapid screening of diclazuril in raw chicken breast and thigh samples. The strip assay had a visual limit of detection (LOD) of 2⯵g/kg and a cut-off value of 20⯵g/kg for diclazuril in chicken samples when evaluated with the naked eye. With the aid of a strip scan reader, the proposed assay obtained a quantitative measurement for diclazuril with an LOD of 1.08⯵g/kg. Therefore, this gold nanoparticle-based lateral-flow strip assay represents a potentially useful tool for on-site detection and rapid initial screening of diclazuril in chicken samples.
Assuntos
Nanopartículas Metálicas , Nitrilas/análise , Triazinas/análise , Animais , Anticorpos Monoclonais/imunologia , Galinhas , Ouro , Limite de Detecção , Fatores de TempoRESUMO
This work presents a colorimetric dye-based array for naked-eye detection of chicken meat spoilage. The array is obtained by fixing five acid-base indicators, m-cresol purple (1), o-cresol red (2), bromothymol blue (3), thymol blue (4), and chlorophenol red (5), and a sensing molecule specific for thiols, 5,5'-dithiobis(2-nitrodibenzoic acid), called Ellman's reagent (6), on a cellulose-based support. The dyes, being permanently charged, are fixed on the support via ion-exchange. The entire degradation process of beast poultry meat, at ambient temperature and in a domestic fridge, is followed by the change of the color of the array, placed in the headspace over the meat samples. The device is set after selection of the most suitable starting form, which could be the acidic or the basic color of indicators, being the proper dye concentration and the dimension of the spots already established. Basing on sensors colors, we identified three levels of the degradation process of chicken meat, named SAFE, WARNING, and HAZARD. By instrumental analysis, we demonstrated that sensors response was correlated to volatile organic compounds (VOCs) composition in the headspace and, thus, to meat spoilage progress. We demonstrated that biogenic amines (BAs), commonly considered a critical spoilage marker, are indeed produced into the samples but never present in the headspace, even in traces, during the investigated time-lapse. The VOC evolution nevertheless allows one to assign the sample as WARNING and further HAZARD. Some indicators turned out to be more informative than others, and the best candidates for a future industrial application resulted in a bromothymol blue (3)-, chlorophenol red (5)-, and Ellman's reagent (6)-based array.
Assuntos
Corantes/análise , Carne/análise , Animais , Azul de Bromotimol/análise , Galinhas , Cor , Colorimetria , Análise de Alimentos/instrumentação , Análise de Alimentos/métodos , Inocuidade dos Alimentos , Fenolsulfonaftaleína/análogos & derivados , Fenolsulfonaftaleína/análise , Timolftaleína/análogos & derivados , Timolftaleína/análise , Compostos Orgânicos Voláteis/análiseRESUMO
Here we report a novel ultrasensitive surface-enhanced Raman scattering (SERS) immunosensor based on the flower-like gold nanoparticles (AuNFs) and magnetic bead separation for homogeneous detection of amantadine (AMD) in chicken just by one-step. The 5, 5'-dithiobis (2-nitrobenzoicacid) (DTNB) modified AuNFs and N-(1-adamantyl) ethylenediamine (AEDA) conjugated denatured BSA (AEDA-dBSA) was used as the SERS nanoprobe. And the capture probe was anti-AMD monoclonal antibody (mAbs)-functionalized magnetic beads (MNBs-mAbs). An immunoreaction occurred between free AMD and SERS nanoprobe for competing limited binding sites of MNBs-mAbs. This work combined inherent sensitive property of SERS with antibody-antigen highly specificity recognition for the AMD detection. The analytical results showed that the SERS-based immunosensor was sensitive, simple and reliable with a limit of detection (LOD) of 0.005â¯ng/mL for AMD, which were 2 orders of magnitude better than an enzyme-linked immunosorbent assay based on the same immunoreagents. Analysis of AMD-spiked chicken samples revealed that the developed immunosensor provided accepted recoveries ranging from 74.76%-89.34% with coefficient of variation less than 15.04%. This strategy represents a simple, reliable, and universal approach for detection of chemical contaminants in food samples.
Assuntos
Amantadina/análise , Técnicas Biossensoriais , Ouro/química , Nanopartículas Metálicas/química , Animais , Galinhas , Limite de Detecção , Análise Espectral RamanRESUMO
The aim of this study was to compare an enzyme-linked fluorescent assay (ELFA)-based and two real-time polymerase chain reaction (PCR) methods with the results of the standard culture-based method EN ISO 6579:2002 (bacteriological standard method used in the European Union) for the detection of Salmonella spp. in raw chicken meat. Our investigations were performed on 141 poultry samples sorted from supermarkets. Relative accuracy, relative specificity and relative sensitivity were determined. According to the ISO 16140:2003 criteria for validation of alternative microbiological methods, the ELFA-based method (VIDAS ICS2 + SLM), and real-time PCR methods (TaqMan, Bax) were comparable to the reference standard method for the detection of Salmonella spp. in chicken meat. The use of these methods provide results within 48 hours with high sensitivity (100%). The TaqMan real-time PCR showed a relative specificity of 98% and both of the real-time PCR methods presented 100%.The VIDAS ICS2 + SLM and the Bax real-time PCR methods showed the highest relative accuracy (100%) and 99% in case of the TaqMan method. In conclusion, both the real-time PCR and the ELFA-based assay can be used as a rapid and user-friendly diagnostic method for detection of Salmonella spp. in chicken meat samples.