RESUMO
In the study, we investigated the practicality of the UV polymerization of aniline for anti-aflatoxin B1 antibody immobilization, and utilization of the resulting biosensor in the impedimetric determination of aflatoxin B1. The anti-aflatoxin B 1 antibody was physically immobilized on gold electrodes by UV polymerization of aniline at a fixed wavelength. The biosensor was based on specific interaction anti-aflatoxin B1 - aflatoxin B1 recognition and investigation of this recognition event by electrochemical impedance spectroscopy. A calibration curve was obtained in a linear detection range 1-20 ng/mL aflatoxin B1. Finally, the biosensor was applied to analysis of a real food sample.
Assuntos
Aflatoxina B1/análise , Compostos de Anilina/síntese química , Anticorpos Imobilizados/química , Anticorpos Monoclonais/química , Técnicas Biossensoriais , Doenças Transmitidas por Alimentos/etiologia , Aflatoxina B1/efeitos adversos , Aflatoxina B1/imunologia , Compostos de Anilina/metabolismo , Reações Antígeno-Anticorpo , Calibragem , Espectroscopia Dielétrica/métodos , Estudos de Viabilidade , Análise de Alimentos , Doenças Transmitidas por Alimentos/prevenção & controle , Humanos , Polimerização/efeitos da radiação , Raios UltravioletaRESUMO
A low-cost and sensitive amperometric biosensor was developed for the determination of α-amylase activity. The biosensor was constructed by immobilizing glucose oxidase-gelatin via glutaraldehyde on the Au electrode surface. Measurements were carried out chronoamperometrically at -0.7 V. Several parameters such as glucose oxidase activity, gelatin amount, and glutaraldehyde percentage for cross-linking were optimized. Optimum pH, optimum temperature, repeatability, and storage stabilities of the biosensor were identified. Under the optimum experimental conditions, a linear calibration curve was obtained for α-amylase between 0.819 and 13.110 U/ml. Sample analyses were carried out by detecting α-amylase activities in baker's yeast samples.
Assuntos
Técnicas Biossensoriais/métodos , Eletroquímica/métodos , Ouro/química , alfa-Amilases/metabolismo , Aspergillus niger/enzimologia , Bacillus subtilis/enzimologia , Eletrodos , Enzimas Imobilizadas/química , Enzimas Imobilizadas/metabolismo , Glucose/metabolismo , Glucose Oxidase/química , Glucose Oxidase/metabolismo , Glutaral/metabolismo , Concentração de Íons de Hidrogênio , Hidrólise , Modelos Lineares , Oxigênio/metabolismo , Amido/metabolismo , Propriedades de Superfície , TemperaturaRESUMO
A glucose oxidase-based biosensor was developed for the determination of α-amylase activity. The determination method is based on monitoring the decrease in dissolved oxygen concentration related to the starch concentration, for which starch gives a reaction with α-amylase. Optimization parameters, including glucose oxidase amount, gelatin amount, and glutaraldehyde percentage for cross-linking, were investigated. The effects of pH, buffer system, and temperature on the biosensor system were also investigated. The biosensor had a linear relation to α-amylase activity and good measurement correlation between 0.66 and 9.83 U/ml. In sample analysis studies, α-amylase activity in baker's yeast was determined by the biosensor.
Assuntos
Técnicas Biossensoriais/instrumentação , Técnicas Biossensoriais/métodos , Técnicas de Química Analítica , Enzimas Imobilizadas/metabolismo , Glucose Oxidase/metabolismo , Oxigênio/análise , Amido/metabolismo , alfa-Amilases/metabolismo , Reagentes de Ligações Cruzadas/química , Eletroquímica , Eletrodos , Gelatina/química , Glucose/metabolismo , Glutaral/química , Concentração de Íons de Hidrogênio , Oxigênio/metabolismo , Reprodutibilidade dos Testes , Sensibilidade e Especificidade , Temperatura , Leveduras/químicaRESUMO
The present work describes the construction and application of a new DNA biosensor for detection of aflatoxin M1. In order to immobilize a thiol-modified single stranded DNA (ss-HSDNA) probe that specifically bound aflatoxin M1, a self-assembled monolayer of cysteamine and gold nanoparticles on the SAM were prepared on gold electrodes, layer-by-layer. The assembly processes of cysteamine, gold nanoparticles, and ss-HSDNA were monitored with the help of electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV) techniques. K3[Fe(CN)6]/K4[Fe(CN)6] solution was used as a redox probe for electrochemical measurements. The biosensor provided a linear response to aflatoxin M1 over the concentration range of 1-14 ng/mL with a standard deviation of ±0.36 ng/mL. Finally, the biosensor was applied to a series of real milk samples.