Desenvolvimento de um biossensor para a detecção de antibióticos β-lactâmicos no leite crú
Arquivos
Data
2012-04-25
Autores
Prado, Thiago Martimiano do [UNESP]
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Editor
Universidade Estadual Paulista (Unesp)
Resumo
O presente trabalho mostra o desenvolvimento do primeiro biossensor descrito na literatura para determinação de antibióticos β-lactâmicos, usando pasta de carbono modificada com a enzima β-lactamase, e sua aplicação em amostras de leite de vaca in natura. A partir de estudos prévios de otimização da preparação do biossensor, o grafite em pó foi ativado com carbodiimida para permitir a ligação covalente da enzima β-lactamase que, junto com o mediador de elétrons ftalocianina de cobalto ofereceram variações na corrente catódica na presença da penicilina G, sendo esta escolhida para representar os antibióticos β-lactâmicos. Utilizando este procedimento para a construção dos biossensores, foi possível registrar voltamogramas cíclicos e amperogramas que permitiram quantificar a benzilpenicilina (penicilina G) em condições de análise também otimizadas, que incluíram estudo da quantidade de mediador na pasta; o pH, tipo e concentração do eletrólito usado para realização das medidas e o potencial aplicado na amperometria. Com o método otimizado foi possível detectar penicilina G em amostras de leite in natura, fortificadas com o antibiótico, com alta exatidão (erro relativo de 1%) e boa precisão (desvio padrão relativo de 8,3%, n = 3), mostrando que o biossensor desenvolvido é uma ferramenta promissora para detecção de penicilinas, e que ao serem realizados mais estudos para diminuir seu limite de quantificação, poderá se tornar uma um método de análise alternativo aos kits comerciais existentes
This work describes the development of the first biosensor described in the literature for the determination of β-lactam antibiotics using a carbon paste electrode modified with the enzyme β-lactamase, and its application in samples of fresh cow's milk. After optimizing the biosensor preparation procedure, the graphite powder was activated with carbodiimide to allow covalent binding of the enzyme β-lactamase, which together with the electron mediator, cobalt phthalocyanine, offered variations in cathodic currents in the presence of penicillin G, which was chosen as representative of the β-lactam antibiotics. Using this procedure for the construction of biosensors, it was possible to record cyclic voltammograms and amperograms that enabled quantification of benzylpenicillin (penicillin G) under analytical conditions that had been optimized in terms of the amount of mediator in the paste, the pH, the type and concentration of the electrolyte used in the measurements, and the applied amperometric potential. With the optimized method, it was possible to detect penicillin G in samples of fresh milk fortified with the antibiotic, with high accuracy (error of 1%) and adequate precision (RSD of 8.3%, n=3), demonstrating that the proposed biosensor is a promising tool for the detection of penicillins. Once quantitation limits have been further improved, the analytical method could become an alternative to existing commercial kits
This work describes the development of the first biosensor described in the literature for the determination of β-lactam antibiotics using a carbon paste electrode modified with the enzyme β-lactamase, and its application in samples of fresh cow's milk. After optimizing the biosensor preparation procedure, the graphite powder was activated with carbodiimide to allow covalent binding of the enzyme β-lactamase, which together with the electron mediator, cobalt phthalocyanine, offered variations in cathodic currents in the presence of penicillin G, which was chosen as representative of the β-lactam antibiotics. Using this procedure for the construction of biosensors, it was possible to record cyclic voltammograms and amperograms that enabled quantification of benzylpenicillin (penicillin G) under analytical conditions that had been optimized in terms of the amount of mediator in the paste, the pH, the type and concentration of the electrolyte used in the measurements, and the applied amperometric potential. With the optimized method, it was possible to detect penicillin G in samples of fresh milk fortified with the antibiotic, with high accuracy (error of 1%) and adequate precision (RSD of 8.3%, n=3), demonstrating that the proposed biosensor is a promising tool for the detection of penicillins. Once quantitation limits have been further improved, the analytical method could become an alternative to existing commercial kits
Descrição
Palavras-chave
Quimica analitica, Biossensores, Penicilina, Analytical chemistry, Biosensors, Penicillin
Como citar
PRADO, Thiago Martimiano do. Desenvolvimento de um biossensor para a detecção de antibióticos β-lactâmicos no leite crú. 2012. 75 f. Dissertação (mestrado) - Universidade Estadual Paulista, Instituto de Química, 2012.