Desempenho e estabilidade de biossensor eletroquímico utilizando eletrodos descartáveis para detecção de Salmonella sp. em leite

• Ano de defesa: 2020
• Autor(a) principal: Brito, Francisca Airlane Esteves de
• Tipo de documento: Dissertação
• Tipo de acesso: Acesso aberto
• Idioma: por
• Palavras-chave em Português: Imunossensor; Método de detecção; Validação; Estocagem
• Link de acesso: http://www.repositorio.ufc.br/handle/riufc/52226

Bacteria of the genus Salmonella are pathogenic bacteria associated with foodborne diseases. The form of detection usually employed is laborious and presents high material consumption. Biosensors for Salmonella are alternative methods that have shown promising results. However, the performance theses biosensors have been rarely evaluated in real samples and the storage has been ignored. Thus, the aim of this study was to evaluate the operating parameters and storage conditions of an electrochemical biosensor using disposable electrodes (screen printed) for the detection of Salmonella sp. in milk. For this, at first, the device was evaluated in buffering conditions in the presence of Salmonella Typhimurium ATCC 51812. Subsequently, samples of contaminated raw milk and whole UHT milk were evaluated by reference method (BAM) to detect Salmonella and by the biosensor. The validation parameters were evaluated according to AOAC recommendations and were false positive rate, false negative rate, sensitivity, specificity and probability of detection (POD). The biosensors for the detection of the bacterium were stored for 15, 30, 60, 90 and 120 days in refrigerated condition (4 ºC) and room temperature (25 ºC) in commercial stabilizing solution and formulated stabilizing solution. The biosensor had a high probability of detection, 1 UFC. mL-1 in buffer solution and 10 CFU. mL-1 in raw milk and UHT milk. The comparison with the traditional method allowed the determination of the performance parameters of the biosensor. The results obtained indicated sensitivity of 100%, specificity of 100%, false positive rate and false negative rate were of 0% for the levels of negative control inoculation, 101 UFC.mL-1 and 103 UFC.mL-1. The difference between the two stabilizing solutions and the temperatures evaluated was statistically significant. The best condition found for the storage of the biosensor was in a formulated stabilizing solution and kept under refrigeration (4 ºC). The biosensors stored in this condition showed 5%, 11,87% and 69,81% of loss of amplitude of electric current in 30, 60 and 90 days, respectively. At 120 days, the biosensor stopped qualitatively detecting the pathogen.