Paper as a Colorimetric Biosensing Platform for Tetracyclines Detection in Milk

• Autor(a) principal: Pagará, Beatriz Condeço Pinto
• Data de Publicação: 2018
• Tipo de documento: Dissertação
• Idioma: eng
• Título da fonte: Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos)
• Texto Completo: http://hdl.handle.net/10362/61057
• topic: Tetracycline antibiotics; colorimetric assay; gold nanoparticles; paper-based biosensors; milk; Domínio/Área Científica::Engenharia e Tecnologia::Engenharia dos Materiais

Tetracyclines are a type of antibiotic that exhibits activity against most gram-positive and gram-negative bacteria. These antibiotics are often added at subtherapeutic levels to feed to act as growth promoters. Due to its low bioavailability, only a fraction of the antibiotic is metabolized in animals, causing waste. These residues can enter human bodies through the food chain and lead to increased antimicrobial resistance, causing allergic or toxic reactions, which led several countries to implement a maximum level of residues for this type of antibiotic. Most methods of detecting TCs are time consuming or inadequate for field analysis. In this way, an inexpensive, easy-to-execute and fast analytical method is required. In this sense, in the present work a colorimetric biosensor was developed in paper for the detection of four type of tetracyclines, presenting an alternative in the performance of point-of-care tests. Paper is low-cost, abundant, biodegradable and easy to dispose of by incineration. The construction of the sensors was performed using Lab-on-Paper technology and is based on the synthesis of gold nanoparticles by reducing a gold salt in which tetracyclines constitute the reducing agent itself. Different concentrations of TCs result in the formation of different colour intensities. Different concentrations of tetracyclines were tested and analysed using ImageJ software, allowing linear calibration lines to be obtained, that relate the concentration of antibiotics in a range between 0.1 and 10 μg/mL and the arithmetic mean of the RGB channels. Validation tests of the sensors developed with TC in milk were also performed. It was observed that it is possible to detect this type of antibiotic in pre-treated milk, and four forms of milk treatment were studied.