Paper-based Colorimetric Biosensor for Lactose Monitoring

• Autor(a) principal: Pereira, Diogo André Marinha
• Data de Publicação: 2022
• Tipo de documento: Dissertação
• Idioma: eng
• Título da fonte: Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos)
• Texto Completo: http://hdl.handle.net/10362/160342
• topic: Paper-based biosensor; lactose; colorimetric detection; ab-on-paper; microfluidics device; enzyme; Domínio/Área Científica::Engenharia e Tecnologia::Outras Engenharias e Tecnologias

Lactose intolerance has become a significant public health concern over the last few years since it is believed that around 65% to 70% of the world’s population has some form of susceptibility to lactose. In this regard, the global dairy industry has developed ways to produce and deliver dairy products with residual lactose concentrations. Today, the sales of lactose-free dairy products are responsible for around 24.7% of the global allergen-free foods market, representing 13.5 billion dollars USD. However, the cost production of lactose-free dairy products is very expensive. It takes longer than standard dairy goods since these products have to go through a much tighter quality control evaluation and require costly and difficult laboratory techniques, such as gas chromatography, high-performance thin-layer chromatography, mass spectrometry, and nuclear magnetic resonance. Thus, there is an imminent need to create a test that is capable of detecting lactose concentrations in different samples with a high degree of sensitivity, low cost, and ease of handling. Therefore, the major objective of this dissertation is to develop a paper-based colorimetric biosensor capable of measuring lactose quantities in different samples. The paper-based devices were prepared utilizing an environmentally friendly and inexpensive technique known as Lab-on-Paper technology, which uses hydrophobic wax printing to build microfluidic channels. This tool is used in conjunction with an enzyme detection technique based on an oxidation-reduction reaction catalyzed by three enzymes (lactase, glucose-oxidase, and peroxidase), and three colorimetric indicators (AB, KI, and TMB). These paper assays were evaluated using several lactose solutions with various concentrations and applied to assess real milk solutions. Further, these tests were subjected to digital analysis, producing calibration curves that make it easy, quick, and affordable to extrapolate the concentrations in each sample. The final biosensor test developed enables lactose detection in a short period of time ( 10 minutes) and has a production cost of around 0.0094 =C.