Development of electrochemical DNA-based sensors and lmmunosensors for lipid transfer protein allergen detection in tomato seeds ; Development of electrochemical genosensors and immunosensors for lipid transfer protein allergen detection in tomato seeds ; Desenvolvimento de genossensores e imunossensores eletroquímicos para a deteção do alérgeno proteínas transportadoras de lípidos nas sementes do tomate

Dissertação de mestrado em Biophysics and Bionanosystems ; In Mediterranean areas tomato allergy has been dramatically increasing and cross-reactive with other fruit allergies because of the similar protein structure between them. Sola l 7 belongs to the non-specific lipid transfer proteins family and is the major allergen in tomato seeds – being one of the key allergens related with several allergic symptoms namely anaphylaxis. To improve food safety, biosensors have become an excellent device for (bio)chemical analysis, specially the electrochemical biosensors which compete with conventional analytical methodologies. This thesis reports the development of 2 new setups of electrochemical DNA-based sensors for sola l 7 DNA detection, and a new electrochemical immunosensor for sola l 7 protein detection and the implementation of these two procedures in a dual biosensor for simultaneous detection. Functionalized magnetic beads (MBs) was used as immobilization platform for electrochemical DNA-based sensor (DNA magnetobiosensor) and immunosensor (magnetoimmunosensor). The implementation of screen-printed carbon electrodes (SPCEs) as transducer and MBs makes these approaches more attractive because of the increased sensitivity, reduced time of analysis and minimization of matrix effects. A limit of detection (LOD) of 0.2 pM was obtained for the DNA magnetobiosensor whereas a LOD of 1.4 μg mL-1 was obtained in the magnetoimmunosensor. Both approaches were tested in real food extracts without previous amplification or preconcentration of the genetic/protein material – which makes from them reliable and promising analytical tools for food safety and consumer protection. ; Nas áreas mediterrânicas, a alergia ao tomate tem aumentado dramaticamente e é reativa, de forma cruzada, com outras alergias a frutas pela similaridade entre as proteínas. A proteína Sola l 7 pertence à família das proteínas transportadoras de lípidos não específicas e é o principal alérgeno nas sementes do tomate, sendo um dos principais componentes ...