|
Author Artigues Cladera, Margalida Esmeralda |
Abstract Electrochemical biosensors are analytical devices that combine the specificity of biochemical recognition processes with the analytical power of electrochemical techniques. Consequently, it is possible to perform rapid, sensitive and reliable determinations of different analytes present in complex samples. For this reason, the use of biosensors is an alternative to classical analytical methods to perform quality control processes in different industrial sectors. In this work, we have developed enzymatic amperometric biosensors based on the immobilization of oxidases on an electrochemical interface of highly ordered titanium dioxide nanotubes array (TiO2NTAs). Thus, processes of enzyme immobilization based on polymeric entrapment and covalent immobilization have been studied. The analytical parameters of these biosensors have been evaluated. For polymeric entrapment processes, kappa-carrageenan, 2-hydroxyethyl methacrylate (HEMA) and chitosan have been studied as immobilization matrices. These hydrogels have been used for the immobilization of the enzyme glucose oxidase (GOx) and it has been observed that both, HEMA and chitosan, generate a favorable microenvironment for the conservation of the activity of the enzyme. For covalent immobilization, pentafluorophenylmethacrylate (PFM) has been used in order to generate bonds between the enzyme molecules and the surface of the transducer. Thus, the electrochemical interface TiO2NTAs has been modified by two plasma techniques: polymerization of PFM and grafting of the same polymer. It has been observed that the polymerized surface of PFM (ppPFM) has a higher hydrophobicity than the surface in which the PFM has been grafted (pgPFM). Hydrophobicity has influence on the adopted enzyme molecules conformation. On the ppPFM surface, conformations with low activity predominate, and on the pgPFM surface most of the population of GOx molecules adopt conformations with catalytic activity. For these reasons, the biosensors with plasma grafted PFM show higher sensitivity in presence of glucose than the biosensors based on the PFM polymerization. Finally, amperometric glucose and glutamate biosensors with polymeric and covalent immobilization matrices have been developed: Ti/TiO2NTAs/GOx/Chitosan, Ti/TiO2NTAs/HEMA-co-EGDA/pgPFM/GOx/Chitosan and Ti/TiO2NTAs/GmOx/Chitosan. These biosensors have been used to determine the glucose and glutamate content in different food samples. The results have been compared with those obtained with reference techniques. |
|
|
Director Colominas Fuster, Sergi |
||
|
Department IQS SE - Química Analítica i Aplicada |
||
|
Date of defense 2019-10-25
|
