Author(s):
Encarnação, João Miguel 
Date: 2007
Persistent ID: http://hdl.handle.net/10400.1/590
Origin: Sapientia - Universidade do Algarve
Subject(s): Teses; Biotecnologia; Bio-sensores
Document details
Development of biosensors for molecular analysis
Description
Tese dout., Ciências Biotecnológicas, Universidade do Algarve, 2007 This thesis deals with the application of piezoelectric sensors, namely quartz crystal microbalances (QCM), for the study of molecular interactions and for biomedical purposes. Piezoelectric transduction allows the detection of biorecognition events and its operation depends on the mechanical vibration of the crystal whose resonance frequency is sensible to surface mass changes. But in liquid medium these sensors also respond to the properties of solutions and adsorbed films. Thus, a major aspect explored in this thesis is the expansion of the physical understanding of the behavior of these sensors in liquid medium and also how organic or biological layers can affect the results and their interpretation. This was achieved using impedance analysis where the behavior of the piezoelectric sensor is interpreted with the help of equivalent electric RLC circuits. The potential electroacoustic interference of charged species in solution was particularly studied and a new equivalent circuit is proposed in order to detect and quantify these effects with the assistance of impedance analysis. The efficiency of the key steps taken for the development of our QCM system, was experimentally demonstrated with the qualitative and quantitative analysis of the process of ii 11-hydroxy-1-undecanothiol SAMs (self-assembled monolayers) formation and the recognition of streptavidin in aqueous medium using biotin modified sensors. Finally the work was focused on the development of a new detection tool for the HIV1 virus using piezoelectric immunosensors based on recombinant antibodies to detect the Vif molecule (virion infectivity factor). The developed immunosensors selectively detected Vif in aqueous solutions and presented specificity and good sensibility when detecting the target protein in complex samples like mixtures of proteins and cell extracts.
Tese dout., Ciências Biotecnológicas, Universidade do Algarve, 2007 This thesis deals with the application of piezoelectric sensors, namely quartz crystal microbalances (QCM), for the study of molecular interactions and for biomedical purposes. Piezoelectric transduction allows the detection of biorecognition events and its operation depends on the mechanical vibration of the crystal whose resonance frequency is sensible to surface mass changes. But in liquid medium these sensors also respond to the properties of solutions and adsorbed films. Thus, a major aspect explored in this thesis is the expansion of the physical understanding of the behavior of these sensors in liquid medium and also how organic or biological layers can affect the results and their interpretation. This was achieved using impedance analysis where the behavior of the piezoelectric sensor is interpreted with the help of equivalent electric RLC circuits. The potential electroacoustic interference of charged species in solution was particularly studied and a new equivalent circuit is proposed in order to detect and quantify these effects with the assistance of impedance analysis. The efficiency of the key steps taken for the development of our QCM system, was experimentally demonstrated with the qualitative and quantitative analysis of the process of ii 11-hydroxy-1-undecanothiol SAMs (self-assembled monolayers) formation and the recognition of streptavidin in aqueous medium using biotin modified sensors. Finally the work was focused on the development of a new detection tool for the HIV1 virus using piezoelectric immunosensors based on recombinant antibodies to detect the Vif molecule (virion infectivity factor). The developed immunosensors selectively detected Vif in aqueous solutions and presented specificity and good sensibility when detecting the target protein in complex samples like mixtures of proteins and cell extracts.
Document Type
Doctoral Thesis
Language English
Advisor(s) Ferreira, Guilherme; Stallinga, Peter
Language English
Advisor(s) Ferreira, Guilherme; Stallinga, Peter
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