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Identifier 000290075
Title Σταθεροποίηση βιομορίων σε νανοδομές για την ανάπτυξη βιοαισθητήρων
Author Βαμβακάκη, Βασιλική Δημητρίου
Thesis advisor Χανιωτάκης, Νίκος
Abstract Biosensors have been under development for over 30 years while research in this field has become very popular the last 15. Severa; drawbacks have impeded the large-scale application and performance of biosensors as reliable analytical instruments. Some of the major obstacles in the biosensor systems success are the low sensitivity, their bad sensor-to-sensot reproducibility, as well as the limited operational and storage stability. Of these, the operational and storage stability of the biosensor is the most critical issue, since controlling the stability of the biological recognition element is very difficult. The biological recognizing systems, such as enzymes and antigens, are from their nature not very stable in a biosensor membrane environment, since they are sensitive to denaturation or inactivation by either fluctuations in the pH, the temperature, as well by the presence of organic solvents and detergents usually employed for the construction of a biosensor. Different approaches have been utilized to improve enzyme stability, including genetic engineering, chemical modification, inclusion of additives and immobilization to various matrices. Genetic engineering involves the optimization of enzyme structures by changing the amino acid sequence. Chemical modifications intend to change the properties of the enzymes by adding functional groups or polymers on their surface, increasing their rigiditym and thus their stability. Additives such as electrolytes, polyelectrolytes and polyols control the water content at the vicinity of the enzymes and generate a cage around the enzymes in order to protect them from denaturation, and improve their stability. At the same time immobilization of enzymes on inorganic, organic or polymeric matrices by simple adsorption, covalent bonding or entrapment is shown to be an efficient stabilization method that increases the rigidity of the enzyme preventing the possibility to unfold and deactivate. Recent advances in the field of nanotechnology has enabled the development and evaluation of nano-systems based on novel nanomaterials that offer new directions in the field of bio-analytical systems. Nanomaterials with at least one of their critical dimesions in the range of 100 nanometers, display unique physical and chamical characteristics, playing an increasingly important role in the development of biosensors. Their high surface ratio, catalytic activity and electron transfer properties make them ideal immobilization matrices, transduction platforms and mediators.
Language Greek
Issue date 2006-12-20
Collection   Faculty/Department--Faculty of Sciences and Engineering--Department of Chemistry--Doctoral theses
  Type of Work--Doctoral theses
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