PhD Candidate
GEORGIOS NIKOLAOS PAPPAS
pappas@materials.uoc.gr
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Title
Thermo-responsive biocompatible polymers for temporally-controlled delivery
Supervisor
VAMVAKAKI MARIA, Professor, Materials Science & Technology Dept. - UOC
Committee Members
PASPARAKIS GEORGIOS, ,
KATHARIOS PANTELIS, ,
Abstract
"Smart" responsive polymers are materials that respond to subtle changes of their environment by altering their physicochemical properties in a predetermined manner. External stimuli that have been used to alter the materials’ properties include chemical, physical and biochemical factors, such as the solution pH, light, enzymes, and others. Thermo- responsive polymers are those which alter their solubility in water as a function of the solution temperature. They are divided into two main classes: those which become insoluble in water as the solution temperature increases and possess the so-called lower critical solution temperature (LCST) and those that are insoluble in water at low temperatures and become soluble when increasing the temperature of the solution and exhibit the characteristic upper critical solution temperature (UCST). The LCST or UCST is a characteristic temperature of each thermo-responsive polymer. The use of thermo-sensitive polymers as segments of block copolymers with a second hydrophilic block, such as poly(ethylene glycol), provides block copolymers that can self-assemble into nanostructures (micelles, vesicles, etc.) in aqueous media, as a function of the solution temperature. These thermo-responsive nanostructures can be used for the release of encapsulated substances as a function of the solution temperature, i.e. they can encapsulate a drug at a specific temperature and release it, upon disassembly, at another temperature. The specific objectives of this project, are the synthesis of multifunctional block copolymers that exhibit a well-defined UCST behavior in aqueous solution, while being simultaneously biocompatible and biodegradable to reduce the impact on the organisms and the environment, and the development of thermo-responsive nanocarriers to be applied in the controlled delivery of active substances. After synthesis the materials and nanostructures will be characterized by a range of techniques and the release profiles of model dyes will be investigated as a function of the solution temperature.