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Polyphosphazenes with stimulated degradation pathways / submitted by M.Sc. Aitziber Iturmendi
AutorInnenIturmendi Aguirrebeitia, Aitziber
Beurteiler / BeurteilerinTeasdale, Ian ; Monkowius, Uwe
ErschienenLinz, 2018
Umfangxviii, 160 Blätter ; 31 cm : Illustrationen
HochschulschriftUniversität Linz, Dissertation, 2018
Bibl. ReferenzOebb
Schlagwörter (EN)polyphosphazenes / degradation / photodegradable / water-soluble polymers / biocompatible polymers / visible-light / tissue engineering / scaffolds
Schlagwörter (GND)Polyphosphazene / Degradation / Wasserlösliche Polymere / Biokompatibilität / Histochemie / Licht
URNurn:nbn:at:at-ubl:1-22691 Persistent Identifier (URN)
 Das Werk ist gemäß den "Hinweisen für BenützerInnen" verfügbar
Polyphosphazenes with stimulated degradation pathways [6.7 mb]
Zusammenfassung (Englisch)

Degradable synthetic polymers are of great importance for many applications such as medical applications, as well as environmental reasons. Polymer degradation, based on the cleavage of covalent bonds, is nearly inevitable but it is time limited. Consequently, degradable polymers should be considered as polymers that degrade in specific conditions and within the timescale of the given application. Hence stimulated degradation pathways, in which the degradation process is initiated by an external trigger such as enzymatic, photochemical, and oxidative environments, are attractive tools to control the degradation of polymers. Poly(organo)phosphazenes are hybrid inorganic-organic polymers with a flexible backbone based on alternation of nitrogen and phosphorus atoms. The organic side groups, covalently bonded to the phosphorous atom, can protect the intrinsic hydrolytic backbone and tune the properties and degradation of the polymer. In this work a variety of degradable poly(organo)phosphazenes are described with different properties to make them water soluble but also porous cross-linked scaffolds. Moreover, pH, oxidation, and photochemical triggering systems can be applied to induce and promote the degradation of the polymers. Particularly, amino acid-based poly(organo)phosphazenes are presented with convenient hydrolytic degradation rates, making them attractive for many biomedical applications. Among the studied poly(organo)phosphazenes it has been shown that the degradation was promoted when the glycine amino acid was incorporated between the polymer backbone and the organic substituent. The work described in this thesis focuses on the synthesis of novel poly(organo)phosphazenes with triggered degradation pathways, that is, on stable polymers that degrade upon a certain stimulus. In the first part of the thesis a pH-triggered system is presented, in which degradation rates are increased at lower pH values. Then as potential stimulus also a known reactive oxygen species (ROS), H2O2 has been employed. ROS, generated in the organism as a consequence of aerobic life, can lead to various diseases when it is overproduced. Therefore, H2O2 has been used as an oxidative trigger leading to polymer degradation. As a third stimulus visible light has been applied which could be of particular interest also for many biological applications due to its mild and deeply penetrating wavelengths as well as spatial and temporal control. In the last part of the thesis degradable cross-linked scaffolds with highly interconnected pores are presented which provide special attraction for cell growth in tissue engineering applications.

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