Development of polyester-based biodegradable optical fibres for biomedical applications

Student thesis: Doctoral Thesis

Abstract

Nowadays, optical fibres are commonly used for telecommunication purposes in which a series light pulses are transmitted through optical fibres. Traditionally, optical fibres are made of glass, but in order to expand the application range to the biomedical field, polymer optical fibres (POFs) may be more appropriate.
The aim of this research, being supported by both Ghent University (UGent) and Vrije Universiteit Brussel (VUB), is to synthesize new polyester-based materials suitable for developing biodegradable optical fibres to be used in the biomedical field. First, the polymers targeted should feature adequate light conducting characteristics (with a maximum attenuation of 10 dB cm-1), in order to be suitable to deliver therapeutic light in vivo. Secondly, the materials should reveal a Tg above physiological temperature (and preferably even higher than 60 °C) in order to guarantee mechanical stability upon implantation and to prevent deformation of the materials at body
temperature. Thirdly, they should be processable to enable manufacturing optical fibres from the newly developed materials. Finally, in order to guarantee fibre integration upon in vivo implantation and to limit the possibility on the occurrence of capsule formation (or any other foreign body responses) occurring around an implanted fibre in vivo, an extracellular matrix mimicking layer should be applied in order to create a better match with the human tissue.

To this end, the current PhD research focussed on the development of
materials for new POFs that meet the requirements mentioned above, with the aim of enabling the development of future devices with unprecedented multi-functionality for in vitro and in vivo biomedical applications, such as subcutaneous cell seeding or photodynamic therapy to treat brain tumours. A first part of the present work discussed the synthesis of degradable polymers with tuneable properties in terms of Tg, degradation time and refractive index in order to select an ideal material to be applied as core or
cladding material, with degradation times that can be selected, depending on the desired duration of the envisaged therapy. A second part of the work focussed on the processing of the materials developed herein. However, due to an insufficient molecular weight of the obtained polymers, PDLLA was selected as an ideal alternative degradable polyester for the processing into POFs. Subsequently, the POFs were coated with several ECM-mimicking hydrogel layers to guarantee adequate fibre integration upon implantation.
Finally, a last part of the work focussed on the optical characterisation of the fibres developed herein. These tests revealed that the obtained fibres showed sufficiently low attenuation values, allowing to presume that the POFs would be suitable for the envisaged biomedical applications. The latter was proven 250 via a proof-of-principle experiment in which the potential of using the POFs developed herein as a light delivery tool for photodynamic therapy was
demonstrated.
Date of AwardNov 2019
Original languageEnglish

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