Oligo(ethylenglycol)acrylat Mikrogele zur Herstellung neuer Biomaterialien

• Oligo(ethylene glycol)acrylate microgels as building blocks for new biomaterials

Melle, Andrea; Pich, Andrij (Thesis advisor); Fabry, Marlies (Thesis advisor)

Aachen (2017)
Dissertation / PhD Thesis

Dissertation, RWTH Aachen University, 2017

Abstract

In the last decades investigation on colloidal aqueous microgels has awaken the interest of many research groups due to their manifold application possibilities e.g. in the biomedical field as triggered drug release system or as protein repellent coating material. The most well-known monomers used for the synthesis of temperature-responsive microgels are N-isopropylacrylamide (NIPAAm) or N-vinylcaprolactam (VCL). However, considering the toxicity of PNIPAAm, alternative monomers with similar, but biomedical friendly properties should be selected. An interesting group of monomers which fulfill all the requirements are oligo(ethylene glycol)acrylates (OEGAs) since they are temperature-sensitive and highly biocompatible. Accordingly, the aim of this thesis is to synthesize and characterize new OEGA based microgels, to investigate the biomedical properties of these microgels and to fabricate new materials out of them.The first part of the thesis focuses on the synthesis and characterization of different oligo(ethylene glycol)acrylate (OEGA) microgels by using the following OEGAs: 2-methoxy ethyl acrylate (MEA), di(ethylene glycol)ethyl ether acrylate (DEGA) and tri(ethylene glycol)ethyl ether acrylate (TEGA). The homopolymerization of the OEGAs to POEGA microgels is investigated in the first step followed by the copolymerization of the OEGAs with VCL in a one-step and two-step synthesis, respectively. Moreover, post-modification of these microgels is achieved by incorporation of functional groups like acrylic acid (AA) or glycidyl methacrylate (GMA). For all systems the influence of the comonomer content on the microgel properties like particle size distribution, hydrodynamic radius, temperature sensitivity and microgel morphology is investigated. The second part of the thesis is based on the investigation of biomedical properties of the PVCL/OEGA microgels. Therefore the hemocompatibility of the PVCL/OEGA microgels is studied in the first place due to its importance for biomedical applications. Then the internalization of PVCL/MEA microgels into HeLa-cells via unspecific interactions is confirmed and no cytotoxicity of the PVCL/MEA microgels towards HeLa-cells can be observed. This property makes these microgels reliable as drug carrier system for cancer therapy. The last part of the thesis contains the investigation of the film-forming properties of the PVCL/OEGA microgels. The protein repellence of the homogenous microgel films is proved qualitatively and quantitatively why the PVCL/OEGA microgels could be used as coating materials for implants and catheters. Also the cytotoxicity of the microgel films towards fibroblasts is proved to be negative which again confirms the biocompatibility of the PVCL/OEGA microgels.