Development and characterisation of biocompatible structures for use in endovascular embolization of intracranial aneurysms

An intracranial aneurysm is a focal dilation and weakening of the arterial blood vessels in the brain. Aneurysms can grow unpredictably, and even small aneurysms (<15 mm) are at risk of rupture, which can cause life-threatening bleeding and brain damage. Although there are surgical and endovascular methods of treating aneurysms, endovascular methods are the most commonly used in the clinic. The aim of endovascular methods is to block the blood flow to the aneurysm, and the most commonly used endovascular treatment in the clinic is endovascular filling using polymer or metal based fillers, coils and fibres. The aim of this study was to develop and characterise biocompatible fillers for use in aneurysm treatment. Biocompatible polymeric structures consisting of micro-nanofibres with a diameter that can pass through the catheter were prepared by electrospinning, taking into account the actual dimensions of the structures used in the clinic. In order to produce the most suitable micro-nanofibre structure, the collector types (iron, brass, etc.), electrospinning system parameters (applied voltage, needle-electrode distance, spiral formation techniques) and polymer material parameters (polymer and solvent type, concentration, etc.) were optimised. As a result of the parameter optimisations, the type of polymer to be used was evaluated as PCL (Polycaprolactone) and tubular structures of different diameters (0.8 mm,1 mm, 2 mm, 3 mm etc.) in PCL micro-nanofibre structure were produced. The PCL micro-nanofibres were then placed in hydrogels prepared with alginate at different viscosities and concentrations to impart swelling properties to the microfibre structures.Within the scope of hydrogel preparation, 3%, w/v alginate solutions prepared at different concentrations were crosslinked with different amounts of CaCl2. Then the hydrogels were dried and their swelling behaviour was investigated in pH 7.4 PBS (Phosphate-buffered saline) solution. The morphological properties of the microstructures of the polymeric fillers were evaluated by SEM and the swelling behaviour of the filler was determined gravimetrically and volumetrically. The mean diameters of the microfibers obtained were measured to be in the range of 2-5 μm. The results of the observed swelling behaviour indicated that all samples showed an increasing swelling trend. The swelling rate increased 5 to 10 times gravimetrically and at least 3 times volumetrically.The tendency of the samples to swell in volume with water uptake also demonstrated the ability to fill and occlude an aneurysm.