The Structural Features of Native Fibrin and Its Conjugates with Polyethylene Glycol and Vascular Endothelial Growth Factor according to Small-Angle X-Ray Scattering

Fibrin is one of the promising biomaterials in tissue engineering for creating favorable conditions for the formation of a capillary-like vascular network. The use of native fibrin is limited due to its rapid degradation and opacity. To improve its properties, including biological ones, various modifications have been proposed, for example, using functionalized polyethylene glycol (PEG). In this work, homobifunctional (O,O''-bis[2-(N-succinimidyl-succinylamino)ethyl])polyethylene glycol of various molecular weights was used to modify fibrin. The modification of fibrin with vascular endothelial growth factor was also analyzed for possible stimulation of the formation of tubule-like structures. Small-angle X-ray scattering (SAXS) data and ab initio modeling of the three-dimensional particle shape showed that PEG–fibrin conjugates consist of filamentous particles, depending on the size of the PEG molecule, the molar ratio of fibrin to PEG, and the presence or absence of vascular endothelial growth factor.