Abstract:

Objective Cardiovascular disease (CVD) is a major global health challenge, with deaths continuing to rise each year. Vascular transplantation is an effective means to save lives, and the development of artificial blood vessels to replace damaged blood vessels is of clinical significance. In this research, polyethylene terephthalate (PET) was used as raw material, which was blended with polyvinylpyrrolidone (PVP) for hydrophilic modification, to prepare hydrophilic PET hollow fiber membrane by microfluidic dry jet wet spinning process. Its application potential in the field of small-diameter artificial blood vessels was explored.

Method PET was added to hexafluoroisopropanol to prepare a spinning solution, which also contained PVP with a mass fraction of 2% and different molecular weights. Using the principle of non-solvent phase separation, several groups of different PET hollow fiber membranes were prepared using a dry-jet wet-spinning process. The microporous structure of the synthesized PET hollow fiber membrane was examined via scanning electron microscopy. Mechanical properties of the membrane were evaluated using a universal material testing machine. Hydrophilic performance was measured by means of a contact angle measuring instrument. Cell compatibility was characterized through cell culture experiments.

Results XPS analysis showed that PVP had been successfully incorporated into PET hollow fiber membranes to provide hydrophilic groups. The introduction of PVP improved the uneven pore structure of the PET hollow fiber membrane in cross-section, and formed a cross-sectional morphology with the coexistence of sponge-like and finger-shaped pores, and the average pore size in the cross-section gradually increased to 26.3 μm, and the uniform pore morphology was conducive to the infiltration of endothelial cells. The dynamic water contact angle of the membrane surface reduced to 38.7° after 60 s, with good hydrophilic properties, facilitateing the attachment of endothelial cells. With the increase of the molecular weight of PVP, the tensile strain of the fiber membrane exhibits an initial increase followed by a subsequent decrease, while the tensile stress decreased from 7 MPa to 4 MPa, indicating an improvement in the elasticity of the fiber membrane and the mechanical strength of the membrane was superior to that of natural blood vessels. The membrane surface always showed a negative charge, which was further enhanced by the negative potential of the surface after the introduction of PVP. The negative charge helped repel platelets and plasma proteins, thereby reducing thrombosis. The retention rate of bovine serum albumin (BSA) by the fibrous membrane is more than 50%. The cell activity of the PET hollow fiber membrane group supplemented with PVP was more than 200%, which was better than that of the pure PET hollow fiber membrane and the control group, and PVP enhanced the wettability of the fiber surface, optimized the cell adhesion and proliferation interface, increased the cell anchor position, and promoted the exchange of substances by regulating the fiber surface microenvironment.

Conclusion In this study, PVP and PET were mixed as spinning liquid, and hydrophilic PET hollow fiber membranes were prepared by the dry jet wet spinning process. The introduction of PVP significantly improved the cross-sectional pore structure of PET hollow fiber membrane, which changed from the combination of dense layer and chaotic finger pores to a uniform loose porous morphology, improved the structural stability of the fiber membrane, and the tensile strain is maximally increased to 9.4%. In addition, the improvement of the hydrophilic properties of the fibrous membrane are conducive to the adhesion of endothelial cells, and the electropositivity of the fibrous membrane surface and the enhancement of the electronegativity after the introduction of PVP can weaken the adsorption of negatively charged substances such as platelets and plasma proteins, and reduce the formation of thrombosis. Compared with the control group, the cell activity results were significantly improved, up to 259%, and the hydrophilic PET hollow fiber membrane prepared in this study had a simple process and uniform pores, which provided a certain reference for the development of small-diameter artificial blood vessels.

Key words: small-bore artificial blood vessel, hollow fiber membrane, polyester, dry spray wet spinning, hydrophilic modification, porous structure, medical textiles, polyvinylpyrrolidone