TABLE 3.

Modifications of polymeric valves.

Modification	Advantages	Comments	References
HEBP-bounded PU	Enhances resistivity to calcification	HEBP is used as an anti-calcification agents	Lamba, 2017
Cholesterol-modified PU	Improves endothelial cell adhesion	Enhances self-endothelialization by increasing cell affinity, decreases thrombosis formation and enzymatic degradation	Bergmeister et al., 2015
Fiber-reinforced SIBS	Ameliorates hemocompatibility	Improves mechanical features, stability and hemocompatibility	Hossainy et al., 2015
RGD incorporation	Promotes endothelial cell adhesion	Improves cell adhesion and endothelialization and hemocompatibility	Danilucci et al., 2019
PIII	Adjusts surface hydrophobicity	Enhances biocompatibility, weakens foreign body response	Chudinov et al., 2019
Nanotopographic surface	Enhances cellular activity	Might improve cell adhesion, growth, proliferation and differentiation	Zarrintaj et al., 2017
Incorporation of nanomaterials	Enhances mechanical features and durability	Nanoparticles can improve biocompatibility, resistance to calcification and stability	Nilforoushzadeh et al., 2018

HEBP, 2-hydroxyethane bisphosphonic acid; PU, polyurethane; SIBS, Styrene Isoprene Butadiene; RGD, a tripeptide containing arginine, glycine and aspartic acid; PIII, Plasma immersion ion implantation.