Bio-inspired anisotropic polymeric heart valves exhibiting valve-like mechanical and hemodynamic behavior

Abstract

Native heart valve leaflets with layered fibrous structures show anisotropic characteristics, allowing them to withstand complex mechanical loading for long-term cardiac cycles. Herein, two types of silk fibroin (SF) fiber membranes with anisotropic (ASF) and isotropic (ISF) properties were prepared by electrospinning, and were further combined with poly(ethylene glycol) diacrylate (PEGDA) hydrogels to serve as polymeric heart valve (PHV) substitutes (PEGDA-ASF and PEGDA-ISF). The uniaxial tensile tests showed obvious anisotropy of PEGDA-ASF with elastic moduli of 10.95±1.09 and 3.55±0.32 MPa, respectively, along the directions parallel and perpendicular to the fiber alignment, while PEGDA-ISF possessed isotropic property with elastic moduli of 4.54± 0.43 MPa. The PHVs from both PEGDA-ASF and PEGDA-ISF presented appropriate hydrodynamic properties from pulse duplicator tests according to the ISO 5840-3 standard. However, finite element analysis (FEA) revealed the anisotropic PEGDA-ASF valve showed a lower maximum principle stress value (2.20 MPa) in commissures during diastole compared with that from the isotropic PEGDA-ISF valve (2.37 MPa). In the fully open state, the bending area of the PEGDA-ASF valve appeared in the belly portion and near the attachment line like native valves, however, which was close to free edges for the PEGDA-ISF valve. The Gauss curvature analysis also indicated that the anisotropic PEGDA-ASF valve can produce appropriate surface morphology by dynamically adjusting the movement of bending area during the opening process. Hence, anisotropy of PHVs with bio-inspired layered fibrous structures played important roles in mechanical and hydrodynamic behavior mimicking native heart valves.

Transcatheter Heart Valves: A Biomaterials Perspective

“…Textile fabric leaflets have faced criticisms because of their increasing rate of biofouling, bacterial infection, thrombogenesis, and extreme regurgitation flow through the pores; [ 79 ] to mitigate the complications mentioned above, the textile materials were coated with poly (ethylene glycol) diacrylate (PEGDA) (Figure 6). [ 79,143 ] In one experiment, the polyester–nylon knitted fabric was wrapped around a stent and immersed in PEGDA solution to crosslink the polymers. [ 79 ] SEM image revealed that PEGDA had covered the surface of the fabric and filled the pores.…”

“…In another experiment, anisotropic silk fiber membranes coated with PEGDA had a 10 MPa elastic modulus along the fiber direction and 3.5 MPa in the transverse direction. [ 143 ] PEGDA‐coated silk fiber membranes were made into three leaflets and sutured together around a stent. From an in vitro study, this valve showed a large EOA (2.6 cm 2 ) but high RF (20%).…”

Recent progress in biomaterials for heart valve replacement: Structure, function, and biomimetic design

“…With the rapid development of material science, polymeric aortic valves are considered to be a competitive candidate for the aortic valve prosthesis that could eliminate shortcomings of the existing artificial heart valves. 2,3,20,46,[69][70][71][72][73][74][75][76][77][78] Researchers have been trying to develop ideal polymeric heart valve for decades. Trace back to the 1960s, the first polymeric heart valve has been implanted into the human body.…”

“…Another example takes the anisotropic properties of native valves into consideration. Guo et al 69 reported a bioinspired polymeric fabricated heart valve by assembling electrospinning silk fibroin membranes with PEDGA hydrogel. In this study, two types of silk fibroin membranes -isotropic silk fibroin (ISF) membrane and directional aligned silk fibroin (DSF) membrane -were prepared with a baffle receiver and a rotating cylindrical receiver, respectively.…”

Bio-inspired hydrogel-based bandage with robust adhesive and antibacterial abilities for skin closure

“…However, the problem of microbial invasion caused by the weak integration between the hydrogel and wound, and the wound infection caused by the bacterial incubated in moist wound environment urgently need to be addressed [13,22,30]. In recent years, most solutions are based on hydrogel as the carrier to deliver antibacterial or silver nanoparticles [31][32][33]. However, inadequate stewardship of antibiotics can lead to antibiotics resistance, and the safety of silver ions is not clear [4,34].…”