Development of thermoplastic polyurethane vascular prostheses

Abstract

In this study, the optimum electrospinning conditions for a thermoplastic polyurethane/N,N-dimethylformamide solution were sought. Under these conditions, polyurethane tubes for artificial blood vessels were produced via electrospinning, and various properties of the specimen were measured. The optimum electrospinning conditions were a concentration of 16 wt %, a voltage of 13.0 kV, and a tip-to-collector distance of 15 cm at 27 C and 80% relative humidity. The thermal behavior from a differential scanning calorimeter showed that this polyurethane web was thermally stable in the body temperature range. Enzyme hydrolysis of the web revealed that the polyurethane vascular prostheses would perform as nondegradable blood vessels in the body system. The pore size range of the electrospun polyurethane vascular prostheses was 0-3.5 lm. With a tensile stress of about 8-9 MPa and a tensile strain of about 80%, the tensile properties were expected to be superior to those of existing vascular prostheses made of polyester and expanded polytetrafluoroethylene. In the last stage, heparin and collagen were treated on the surfaces of artificial vessels to reduce the probability of thrombi forming during the initial stage of grafting, and so the treated specimens exhibited a lower possibility of thrombi forming than untreated ones in a blood coagulation test.

Electrospinning of thermoplastic polyurethane microfibers and nanofibers from polymer solution and melt

“…They investigated the effects of processing condition (electrical field) and solution properties (concentration, viscosity, and temperature) on the process and properties of electrospun fibers. They found that increasing the voltage resulted in higher flow rate with a relationship of flow rate ∼ (voltage)3. Also, multiple jets were formed instead of one at higher electrical field and the number of jets formed linearly increased with increasing the electrical field.…”

“…Thermoplastic polyurethane (TPU) typically includes 60–85% soft segments and shows desirable properties for particularly medical applications. These properties include elasticity, compatibility with tissue and blood, thrombo resistance, controlled degradation,1 excellent hydrolytic stability, and resistivity to microorganisms and abrasion 2, 3. TPUs are also considered to be a good candidate for ultra‐light protective clothing and synthetic biomaterials such as artificial vascular grafts 3.…”

“…These properties include elasticity, compatibility with tissue and blood, thrombo resistance, controlled degradation,1 excellent hydrolytic stability, and resistivity to microorganisms and abrasion 2, 3. TPUs are also considered to be a good candidate for ultra‐light protective clothing and synthetic biomaterials such as artificial vascular grafts 3. However, such applications require high surface area to volume ratio and small pore sizes that could be obtained using submicron‐to‐nanofibers.…”

Electrospinning of unidirectionally and orthogonally aligned thermoplastic polyurethane nanofibers: Fiber orientation and cell migration

“…TPU belongs to the polyurethane (PU) family and is widely commercially available. It has extensive potential to be used in soft tissue engineering applications such as in wound dressings and vascular grafts . Although aligned PU and PU composite (e.g., PU/carbon nanotube (CNT) and TPU/chitosan/collagen electrospun fibers have been prepared using a rotation drum as the collector, the extent of fiber orientation had a large deviation which might not have been high enough to direct cell migration.…”

“…It has extensive potential to be used in soft tissue engineering applications such as in wound dressings 30 and vascular grafts. 31 Although aligned PU 32 and PU composite (e.g., PU/ carbon nanotube (CNT) 33 and TPU/chitosan/collagen 34 electrospun fibers have been prepared using a rotation drum as the collector, the extent of fiber orientation had a large deviation which might not have been high enough to direct cell migration. Moreover, to the best of our knowledge, no studies have been published that incorporate conductive plates to produce aligned or orthogonal TPU electrospun fibers.…”