Long term in vitro biostability of segmented polyisobutylene-based thermoplastic polyurethanes

Area of Science:

• Biomaterials science
• Polymer chemistry
• Materials science

Background:

• Thermoplastic polyurethanes (TPUs) are widely used in biomedical applications.
• Assessing the long-term biostability of TPUs is crucial for their in vivo performance.
• Metal ion oxidative degradation (MIO) is a significant factor affecting TPU longevity.

Purpose of the Study:

• To evaluate the in vitro biostability of novel thermoplastic polyurethanes (TPUs) containing mixed polyisobutylene (PIB)/poly(tetramethylene oxide) (PTMO) soft segments.
• To predict the resistance of these TPUs to metal ion oxidative degradation (MIO) in vivo.
• To compare the stability of PIB-based TPUs against commercial TPU controls.

Main Methods:

• Accelerated in vitro aging of TPUs in 20% H(2)O(2) solution with 0.1M CoCl(2) at 50 °C for 12 weeks.
• Analysis of weight loss, tensile strength, molecular weight changes (M(n)), and surface morphology using scanning electron microscopy (SEM).
• Characterization of chemical changes using attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR).

Main Results:

• PIB-based TPUs exhibited significantly higher oxidative stability compared to commercial Pellethane TPUs.
• After 12 weeks, PIB-PTMO TPUs showed 6-10% weight loss, while Pellethane TPUs degraded completely within 9 weeks.
• ATR-FTIR, tensile strength, molecular weight, and SEM analyses confirmed superior biostability and resistance to MIO in PIB-based TPUs.

Conclusions:

• Thermoplastic polyurethanes (TPUs) incorporating PIB/PTMO soft segments demonstrate excellent resistance to metal ion oxidative degradation (MIO).
• These novel PIB-based TPUs offer a promising alternative to conventional TPUs for long-term biomedical applications requiring high biostability.
• The study highlights the potential of PIB-based TPUs for improved performance and longevity in challenging biological environments.