Shape-memory materials implantable devices

Stimuli-responsive polymers have gained increasing interest and served in a vast number of medical and/or pharmaceutical applications such as implants, medical devices or controlled drug delivery systems, enzyme immobilization, immune-diagnosis, sensors, sutures, adhesives, adsorbents, coatings, contact lenses, renal dialyzers, concentration and extraction of metals, for enhanced oil recovery, and other specialized systems (Chen and Hsu 1997 Chen et al. 1997 Wu and Zhou 1997 Yuk et al. 1997 Bayhan and Tuncel 1998 Tuncel 1999 Tuncel and Ozdemir 2000 Hoffman 2002 en and Sari 2005 Fong et al. 2009). Some novel applications in the biomedical field using stimuli-responsive materials in bulk or just at the surface are shape-memory (i.e., devices that can adapt shape to facilitate the implantation and recover their conformation within the body to... 

In this chapter, we focus on recent efforts to design and fabricate soft shape-memory materials, including both polymeric and supramolecular systems. We first classify these materials based on their micro- and nanostructure (Section 5.2.2). We then highlight how soft shape-memory materials have been applied to biomedical applications as implantables (Section 5.2.3.1), drug delivery devices (Section 5.2.3.2), and tissue engineering scaffolds (Section 5.2.3.3). In addition, we briefly discuss future trends for utilizing soft shape-memory materials for biomedical applications (Section 5.2.4). 

Conductive polymer nanocomposites may also be used in different electrical applications such as the electrodes of batteries or display devices. Linseed oil-based poly(urethane amide)/nanostuctured poly(l-naphthylamine) nanocomposites can be used as antistatic and anticorrosive protective coating materials. Castor oil modified polyurethane/ nanohydroxyapatite nanocomposites have the potential for use in biomedical implants and tissue engineering. Mesua ferrea and sunflower seed oil-based HBPU/silver nanocomposites have been found suitable for use as antibacterial catheters, although more thorough work remains to be done in this field. ° Sunflower oil modified HBPU/silver nanocomposites also have considerable potential as heterogeneous catalysts for the reduction of nitro-compounds to amino compounds. Castor oil-based polyurethane/ epoxy/clay nanocomposites can be used as lubricants to reduce friction and wear. HBPU of castor oil and MWCNT nanocomposites possesses good shape memory properties and therefore could be used in smart materials. ... 

Once an SMP device is implanted within the body and fully activated, the device ceases to be shape-memory and should have the properties of a typical polymer-based device and are subject to all the same long-term performance concerns. Obviously, long-term biocompatibility and carcinogenicity are a concern of implantable polymeric materials however, mechanical properties of polymers with respect to water absorption and biodegradation will be discussed for the remainder of this chapter. 

The third group includes thermoresponsive polymers. The strategy to apply magnetic induction to these materials allows the development of both implantable and shape-memory devices (Thevenot et al. 2013). 

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