Polyurethanes biomedical devices

Polyurethanes were first suggested for use as biomaterials in 1967 [36]. Polyurethane materials have excellent mechanical properties, making them suitable for many different biomedical applications. Currently, a variety of polyurethanes are used in biomedical devices like coatings for catheters and pacemaker leads (Table A.2). The biocompatibility of biomedical polyurethanes appears to be determined by their purity i.e., the effectiveness of the removal from the polymer of catalyst residues and low molecular weight oligomers [37]. The surface properties of commercially available polyurethanes, which are critically important in determining biocompatibility, can vary considerably, even among lots of the same commercially available preparation [38]. 

Huang, W. M. 2010. Thermo-moisture responsive polyurethane shape memory polymer for biomedical devices. The Open Medical Device Journal 2 11-19. 

Recent publications describe the effects of silica on the conductivity and mechanical properties of a polyethylene oxide/ammonium bifluoride complex containing propylene carbonate [36], as a foam stabilizer in polyester polyurethane foams, and on the properties of polylactic acid nanocomposites prepared by the sol-gel technique [37] (see also Chapter 24), on the mechanical properties and permeability of i-PP composites [38], on the surface hardness of polymers for biomedical devices [39], on enhanced properties of polymer interlayers that are used in multiple layer glazing panels [40]. 

Das B et al (2013) Bio-based hyperbranched polyurethane/Fe304 nanocomposites smart antibacterial biomaterials for biomedical devices and implants. Biomed Mater 8(3) 035003... 

Biomedical polyurethanes have also been modified with organically modified layered silicates (OLS) to improve mechanical properties and reduce gas permeability. Xu et al. [26] demonstrated an increase in tensile modulus with increased OLS concentration without the loss of strength and ductihty that is typical for filler systems. Additionally, they observed a fivefold decrease in water vapor permeability, which is a major advantage for blood-contacting biomedical devices. 

In this chapter and the one that follows, we will review the research concerning the uses of polyurethanes in biomedical applications. Such uses range from topical application of hydrophilic polyurethane pads to the implantation of scaffolds of reticulated foam as organ-assist devices. The range of applications is broad and each use requires that specific problems associated be addressed. This chapter begins with a discussion of biocompatibility — a broad concept ranging from the simple nonir-ritating characteristics required for topical applications to the complex type of compatibility (hemocompatibility) that allows use with whole blood. 

In-Vivo Percutaneous Implant Experiment. The principle of percutaneous attachment has extensive application in many biomedical areas, including the attachment of dental and orthopedic prostheses directly to skeletal structures, external attachment for cardiac pacer leads, neuromuscular electrodes, energy transmission to artificial heart and for hemodialysis. Several attempts to solve the problem of fixation and stabilization of percutaneous implants(19) have been made. Failures were also attributed to the inability of the soft tissue interface to form an anatomic seal and a barrier to bacteria. In the current studies, the effect of pore size on soft tissue ingrowth and attachment to porous polyurethane (PU) surface and the effect of the flange to stem ratio and biomechanical compliance on the fixation and stabilization of the percutaneous devices have been investigated.(20)... 

As we shall see in Chapter 15, polyurethane is a polymer of choice for a wide variety of biomedical applications. Polyurethane is used extensively in the construction of devices such as vascular prostheses, membranes, catheters, plastic surgery, heart valves, and artificial organs. Polyurethanes are also used in drug delivery systems such as the sustained and controlled delivery of pharmaceutical agents, for example, caffeine and prostaglandin. ... 

TABLE 7.1 List of Published Patents for Drug Delivery, Tissue Engineering, and Medical Devices Using Biomedical Polyurethanes ... 

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. ... 

D Annis, T V How, A C Fisher, Recent Advances in the Development of Artificial Devices to Replace Diseased Arteries in Man A New Elastomeric Synthetic Artery. In Polyurethanes in Biomedical Engineering, Planck H, Egbers G, Syre I (Eds), Elsevier Science Publishers B.V. Netherlands, 1984. 

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