Medical Applications of Grafted Surfaces

Most biomedical materials are used in constant contact with living systems, such as blood, cells, and tissues. Since the material surface can undergo unfavorable biological responses when in contact with a recipient, most of the conventional surfaces need to be modified so that the materials can function as designed. 

In this section, we will highlight the use of the grafting technique for designing polymeric biomaterial surfaces that exhibit non-fouling property, selective protein adsorption, enhanced tissue adhesion, and minimum frictional damage to mucosa membranes. 

Note the number in parentheses denotes the zeta potential in mV 

Yoshikimi Uyama, Koichi Kato, Yoshito Ikada 

Rejection of protein adsorption to the outermost grafted surface is attributed to a steric hinderance effect due to the tethered chains. A grafted surface in contact with an aqueous medium, a good solvent of the chains, has been identified to have a diffuse structure [57,151,152]. Reversible deformation of the tethered 

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In dentistry, silicones are primarily used as dental-impression materials where chemical- and bioinertness are critical, and, thus, thoroughly evaluated.546 The development of a method for the detection of antibodies to silicones has been reviewed,547 as the search for novel silicone biomaterials continues. Thus, aromatic polyamide-silicone resins have been reviewed as a new class of biomaterials.548 In a short review, the comparison of silicones with their major competitor in biomaterials, polyurethanes, has been conducted.549 But silicones are also used in the modification of polyurethanes and other polymers via co-polymerization, formation of IPNs, blending, or functionalization by grafting, affecting both bulk and surface characteristics of the materials, as discussed in the recent reviews.550-552 A number of papers deal specifically with surface modification of silicones for medical applications, as described in a recent reference.555 The role of silicones in biodegradable polyurethane co-polymers,554 and in other hydrolytically degradable co-polymers,555 was recently studied. 

The same authors developed a process of encapsulation of polymers swelled by halogenated solvents in which ozone is greatly soluble but not monomers to be grafted. After ozonization of polymers swelled in solvents, mixtures of mono unsaturated or di unsaturated monomers are added to the activated polymers. Then, grafting is operated by UV irradiation. Grafting is mainly located at the surface of the starting polymer what prevents the modification of its intrinsic properties. This process permits to produce hydrophilic polysiloxanes used in medical applications (contact lenses, tubes, catheters, etc.). 

Graft copolymers combine the properties of their polymeric constituents and as such are polymer alloys, which open a vast field of new polymeric species. This is why active research along these lines is performed in many academic and industrial research laboratories all over the world. However, only few applications have reached a commercial level today. They involve the production of specific polymeric adhesives, perm-selective membranes, bio-medical devices and the surface modification of certain products. 

Abstract Surface properties are a critical aspect of textiles for medical applications. This chapter discusses some popular surface modification techniques plasma activation, plasma polymerization, chemical grafting, and polymer encapsulation of nanoparticles. 

The grafted polymer poly[(ethylene-co-vinyl acetate-co-carbon monoxide)-graft-vinyl chloride] (PVC/EVACO) known in medical applications as plasticized poly(vinyl chloride) was apphed as a carrier polymer for the covalent immobilization of fibronectin. The surface modifications were carried out on foils both with closed surface structure and with microporous surfaces produced by a phase-inversion technique. The vinyl acetate groups of the carrier polymer were saponified and then reacted with hexamethylene diisocyanate (HDI) as a spacer. Fibronectin is immobilized upon reaction of the free isocyanate group with an amino group of the protein (Fig. 33). The saponification of the carrier polymer was verified by IR-ATR and XPS [149]. The presence of hydroxyhc groups after hydrophihzation is demonstrated by a contact angle of 61° while that of the basic polymer is 110°. 

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