Starch/ethylene vinyl alcohol blend SEVA

Mendes and coworkers [275] described an extensive biocompatibility evaluation (in vitro and in vivo) of biodegradable starch-based materials aimed at orthopaedic applications as temporary bone replacement/fixation implants. For that purpose, they studied a polymer starch/ethylene vinyl alcohol blend (SEVA) and a composite of SEVA reinforced with HAp particles. As a result of their investigation it was found that SEVA and SEVA/HAp materials did not show relevant toxicity in both short- and long-term in vitro testing. Furthermore, when implanted in muscle or bone tissue, these materials induced a satisfactory tissue response. 

Marques et al. (2002) studied the biocompatibility of starch-based polymers. The materials used for this study were (i) a 50/50 (wt%) blend of cornstarch and ethylene vinyl alcohol (SEVA-C), (ii) SEVA-C reinforced with 30 % (wt) of hydroxyapatite, (iii) a 50/50 (wt%) blend of cornstarch and cellulose acetate (SCA), and (iv) SCA reinforced with 30 % (wt) of hydroxyapatite. In the composites the average size of 90 % of the HA particles was found to be below 6.5 mm. Cytotoxicity tests with the extract of the materials were performed in order to evaluate the presence and or release of toxic leachables and degradation products. Cell material interactions on the surface of the polymers were observed by scanning electron microscopy (SEM) and related to the materials formulations. The short-term effect of leachables from starch-based polymers was quantified by exposing L929 cell to the degradation products released by those materials after immersion in culture medium. 

Figure13.2 Substrates from blend of starch for 2 days (a) 10 min in O2 and applying a power with ethylene vinyl alcohol (SEVA) (50/50 wt%) of BOW (b) 30 min, O2 and power of SOW ...

Different degradable porous architectures have thus been developed using polymers based on blends of com starch with poly(ethylene-co-vinyl alcohol)(SEVA-C, Novamont, Italy) and cellulose acetate (SCA, Novamont, ltaly)(Gomes et al., 2001). These materials present a non-cytotoxic behavior and are under consideration for a wide range of biomedical applications, such as scaffolds for bone-tissue engineering (Salgado et al., 2004). 

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