The effect of coating type on mechanical properties and controlled drug release of PCL/zein coated 45S5 bioactive glass scaffolds for bone tissue engineering

摘要

Bioactive glass-based scaffolds prepared using the replica method have suitable pore macrostructures for bone tissue engineering applications (average pore size 300 urn and porosity - 96%). By optimizing a method for dip coating of BG scaffolds by PCL and zein, the compressive strength and mechanical stability were significantly increased. By increasing the concentration of the polymer, the compressive strength of the coated scaffold was increased. It was also evident that the stress-strain curve for the scaffold coated with the high concentration of polymer solution was much less jagged, and the shape more resembles the ideal curve for relatively tough highly porous foams. Both un-coated and PCL/zein coated scaffolds possessed appropriate bioactivity to form bone-like apatite layers after 2 weeks of immersion in SBF. The PCL/zein composite coating was also developed to enhance the biological activity of BG scaffolds, e.g. inducing faster HA formation. On the other hand, because of hydrophilic nature of zein, the water contact angle and the weight loss of coating were augmented by increasing zein concentration. It was found that the presence of zein accelerates degradation rate of the coating in the time period investigated. The present results show a way for controlling the in vitro degradation behavior of the coating by engineering the concentration of zein. The study described here offers an example of the organized design and preparation of novel type of drug controlled-release composite scaffolds and TCH for providing the drug release profiles. In order to impart control drug delivery function the scaffold was coated by a blend of PCL and zein. Sustained release of tetracycline was confirmed, and the proportion of zein in the coating had a great impact on the drug release behavior. The PCL/zein coated BG scaffolds presented a controlled drug release rate indicating that these scaffolds are promising candidates for in-situ drug release in bone tissue engineering applications.