Bioactive scaffolds with drug delivery capability: Progress and challenges

P. NOOEAID; W. LI; V. MOURIÑO; A. R. BOCCACCINI

Egmond Aan Zee

Simposio; 13th European symposium on controlled drug delivery; 2014

Controlled Release Society

Introduction Scaffolds for bone regeneration loaded with bioactive molecules, e.g. growth factors, and drugs continue to attract attention because of their ability to regulate cell growth and to enhance bone regeneration coupled with anti-infection properties [1-3]. An important family of scaffolds for bone tissue engineering involves the combination of a bioactive glass 3D porous matrix coated with a biodegradable polymer [4]. Several natural and synthetic polymers are being investigated as the organic component of such composite scaffolds. In addition to improving the mechanical properties of the bioactive glass matrix the polymer phase can be exploited as a carrier for bioactive molecules or therapeutic drugs. One important advantage of this type of composite scaffolds is that the release rate of the drug can be de-coupled from the intrinsic degradation of the scaffold structure, hence the drug release kinetic does not affect the time dependent mechanical properties of the scaffold. In addition, by using bioactive glasses, the release of specific ions as dissolution products of the degrading structure can be beneficial for osteogenesis and angiogenesis [5]. In this study a novel bioactive scaffold exhibiting drug delivery capability was developed based on bioactive glass foam coated with a combination of two biodegradable polymers, namely PDLLA and alginate, which were loaded with tetracycline hydrochloride (TCH). Results and Discussion A double layered coating based on PDLLA and TCH loaded alginate was applied on bioactive glass derived scaffolds of 45S5 Bioglass® composition. The surface of the coated scaffold was homogeneous and smooth and it was found that the polymer covered the struts uniformly even though some uncovered areas were also observed. The presence of PDLLA led to scaffolds with improved mechanical properties. In terms of drug release, an initial burst release of 53 % after 1 h was measured on non-coated scaffolds, which increased to 99 % in the following 4 h. On the other hand, in polymer coated scaffolds, the initial burst release was lower (22 %). The TCH-loaded polymer coated scaffolds provided almost complete drug release over 14 days in a sustained manner. Drug molecules embedded in the coating can diffuse through available pathways, i.e. pores and channels, into the medium and key factors influencing the drug release were found to be linked to the coating homogeneity and its degradation kinetics, as investigated in this study. Conclusion The present approach using alginate coating as drug carrier in Bioglass®-based scaffolds has led to mechanically competent scaffolds exhibiting superior performance as drug delivery devices in terms of water soluble drug entrapment and protection. Further studies are required to characterize the cell response to the scaffolds and their bone forming ability both in vitro and in vivo. References 1.T. Garg, O. Singh, S. Arora, et al., Crit Rev Ther Drug Carrier Syst 2012, 29, 1-63. 2.S. H. Lee. H. Shin H., Adv Drug Deliv Rev 2007, 59, 339-59. 3.V. Mourino, A. R. Boccaccini, J R Soc Interface 2010, 7, 209-27. 4.D. M. Yunos, O. Bretcanu, A. R. Boccaccini, J. Mater. Sci. 2008, 43, 4433-4442. 5.A. Hoppe, N. S. Guldal, A. R. Boccaccini, Biomaterials 2011, 32, 2757-74.