A biomimetic strategy for controllable degradation of chitosan scaffolds
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Changren Zhoub) Department of Materials Science and Engineering, Jinan University, Guangzhou 510632, China
Yan Sun Department of Biotechnology, Guangdong Pharmaceutical University 510006, China (Received 1 February 2012; accepted 10 May 2012)
Controllable degradation of scaffolds plays an important role in tissue engineering applications. Here, we describe a biomimetic approach to control chitosan scaffold degradation by incorporating lysozyme-loaded poly(D,L-lactic-co-glycolic acid) microspheres in 3D chitosan scaffolds. In vitro degradation tests reveal that the degradation rate increased when the mass ratio of microspheres-to-chitosan increased whereas the contrast group showed a visible turning point at 28d. In vivo degradation rate was much faster than that in vitro, and the relationship between in vitro degradation and in vivo degradation was correlative. Finally, for determining the primary biocompatibility of the combined scaffolds, studies such as cytotoxicity assay, cell attachment study and histological evaluation were carried out. It is concluded that the combination method of enzyme and scaffold is suitable for chitosan scaffold degradation; it also demonstrates an alternative strategy for other biomaterials used in tissue engineering. I. INTRODUCTION
Chitosan, which can be extracted from crustaceans shells1 or microbial cell walls such as fungi,2 is a linear polysaccharide composed of glucosamine and N-acetyl glucosamine linked through b-1,4 glucosidic bonds. It has become one of the most widely used biomaterials due to its excellent biocompatibility, biodegradability, nutritional function and pharmacological efficacy.3,4 As a promising biomaterial in tissue engineering application, the degradation behavior of chitosan plays a crucial role on the long-term performance of the tissue-engineered cell/material constructs. The degradation kinetics may affect many cellular processes, including cell growth, tissue regeneration, and host response.5 But the disadvantage of using chitosan alone as a scaffold is that chitosan itself has a very slow degradation rate, and its molecules degrade in an uncontrollable manner.6 Many investigations have been published on the degradation of chitosan scaffold. Most of them showed that the molecular weight and degree of N-deacetylation (DD) are the key factors controlling the degradation of chitosan.7–9 The problem of effectively controlling the chitosan scaffold degradation needs to be resolved when the molecular weight and DD are certain parameters. A few publications have focused on the influence of porosity and fiber diameter10,11 or different ratios of
Address all correspondence to these authors. a) e-mail: [email protected] b) e-mail: [email protected] DOI: 10.1557/jmr.2012.176 J. Mater. Res., Vol. 27, No. 14, Jul 28, 2012
chitosan blends12,13 on the degradation of chitosan scaffolds. Others were mainly about adjusting the extent of crosslinking to control the degradation rate.14–16 In our opinion, a biomimetic approach may be attempted to solve this problem. Lysozym
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