Functionally gradient chitosan/hydroxyapatite composite scaffolds for controlled drug release

Abstract

This study explored the potential of chitosan/hydroxyapatite (HA) composites to act as a controlled drug delivery system by developing functional scaffolds with a gradient of structure and drug concentration. Firstly, a porous composite scaffold was prepared and tetracycline hydrochloride (TCH) was impregnated in the scaffold as a model drug. The pore size of the scaffold was negatively dependent on the HA content and ranged about 40-250 lm. Subsequently, a porous chitosan/HA composite layer without drug was coated on the scaffold to create a gradient drug concentration in the specimen. The in vitro drug-release test demonstrated that the porous layer without drug on the outer surface of the scaffold significantly reduced the initial burst of drug release and extended the release period. Finally, a successive and dense chitosan/HA composite layer endowed the scaffold with a sustained, drugrelease pattern without any initial drug burst. These findings confirmed the high effectiveness of the hybrid scaffolds in regulating the release of drugs, and hence their capability to serve as a temporary drug carrier in tissue regeneration. These functional scaffolds also have potential application to the delivery of some bioactive molecules such as growth factors. '

Fabrication of chitosan/bioactive glass composite scaffolds for medical applications

“…This study revealed that CH/BGi scaffolds pores quite resemble a typical spongy 3D structure, with open pores, anisotropic porosity, and pore size ranging from 50 to 100 μm, as reported by [6,10,26,27]. The surface morphology of the composite scaffold was rough because of the introduction of HA crystals in concordance with [28].…”

“…In concordance with [27,29], it looks like on CH/Bgi samples, once BG nuclei were formed on the surface of chitosan scaffold, those could grow and spread out on the surface of scaffold with the increasing BG content.…”

Chitosan/hydroxyapatite scaffolds for tissue engineering manufacturing method effect comparison

“…The presence of small pores less than 20 µm is also important for the protein absorption, ionic solubility, and the attachment of osteoblasts on the scaffolds [20]. This study revealed that CH/ HAis scaffolds pores quite resemble a typical spongy 3D structure, with open pores, anisotropic porosity, and pore size ranging from 50-100 μm, as reported by [16,21]. The surface morphology of the composite scaffold was rough because of the introduction of HA crystals in concordance with [22].…”

“…In concordance with [21,23], it seems that in CH/HAis, once HA nuclei were formed on the surface of chitosan scaffold, could grow and spread out on the surface of scaffold with the increasing HA content.…”

Enhanced biocompatibility and adhesive properties of modified allyl 2-cyanoacrylate-based elastic bio-glues

“…The low release velocity of EGF-included chitosan micro-bead/PAC/PLCL mixtures was furthermore likely to be due to low diffusion by the PAC/PLCL mixture coating the chitosan micro-beads. The higher release velocity is moreover indicative of faster diffusion over a large surface area of the 3D porous structure and the presence of exposed protein on the surface, as mentioned in a previous study [21]. To facilitate improved wound healing efficiency, EGF-included chitosan micro-beads were therefore prepared and applied directly to incision areas before the application of bio-glue.…”