Generation of Chitosan-Polycaprolactone Porous Structures

Tissue engineering aims at regenerating natural tissues. New tissues could be created using the knowledge of biomaterials. To form functional tissues biomaterials are designed to direct the growth of cells by providing chemical compatibility and similar mechanical properties as at the site of implantation. For this purpose, tissue engineering techniques require the use of scaffolds with open pore morphology to ensure the cells and nutrients could pass into and out of the scaffolds while also supporting the structure of the tissue where it is implanted. Strategies for developing new biomaterials that exhibit unique and desired properties in tissue regeneration applications would be greatly aided by blending polymers. By blending polymers we could complement them and overcome the individual deficiencies either polymer might have. Previously, a study on blending chitosan, a naturally derived polymer, with ε-polycaprolactone (PCL), a synthetic polymer, was conducted in 25:75, 50:50, and 75:25 chitosan to PCL mass ratios dissolved in a 77% aqueous acetic acid solvent. However, when we tried to form scaffolds from the blend by lyophilization, it lacked structural integrity. In this study, 25% aqueous acetic acid solvent with the same mass ratios were used to prepare porous scaffolds from chitosan-PCL blends in order to improve the stability and strength of the scaffolds. For this purpose, we explored freeze extraction, freeze gelation, and freeze drying techniques. Freeze extraction of chloroform from frozen 80kD and 42.5kD PCL with acetone resulted in stable scaffolds that appeared like white disks. Observations from the SEM analysis exhibited increasing the concentration of PCL increased the number of the spherical particles. However, the structural stability of the scaffold had no observed significant difference from 42.5kD and 80kD. Porous chitosan-PCL blend scaffolds made with the 77% aqueous acetic acid solvent lacked structural integrity. However, chloroform assisted dissolution of PCL in conjunction with 25% aqueous acetic acid solvent resulted in formation of structurally stable scaffolds via lyophilization. These scaffolds were tested for cytocompatibility using chicken chorioallantoic membrane (CAM) assays in situ. The observed 3D morphology and formation of vasculature suggests these scaffolds are cytocompatible.