Preparation And In Vitro Biocompatibility Assay Of Gelatin/Montmorillonite-Chitosan Biomaterial

Gelatin, which is a kind of hydrophilic protein, is partially denatured derivative of collagen. As a natural amphoteric polyelectrolyte, a variable number of positive and negative charges are randomly located on molecular chains. Montmorillonite (MMT) is a kind of natural nano-scale layered silicate. Macromolecules in solution can insert into MMT layers to form the intercalated composite. In this paper, a novel kind of biomaterial for tissue engineering based on gelatin/MMT-chitosan (Gel/MMT-CS) was prepared by solution intercalation process. The microstructure was investigated by X-Ray diffraction (XRD) and Fourier transformed infrared (FT-IR) analysis. The intercalation structure was testified through the obvious increase of the distance of MMT layers and polyelectrolyte complexes (PEC) was formed as the intense interaction between gelatin and chitosan.Three-dimensional porous Gel/MMT-CS scaffold was prepared by freeze-drying technique. Scanning electron microscope images (SEM) revealed that the scaffolds possessed high porosity (>90%), proper pore size and good inter-connection, which were suitable for cells implantation. The results suggested that when the solid concentration decreased, the scaffolds,thickness and apparent density dropped, the pore size increased, the pore wall became thinner and the inter-connection between pores was better. The water content reached the maximum with 3.6% solid concentration. The dropping of the pre-freezing temperature caused the reduction of the pore size, the scaffolds,thickness and the water content, but the density increased. The Gel/MMT-CS scaffolds with low MMT content possessed similar pore shape with Gel-CS scaffolds. When MMT content reached 20%, the pore shape became irregular, and the water content came down.This paper investigated the in vitro hydrolytic and enzymatic degradation properties of Gel/MMT-CS membranes and porous scaffolds. Because of the effective obstruct towards the infiltration of liquid low molecules, and the shield function to the hydrophilic groups on gelatin chains, the degradation rate decreased when MMT content increased. The introduced intercalation structure endowed Gel/MMT-CS nanocomposite with a controllable degradation rate when changing the MMT contents. The mechanical tests indicated that the nano-scale distributed MMT could improve the mechanical properties of intercalated nanocomposite remarkably. Meanwhile, the wet strength increased significantly compared to Gel-CS composite. High concentration is advantageous to better mechanical properties of porous scaffolds.