Fabrication And Properties Of Collagen/Bacterial Cellulose Composites

With the development of tissue engineering, the research of artificial skin scaffold has become important increasingly. Nowadays, developing more advantageous composite materials is a hot spot. Bacterial cellulose (BC), as a new artificial skin material, has excellent biocompatibility and biodegradability. Collagen (COL) is the more widely used artificial skin material with low antigen, physical activity and so on. The paper mainly explored the potential application of BC and COL/BC composite as scaffolds in artificial skin tissue engineering. In this experiment, BC was produced by Acetobacter xylinum in static culture using a bionanotechnology and the COL/BC was generated by the modified cultivation. SEM, TEM, XRD, ATR-FTIR, TG, mercury intrusion pore measurement and in vitro cell culture experiment were employed to investigate the morphology, microstructure and properties of the BC and COL/BC.The microstructure of BC and its properties such as effects in pore sizes and dimension distribution, water holding capacity, water vapour transmission rate (WVTR), tensile properties, thermal stability, biodegradation, biocompatibility and so forth were tested to evaluate its potential as artifical skin. The results of experiments showed that BC was characterized by a triple-helical porous structure with pore size ranging from 3.5 nm to 6500 nm and the average pore size of 960 nm. BC displayed high water holding capacity. In comparison to the wet BC membrane, dry BC membrane had higher elongation rate at break and lower Young's modulus and tensile strength. Thermogravimetry analysis indicated that the thermal stability of BC was fine. However, the cell culture experiment showed that BC presented perfect property in biocompatibility as well.Furthermore, the structural characteristics of COL/BC composite, which was generated by bionanotechnology, were investigated by SEM, EDS, TEM, XRD, and ATR-FTIR. The results of SEM and TEM showed that COL/BC was characterized by a triple-helical porous structure and gummy matter almost uniformly distributed among the matrix. They were conglutinated together. The patterns of XRD proved that COL and BC were not mechanically mixed, instead they interacted physiocemically, which made the crystallinity higher to some extent. The water vapour transmission rate (WVTR) of COL/BC increased with the relative humidity. At high relative humidity, WVTR of COL/BC was lower than BC due to COL combining with water vapour. With the decreasing of the relative humidity, WVTR of COL/BC was identical to that of BC. The lowest WVTR of COL/BC met the requirements of artificial skin. In comparison to the BC membrane, COL/BC membrane had higher Young's modulus. Additionally, the swelling behaviors and mechanical properties increased concurrently. DSC results showed that the glass transition temperature of COL was 176°C, and thermal stability declined slightly comparing with BC. COL/BC displayed a good thermal stability which could meet the sterilization requirements of biomedical materials at 121°C.