Abstract
A naturally occurring crosslinking agent, genipin, was used in this study to crosslink gelatin to develop a biodegradable film for biomedical applications. This study attempted to understand how different drying methods, oven-drying (80°C), room temperature-drying (RTD, 25 °C) and freeze-drying (-20°C) affected the characteristics of biomaterials. The physical and chemical characteristics of genipin cross-linked gelatin film, after drying using the three methods, were investigated. Both the drying rate and ratio were highest in the oven, followed by room temperature-drying and freeze-drying. Scanning electron microscope (SEM) images reveal the oven-dried films had a smooth surface morphology and their cross-sections exhibited a fusion-like appearance. The films dried at room temperature had flat and smooth surface structures and cross-sections. The cross-sections of the freeze-dried films were as porous as its surface morphology. The oven-dried film had the highest glass transition temperature (T <sub>g</sub> ) and melting point (T <sub>m</sub> ), followed by the freeze-dried film and the film dried at room temperature. The tensile test indicated that the tensile strength of the oven-dried film was the highest, followed by those dried at room temperature and freeze-dried film. However, the tensile elongation and toughness followed the order RTD < Oven » Lyophilizer. In the rehydration test, the film dried at room temperature presented the highest weight-change ratio; the weight-change ratio of the oven-dried film almost equaled that of the freeze-dried film. However, the thickness-change ratio of the films dried by different methods varied significantly (P < 0.05). The attenuated total reflection Fourier-transform infrared (ATR-FTIR) spectrometric absorption peaks were similarly consistent among the films dried by the three methods. The order of absorption intensity of the peaks was Lyophilizer & Oven < RTD. Energy-dispersive X-ray (EDX) analysis identified carbon, nitrogen and oxygen on the surfaces of all of the dried films. The oxygen concentration was almost the same as in the variously dried films; however, the carbon and nitrogen contents varied significantly (P < 0.05).