SUMMARY
The effects of concentration and sonication on the liquid crystalline phases of collagen were investigated by several methods, especially by atomic force microscopy (AFM). X-ray diffraction (XRD) results reflected that the triple-helical structure of collagen was nearly unchanged after sonication. Moreover, differential scanning calorimetry (DSC) examinations indicated that the thermal stability of the sonicated collagen was close to that of native collagen. AFM observations revealed that collagen with concentration of 60 mg/mL exhibited a more obvious ordered array compared with that of 30 mg/mL when both samples were treated by sonication. Furthermore, the 60 mg/mL collagen solution without sonication could still form precholesteric patterns, but the liquid phase could not be observed for the 30 mg/mL collagen solution. As a whole, AFM was an effective method for the observation of the liquid crystalline phases of collagen.