BACKGROUND:An ideal scaffold material needs appropriate degradation rate and certain mechanical properties, but the traditional colagen sponge scaffold has rapid degradation velocity and low mechanical strength, which is easy to colapse and difficult to maintain its natural form. Traditional cross-linking methods also have the problems of cytotoxicity or colagen denaturation, severely limiting the application of colagen. OBJECTIVE:To design a new cross-linking method for colagen and to optimize the self-assembly process so as to develop a colagen sponge scaffold with good mechanical properties and resistance to degradation. METHODS:Colagens were modified by self-assembly technology to prepare colagen fibrils which were then freeze-dried into fibrilar colagen sponges. Meanwhile, we optimized the conditions of self-assembly by using orthogonal experiment based on univariate analysis of the effect of initial colagen mass concentration, final phosphate concentration and pH value on the conversion yield of colagen self-assembly. RESULTS AND CONCLUSION:We optimized the conditions of self-assembly revealed that the optimum conditions to prepare colagen fibrils were determined as pH=8.0, initial colagen concentration=2 mg/mL, and final concentration of phosphate=15 mmol/L. The results of scanning electron microscope showed that fibrilar colagen sponges were characterized by refined porous structure which was connected by colagen fibrils. In addition, the fibrilar colagen sponges showed better equilibrium-sweling ratio, water retaining property and mechanical strength compared with unmodified colagen spondages (P < 0.05), to solve the problems in rapid degradation.