The ultraviolet photometry is an effective method to investigate the kinetic process of biomineralization because it can be used to monitor the reaction in real time without disturbance. This paper reports an interesting phenomenon in experiment on collagen mineralization. An abnormal negative peak was found in kinetic ultraviolet absorb curve of collagen/calcium phosphate biomineralization system in Tris-HCl buffer(pH=7.4). Influence of several experiment conditions on the negative peak was studied. SEM observation of the sample before and after the negative peak revealed that the crystals morphology and the aggregation of the mineralized collagen fibers are different. It indicated that the negative peak in the kinetic curve is an optical phenomenon related to the compositional and structural change of the mineral, which are the important elements in biomineralization mechanism study.
