Abstract: The periodic precipitation patterns of calcium bilirubinate were produced in the metal ion-deoxycholate-bilirubinate diffusion system. By considering of the interactions among the bilirubinate, deoxycholate, Cu2＋ and Ca2＋, the growth regulations of periodic precipitation patterns were investigated. It was found that the deoxycholate and bilirubinate could form the reunited micelle that could diffuse and react with metal ions in agar gels. When meeting with Ca2＋, the bilirubinate will separate out from micelle to produce calcium bilirubinate. When meeting with Cu2＋＋Ca2＋ ions, deoxycholate would first unite with Cu2＋ ions, then the bilirubinate would further separate out from micelle and react with Ca2＋ ions to produce calcium bilirubinate. Because the reunited micelle has bigger volume and slower speed in diffusion and reaction, its duration to produce precipitation pattern is much longer (roughly 6 months), which is more like the duration of gallstone growth. It was also found that when the copper ions present, the durations of the pattern formation became shorter.

Key words: Gallstone, Periodic precipitation, Bilirubinate, Reaction-diffusion system