Charge balancing stabilized apatite enter into collagen fibers by osmotic pressure to induce the formation of intrafibrillar mineralization

Intrafibrillar mineralized collagen is the main form of natural mineralized collagen in bone matrix. However, the mechanism involved in the intrafibrillar mineralization is still unclear. Here, by measuring the changes of Zeta potential and adjusting the osmotic pressure of collagen fibers to study the mechanism of intrafibrillar mineralization. The changes in zeta potential and reduction in size during the formation of amorphous calcium phosphate (ACP) after adding negatively charged polyacrylic acid (PAA) and positively charged cationicpolyacrylamide (CPAM) indicate that the stabilization mechanism of ACP induced by polyelectrolyte compound is charge balance. Then, osmotic pressure pressures charge balancing stabilized ACP into collagen fibers to induce intrafibrillar mineralization. This discovery provides basis for further understanding the intrafibrillar mineralization, preparing new biomimetic mineralized materials and promoting the development of tissue engineering.