Control of morphology and structure of calcium carbonate crystals by heparin

Abstract

Growth control of calcium carbonate crystal by organic chemicals contributes an important part to its mineralizing mechanism and biomimetic preparation. The influence of heparin (HEP) on morphology and structure of calcium carbonate generated by CaCl2/Na2CO3 solution was studied by a scanning electron microscope, an X-ray diffraction machine, a Fourier transform infrared spectrophotometer and a fluorescent spectrophotometer. The results showed that the calcite formed in the absence of HEP, while the addition of HEP induced changes in the morphology and structure of calcium carbonate crystals. In the presence of 2.5 mg/mL HEP, calcium carbonate was stimulated to grow orientationally, forming a spherical vaterite with a diameter of 1.5 μm. By X-ray diffraction, the contents of vaterite were counted to be 57.43% and 64.9% in the presence of 5 mg/mL and 20 mg/mL HEP, respectively. The resulted CaCO3/HEP microspheres achieved an 80% efficiency for HEP encapsulation. These results may provide novel references for studying the mechanism of biomineralization and the synthesis of HEP-functionalized materials.