LAUSR

In this work, we test the hypothesis that the Mg2+ content in biogenic aragonite has a systematic relationship with biomolecules. A series of biomimetic experiments were conducted to show the dependence of Mg2+ in aragonite on the model organic molecules added to the mineralizing solution, including the concentration of various organics, mineralization temperature, Mg/Ca ratio and Mg2+ initial concentration. The mineralized products were characterized by powder X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), field emission scanning electron microscopy (FESEM), thermogravimetric analysis (TGA), and inductively coupled plasma-atomic emission spectrometry (ICP-AES). High Mg2+ is detected in aragonite obtained in the presence of organics, whereas the lowest Mg2+ is measured in aragonite without organics. Moreover, the concentration of Mg2+ in aragonite increases gradually with the amended organics. Mg K-edge NEXAFS spectra show that the magnesium microenvironment in aragonite is similar to the organic-associated environment, indicating that the Mg2+ ions are not on the aragonite lattices, but adhere to the intracrystalline organics. Furthermore, the mineralization temperature, Mg/Ca ratio and Mg2+ content in mineralization medium significantly influence Mg2+ content in aragonite, reiterating the effect of the microenvironment on aragonite biomineralization.