Crystallization of dicalcium phosphate dihydrate with presence of glutamic acid and arginine at 37 °C

• DCPD is prepared by biomimetic mineralization with glutamic acid and arginine.
• Plate-like DCPD is fabricated with decreased size when increasing arginine addition.
• Fluorescein leads to the formation of large DCPD due to consumption of OH− ions.
• Antisolvent crystallization of DCPD varies with desolvation reaction of Ca2 + ions.

The formations of non-metabolic stones, bones and teeth were seriously related to the morphology, size and surface reactivity of dicalcium phosphate dihydrate (DCPD). Herein, a facile biomimetic mineralization method with presence of glutamic acid and arginine was employed to fabricate DCPD with well-defined morphology and adjustable crystallite size. In reaction solution containing more arginine, crystallization of DCPD occurred with faster rate of nucleation and higher density of stacked layers due to the generation of more OH− ions after hydrolysis of arginine at 37 °C. With addition of fluorescein or acetone, the consumption of OH− ions or desolvation reaction of Ca2 + ions was modulated, which resulted in the fabrication of DCPD with adjustable crystallite sizes and densities of stacked layers. In comparison with fluorescein-loading DCPD, dicalcium phosphate anhydrate was prepared with enhanced photoluminescence properties due to the reduction of self-quenching effect and regular arrangement of encapsulated fluorescein molecules. With addition of more acetone, DCPD was prepared with smaller crystallite size via antisolvent crystallization. The simulated process with addition of amino acids under 37 °C would shed light on the dynamic process of biomineralization for calcium phosphate compounds.

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