The invention relates to a process for the preparation of a citrate-coated amorphous calcium phosphate nanoparticle which comprises the following steps: 1) providing a first solution of a salt of calcium and a citrate salt wherein the molar ratio of citrate ion to calcium ion is in the range from 1 to 2 thus obtaining a clear first solution； 2) providing a second solution of a salt capable to give phosphate anion and a carbonate salt； 3) mixing together the first and the second solution at a pH in the range from 8 to 11； 4) precipitating the nanoparticle； and 5) drying the nanoparticle obtained from step 4). Preferably and advantageously the invention provides for the addition of a fluoride compound in step 2) for obtaining a fluorine-doped citrate-coated calcium phosphate nanoparticle or a nanoparticle agglomerate. The nanoparticle/nanoparticle agglomerate of the invention has a peculiar superficial area and a diameter that allow to use it as a biomaterial for dentistry application.本發明係與一種製備檸檬酸鹽塗覆的非晶形磷酸鈣奈米粒子的方法有關，其包含以下的步驟：1）提供鈣鹽以及檸檬酸鹽的第一溶液，其中檸檬酸根離子對鈣離子的莫耳比率係在1到2的範圍內，因此獲得澄清的第一溶液；2）提供能夠產生磷酸根陰離子的鹽以及碳酸鹽的第二溶液；3）在8到11的pH範圍內將該澄清的第一溶液以及該第二溶液混合在一起；4）使該奈米粒子沉澱；以及5）使從步驟4）所獲得的該奈米粒子乾燥。較佳且有利地，本發明提供了在步驟2）中添加氟化物化合物，用於獲得氟摻雜檸檬酸鹽塗覆的非晶形磷酸鈣奈米粒子或者奈米粒子團聚物。本發明的奈米粒子/奈米粒子團聚物具有特別的表面積以及直徑，使得允許其作為用於牙科應用的生物材料。
