A method for the production of a solid, degradable polyphosphate material having calcium counterions comprises: (i) dissolving a polyphosphate salt in an aqueous solvent, such as water, and adjusting the pH value of the solution to alkaline values； (ii) adding a solution of a calcium salt solution to the polyphosphate salt solution, and adjusting the pH value to alkaline values, (iii) optionally, washing with a solvent, for example ethanol, and (iv) collecting the particles formed. The method in steps (i) to (iii) is performed at ambient temperature, and the material has a hardness similar to that of bone tissue, and is morphogenetically active. Preferably, the polyphosphate is sodium phosphate, and has a chain length in the range of 3 to 1000 phosphate units. The calcium salt solution may be calcium chloride, and the pH may be adjusted to 10. The amorphous nanoparticles made by the method may be used in bone regeneration and repair and in dentistry, or for drug delivery.
