Hydrophilic polymers are known to induce the deposition of sparingly soluble salts. Poly-2-hydroxyethyl
methacrylate, (PHEMA), a hydrogel used for the fabrication of contact and intraocular lenses has been
reported to favor the nucleation and crystal growth of calcium phosphate. PHEMA disks coated with
graphene oxide (GO) were good nucleators of Hydroxyapatite (HAP). which precipitated at rates higher
in comparison with the respective on the uncoated material. The mechanism of HAP crystal growth was
controlled by surface diffusion as shown by the dependence of the rates on the relative supersaturation
with respect to HAP. GO was reduced with phenyl hydrazine at ambient conditions yielding reduced GO
(rGO) coated PHEMA. The hydrophobic rGO, inhibited drastically the crystal growth of HAP suggesting
that surface hydrophilicity is a very important feature favoring nucleation and growth of sparingly soluble
salts, possibly through the development of locally high supersaturation because of surface complexation.