Figure 1.

Schematic diagram of the growth phases of CNP (cross-sectional view) cultured with and without FBS with corresponding SEM and LM images, and LM observation of dissolution of SF-CNP to S-CNP. A, B, and C are the forms of CNP in the presence of serum (S-CNP). (i): SEM image of S-CNP. D, E, and F are the forms of CNP in the absence of FBS (SF-CNP). (ii): LM image of apatite layers of SF-CNP. (iii): SEM image of the formation shown in (ii). G: Schema of SF-CNP when exposed to FBS, apatite layers dissolve releasing the S-CNP within 24 h. (iv): SEM image of phase G. G1–G5: A series of LM images showing the dissolution of SF-CNP apatite layers and clumps of S-CNP released, with the replenishment of FBS. Bars: (i) = 100 nm; (ii) = 5 μm; (iii) = 2 μm; (iv) =1 μm; (G1–G5) = 5 μm.

Abbreviations: CNP, calcifying nanoparticles; FBS, fetal bovine serum; LM, light microscopy; SEM, scanning electron microscopy.