Calcium salt deposition by cells grown on coated nanosprings. A. Cells were grown on normal growth conditions or on NS + TiO2/Au/ZnO for 36 days. Cultures were stained by the Von Kossa staining method, which results in all nuclei being labeled in red, and calcium salt mineralized nodules staining brown to black depending on the level of calcification. For comparison Van Kossa staining of discs with nanosprings but no cells are included. B. Cultures shown in A were evaluated by FESEM at a magnification of 10.00 KX. Scale bar = 1 μm.