Mean ± standard error of the mean of the measured (a) Ca2+ and (b) PO43− concentrations following the demineralization of the collagen-mica substrates after immersion in SBF for 5, 10, and 24 hours in the presence of adsorbed BSA, BSP, DPP, or OPN. The concentrations were determined using calcium and phosphate assay kits for a minimum of 7 independently prepared samples (n≥7). A * represents a statistically significant difference between the surfaces being compared at a 95% confidence interval (p<0.05).