Fig. 1

A schematic image of the set-up used in the in-situ quartz crystal microbalance with dissipation (in-situ QCM-D) experiments. Briefly, clean QCM-D sensor chips were mounted on the instrument and PBS flushed through the system until a stable baseline of ∆f and ∆D was observed. Test solutions were then flowed over the hydroxyapatite surface for 20 min, followed by a PBS rinse for 15 min