Nucleation of calcium phosphate on 11-mercaptoundecanoic acid self-assembled monolayer in a pseudophysiological solution

Heterogeneous nucleation of calcium phosphate on an 11-mercaptoundecanoic a cid self-assembled monolayer (SAM) in a pseudophysiological solution was in vestigated by in situ and ex situ atomic force microscopy. Calcium phosphat e nanodots of 5-10 nm diameter were arranged two-dimensionally in a hexagon al closely packed structure in the initial stage of nucleation (less than o r equal to3 h), reflecting the molecular arrangement of a thiol layer. Afte r this stage, the surface was covered by random nucleated calcium phosphate particles of 20-30 nm diameter. Measurement of the growth rate of a calciu m phosphate layer and X-ray photoelectron spectroscopy analysis were perfor med and possible qualitative models of calcium phosphate growth on a SAM we re presented.