Modulating calcium phosphate formation using CO2 laser engineering of a polymeric material

The use of CO2 laser surface treatment of Nylon 6,6 to modulate calcium phosphate formation following immersion in SBF for 14 days is described. Using white light interferometry (WLI), it was determined that the laser surface processing gave rise to maximum Ra and Sa parameters of 1.3 and 4.4 micron, respectively. XPS enabled a maximum increase in surface oxygen content of 5.6 at% to be identified. The laser-induced surface modifications gave rise to a modulation in the wettability characteristics such that the contact angle, theta, decreased for the whole area processed samples, as expected, and increased for the patterned samples. The increase in theta was attributed to a transition in wetting nature to a mixed-state wetting regime. Calcium phosphate formed on each surface after 14 days. The largest increase in mass, due to calcium phosphate formation, was brought about by the whole area processed sample irradiated with a fluence of 51 J/cm2. No correlation between the calcium phosphate formation and the laser patterned surface properties was determined due to the likely affect of the mixed-state wetting regime. Strong correlations between theta, the surface energy parameters and the calcium phosphate formation for the whole area processed samples allowed the potential for this surface treatment technique in predicting the bone forming ability of laser processed materials.