Characterising Hydroxyapatite Deposited from Solution onto Novel Substrates in Terms of Growth Mechanism and Physical Chemical Properties

Bulk titanium is the most common metal for orthopaedic implants but there are some concerns surrounding it’s use. Research in the last decade has focussed on alternatives to titanium alloys, however these materials are hindered by the adhesion of a hydroxyapatite layer to non-bulk Titanium parts. Demonstrated in this work is the ability to grow hydroxyapatite on surfaces other than bulk metallic parts through process and characterisation of coating properties.

Hydroxyapatite is grown from saturated solution precursors onto thin titanium films and silicon substrates and its efficacy is proven to be dependent on substrate roughness measured at AFM. The mechanism of the hydroxyapatite growth is investigated in terms of initial attachment and morphological development through SEM analysis. Bulk titanium parts are coated in the same manner as means of comparison. Characterisation of hydroxyapatite layers by XRD demonstrate how the hydroxyapatite forms from amorphous phases to preferential crystal growth along the [002] direction and TEM imagery confirms specific d spacings. SEM-EDX and FTIR data shows adherence to known HA phases through elemental atomic weight percentages and bond assignment. All data is collated and review through the lens of different substrates whereby it is proven that once hydroxyapatite seeds it grows identically regardless of substrate.