Model study of biostability of DPPC layers deposited by LB/LS on Ti–6Al–4V alloy

This paper reports surface property research on bare Ti–6Al–4V alloy covered with 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC), which is the main component of cell membranes. The monolayer and bilayer of the phospholipid were deposited by the Langmuir–Blodgett (LB)/Langmuir–Schaefer (LS) technique, and their biostability was investigated in water, phosphate-buffered saline (PBS), simulated body fluid (SBF) and 1% Triton X-100 aqueous solution at 37°C. Moreover, their biostability is compared with that of films prepared by spreading method. The surface free energy changes calculated by Lifshitz–van der Waals/acid–base and contact angle hysteresis measurement are consistent with the changes in surface roughness obtained by optical profilometry. The films prepared by both methods were relatively stable in water. PBS and SBF solutions caused large effects in the change in the layers’ polar component – that is, the electron donor parameter. Also, significant changes took place when Triton X-100 solution was applied, probably because of the DPPC film removal by the surfactant. Finally, it appeared that no drastic differences in the energy changes were observed between the DPPC layers dried overnight in a vacuum desiccator and those dipped into the SBF solution immediately after their deposition on Ti–6Al–4V alloy by the LB/LS method.