Using UV laser surface treatment to modify the wettability characteristics of polyamide 6,6 and its effects on osteoblast cell activity

Lasers can be used to modify the surface characteristics of a number of different materials for many applications. This paper details the way in which a KrF excimer laser can be utilized to surface pattern and whole area irradiate nylon 6,6. 50 and 100 μm dimensioned trench and hatch patterns were induced in addition to the whole area irradiative processing which used fluences ranging from 26 to 90 mJcm^-2. Using white light interferometery, it was found that the largest roughness, Sa, was 1.53 μm which arose from the 100 μm hatch excimer patterned sample. A sessile drop device determined that the contact angle increased by up to 25° for the patterned samples and decreased by up to 15° for the whole area processed samples. It is believed that the observed increase in contact angle can be attributed to the likely existence of a mixed-state wetting regime. The observed decrease in contact angle can be explained by a modification of the surface chemistry and an increase in polar component (γ^p) and total surface energy (γ^T) Osteoblast cell activity was analyzed by carrying out cytotoxicity and alkaline leukocyte phosphatase (ALP) activity experiments, two major factors which are linked to sufficient cell growth and proliferation. Furthermore, a correlative link has been established between the wettability characteristics and biomimetic response.