Dsa30 drop shape analysis system

The surface morphology and elemental composition of the samples before and after immersion testing were examined under a scanning electron microscope (SEM, Philips XL 30 ESEM TMP) coupled with energy X-ray dispersive spectroscopy system (EDS, EDAX Sapphire Spectrometer). The structural aspects of the experimental samples were determined by using a Panalytical X-Pert PRO Diffractometer (Malvern, UK), which works in Bragg-Brentano symmetric geometry. The contact angle measurements (CA) were made in order to determinate the wettability properties of the surface that is very important in the case of implantable biomaterials. A KRÜSS DSA30 Drop Shape Analysis System was used, and obtained images were processed by aligning the tangent at the profile of the sessile drop at the point of contact with the surface. Contact angle measurements were made in triplicate and an average value was calculated.

The measurements of the surface contact angles were performed on the KRÜSS DSA30 Drop Shape Analysis System using the Fowkes method [60 ]. This method is based on a combination of the knowledge of Fowkes on the one hand and Owens, Wendt, Rabel, and Kaelble on the other, as Fowkes initially determined only the disperse part and the latter determined both the components of the surface energy. In the first step the disperse part of the surface energy of the solid is calculated by making contact angle measurements with at least one purely dispersed liquid. By combination of the surface tension equation of Fowkes for the disperse part of the interactions: ${\gamma }_{sl}={\sigma }_s+{\sigma }_l-2\sqrt{{\sigma }_s^D·{\sigma }_l^D}$
with the Young’s equation: ${\sigma }_s={\gamma }_{sl}+{\sigma }_l\cdot \cos \mathsf{\theta }$
the following equation for the contact angle is obtained after transposition: $\cos \mathsf{\theta }=2\sqrt{{\sigma }_s^D}\cdot \frac{1}{\sqrt{{\sigma }_l^D}}-1$
Further, based upon the general equation for a straight line,

cosθ is then plotted against the term $\raisebox{1ex}{$1$}\!\left/ \!\raisebox{-1ex}{$\sqrt{{\sigma }_l^D}$}\right.$ . The term $2\sqrt{{\sigma }_s^D}$ can be determined from the slope m.

The samples’ wettability was assessed by contact angle measurements performed using the KRÜSS DSA30 Drop Shape Analysis System.
The contact angle measurements were performed using the sessile drop method, with each measurement being repeated five times. The samples were fixed on a support to ensure flatness, and, using the automatic dosing system, drops of distilled water with variable volumes were deposited (5–15 µL) depending on the available flat surface. Once the drop of distilled water was deposited, an image was captured using the built-in measuring system camera. The obtained images were processed with the help of the ImageJ software, with which the contact angle was determined.