Drop shape analyzer

Static contact angle of PCL, PCL/polyDOPA and PCL/polyDOPA/G films and scaffolds was measured at room temperature to evaluate the effect of surface modification on sample surface wettability (Wang et al., 2011 (link)). Moreover, to evaluate coating stability, static contact angle measurements were also performed on PCL, PCL/polyDOPA, PCL/G, PCL/polyDOPA/G films after their incubation at 37°C in PBS solution for 1, 3 and 7 days. The analysis was carried out using Drop Shape Analyzer equipped with Advanced software (KRÜSS GmbH—KRÜSS Scientific Instruments) selecting the sessile drop method. A drop of MilliQ water (2 µL) was placed on sample surface and the contact angle was sized. For each type of sample, measurements were performed at least five times at different locations right after drop deposition and 5 s later. Measurements were performed in triplicate. Static contact angles were reported as average values ± standard deviation.

The wettability of the composite films was assessed by water contact angle (WCA) measurement using goniometer (Drop Shape Analyzer, KRÜSS GmbH, Hamburg, Germany) at room temperature. The sessile drop of deionized water was deposited on the surface and contact angle was calculated. For each type of material, six drops were measured and the average value was reported.

The KRUSS Drop Shape Analyzer was used along with DSA25 and ADVANCE software to analyze the surface wettability of the composite. Distilled water was used as the liquid for drop deposition.

The contact angle describes the hydrophilicity of the membrane, and it was analyzed using a Drop Shape Analyzer (Kruss, Hamburg, Germany). Each membrane sample was dried before testing and six readings were taken for accuracy with the average value calculated accordingly.
Silver nanoparticles were immobilized on membrane surfaces, which influenced the membrane surface charge [36 (link)]. The surface charge of membranes was characterized by measuring the streaming zeta potential using an electrokinetic analyzer (Anton Paar SurPASS, Ashland, VA, USA). The adjustable gap cell was set as a gap of 90-110 μm using 0.01 M KCl as the electrolyte.
Surface samples of five membranes were freeze-dried overnight to remove moisture and then analyzed using a K-Alpha X-ray photoelectron spectroscopy (XPS, Thermo Scientific, MA, USA). XPS provides information of elemental compositions based on the corresponding binding energies excited by X-ray beams. In this study, S_2p, C_1s, Ag_3d5/2, Ag_3d3/2, and O_1s core level peaks were observed verifying the immobilization of AgNP onto the membranes.

The hydrophilicity and hydrophobicity of the titanium plate surface were evaluated by the water contact angle. The droplets of 5 μL deionized water were dripped on the surface of the samples, and a picture was taken to record and calculate the static contact angle of titanium plates before and after bio-aging (Drop Shape Analyzer, KRUSS K100, Hamburg, Germany).