2. Materials and methods
2.1. Obtaining EPS from C. tetrapirenoidosa
The excreted exopolysaccharide system from the culture of the
microalgae C. tetrapirenoidosa (EPS) was prepared according to the
literature [26]. The culture was submitted to centrifugation, filtration
using a hollow fiber cartridge that allows the separation of
the high molecular size polysaccharide, dialysis and lyophilization
to obtain a pellet ready to be dissolved in purified water (Milli-
Q® system from Millipore – pH 5.6; resistivity 18 M cm−1) and to
be further used as part of the aqueous subphase of lipid Langmuir
films. All of the materials from the microalgae were obtained from
the same, certifiably clean and axenic inoculum from a single cell,
which was obtained from the Barra Bonita Reservoir in the state of
São Paulo, Brazil, thus maintaining the quality assurance and uniformity
of the results. The composition of the extract was described
in the literature [27] as 29.3% glucose, 24.2% mannose, 21.9% rhamnose,
7.8% xylose, 6.6% glucuronic acid, 5.6% fucose, 2.0% galactose,
1.8% galacturonic acid, and 0.8% arabinose.