The CS solution was prepared by dissolving 6.5 g CS
powder in 300 ml 0.1 N HCl, neutralized with 0.1 N
NaOH, followed by addition of distilled water until a total
volume of 1 l and pH = 6.0 were reached. Xa solution was
prepared under stirring by dissolving 6.5 g of dried powder
into 1 l distilled water. The Xa–CS hydrogels were prepared
as capsules in the following way: 880 ml of the
previously degassed Xa solution were added dropwise
through a syringe needle (1.1 mm diameter) using a peristalic
pump (flow rate 3 ml/min) to 400 ml of CS solution.
The obtained hydrogel capsules were kept for maturation
under mild magnetic agitation for 30 min at room temperature.
After filtration, the hydrogel capsules were
washed with distilled water until neutral pH and freezedried
(Alpha 1-4 LSC, Christ, Germany). Figure 1 shows
an optical picture of the hydrogel capsules, with showing
an average diameter of 3 mm. The shape of the formed
capsules was not spherical but rather elongated, probably
due to increased viscosity of Xa drops and to the complexation
process under stirring. This does not pose a disadvantage
regarding their behaviour during THP release.