. Experimental design
2.2.1. Full factorial design
A “full factorial design” containing all possible combinations
between the factors and their levels was chosen (Fig. 1). Three
factors (corresponding to the polymers CS, PEC and HA) at two
different levels, corresponding to two different concentrations,
were investigated (Fig. 1). The polymer concentrations considered
were: 0.5%, 1% w/w for CS and PEC; 0.3%, 0.5% w/w for HA. Eight
capsule formulations were prepared. Polymer concentrations
employed for their preparation are reported in Table 1: for each
polymer the upper level is indicated as +1 and the lower level as 1.
The response variables considered were: particle size, hydration
properties and mechanical resistance to compression.