A researcher prepares a biomaterial consisting of sodium alginate and chitosan. To achieve this, mix both polymers in equal proportions and also add CaCl2 (commonly used to crosslink alginate). After obtaining the material, the researcher decides to test the stability of the material obtained in a PBS solution (pH = 7.4 and ionic strength of 150 mM) at 37 C, in order to evaluate simulated physiological conditions. However, when the biomaterial comes into contact with PBS, it dissolves and a precipitate is obtained. Propose an explanation for what happened