Core-Dependent Desorption Behavior of Polyelectrolyte Microcapsules in NaCl and Na₂SO₄ Solutions

Polyelectrolyte microcapsules (PMCs) have a wide range of applications in fields such as medicine, pharmacology, diagnostics, etc., and can be used as targeted drug delivery vehicles, diagnostic systems and smart materials. However, the existing research indicates that the type of core can influence the properties of the PMC shell. Consequently, we hypothesized that the type of core used for the formation of the PMC may also affect the desorption of the shell's polyelectrolytes. In this study, the desorption of polyelectrolytes of PMCs, formed on polystyrene cores (PMC_Ps) and MnCO₃ (PMC_Mn) and CaCO₃ cores (PMC_Ca), incubated in either NaCl or Na₂SO₄ solution, was investigated. It was demonstrated that the low ionic strength of the solution (up to 200 mM NaCl) has a negligible effect on the desorption of PMC_Ca. However, in the case of PMC_Ps and PMC_Mn, an increase in desorption was observed at 100 and 200 mM NaCl. Increasing the ionic strength to 1000 mM and 2000 mM resulted in a gradual increase in the desorption of the polyelectrolytes PMC_Ca and PMC_Mn, while for PMC_Ps, the maximum desorption was already observed at 1000 mM. Additionally, an increase in desorption was detected upon incubation in various concentrations of sodium sulfate (5-50 mM), although the desorption did not differ significantly across all types of PMCs. Nevertheless, for PMC_Mn, the maximum desorption was observed at a sodium sulfate concentration of 50 mM, whereas for other types of capsules, the maximum desorption occurred at a concentration of 100 mM. These results support the hypothesis that the type of core used in the formation of PMCs influences the desorption of the shell polyelectrolyte.