Different particle size of microspheres prepared in aqueous two-phase system: Effect of continuous phase and hydrolysis time of waxy potato starch

In aqueous two-phase systems (ATPS), how to control precisely the particle size of SMs remains challenging, particularly the role of the continuous phase and starch structural properties has not been thoroughly investigated. This study aimed to regulate the particle size of SMs prepared in aqueous two-phase system (ATPS) by modifying the continuous phase and acid hydrolysis time of waxy potato starch. The considered continuous phase was polyethylene glycol (PEG) and polyvinylpyrrolidone (PVP), and the starches were treated with varying the duration of acid hydrolysis. After 8 h of acid hydrolysis, the molecular weight of starch reduced from 1.45×10 7 Da to 3.03×10 5 Da. The resulting particle size of SMs exhibited 10.6 μm in the PVP system, compared to 30 μm in the PEG system. Additionally, SMs prepared in PVP system showed higher crystallinity, short-range order, enthalpy, and pasting temperature, along with smaller particle sizes, for the same acid hydrolysis time. BSA loading tests indicated that SMs with smaller particle sizes had higher drug loading capacity, with PVP-10h showing more than twice the capacity of PEG-10h. The study enabled the researcher to select the appropriate continuous phase and acid hydrolysis time for preparing SMs based on desired physicochemical properties.