Fig. 3: Numerical simulation of the droplet solidification and drug encapsulation.

a Concentration fields of MPS on the mid-plane of the droplet. The color bar on the right side represents the concentration magnitude of MPS. b The shrinking of a droplet as a function of time during the solidification process. c Nominal concentration (mass of drug divided by volume of droplet) of MPS at different states (dissolved and precipitated) in the droplet during the solidification process. d Transmission electron microscope images of thin section of bare AcDX, MPS@AcDX, and washed thin section of MPS@AcDX. e The impact of initial dimethyl sulfoxide ratio in the inner fluid on the simulated diffusion time that taken for MPS to reach the saturation concentration in droplets. f, g Numerically simulated (f) and experimental (g; n = 3) loading degree and encapsulation efficiency of AcDX microspheres prepared by varying the dimethyl sulfoxide ratio in the inner fluid. AcDX concentration and MPS concentration are set at 10 mg/mL and 30 mg/mL, respectively. Data are presented as mean values ± SD. h The impact of initial MPS concentration in the inner fluid on the numerically simulated diffusion time that taken for MPS to reach saturation concentration in the droplets. i, j Numerically simulated (i) and experimental (j; n = 3) loading degree and encapsulation efficiency of AcDX microspheres. AcDX concentration and dimethyl sulfoxide ratio are set at 10 mg/mL and 10% v/v, respectively. Data are presented as mean values ± SD.