Fig. 4

SEM images and size of blended spheres. a H2.1MS1:MS2, b H2.1MS1:DOXMS2 and c MS1:DOXMS2 particles were formed by blending the indicated silks at a volume ratio of 8:2, and then silk solutions with an initial concentration of 0.5 mg/mL were mixed with 2 M potassium phosphate buffer, pH 8, using high-pressure syringe pumps. Scale bar—1 µm. d The mean size of the spheres was determined by the analysis of the diameter of 100 particles in SEM images. The mean and standard deviation of three independent experiments are shown