Table 1. Zeta Potential of Silk Hydrogels after Ultrasonic Treatment at Different Ultrasonic Intensities.

	hydrogels (no treatment)	100 W	200 W	500 W
zeta potential (mV)	–52.7 ± 1.76	–52.2 ± 2.86	–53.1 ± 1.76	–53.8 ± 2.05