*2.5. Preparation of Hyaluronic Acid-Graft-Amphiphilic Gelatin Microcapsule (HA-AGMC)*

The amphiphilicity and the self-assembly property of AG together with SPIOs have been investigated by Li et al. and Chiang et al. [19,26]. HA-AGMCs were prepared through a simple double emulsion process. First, AG-g-HA (80 mg) was added to deionized water (1.6 mL) and NaOH solution (1.6 mL, 0.1 N). The solution (0.6 mL) with hydrophobic SPIO (10 mg) in chloroform (1 mL) were emulsified to obtain a water-in-oil (W/O) emulsion. AG-g-HA solution (2.4 mL) was added to proceed the secondary emulsion to form the W/O/W emulsion. Afterward, the organic solvent was removed by rotary evaporator at 33 ◦C. The final HA-AGMC products were washed 3 times and re-dispersed with deionized water.

### *2.6. Characterization of HA-AGMCs*

The size and zeta potential of HA-AGMCs were characterized by dynamic light scattering (Beckman Coulter Delsa™ Nano C particle analyzer, Beckman Coulter, Brea, CA, USA). The morphology of HA-AGMCs were characterized by scanning electron microscope (SEM, JEOL-6700, JEOL, Tokyo, Japan) and transmission electron microscope (TEM, JEM-2100, JEOL, Tokyo, Japan). The samples of SEM were prepared by placing HA-AGMCs solution on a silicon wafer and drying in a vacuum desiccator. TEM samples were prepared by laying HA-AGMCs solution on a carbon coated grid, followed by removing the excess liquid on the grid, and drying in a vacuum desiccator.
