Fig. 2. Scanning electron microscopy images of (a) PS beads (90 μm), (b) the surface-modified PS beads with chitosan (PS beads/chitosan), and (c) beads further treated with tannic acid (PS beads/chitosan–TA). The square regions (yellow) of the surface of the beads were magnified in the next row. (d) Atomic percentage of the surface of the beads according to the modification. (e) Zeta potential of PS beads according to the modification.
