Fig. 4. Scanning electron microscopy images of (a) PS beads (0.5 μm), (b) surface modified PS beads with chitosan (PS beads/chitosan), and (c) beads further treated with tannic acid (PS beads/chitosan–TA). (d) Atomic percentage of the surface of the beads according to the modification. (e) Size distribution of PS beads according to the modification. (f) Zeta potential of PS beads according to the modification.
