Figure 5. The scaffold-based encapsulation models.

(A) Multicellular tumor spheroids based on core-shell microcapsules. The shell is constituted by an alginate hydrogel of controllable thickness, and the core is constituted by hydrogel of liquefiable property and cells; (B) Multicellular tumor spheroid based on ultrathin matrix. First, the gelatin layer is gained by gelatin solution treatment. After that, an anionic polyelectrolyte layer is deposited on the gelatin layer by adding alginate solution. This procedure is repeated three times by the sequential deposition of oppositely charged PE layers. In the end, a cationic PE layer chitosan is deposited on the assembly and the multicellular tumor spheroids are obtained.