Fig. 3A shows that the network structures of the O/W microemulsion containing 13% (w/w) Poloxamer 407 had not been formed completely, and that the system was still loose and collosol. We found that as the concentration of Poloxamer 407 increased, the whole microemulsion would contribute to the formation of the hydrogel. When the concentration of Poloxamer 407 was 14% (w/w), the interconnected network structures had been formed. By comparison, the network structures of systems containing 16% (w/w) Poloxamer 407 ( Fig. 3B) were more compact and the rheological measurement revealed that the dynamic viscoelasticity of this system was strongest. When the concentration of Poloxamer 407 increased to 17% (w/w) ( Fig. 3C), the structures were relatively disorganized. This may be the result of incomplete swelling of the matrix at this concentration.