Figure 2. In vitro degradation kinetics of cell-free core / 2-/4-OMA shell microgels over 48 h.

Each microgel was prepared without cells in the core filled by PBS. (a) The resultant microgels exhibited a round particle shape at 0 h, but this spheroidal structure gradually began to collapse over the time. The OMA components were nearly gone within 48 h in both groups. (b) Quantification of the degraded amount of 2-/4-OMA was measured by DMMB assay. The degradation rate of 4-OMA was faster than 2-OMA due to its higher oxidation degree. Generation of different sizes of 4-OMA core/shell microgels. (c) Different sizes of NIH3T3 encapsulated core/ 4-OMA shell microgels were produced by modulating the air-flow. After 7 days of culture, various sizes of spheroidal NIH3T3 aggregates were obtained and (d) their average diameters were measured.