Fig. 2. Test of nonfouling property, immunomodulatory effect, and phagocytosis.

(A) Fibrinogen adsorbed onto TCPS, MPC, NZPS, and ZPS hydrogel surfaces measured by ELISA. (B) RAW 264.7 macrophages (10⁵ per well) were treated with the MPC, NZPS, or ZPS nanogels at various concentrations (10, 25, 50, 100, 200, and 1000 μg/ml) for 18 hours followed by the stimulation of LPS (100 ng/ml) for 48 hours. The level of TNF-α secretion in the supernatant was measured by an ELISA kit. (C) The MPC, NZPS, or ZPS nanogels (100 μg/ml) were preincubated with an annexin V solution at various concentrations (0, 10, 25, 50, 100, and 200 μg/ml) for 6 hours. RAW 264.7 macrophages (10⁵ per well) were then treated with these nanogels (100 μg/ml) for 18 hours followed by the stimulation of LPS (100 ng/ml) for 48 hours. The level of TNF-α secretion in the supernatant was measured by the ELISA kit. (D) RAW 264.7 macrophages (10⁵ per well) were incubated with MPC, NZPS, or ZPS nanogels encapsulating FITC-BSA for 30, 60, 120, and 180 min, after which the cells were washed and lysed for the detection of recovered fluorescence. Statistical significance was determined using Student’s t test. NS, no significance. *P < 0.05 and ***P < 0.001. Data are represented as mean ± SEM.