2,2-Azobis(2-isobutyronitrile)
(AIBN), ethylene glycol dimethacrylate (EGDMA), methacrylic acid (MAA),
IgG from human serum, and phosphate-buffered saline (PBS) were purchased
from Sigma-Aldrich (Milwaukee, WI, USA). All analytical-research-grade
chemicals were used without further purification.