Purpose: To synthesize P[(Folate-Allylamine)-co-(N-isopropylacrylamine)- co-Acrylamide] (P(FoAAn-co-NIPA-AAm), folate-NHG) with appropriate diameter and lower critical solution temperature (LCST) for targeting to folate receptor (FR) expressing tumors.
Methods: Folate-NHG was synthesized by free-radical precipitation polymerization method reported in our previous work and other reports. LCST, diameter and morphology of folate-NHG were characterized by UV-vis spectrophotometer, laser particle size analyzer (LPSA) and transmission electron microscope (TEM), respectively. No.12 near infrared dye (NIRD-12) was entrapped into folate-NHG by hydrophobic association to trace the in vivo dynamic behavior of folate-NHG. This process was evaluated by a homemade near infrared (NIR) imaging system.
Results: Spherical folate-NHG with diameter of about 50 nm and LCST of about 40 degrees C was successfully synthesized. The photo stability of NIRD-12 was strengthened after being entrapped into folate-NHG, which enabled NIRD-12 to better trace the in vivo dynamic process of folate-NHG. Folate-NHG showed good targeting capability for all three folate receptor expressing tumor models (SMMC-7721, Bel-7402 and HeLa) with different sizes, and this accumulation could last for more than 96 h. D-folate-NHG, synthesized with double amount of FoAAn, showed better targeting effect for SMMC-7721 tumor model than that of folate-NHG.
Conclusions: Folate-NHG could actively accumulate in three models of folate receptor positive tumors with different sizes and keep retention for more than 96 h, which enables it to be used as a diagnostic reagent or anti-tumor drug carrier for tumor therapy.