Incorporation of metal free and Ga 5,10,15,20-tetrakis(4-bromophenyl) porphyrin into Pluronic F127-folic acid micelles

ClGa 5,10,15,20-Tetrakis (4-bromophenyl) porphyrinato (ClGaTBrPP) and its metal free derivative were successfully synthesized and incorporated into Pluronic F127 polymeric micelles that has been conjugated to folic acid (FA) to form ClGaTBrPP-F127-FA (or H₂TBrPP-F127-FA). For comparison, ClGaTBrPP-F127 and H₂TBrPP-F127 (without FA) were also formed. The singlet oxygen quantum yield for ClGaTBrPP-F127-FA was higher (Φ_Δ = 0.44) than that of H₂TBrPP-F127-FA (Φ_Δ = 0.37), due to the heavy atom effect of Ga in the former which encourages intersystem crossing to the triplet state. The same applies to ClGaTBrPP-F127 (Φ_Δ = 0.47) and H₂TBrPP-F127 (Φ_Δ = 0.41). Thus, Φ_Δ values decreased in the presence of FA, but still high enough for practical application of the nanodrug system. The binding constants K_b were determined to be 1.08 × 10⁴ M⁻¹, 2.51 × 10⁵ M⁻¹, 1.52 × 10³ and 2.68 × 10³ for H₂TBrPP+F127-FA, ClGaTBrPP+F127-FA, ClGaTBrPP-F127 and H₂TBrPP-F127, respectively. The K_p values were determined in biphasic octanol and water system.