Transferrin-conjugated lipid-coated PLGA nanoparticles for targeted delivery of aromatase inhibitor 7α-APTADD to breast cancer cells

Transferrin (Tf)-conjugated lipid-coated poly(d,l-lactide-co-glycolide) (PLGA) nanoparticles carrying the aromatase inhibitor, 7α-(4′-amino)phenylthio-1,4-androstadiene-3,17-dione (7α-APTADD), were synthesized by a solvent injection method. Formulation parameters including PLGA-to-lipid, egg PC-to-TPGS, and drug-to-PLGA ratios and aqueous-to-organic phase ratio at the point of synthesis were optimized to obtain nanoparticles with desired sizes and drug loading efficiency. The optimal formulation had a drug loading efficiency of 36.3±3.4%, mean diameter of 170.3±7.6nm and zeta potential of -18.9±1.5mV. The aromatase inhibition activity of the nanoparticles was evaluated in SKBR-3 breast cancer cells. IC₅₀ value of the Tf-nanoparticles was ranging from 0.77 to 1.21nM, and IC₅₀ value of the nanoparticles was ranging from 1.90 to 3.41nM (n=3). The former is significantly lower than the latter (p<0.05). These results suggested that the aromatase inhibition activity of the Tf-nanoparticles was enhanced relative to that of the non-targeted nanoparticles, which was attributable to Tf receptor (TfR) mediated uptake. In conclusion, Tf-conjugated lipid-coated PLGA nanoparticles are potential vehicles for improving the efficiency and specificity of therapeutic delivery of aromatase inhibitors.