In part because of their high drug loading, nanocrystals (NCs) have seen extensive use in drug delivery, particularly for insoluble or poorly soluble drugs. It remains a challenge, however, to prepare stable nanocrystals with tumor-targeting capability. Here, we designed a novel preparation of stable paclitaxel (PTX) nanocrystals with efficient active tumor-targeting properties. PTX NC was prepared using a bottom-up method and modified with both poly(ethylene glycol) (PEG) and folic acid (FA) derivatives using film hydration. The resulting PTX NC@lipid-PEG-FA had a rodlike shape, with hydrodynamic diameters and drug loading values of 201.90 ± 2.92 nm and 31.07 ± 3.41%, respectively. The size of the PTX NC@lipid-PEG-FA was unchanged after 168 h in the presence of plasma, whereas nonmodified paclitaxel nanocrystals (PTX NC) exceeded 600 nm within 12 h under the same conditions. Cellular uptake and cellular growth inhibition experiments in 4T1 breast cancer cells showed the superiority of PTX NC@lipid-PEG-FA over PTX NC or PEGylated paclitaxel nanocrystals without FA modification (PTX NC@lipid-PEG). A pharmacokinetic evaluation in rats revealed that PTX NC@lipid-PEG-FA significantly prolonged the circulation of PTX in the bloodstream, in comparison with PTX NC or Taxol. Tissue distribution and in vivo antitumor studies in 4T1 orthotopic breast cancer-bearing nude mice showed that PTX NC@lipid-PEG-FA significantly increased the intratumor accumulation of PTX and efficiently inhibited tumor growth, in comparison with PTX NC@lipid-PEG, PTX NC, or Taxol. In summary, PTX NC@lipid-PEG-FA showed good potential for breast cancer-targeted delivery for insoluble therapeutics.
Keywords: active targeting; breast cancer; folic acid; nanocrystals; paclitaxel.