Anticancer activity of polymeric nanoparticles containing linoleic acid-SN38 (LA-SN38) conjugate in a murine model of colorectal cancer

Biodegradable polymeric nanoparticles (NPs) have been used frequently as nanocarriers for anticancer drugs. Linoleic acid conjugated SN38 (LA-SN38)-loaded NPs (EBNPs) were developed using biodegradable poly (ethylene oxide)-poly (butylene oxide) (PEO-PBO) diblock copolymer by titration hydration method without using a toxic organic solvent. The EBNPs had high drug loading efficiency and entrapment efficiency for LA-SN38, at 7.53% and 93.55%, respectively. The polydispersity index (PDI) and average diameter were 0.173 +/- 0.019 and 226.1 +/- 1.2 nm, respectively. The transmission electron microscope (TEM) image presented that the NPs were homogeneous in size and had spherical structures. In vitro study showed the release behavior of EBNPs was slow and sustained. Furthermore, cytotoxicity and apoptosis assay proved that EBNPs were more effective in growth inhibition of human colon cancer cells. Cell uptake experiments further demonstrated that EBNPs could avoid the phagocytosis by macrophages and promote the uptake by cancer cells. In vivo, EBNPs had prolonged blood circulation time and tumor selectivity in biodistribution. The tumor inhibitory rate of EBNPs was higher compared to SNPs group and CPT-11group (P < 0.01), and the drug did not show significant systemic toxicity at the tested dose. These results indicated that EBNPs are a promising candidate for delivery of LA-SN38 to treat colorectal cancer.