pH-sensitive polymeric nanoparticles of quercetin as a potential colon cancer-targeted nanomedicine

Quercetin (QCT) is an abundant plant polyphenol with demonstrated efficacy in several diseases including colon cancer. Herein we have developed polymeric nanoparticles (NPs) of QCT based on the pH-sensitive polymer Eudragit (R) S100 to achieve colon pH-specific drug release following oral administration. NPs were prepared by the nanoprecipitation technique and showed a mean diameter of 66.8 nm and a partially negative surface charge of -5.2 mV. NPs contained on average 2.2% w/w QCT at an encapsulation efficiency of 41.8%. IR spectroscopy and differential scanning calorimetry (DSC) both revealed the presence of intermolecular interactions, most likely H-bonding, between QCT and Eudragit (R) S100, which likely contributed to drug loading. DSC also indicated that the drug was present in the NPs in an amorphous state, which was further confirmed by X-ray diffraction. In vitro release testing showed a delay in drug release in acidic pH, but complete release within 24 hat pH 7.2. A cytotoxicity assay was performed on CT26 murine colon carcinoma cells, where QCT-loaded NPs displayed significantly higher potency (IC50 = 0.8 mu M) than free QCT (IC50 = 65.1 mu M). Our findings present a promising nanomedicine for colon-targeted delivery of QCT in diseases such as colon cancer.