Formulation of LDL Targeted Nanostructured Lipid Carriers Loaded with Paclitaxel: A Detailed Study of Preparation, Freeze Drying Condition, and In Vitro Cytotoxicity

In the present study, cholesterol nanostructured lipid carriers with various oleic acid content loaded with paclitaxel (PTX) were prepared by solvent emulsification-diffusion method using a Taguchi design. Size, zeta potential, entrapment efficiency, drug loading, and release percent of NLCs were measured. The results indicated that the most effective factors on the size were oleic acid content and surfactant percent. Zeta potential was more affected by the drug content. Drug to-lipid weight ratio was the most effective factor on entrapment efficiency and drug release from NLC. In the present work, the effect of lyophilization on the particle size and release properties of NLCs was also evaluated. The results revealed no differences between the characteristics of NLCs before and after freeze drying by using 25% w/w sorbitol as cryoprotectant. Cytotoxicity studies indicate that PTX associated with the NLC is also effective in HT-29 cell lines and enters the cancer cells selectively through the LDL receptor endocytic pathway. The IC50 values of free PTX solubilized in Cremophor EL and NLC-born PTX after 72 h exposure were 8.32 +/- 1.35 ng/mL and 5.24 +/- 0.96 ng/mL, respectively.