Development of DH-I-180-3 loaded lipid nanoparticle for photodynamic therapy

Photodynamic therapy (PDT) is a promising noninvasive treatment modality for cancer. Photosensitizer and specific wave length of light are the key component of PDT. DH-I-180-3, a second generation photosensitizer, was incorporated into lipid nanoparticle for simultaneous fluorescent imaging and targeting therapy. Solid lipid nanoparticle (SLN) and nanostructured lipid carriers (NLC) based on poloxamer 188 as surfactant and lecithin as co-surfactant were prepared using solvent evaporation and hot homogenization technique. Stearic acid and Capmul(®) MCM C8 were utilized as solid lipid and liquid lipid, respectively. The particle size of SLN and NLCs was around 200 nm and decreased when a part of stearic acid was replaced with Capmul(®) MCM C8. Drug loading efficacy was significantly enhanced when the percentage amount of liquid lipid increased. All the polydispersity indices of the SLN/NLCs were below 0.3, and displayed a narrow particle size distribution. Zeta potentials of all the lipid nanoparticles were below -30 mV, maintaining sufficient repulsive force and achieving enhanced physical stability. No significant change in the particle size and polydispersity index was observed from lyophilized SLN/NLCs. When the photocytotoxic effects of the formulations were evaluated in MCF-7 cells, GI 50 of SLN was less than half of DH-I-180-3 solution, and NLCs containing either 5 or 15%w/w of Capmul(®) MCM C8 exerted higher cytotoxicity than SLN. The fluorescence microscope images displayed enhanced cellular accumulation of DH-I-180-3 loaded in SLN and NLCs, which was closely correlated with the photocytotoxicity results. It was concluded that the incorporation of DH-I-180-3 into the nanoparticles enhanced their targeting efficacy and improved photocytotoxicity.