Investigating the <i>in vivo</i> distribution characteristics of gel-in-water nanogel emulsions and demonstrating their efficacy in treating C26 tumor-bearing mice

Nanotechnology has been advancing drug delivery systems (DDSs) for decades. Nanoparticle DDSs, in which nanometric carriers deliver drugs to the target site, are highly valued for cancer treatment. In this study, based on nanoemulsion technology, gel-in-water (G/W) nanoemulsion was developed by using an organogel, i.e. 12-hydroxystearic acid and castor oil, followed by encapsulation of the model anticancer drug paclitaxel (PTX) within the nanogel droplets. The G/W was prepared using ultrasound and stabilized with a nonionic surfactant. The enhanced permeability and retention of G/W were investigated by encapsulating coumarin-6 and comparing it with an oil-in-water (O/W) nanoemulsion. Temporal changes in tissue distribution of both nanoemulsions were used to assess the effect of gelation on drug distribution. Regardless of the tissue type, the extraction efficiency of G/W was lower compared to O/W. The fluorescence intensity of coumarin-6 in G/W was higher compared to O/W. The size of G/W nanoparticles affects lung distribution and blood retention. PTX-loaded G/W (PTX-G/W) nanoparticles effectively treated colon cancer <i>in vivo</i>. They also exhibited antitumor activity against colon26 (C26) cells <i>in vitro</i>. The impact of particle size on the <i>in vivo</i> tissue distribution of G/W nanoemulsions suggests an improvement in drug delivery to the tumor site <i>via</i> nanoparticles.