Fluorescent Rhein-Loaded Liposomes for In Vivo Biodistribution Study

Objectives: This work aimed to develop and investigate liposomes incorporating Rhein (Lip-Rh) into the liposomal membrane to enhance the compound's water solubility and oral bioavailability. Methods: Liposomes were produced by the thin lipid film technique, with a phosphatidylcholine-to-cholesterol molar ratio of 5:1, dissolved in chloroform and methanol, and thereafter hydrated with ultrapure water and subjected to sonication. The resultant liposomes were studied from a physicochemical perspective using DLS, zeta potential, STEM, UV-Vis, and fluorescence spectroscopies, while oral bioavailability was assessed by fluorescence imaging. Additionally, cell viability assays were performed on tumour cells (MCF-7) in comparison to normal cells (HGFs). Results: The resultant nanoparticles exhibited relatively uniform sizes and narrow size distribution. In vivo fluorescence imaging studies performed on Wistar rats demonstrated significantly enhanced oral bioavailability for Lip-Rh, with rapid absorption into the bloodstream observed one hour after administration, in contrast to the free compound dissolved in vegetable oil. Cell viability assays demonstrated higher cytotoxicity of Lip-Rh towards MCF-7 cells compared to HGF cells, highlighting the selective therapeutic potential of the product. Moreover, we determined that the optimal dose of Rhein per kilogram of body weight, when encapsulated in liposomes, is approximately 2.5 times less than when Rhein is delivered in its unencapsulated form. Conclusions: Lip-Rh is a promising candidate for oncological treatments, presenting three key advantages: increased cytotoxicity towards tumour cells, protection of normal tissues, and the practicality of oral delivery. Additional investigation is required to explore its application in anticancer therapy, whether as monotherapy or as a complementary treatment.