An oral delivery approach for riboflavin-targeted platinum(II)-loaded lipid nanoparticles into alginate-gelatin matrices against 2D and 3D colorectal carcinoma models

This study investigated the use of riboflavin-targeted Nanostructured Lipid Carriers (R-NLCs) to deliver a platinum-based anticancer drug [PtCl(8-O-quinolinate)(dmso)] (8-QO-Pt) to colorectal cancer cells. Three different R-8-QO-Pt-NLC formulations were prepared via hot-homogenization by ultrasonication method. The physicochemical characterizations of NLCs were analyzed by small- and wide-angle X-ray scattering (SAXS/WAXS) and fourier transformed infrared spectroscopy (FTIR). The cytotoxic effects and IC₅₀ values of R-8-QO-Pt-NLC formulations were compared with those of the free 8-QO-Pt. Cellular uptake and apoptosis were evaluated towards HCT 116 cells in monolayer (2D). The liquid overlay technique was used to generate 3D multicellular tumor spheroids, MCTS. The anticancer and antimetastatic activities of the free 8-QO-Pt and R-8-QO-Pt-NLCs were determined in MCTS. The results revealed that R-8-QO-Pt-NLC exhibited greater cytotoxicity and lower IC₅₀ values than free 8-QO-Pt in both 2D and 3D cell cultures. Furthermore, results showed that the volumes of the spheroids were reduced in response to increasing concentrations of R-8-QO-Pt-NLC, showing higher inhibition of cell migration in colorectal cancer spheroids at concentrations of 10.0, 15.0, and 25.0 μM than free 8-QO-Pt. To provide protection against gastric acid conditions, an additional drug delivery system based on alginate (Alg) and gelatin (Gel) beads for R-8-QO-Pt-NLC oral administration was developed. While free and R-NLC encapsulated 8-QO-Pt were practically inactivated at pH 1.2 and 37 °C, it was revealed that the Alg-Gel beads retain 5.7 times the initial activity of the R-8-QO-Pt-NLC. The findings of this research indicate that R-8-QO-Pt-NLC embedded in Alg-Gel beads are promising hydrogels for targeted colorectal delivery systems.