Preliminary evaluation of zeolite-based platforms as potential dual drug delivery systems against microbial infections in the tumor microenvironment

Several zeolite-based delivery systems (ZDS) built with faujasite structure were prepared containing silver (Ag+) and 5-Fluorouracil (5-FU) as antimicrobial and antineoplastic agents, respectively. The idea behind this drug combination is an answer to the increasing evidence of colonization of tumor microenvironments by pathogenic microorganisms and their active role in tumor growth. Two ZDS with a fixed load of 5-FU and different silver loads, Ag7(5-FU)@Y and Ag4(5-FU)@Y, were prepared through ion-exchange of silver followed by 5-FU encapsulation in liquid phase. The developed ZDS were characterized in-depth by scanning microscopy (SEM), thermogravimetric analysis (TGA), N2 adsorption analysis, ICP-AES analyses and X-ray photoelectron spectroscopy (XPS), and successfully confirmed the incorporation of both drug-active species into the zeolite framework without inducing structural alteration. Finally, the antimicrobial properties of the ZDS were investigated against various strains of bacteria. ZDS containing both drug-active species - Ag and 5-FU - displayed lower Minimum Inhibitory Concentration (MIC) values than AgxY, indicating higher effectiveness in inhibiting bacterial growth. Ag4(5-FU)@Y resulted to be the most favourable combination exhibiting efficient encapsulation of 5-FU while containing an efficient amount of silver.