Aluminum Doped MCM-41 Nanoparticles as Platforms for the Dual Encapsulation of a CO-Releasing Molecule and Cisplatin

Mesoporous silica Al-MCM-41 nanoparticles have been used, for the first time, as vehicles for the single and dual encapsulation of the cationic CO-releasing molecule (CORM) [Mn(1,4,7-triazacyclononane)(CO)₃]⁺ (ALF472⁺) and the well-known antineoplastic drug, cis-[PtCl₂(NH₃)₂] (cisplatin). Thus, two new hybrid materials, namely, ALF472@Al-MCM-41 and ALF472-cisplatin@Al-MCM-41, have been isolated and fully characterized. The results reveal that the presence of CORM molecules enhances cisplatin loading 3-fold, yielding a cargo of 0.45 mmol g^-1 of ALF472⁺ and 0.12 mmol g^-1 of the platinum complex for ALF472-cisplatin@Al-MCM-41. It is worth noting that ALF472@Al-MCM-41 shows a good dispersion in phosphate buffered saline solution, while the dual hybrid material slightly aggregates in this simulated physiological medium (hydrodynamic size: 112 ± 23 and 336 ± 50 nm, respectively). In addition, both hybrid materials (ALF472@Al-MCM-41 and ALF472-cisplatin@Al-MCM-41) behave as photoactive CO-releasing materials, delivering 0.25 and 0.11 equiv of CO, respectively, after 24 h and exhibiting a more controlled CO delivery than that of the free CORM. Finally, metal leaching studies have confirmed the good retention capacity of Al-MCM-41 toward the potentially toxic manganese fragments (86% of retention after 72 h) as well as the low release of cisplatin (ca. 7% after 72 h).