Preparation and characterization of multifunctional mesoporous silica nanoparticles for dual magnetic resonance and fluorescence imaging in targeted cancer therapy

We have constructed a theranostic drug delivery system, composed of a carrier and a drug. Europium (Eu³⁺) and gadolinium (Gd³⁺) were doped into mesoporous silica nanoparticles (MSNs) to form the carrier (EuGd-MSNs). The surface of EuGd-MSNs was then grafted by disulfide bonds with L-cysteine (Cys) and folic acid (FA), respectively. This theranostic drug delivery system, FA-EuGd-MSNs-SS-Cys, is capable of serving as a both diagnostic and therapeutic tool for imaging-tracing and providing disease treatment. FA targeting achieved with selectivity and phagocytosis specificity more efficiently. The evaluation of the cellular uptake shows that FA-EuGd-MSNs traps more cancer cells than EuGd-MSNs. The cell material shows that the intense intracellular red fluorescence emitted from the Eu³⁺ reveals that a significant amount of FA-EuGd-MSNs is ingested by Hela cells, and the paramagnetic functionality of the Gd³⁺ enhances the photoluminscence sensitivity through MRI, which shows EuGd-MSNs to be an efficient dual imaging agent. In a cytotoxicity evaluation of FA-EuGd-MSNs-SS-Cys by MTT, the Cys serves as an anticancer reagent. Cancer treatment can use drug therapies with higher concentration glutathione (GSH) to cut disulfide bonds intracellularly and allow the Cys to treat the disease more effectively. The EuGd-MSNs also presents excellent properties, including a lack of cyto-toxicity, good biocompatibility, and stability when it is cultivated with normal L929 cells. The FA-EuGd-MSNs-SS-Cys presents a useful theranostic nano-platform, with four primary functionalities: imaging probes, tracing, delivering therapeutic drugs, and a targeting ligand that can serve as an all-in-one diagnostic and therapeutic tool for cancer and aging-related diseases.