Design and Characterization of Langmuir–Blodgett Films Incorporating Europium Complexes and Nucleoside Derivatives for Cancer Therapeutic Applications

The design of multifunctional nanostructured materials with potential for both diagnostic and therapeutic use, the so-called theranostic platforms, is a promising strategy in cancer research. In this study, we report the fabrication and physicochemical characterization of Langmuir and Langmuir-Blodgett (LB) films composed of a triacylated uridine derivative (PNM2), previously described as a prodrug with anticancer potential, and the europium complex Eu-(tta)₃(H₂O)₂, known for its luminescent and structural probe properties. Langmuir monolayers at the air-water interface exhibited high rigidity for PNM2, which was modulated upon incorporation of the europium complex. Surface pressure-area isotherms, surface potential data, and dilatational rheology confirmed a transition toward a more fluid-like yet stable film. PM-IRRAS and Brewster angle microscopy indicated uniform molecular organization and specific interactions between Eu³ ⁺ and the carbonyl groups of PNM2. Upon transfer to solid substrates, LB films preserved this organization and exhibited strong photoluminescence, with emission spectra confirming efficient energy transfer via the antenna effect. Lifetime and quantum efficiency measurements revealed reduced water coordination and enhanced radiative decay. These results demonstrate that PNM2-Eu-(tta)₃(H₂O)₂ films are structurally robust and optically responsive systems, offering a promising foundation for the development of biofunctional interfaces with potential theranostic applications, including cancer sensing and localized drug delivery.