Synthesis and Intracellular Uptake of Rhodamine-Nucleolipid Conjugates into a Nanoemulsion Vehicle

Neurodegenerative diseases represent some of the greatest challenges for both basic science and clinical medicine. Due to their prevalence and the lack of known biochemical-based treatments, these complex pathologies result in an increasing societal cost. Increasing genetic and neuropathological evidence indicates that lysosomal impairment may be a common factor linking these diseases, demanding the development of therapeutic strategies aimed at restoring the lysosomal function. Here, we propose the design and synthesis of a nucleolipid conjugate as a nonviral chemical nanovector to specifically target neuronal cells and intracellular organelles. Herein, thymidine, appropriately substituted to increase its lipophilicity, was used as a model nucleoside and a fluorophore moiety, covalently bound to the nucleoside, allowed the monitoring of nucleolipid internalization in vitro. To improve nucleolipid protection and cellular uptake, these conjugates were formulated in nanoemulsions. In vitro biological assays demonstrated cell uptake- and internalization-associated colocalization with lysosomal markers. Overall, this nucleolipid-nanoemulsion-based formulation represents a promising drug-delivery tool to target the central nervous system, able to deliver drugs to restore the impaired lysosomal function.