Internalization by PMMA nanoparticle-mediated endocytosis of a survivin molecular beacon as theranostic agent in human cancer cells.

One of the main goals in nanomedicine is the development of effective drug delivery systems. Polymeric nanoparticles (NPs) have been exploited as nanocarriers for their stability, handiness and biocompatibility. In this context, NPs have been coupled to molecular beacons (MBs), theranostic agents that conjugate the sensing of specific mRNA with a silencing activity. The aim of this work was to evaluate by confocal microscopy and fluorescence measurements: a) the involvement of endocytosis in the NP uptake; b) the NP fate at different times of cell incubation to verify their localization in lysosomes; c) the MB localization on the Endoplasmic Reticulum (ER) where the target mRNA is located. Results: a) PMMA-NPs promote endocytosis; b) strong co-localization of NP and lysosome tracker fluorescence after 2- 48 hours of incubation; c) co-localization of the MB fluorescence with the ER-marker signal after 90' of incubation. The data highlight the ability of the PMMA-NPs to promote the survivin-MB internalization by endocytosis and demonstrate that the PMMA-NPs are an appropriate delivery system capable of being eliminated by cells; these evidences also contribute to consider the MB as an effective tool for the intracellular sensing.