The robustness of mesoporous MCM-41 as a vehicle for drug delivery has been extensively studied, with synthetic modifications allowing for release triggered by various stimuli, including light, pH, redox reactions, and magnetic actuation.  Azobenzene, known for its cis/trans isomerization photoproperties, has been incorporated in mesoporous MCM-41 as a nanoimpeller, using the large amplitude motion to drive out cargo from the silica pores.  Previous in vitro studies have shown that azobenzene nanoimpellers are capable of delivering an anti-cancer drug, camptothecin, into PANC-1 cancer cells upon visible light irradiation.  To further study these machines in action, we modified an epi-fluorescence microscope to measure the fluorescence spectra of released cargo inside of living cells as a function of time.   Preliminary studies have shown that release of propidium iodide can be seen in as little as five minutes with cw visible excitation at laser powers of 10 mW.  A characteristic spectral blue-shift of ~15 nm is observed as propidium iodide intercalates into nuclear DNA, confirming that the cargo was successfully delivered into the nucleus.  Additional experiments involving spinning-disk confocal microscopy and studies of the rates of intracellular organelle staining will be presented.

Nanomachine-controlled cargo release monitored in single living cells

241st National Meeting (2011)

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