Nanodiamonds internalization in MCF7 cells monitored by cell membrane stiffness changes and their luminescent signal
Résumé
Luminescent nanodiamonds (ND) are attractive tools for nanoscale biologic cellular imaging allowing both photoluminescence (PL) and magnetic resonance imaging [1]. Recent technological developments enable to fabricate bright NDs with high content of nitrogen-vacancy centres [2] that are anticipated to serve as a cell probes. In this work we present novel method of NDs detection in cellular environment. We demonstrate simultaneous visualization of NDs and of the non- labeled nucleus of living cells based on Raman and PL detection as a new tool for the localization of internalized nanoparticles.
To this end, NDs of size ranging from ultra-small particles ~ 5 nm to 60 nm were used, prepared from Ib synthetic diamond. Cells used for this experiment were from mammalian breast cancer (MCF7). We report on accomplishing to successfully internalize ND particles in MCF7 cells. We show that ND internalization can be monitored by Raman imaging method using K-mean cluster analysis. Whilst standard Raman imaging methods of NDs make use of the sp3 diamond Raman signal, which limits their use to 100 nm size particles or bigger [3], here we employ Raman imaging in a novel way to detect small near-IR cellular probe. Changes of cells stiffness were detected by force measurement in atomic force microscopy after incubating cells with NDs, suggesting cell membrane hardening upon ND uptake.
[1] L. Moore, M. Nesladek et al., Nanoscale (2014)
[2] J. Havlik, M. Gulka, M. Nesladek et al., Nanoscale (2013) [3] C.-Y. Cheng et al., Applied Physics Letter (2007)