Autori: Simona Cîntã Pînzaru, C. A. Dehelean, A. Fãlãmas, C. Soica, S. Ciurlea, C. Danciu
Editorial: Beat Loffler, Patrik Hunziker, H. Leidenfrost AG , 6/2013 CLINAM Conference Proceedings, 6, p.208-210, 2013.
Cellular imaging techniques are crucial in life science research based in part on the notion that „seeing is believing.” Among various imaging techniques, Raman spectroscopy based on the inelastic scattering of coherent light on molecules, provide a unique approach within a non-destructive manner. Because of the low scattering efficiency of about a million fold lower than the laser intensity used for excitation, surface enhanced Raman scattering (SERS) with noble metal nanoparticles .providing 106 to 1014 enhancement of the scattered signal, is widely used in prospecting the biological processes at cellular and molecular level. As a response to the increasing demand to develop new, sensitive, noninvasive and accurate methods in early diagnostic and to track the molecular changes in early stage of malignancy or in the therapy monitoring, an interdisciplinary approach exploiting the surface plasmon resonance  of the pure nanoparticles and ultrasensitive Raman spectroscopic techniques are employed here to get insight into the cellular events in the case of melanoma cells. Due to its unique ability to provide ultrasensitive detection limits, SERS has been used to provide rich information in medical nanodiagnostic . Concepts like SERS active needle, in vivo SERS reporters, SERS tumor targeting, SERS molecular diagnostic, SERS cellular imaging, are currently expanding in the nanomedicine field. As recently summarized, [2, 3] SERS is currently a mature, powerful vibrational spectroscopic technique, that gained increasing interest in medical diagnostic over the last decade and the number of applications in medical studies is rapidly increasing. The molecular species located in the close vicinity of the uptaken nanoparticles exhibit strong Raman scattering which represents the SERS signal with high spatial resolution, enabling unprecedent capability in cells or tissue studies. However, a complete understanding of the intracellular uptake, transport, metabolism and subcellular distribution of nanostructured materials remains limited. Nevertheless, overall findings reported that live cells trap NPs of proper dimension in vesicles, hampering them to get into nucleus, although the SERS signals from cells were assigned mostly to nucleus components vibrational modes. Various nanoarchitectures from a noble metal or silica core covered with Raman reporter molecules or different linkers have been reported, aiming to provide good stability, biocompatibility and reproductive SERS signal for specific biological molecule, however, such architectures so far are not reported in live cell uptake, probably because of the difficulty in cell incubation. Linkers or specific molecular tags could indeed provide unambiguous SERS signal but could as well interact with various compounds while penetrating cell membrane. The lack of reproducibility in SERS signal was rather judged as a need to optimise such nanoarchitectures rather than taking into account the „live” system, i.e live cell, where biological processes are rolling on.
We investigated this process inside the live cells in the case of four different B16 melanoma cell lines, B164A5, B16F10, B16GMCSF, and B16FLT3 respectively, using Ag nanoparticles (AgNPs), a confocal Raman microscope Bruker Senterra and a near infrared (NIR) laser line at 785 nm, for noninvasive excitation of the cells. The incidemt laser power on the cell was about 3 mW. We evaluated the nanoparticles uptake ability of the cells using transmission electron microscopy (TEM) in conjunction with the SERS measurements.
Cuvinte cheie: nanomedicine, SERS, nanoparticles