No abstract

No abstract

The dependence of the Surface Enhanced Raman Scattering (SERS) by gold nanoparticles on their shape is examined using the organic dye, rhodamine 6G (R6G) as probe molecule. SERS has been explored extensively for applications in sensing and imaging, but the design and optimisation of efficient substrates is still challenging. In order to understand and optimise the SERS process in nanoparticles, gold nanospheres and their aggregates, nanotriangles, and nanostars of similar dimensions were synthesised and characterised according to their average size, zeta potential and UV/visible absorption. SERS from R6G was negligible for unaggregated nanospheres at 532 nm, close to the maximum of the surface plasmon resonance (SPR) at 560 nm. Upon aggregation of the nanospheres, the SPR shifts to ~660 nm, attributable to local surface plasmon "hotspots" between the spheres, and the SERS signal of R6G is significantly increased, at 785 nm. In monodisperse gold nanotriangles, the SPR is located at ~800 nm, and significant SERS of R6G is observed using 785 nm as source, as is the case for gold nanostars, which exhibit a double SPR with maxima at ~600 nm and ~785 nm, attributable to the core sphere and vertices of the structures, respectively. In suspensions of equal nanoparticle and dye concentration, the SERS effect increases as nanospheres

No abstract

Single walled carbon nanotubes induce indirect cytotoxicity by medium depletion in A549 lung cells." Toxicology Letters, 179, 78-84 (2008) t r a c tThe ability of two types of single walled carbon nanotubes (SWCNT), namely Arc Discharge (AD) and HiPco ® single walled carbon nanotubes, to induce an indirect cytotoxicity in A549 lung cells by means of medium depletion was investigated. The nanotubes were dispersed in a commercial cell culture medium and subsequently removed by centrifugation and filtration. Spectroscopic analysis confirmed the removal of the nanotubes and showed differing degrees of alteration of the composition of the medium upon the removal of the nanotubes. The ability to induce an indirect cytotoxic effect by altering the medium was evaluated using two endpoints, namely the Alamar Blue (AB) and the Clonogenic assay. Exposure of the A549 cells to the depleted medium which had previously contained carbonaceous nanoparticles, revealed significant cytotoxicity for both endpoints employed. The results presented demonstrate that single walled carbon nanotubes can induce an indirect cytotoxicity by alteration of cell culture medium (in which they have previously been dispersed) which potentially results in a false positive toxic effect being observed in cytotoxicity studies.

Raman spectroscopy is used for the localization and tracking of chemotherapeutic drug, doxorubicin, in the intracellular environment of lung cancer cell line. Results show the potential of the technique to monitor the mechanisms of action and response on a molecular level, with subcellular resolution.Please check this proof carefully. Our staff will not read it in detail after you have returned it.Translation errors between word-processor files and typesetting systems can occur so the whole proof needs to be read. Please pay particular attention to: tabulated material; equations; numerical data; figures and graphics; and references. If you have not already indicated the corresponding author(s) please mark their name(s) with an asterisk. Please e-mail a list of corrections or the PDF with electronic notes attached -do not change the text within the PDF file or send a revised manuscript. Corrections at this stage should be minor and not involve extensive changes. All corrections must be sent at the same time.Please bear in mind that minor layout improvements, e.g. in line breaking, table widths and graphic placement, are routinely applied to the final version.We will publish articles on the web as soon as possible after receiving your corrections; no late corrections will be made. Please ensure that all queries are answered when returning your proof corrections so that publication of your article is not delayed. Vibrational spectroscopy, including Raman spectroscopy, has been widely used over the last few years to explore potential biomedical applications. Indeed, Raman spectroscopy has been demonstrated to be a powerful non-invasive tool in cancer diagnosis and monitoring. In confocal microscopic mode, the technique is also a molecularly specific analytical tool with optical resolution which has potential applications in subcellular analysis of biochemical processes, and therefore as an in vitro screening tool of the efficacy and mode of action of, for example, chemotherapeutic agents. In order to demonstrate and explore the potential in this field, established, model chemotherapeutic agents can be valuable. In study paper, Raman spectroscopy coupled with confocal microscopy were used for the localization and tracking of the commercially available drug, doxorubicin (DOX), in the intracellular environment of the lung cancer cell line, A549. Cytotoxicity assays were employed to establish clinically relevant drug doses for 24 h exposure, and confocal laser scanning fluorescence microscopy was conducted in parallel with Raman spectroscopy profiling to confirm the drug internalisation and localisation. Multivariate statistical analysis, consisting of PCA ( principal components analysis) was used to highlight doxorubicin interaction with cancer cells and spectral variations due to its effects before and after DOX spectral features subtraction from nuclear and nucleolar spectra, were compared to non-exposed control spectra. Results show that Raman micro spectroscopy is not only able to detect doxorubicin inside cells an...

No abstract

Raman microscopy is employed to spectroscopically image biological cells previously exposed to fluorescently labelled polystyrene nanoparticles and, in combination with Kmeans clustering and Principal Component Analysis (PCA), is demonstrated to be capable of localising the nanoparticles and identifying the subcellular environment based on the molecular spectroscopic signatures. The neutral nanoparticles of 50 nm or 100 nm, as characterised by dynamic light scattering, are shown to be non-toxic to a human lung adenocarcinoma cell-line (A549), according to a range of cytotoxicity assays including Neutral Red, Alamar Blue, Coomassie Blue and (3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT). Confocal fluorescence microscopy identifies intracellular fluorescence due to the nanoparticle exposure, but the fluorescence distribution is spatially diffuse, potentially due to detachment of the dye from the nanoparticles, and the technique fails to unambiguously identify the distribution of the nanoparticles within the cells. Raman spectroscopic mapping of the cells in combination with K-means cluster analysis is used to clearly identify and localise the polystyrene nanoparticles in exposed cells, based on their characteristic spectroscopic signatures. PCA identifies the local environment as rich in lipidic signatures which are associated with localisation of the nanoparticles in the endoplasmic reticulum. The importance of optimised cell growth conditions and fixation processes is highlighted. The preliminary study demonstrates the potential of the technique to unambiguously identify and locate nonfluorescent nanoparticles in cells and to probe not only the local environment but also changes to the cell metabolism which may be associated with cytotoxic responses.