Double Amino Functionalized Ag Nanoparticles as SERS Tags in Raman Diagnostic

Surface enhanced Raman scattering (SERS) effect is currently exploited as the basis of a new type of optical labels for in vivo investigation of the tissues, especially for early medical diagnostic. Silver colloidal nanoparticles decorated with chemisorbed cresyl violet molecular species could act as hybrid SERS labels. Their Raman scattering properties have been characterized here using different SERS techniques, and probing different excitation wavelengths, even in the near infrared. Obtaining FT-SERS signal of cresyl violet is of particular importance for applying FT-Raman spectroscopy to the tissues or cells, in providing sensitive information in the close vicinity of the SERS label incubated into the biological sample. Furthermore, upon chemisorption on the silver nanoparticles, cresyl violet molecular orientation provided both amino functional groups free of interaction with the silver, resulting double amino-functionalized Ag nanoparticles suitable for DNA tagging. SERS tests of melanoma induced in mouse using CV-Ag SERS label suggested the possibility to setup the tissue labeling procedure for skin cancer monitoring.(doi: 10.5562/cca2067

A characterization of four B16 murine melanoma cell sublines molecular fingerprint and proliferation behavior

Background: One of the most popular and versatile model of murine melanoma is by inoculating B16 cells in the syngeneic C57BL6J mouse strain. A characterization of different B16 modified cell sub-lines will be of real practical interest. For this aim, modern analytical tools like surface enhanced Raman spectroscopy/scattering (SERS) and MTT were employed to characterize both chemical composition and proliferation behavior of the selected cells. Methods: High quality SERS signal was recorded from each of the four types of B16 cell sub-lines: B164A5, B16GMCSF, B16FLT3, B16F10, in order to observe the differences between a parent cell line (B164A5) and other derived B16 cell sub-lines. Cells were incubated with silver nanoparticles of 50–100 nm diameter and the nanoparticles uptake inside the cells cytoplasm was proved by transmission electron microscopy (TEM) investigations. In order to characterize proliferation, growth curves of the four B16 cell lines, using different cell numbers and FCS concentration were obtained employing the MTT proliferation assay. For correlations doubling time were calculated. Results: SERS bands allowed the identification inside the cells of the main bio-molecular components such as: proteins, nucleic acids, and lipids. An "on and off" SERS effect was constantly present, which may be explained in terms of the employed laser power, as well as the possible different orientations of the adsorbed species in the cells in respect to the Ag nanoparticles. MTT results showed that among the four tested cell sub-lines B16 F10 is the most proliferative and B164A5 has the lower growth capacity. Regarding B16FLT3 cells and B16GMCSF cells, they present proliferation ability in between with slight slower potency for B16GMCSF cells. Conclusion: Molecular fingerprint and proliferation behavior of four B16 melanoma cell sub-lines were elucidated by associating SERS investigations with MTT proliferation assay

Raman Spectroscopy Techniques and Technology as a Tool in Environmental Water Analysis

Although the normal Raman scattering effect is inherently weak in diluted solutions such as environmental waters and dedicated enhancing techniques are already suitable for trace analysis of many harmful compounds, pollutants, toxins, and other species from aquatic environments, here we demonstrate how Raman spectroscopy techniques and technology can be effectively applied for environmental water analysis. Usually, normal Raman spectra of environmental waters, such as seawater, salt lakes waters show a weak-medium sulfate signal at about 981 cm-1 along with the stretching and bending modes of water. Rarely, weak bands attributable to dissolved CO2 and HCO3- are visible with weak intensity. We compared NIR-Raman and Raman spectra with visible laser excitation at 532 nm, which is resonant for carotenoids-containing microorganisms from water in bulk liquid or drop coating deposition samples, in multiple water samples from different spatial and temporal locations to include seawaters from Adriatic Sea (oligotrophic), Black Sea (eutrophic) and salt lakes waters (Cojocna Lakes (Lake1 and Lake2), Ursu Lake, Dead Sea). Valuable information can be obtained by combining resonance Raman spectroscopy using a Renishaw InVia Raman system coupled with a Leica research-grade microscope with a 532 nm laser with information from the FT-Raman spectra of the same waters. When photosynthetic microorganisms are abundant, in non-resonance conditions, a weak band of carotenoids is visible in FT-Raman or NIR-Raman spectra, suggesting photosynthetic microorganisms abundance. Such bulk waters show a high fluorescence background that sometimes covers any band, or reveal resonantly-enhance carotenoid bands arising from microorganisms under 532 nm excitation when Raman spectra of bulk liquid are tried. Drop coating deposition Raman (DCDR) technique could be more effectiv in rapidly assessing water droplet content under confocal micro-Raman spectroscopy. Both FT-Raman and microscopy techniques always record the sulfate ν1 (SO42-) Raman band at ~981 cm- 1 and water bands, δ(OH) at ~1637 cm-1 and ν(OH) Raman band at ~3218 cm-1 as shown in several comparative examples. Relative intensity ratio of ~981 cm- 1 and ~1637 cm-1 is proportional to sulfate concentration and can be used for quantitative sulfate analysis, based on an adequate calibration curve of sulfate solutions. Two sample tests for variance (F-test) revealed significant differences between relative intensity ratio between the Black Sea and Adriatic Sea samples when p<0.05. SO42- concentration variation is accompanied by other ion concentration variations and, thus, linked with salinity, conductivity and pH, which are related to climate events, and also influence the distribution of aquatic organisms. Thus, combined Raman spectroscopy techniques and technology for environmental water measurements can provide fast and useful information for monitoring programs and highlight large differences between oligotrophic and eutrophic seawaters or salt lakes and their spatial-temporal dynamic change

Raman Study of Natural Berlinite from the Cioclovina Cave Phosphate Deposit

Natural berlinite from a heated sedimentary sequence in Cioclovina Cave (Romania) was studied using Raman spectroscopy complemented with infrared techniques. Vibrational data acquired at room temperature were compared with those reported for synthetic berlinite in ambient conditions. The symmetry of the (PO4)3− units is confirmed by the observation of characteristic bands attributed to the ν1(PO4)3− stretching mode, both the ν4 and ν2 bending regions at 500–595 cm−1, and 350–500 cm−1, respectively. The berlinite Raman fingerprint was unambiguously identified at 1111 and 1104 cm−1, confirming the identity of the species and elucidating some controversial reports in the mineralogy field. The vibrational data of natural berlinite relates to its crystallography, and along with the spectra–structure correlation, confirmed an almost ideal natural berlinite crystal

FT-Raman and FT-Infrared investigations of archaeological artefacts from Foeni Neolithic site (Banat, Romania)

An impressive collection of chert artefacts from the Foeni Neolithic archaeological site (Timiş County, Banat region, Romania) is hosted by the Banat Museum in Timişoara. A representative set of seven specimens was non-destructively investigated using FT-Raman and ATR-FT-IR spectroscopy. The research was carried out for checking if these readily-available, non-destructive, fast, and cheap methods, which do not require preliminary sample preparation could provide significant information for characterizing the mineral composition of chert artefacts. Based on vibrational data, it was confirmed that the raw material was represented by microcrystalline quartz and moganite, with local concentrations of accessory minerals (calcite, dolomite, and clay minerals). In spite of their wide macroscopic heterogeneity (colour, transparency), based on single point FT-Raman measurements the chert artefacts could not be assigned to distinctive groups of raw silica materials, in order to provide specific arguments for provenance studies. However, the presence of specific accessory minerals (dolomite, illite) pointed to distinctive genetic conditions in the case of one lithic material. Sets of measurements (mapping) are required for statistically characterizing each artefact specimen. IR data were less significant, due to the rough surface texture of the specimens in contact with the ZnSe crystal of the ATR-FT-IR module. However, illite was identified based solely on its contribution to the IR spectrum. This pioneering study on chert artefacts from Romania based on optical spectroscopic methods shows that there are good premises for a systematic investigation of highly-valuable museum collections, in particular in terms of chert geology

Surface-Enhance Raman Spectroscopy Detection of Thiabendazole in Frozen Food Products: The Case of Blueberries and Their Extracts

To improve the control and detection methods of thiabendazole (TBZ), a fungicide and parasiticide often used in food products, we investigated the performance of the SERS technique applied to frozen blueberry fruits available on the market. TBZ-treated fruit extracts provided a multiplexed SERS feature, where the SERS bands of TBZ could be distinctly recorded among the characteristic anthocyanidins from blueberries. Quantitative SERS of TBZ in a concentration range from 20 µM to 0.2 µM has been achieved in solutions. However, quantitative multiplexed SERS is challenging due to the gradually increasing spectral background of polyphenols from extracts, which covers the TBZ signal with increasing concentration. The strategy proposed here was to employ food bentonite to filter a substantial amount of flavonoids to allow a higher SERS signal-to-background recording and TBZ recognition. Using bentonite, the LOD for SERS analysis of blueberry extracts provided a detection limit of 0.09 µM. From the relative intensity of the specific SERS bands as a function of concentration, we estimated the detection capability of TBZ to be 0.0001 mg/kg in blueberry extracts, which is two orders of magnitude lower than the maximum allowed by current regulations

Detection and Characterization of Nodularin by Using Label-Free Surface-Enhanced Spectroscopic Techniques

Nodularin (NOD) is a potent toxin produced by Nodularia spumigena cyanobacteria. Usually, NOD co-exists with other microcystins in environmental waters, a class of cyanotoxins secreted by certain cyanobacteria species, which makes identification difficult in the case of mixed toxins. Herein we report a complete theoretical DFT-vibrational Raman characterization of NOD along with the experimental drop-coating deposition Raman (DCDR) technique. In addition, we used the vibrational characterization to probe SERS analysis of NOD using colloidal silver nanoparticles (AgNPs), commercial nanopatterned substrates with periodic inverted pyramids (KlariteTM substrate), hydrophobic Tienta&reg; SpecTrimTM slides, and in-house fabricated periodic nanotrenches by nanoimprint lithography (NIL). The 532 nm excitation source provided more well-defined bands even at LOD levels, as well as the best performance in terms of SERS intensity. This was reflected by the results obtained with the KlariteTM substrate and the silver-based colloidal system, which were the most promising detection approaches, providing the lowest limits of detection. A detection limit of 8.4 &times; 10&minus;8 M was achieved for NOD in solution by using AgNPs. Theoretical computation of the complex vibrational modes of NOD was used for the first time to unambiguously assign all the specific vibrational Raman bands

Evaluation and differentiation of the <it>Betulaceae</it> birch bark species and their bioactive triterpene content using analytical FT-vibrational spectroscopy and GC-MS

<p>Abstract</p> <p>Background</p> <p>Aiming to obtain the highest triterpene content in the extraction products, nine bark samples from the forest abundant flora of Apuseni Mountains, Romania were Raman spectroscopically evaluated. Three different natural extracts from <it>Betula pendula Roth</it> birch bark have been obtained and characterized using Fourier transform vibrational spectra.</p> <p>Results</p> <p>This study shows that principal components of the birch tree extract can be rapidly recognized and differentiated based on their vibrational fingerprint band shape and intensity. The vibrational spectroscopy results are supported by the GC-MS data. Based on IR and Raman analysis, one can conclude that all the extracts, independent on the solvent(s) used, revealed dominant betulin species, followed by lupeol.</p> <p>Conclusions</p> <p>Since Raman measurements could also be performed on fresh plant material, we demonstrated the possibility to apply the present results for the prediction of the highest triterpene content in bark species, for the selection of harvesting time or individual genotypes directly in the field, with appropriate portable Raman equipment.</p

Biocompatible Magnetic Colloidal Suspension Used as a Tool for Localized Hyperthermia in Human Breast Adenocarcinoma Cells: Physicochemical Analysis and Complex In Vitro Biological Profile

Magnetic iron oxide nanoparticles are the most desired nanomaterials for biomedical applications due to their unique physiochemical properties. A facile single-step process for the preparation of a highly stable and biocompatible magnetic colloidal suspension based on citric-acid-coated magnetic iron oxide nanoparticles used as an effective heating source for the hyperthermia treatment of cancer cells is presented. The physicochemical analysis revealed that the magnetic colloidal suspension had a z-average diameter of 72.7 nm at 25 °C with a polydispersity index of 0.179 and a zeta potential of −45.0 mV, superparamagnetic features, and a heating capacity that was quantified by an intrinsic loss power analysis. Raman spectroscopy showed the presence of magnetite and confirmed the presence of citric acid on the surfaces of the magnetic iron oxide nanoparticles. The biological results showed that breast adenocarcinoma cells (MDA-MB-231) were significantly affected after exposure to the magnetic colloidal suspension with a concentration of 30 µg/mL 24 h post-treatment under hyperthermic conditions, while the nontumorigenic (MCF-10A) cells exhibited a viability above 90% under the same thermal setup. Thus, the biological data obtained in the present study clearly endorse the need for further investigations to establish the clinical biological potential of synthesized magnetic colloidal suspension for magnetically triggered hyperthermia

Development and Characterization of Fe3O4@Carbon Nanoparticles and Their Biological Screening Related to Oral Administration

The current study presents the effect of naked Fe3O4@Carbon nanoparticles obtained by the combustion method on primary human gingival fibroblasts (HGFs) and primary gingival keratinocytes (PGKs)—relevant cell lines of buccal oral mucosa. In this regard, the objectives of this study were as follows: (i) development via combustion method and characterization of nanosized magnetite particles with carbon on their surface, (ii) biocompatibility assessment of the obtained magnetic nanoparticles on HGF and PGK cell lines and (iii) evaluation of possible irritative reaction of Fe3O4@Carbon nanoparticles on the highly vascularized chorioallantoic membrane of a chick embryo. Physicochemical properties of Fe3O4@Carbon nanoparticles were characterized in terms of phase composition, chemical structure, and polymorphic and molecular interactions of the chemical bonds within the nanomaterial, magnetic measurements, ultrastructure, morphology, and elemental composition. The X-ray diffraction analysis revealed the formation of magnetite as phase pure without any other secondary phases, and Raman spectroscopy exhibit that the pre-formed magnetic nanoparticles were covered with carbon film, resulting from the synthesis method employed. Scanning electron microscopy shown that nanoparticles obtained were uniformly distributed, with a nearly spherical shape with sizes at the nanometric level; iron, oxygen, and carbon were the only elements detected. While biological screening of Fe3O4@Carbon nanoparticles revealed no significant cytotoxic potential on the HGF and PGK cell lines, a slight sign of irritation was observed on a limited area on the chorioallantoic membrane of the chick embryo