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The potential of Raman spectroscopy with excitation in the visible as a tool for quantitative determina- tion of single components in food industry products was investigated by focusing the attention on glu- cose content in commercial sport drinks. At this aim, micro-Raman spectra in the 600-1600 cm À1 wavenumber shift region of four sport drinks were recorded, showing well defined and separated vibra- tional fingerprints of the various contained sugars (glucose, fructose and sucrose). By profiting of the spectral separation of some peculiar peaks, glucose content was quantified by using a multivariate statis- tical analysis based on the interval Partial Least Square (iPLS) approach. The iPLS model needed for data analysis procedure was built by using glucose aqueous solutions at known sugar concentrations as cali- bration data. This model was then applied to sport drink spectra and gave predicted glucose concentra- tions in good agreement with the values obtained by using a biochemical assay. These results represent a significant step towards the development of a fast and simple method for the on-line glucose quantifica- tion in products of food and beverage industry.

A Micro-Raman spectroscopy investigation has been performed on human mammary epithelial cells after irradiation by different X-ray doses. The analysis by interval­ Principal Component Analysis (iPCA) has allowed us to outline the subtle differences in the Raman spectra induced by irradiation. In particular, this experimental approach has enabled to delineate radiation-induced changes in structure, protein, nucleic acid, lipid, and carbohydrate content. This has further confirmed that micro-Raman spectroscopy coupled to properly chosen data analysis methods is a very sensitive technique to detect molecular changes even in single human cells following exposure to ionising radiation. This would help developing innovative approaches to monitor radiation treatment effects so as to reduce the overall radiation dose and minimize damage to the surrounding healthy cells, both aspects being of great importance in the field of radiation therapy. Keywords-Micro-Raman spectroscopy; X-ray induced damage cells; interval principal component analaysis

Raman micro-spectroscopy and different approaches for multivariate analysis were used for an investigation of subcellular regions of X-ray exposed single SH-SY5Y human neuroblastoma cells. Nucleus and cytoplasm regions of single cells were investigated after X-rays irradiation (0, 2, 4, 6 and 8 Gy). Cells fixed immediately after irradiation and 24h irradiation were considered. Principal component analysis (PCA) and interval-PCA (i-PCA) were used for analyzing the spectra in order to highlight the changes due to the different treatments. Biochemical changes occurring in the nucleus and cytoplasm regions of single cells upon X-ray irradiation were observed. The analysis of Raman spectra allowed us to detect modifications in the contribution from proteins, nucleic acids, lipids, and carbohydrates of cells, induced at different extent on the two cell regions. The biochemical changes occurring in these cells were also discussed by using an alternative approach, namely the analysis of difference spectra, obtained by subtracting the cytoplasm-related spectrum from the corresponding one detected at the nucleus. The proposed approach enabled us to evidence some features not outlined in previous investigations. The results showed that it is possible to study in a selective way the effects of ionizing radiation on different neuroblastoma cell spatial regions. An increase of the signal related to the nucleobases, a decrease of DNA and/or RNA backbone contribution, a protein rearrangement with changes in the secondary structure, and an increase in lipid saturation were observed. These results indicated that the development of accurate data analysis methods enabling to take into account the complexity of the Raman spectra of cells and tissues and the high number of spectra needed to consider the intrinsic variability of biological samples.

Olive oil is a major fat source of the Mediterranean diet. For its unique functional and technological properties, olive oil is highly appreciated all over the world. Very sensitive techniques are currently required to determine chemical composition, to evaluate olive oil authenticity and to quantify vegetable adulterants or degradation compounds. A class of techniques that can be particularly interesting in olive oil characterization is represented by those based on light scattering. These techniques can provide important information on physical properties, conservation state and possible adulteration without complicate or time expensive procedures. Among these, static and dynamic light scattering, diffuse wave spectroscopy, different kinds of Raman spectroscopy are the most used. In this short review, basic concepts about the experimental aspects of these techniques are presented together with some of the most generally used data analysis procedures. Some selected examples of the most interesting applications of these techniques are also proposed.

Monitoring cell culture media by traditional methods has high costs and requires significant analytical expertise and laboratory space. Surface-Enhanced Raman spectroscopy (SERS) can offer a method for a simple and fast analysis of cell culture media under different conditions. In particular, to examine cell culture media during cell exposure to ionizing radiation deserves particular attention. In this way, useful information on the complex processes occurring during the interaction between cells, cell culture media and radiation can be obtained. We report about a SERS study of the radiation-induced changes on cell culture media that were in contact or not with human cells. SERS measurements were performed by using commercial substrates and a conventional micro-Raman spectroscopy set-up. By employing a suitable data treatment based on “wavelet” denoising algorithm and background subtraction, spectra with clear Raman features were obtained for two cell culture media that were subject to different irradiation treatments. The obtained results evidence that SERS can be used to rapidly identify and monitor chemical changes in cell culture media.

Raman micro-spectroscopy was performed in vitro on nuclear and membrane regions of single SH-SY5Y human neuroblastoma cells after irradiation by graded X-ray doses (2, 4, 6, 8 Gy). The acquired spectra were analyzed by principal component analysis (PCA) and interval-PCA (i-PCA) methods. Biochemical changes occurring in the different regions of single cells as a consequence of the radiation exposure were observed in cells fixed immediately after the irradiation. The most relevant effects arose from the analysis of the spectra from the cell nucleus region. The observed changes were discussed in terms of the modifications in the cell cycle, resulting in an increase in the DNA-related signal, a protein rearrangement and changes in lipid and carbohydrates profiles within the nucleus. Potential markers of an apoptotic process in cell population irradiated with 6 and 8-Gy X-ray doses could have been singled out. No significant effects were found in spectra from cells fixed 24 h after the irradiation, thus suggesting the occurrence of repairing processes of the X-ray induced damage.

Previous works showed that spatially resolved Raman spectra of cytoplasm and nucleus region of single cells exposed to X-rays evidence different features. The present work aims to introduce a new approach to profit from these differences to deeper investigate X-ray irradiation effects on single SH-SY5Y human neuroblastoma cells. For this aim, Raman micro-spectroscopy was performed in vitro on single cells after irradiation by graded X-ray doses (2, 4, 6, 8 Gy). Spectra from nucleus and cytoplasm regions were selectively acquired. The examination by interval Principal Component Analysis (i-PCA) of the difference spectra obtained by subtracting each cytoplasm-related spectrum from the corresponding one detected at the nucleus enabled us to reveal the subtle modifications of Raman features specific of different spatial cell regions. They were discussed in terms of effects induced by X-ray irradiation on DNA/RNA, lipids, and proteins. The proposed approach enabled us to evidence some features not outlined in previous investigations.

Graphene provides a unique way of sensing the local pH level of substances on the micrometric scale, with important implications for the monitoring of cellular metabolic activities where proton excretion could occur. Accordingly, an innovative biosensing approach for the quantification of the pH value of biological fluids, to be used also with small amounts of fluids, was realized and tested. It is based on the use of micro-Raman spectroscopy to detect the modifications of the graphene doping level induced by the contact of the graphene with the selected fluids. The approach was preliminarily tested on aqueous solutions of known pH values. It was then used to quantify the pH values of cell culture media directly exposed to different doses of X-ray radiation and to media exposed to X-ray-irradiated cells. The Raman response of cells placed on graphene layers was also examined.

Surface-enhanced Raman Spectroscopy (SERS) is a vibrational spectroscopy holding potentials for a rapid evaluation of quality and composition of food industry products without any need of sample preparation. Among many nanomaterials, gold nanoparticles (GNPs) and their colloidal dispersions have attracted great interest for SERS applications due to their unique properties of small size, large surface area to volume ratio, high reactivity to the living cells, stability over high temperatures. In this frame, a low-cost substrate, based on home-made 30-nm sized GNPs, has been designed and used for the investigation of commercial fruit juices and pulp. Thanks to the use of a wavelet denoising procedure and background subtraction spectra with clear features have been obtained. Their analysis has enabled to evidence the presence of components of great importance for the quality evaluation of the products, such as fructose and pectin. The overall inspection of the results has confirmed the potentialities of SERS in food industry.

Micro-Raman technique can be particularly useful to investigate the chemical changes induced in structure, protein, nucleic acid, lipid, and carbohydrate contents of cells. The aim of this work is to inspect the possibility to employ Raman microspectroscopy to detect biochemical modifications in human mammary epithelial cells after exposure to different Xray doses. The samples consisted of cells cultured on polylysine-coated glass coverslips. After the exposition, control and treated cells were washed in phosphate-buffered saline (PBS) and then fixed in paraformaldehyde 3.7%. They were examined using a confocal micro-Raman system equipped with a He-Ne laser (λ = 632.8 nm; power on the sample= 3.5mW). Differences in the intensity ratio of specific Raman vibrational markers commonly assigned to phenylalanine and tyrosine amino acids (at 1000, 1030, 1618 cm -1 ), DNA bases (787, 1090, 1305 cm -1 ), and amide III (1237, and 1265 cm -1 ) with respect a reference peak (the one of lipids at 1450 cm -1 ) were evidenced between control and exposed cells. These differences may be indicative of damage in exposed cells as the fragmentation of individual amino acids and DNA bases, crosslink effects in molecular structure of DNA and protein conformational change that especially tend to "unwind" the protein due to the breaking of hydrogen bonds between peptide chains.

Liquid samples of clarified apple and apricot juices at different production stages were investigated using visible light micro-Raman spectroscopy in order to assess its potential in monitoring fruit juice production. As is well-known, pectin plays a strategic role in the production of clarified juice and the possibility of using Raman for its detection during production was therefore evaluated. The data analysis has enabled the clear identification of pectin. In particular, Raman spectra of apple juice samples from washed and crushed fruits revealed a peak at 845 cm-1 (typical of pectin) which disappears in the Raman spectra of depectinised samples. The fructose content was also revealed by the presence of four peaks at 823 cm-1, 872 cm-1, 918 cm-1 and 975 cm-1. In the case of apricot juice, several Raman fingerprints of β-carotene at 1008, 1159 and 1520 cm-1 were also highlighted. Present results resulted interesting for the exclusive use of optical methods for the quantitative determination of the above-mentioned substances in place of the biochemical assays generally used for this purpose, which are time consuming and require different chemical reagents for each of them. © 2007 by MDPI.