Gingival crevicular fluid (GCF) is an exudate originating in the epithelium lining of the gingival sulcus. GCF analysis can represent a simple and noninvasive tool for monitoring periodontal and bone remodeling during the orthodontic tooth movement (OTM). Gingival crevicular fluid (GCF) samples were investigated by using Fourier transform infrared (FTIR), Raman, and Surface-Enhanced Raman (SERS) micro-spectroscopies. Samples were collected at different stages of orthodontic treatments. Vibrational spectra were acquired on the collected samples for characterizing the biochemical changes that are present during the OTM. The attention was focused on the amide I band region (1500 to 1800 cm-1) of the spectra acquired by using FTIR, Raman, and SERS spectroscopy. Deconvolution procedures were adopted for analyzing this spectral region by means of Gaussian–Lorentzian functions for infrared spectra and Lorentzian ones for Raman spectra. This analysis evidences the different contributions of subcomponents of the amide I band and their changes. These alterations can be attributed to changes in the secondary structure of GCF proteins or to the formation of amyloid aggregates induced by the mechanical stress associated to orthodontic treatments. The results of the present investigation confirm that vibrational spectroscopies can be usefully employed for monitoring orthodontic treatments.
Significance: A noninvasive method based on surface-enhanced Raman spectroscopy (SERS) of tears was proposed as a support for diagnosing neurodegenerative pathologies, including different forms of dementia and Alzheimer’s disease (AD). In this field, timely and reliable discrimination and diagnosis are critical aspects for choosing a valid medical therapy, and new methods are highly required.
Aim: The aim is to evince spectral differences in SERS response of human tears from AD affected, mild cognitive impaired (MCI), and healthy control (Ctr) subjects.
Approach: Human tears were characterized by SERS coupled with multivariate data analysis. Thirty-one informed subjects (Ctr, MCI, and AD) were considered.
Results: Average SERS spectra from Ctr, MCI, and AD subjects evidenced differences related to lactoferrin and lysozyme protein components. Quantitative changes were also observed by determining the intensity ratio between selected bands. We also constructed a classification model that discriminated among AD, MCI, and Ctr subjects. The model was built using the scores obtained by performing principal component analysis on specific spectral regions (i-PCA).
Conclusions: The results are very encouraging with interesting perspectives for medical applications as support of clinical diagnosis and discrimination of AD from other forms of dementia.
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.
Gingival crevicular fluid (GCF) is a site-specific exudate in the gingival sulcus. GCF composition changes in response to diseases or mechanical stimuli, such as those occurring during orthodontic treatments. Raman microspectroscopy (μ-RS) and surface-enhanced Raman spectroscopy (SERS) were adopted for a GCF analysis during different initial phases of orthodontic force application. GCF samples were pooled from informed patients using paper cones. SERS spectra were obtained from GCF extracted from these cones, whereas μ-RS spectra were directly acquired on paper cones without any manipulation. The spectral characteristics of the main functional groups and the changes in cytochrome, amide III, and amide I contributions were highlighted in the different phases of orthodontic treatment with both SERS and μ-RS analysis. μ-RS directly performed on the paper cones together with proper statistical methods can offer an effective approach for the development of a tool for monitoring the processes occurring during orthodontic treatments, which may help the clinician in the choice of type of treatment individually for each patient and accelerate and improve the orthodontic therapy.
A micro-Raman spectroscopy investigation has been performed in vitro on single human mammary epithelial cells after irradiation by graded x-ray doses. The analysis by principal component analysis (PCA) and interval-PCA (i-PCA) methods has allowed us to point out the small differences in the Raman spectra induced by irradiation. This experimental approach has enabled us to delineate radiation-induced changes in protein, nucleic acid, lipid, and carbohydrate content. In particular, the dose dependence of PCA and i-PCA components has been analyzed. Our results have confirmed that micro-Raman spectroscopy coupled to properly chosen data analysis methods is a very sensitive technique to detect early molecular changes at the single-cell level following exposure to ionizing radiation. This would help in developing innovative approaches to monitor radiation cancer radiotherapy outcome 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.
An "in vitro" study of Raman spectra from oral human tissues is reported in order to the develop a diagnostic method
suitable for "in vivo" oral pathology follow-up. The investigated pathology is Pemphigus Vulgaris (PV) for which new
techniques for guiding and monitoring therapy would be particularly useful. Raman spectra were obtained in the
wavenumber regions from 1000 to 1800 cm-1 and 2700 to 3200 cm-1 from tissues from patients at different stages of
pathology (active PV, under therapy and in PV remission stage) as confirmed by histopathological and
immunofluorescence analysis. Differences in the spectra depending on tissue illness stage arise in 1150-1250 cm-1
(amide III) and 1420-1450 cm-1 (CH3 deformation) regions and around 1650 cm-1 (amide I) and 2930 cm-1 (CH3
symmetric stretch). A wavelet deconvolution procedure was applied to the spectra for better discriminating among the
three different stages of illness and a linear regression analysis was used to fully exploit the content of information of
Raman spectra.
Pemphigus vulgaris (PV) is a potentially fatal autoimmune disease that cause blistering of the skin and oral cavity. It is characterized by disruption of cell-cell adhesion within the suprabasal layers of epithelium, a phenomenon termed acantholysis Patients with PV develop IgG autoantibodies against normal constituents of the intercellular substance of keratinocytes. The mechanisms by which such autoantibodies induce blisters are not clearly understood. The qualitative analysis of such effects provides important clues in the search for a specific diagnosis, and the quantitative analysis of biochemical abnormalities is important in measuring the extent of the disease process, designing therapy and evaluating the efficacy of treatment. Improved diagnostic techniques could permit the recognition of more subtle forms of disease and reveal incipient lesions clinically unapparent, so that progression of potentially severe forms could be reversed with appropriate treatment. In this paper, we report the results of our micro-Raman spectroscopy study on tissue and blood serum samples from ill, recovered and under therapy PV patients. The complexity of the differences among their characteristic Raman spectra has required a specific strategy to obtain reliable information on the illness stage of the patients For this purpose, wavelet techniques and advanced multivariate analysis methods have been developed and applied to the experimental Raman spectra. Promising results have been obtained.
A wavelet multi-component decomposition algorithm has been used for data analysis of micro-Raman spectra
from human biological samples. In particular, measurements have been performed on some samples of oral tissue
and blood serum from patients affected by pemphigus vulgaris at different stages. Pemphigus is a chronic,
autoimmune, blistering disease of the skin and mucous membranes with a potentially fatal outcome. The disease
is characterized histologically by intradermal blisters and immunopathologically by the finding of tissue bound
and circulating immunoglobulin G (IgG) antibody directed against the cell surface of keratinocytes. More than
150 spectra were measured by means of a Raman confocal microspectrometer apparatus using the 632.8 nm line
of a He-Ne laser source. A discrete wavelet transform decomposition method has been applied to the recorded
Raman spectra in order to overcome related to low-level signals and the presence of noise and background
components due to light scattering and fluorescence. The results indicate that appropriate data processing can
contribute to enlarge the medical applications of micro-Raman spectroscopy.
The formation of a hybrid layer at the dentin/resin interface is a critical point in the curative processes. New restorative materials are currently under investigation in order to improve the characteristics of this interface layer. In this paper micro-Raman spectroscopy and Environmental Scanning Electron Microscope (E-SEM) analysis have been performed to investigate the interface properties of three different restorative materials.
The experimental investigation has been performed on tooth cavities prepared both by Er:YAG laser ablation and by conventional diamond bur. Laser prepared cavities were realized using 100 ms pulsed light beam with energy of 350 mJ, at a frequency of 20 Hz. The cavities were filled with three different composites: True-Vitality (Den-Mat), Enamel Plus (Micerium), Supreme (3M). The treated samples were sectioned perpendicularly to the exposed dentin surface and the morphological characterization of the samples was performed by means of E-SEM operating in wet mode. This equipment permits to obtain a high-resolution image of surface without conductive coating process. The same samples were then examined by micro-Raman spectroscopy that has already shown its validity in the study of dentin/resin interfaces.
Raman spectroscopy of oral tissues is a promising tool for in vivo diagnosis of oral pathologies, due to the high chemical and structural information content of Raman spectra. However, measurements on biological tissues are usually hindered by low level signals and by the presence of interfering noise and background components due to light diffusion or fluorescence processes. Numerical methods can be used in data analysis, in order to overcome these problems. In this work the wavelet multicomponent decomposition approach has been tested in a series of micro-Raman measurements performed on “in vitro” animal tissue samples. The experimental set-up was mainly composed by a He-Ne laser and a monochromator equipped with a liquid nitrogen cooled CCD equipped with a grating of 1800 grooves/mm. The laser light was focused on the sample surface by means of a 50 X optical objective. The resulting spectra were analysed using a wavelet software package and the contribution of different vibration modes have been singled out. In particular, the C=C stretching mode, and the CH2 bending mode of amide I and amide III and tyrosine contributions were present. The validity of wavelet approach in the data treatment has been also successfully tested on aspirin.
Cavities in human teeth were fabricated by means of Er:YAG laser and compared with samples processed by using conventional drill. The cavities of lased and unlased samples were cured with two different composite resins ( Bis-GMA vs PEX) to investigate differences in their adhesion properties. Morphological characterization of the sample surfaces by SEM analysis was performed. The same samples were then examined by micro-Raman spectroscopy by using He-Ne laser visible light excitation, in order to characterize the dentin/resin interfaces.
The Raman spectra exhibited typical peaks of dentine. Resin contributions to the Raman spectra were also detected and have been used to monitor the interface properties of the boundary region. The dependence of the Raman spectrum on spatial position has been monitored. In both lased and unlased samples the PEX diffusion in dentine is limited in a region of order of 10 μm depth. A larger interdiffusion region is observed at the boundary of dentine and Bis-GMA resin.
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