Endometrial cancer is the sixth most common cancer and the fourth leading cause of death amongst women worldwide. Currently there are no screening strategies successfully implemented in clinical practice for the general population. Present diagnostic approaches are invasive, costly and time consuming. Here, we present results of a simple blood test showing promise for endometrial cancer detection. Both Raman and FtIR-ATR (Fourier transform Infrared Attenuated Total Reflection) spectroscopies, of blood plasma taken from patients with and without endometrial cancer, as ascertained by histopathology, are shown to yield discrimination of endometrial cancer. Spectral data classification is performed using Quasar open-source software.
Recent advances on micro Spatially Offset Raman Spectroscopy (micro-SORS), an optical spectroscopy method able to non-invasively investigate at the microscale the molecular composition of the subsurface of turbid materials, will be presented. The recent research topics include the application of micro-SORS to non-invasively reconstruct the diffusion profiles of conservation treatments applied in calcium-based matrices, the first in-situ surveys of prestigious panel paintings with a portable micro-SORS prototype derived modifying a commercial portable Raman spectrometer, and proof-of-concept experiments performed coupling micro-SORS with Time-Gated Raman Spectral Multiplexing method for the non-invasive suppression of the fluorescence originated by the subsurface.
Raman spectroscopy mapping was used to study ex vivo fresh lung tissues and compare to histology sections. The Raman mapping measurements revealed differences in the molecular composition of normal lung tissue, adenocarcinoma, and squamous cell carcinoma (SCC). Molecular heterogeneity of the tissue samples was well captured by the k-means clustering analysis of the Raman datasets, as confirmed by the correlation with the adjacent haematoxylin and eosin (H&E) stained tissue sections. The results indicate that the fluorescence background varies considerably even in samples that appear structurally uniform in the H&E images, both for normal and tumor tissue. The results show that characteristic Raman bands can be used to discriminate between tumorous and nontumorous lung tissues and between adenocarcinoma and SCC tissues. These results indicate the potential to develop Raman classifications models for lung tissues based on the Raman spectral differences at the microscopic level, which can be used for tissue diagnosis or treatment stratification.
Due to the high flexibility and throughput, Spatial Light Modulator (SLMs) have been widely used in optical microscopy and spectroscopy for various applications. In this talk, I will present some example applications of Raman spectroscopy using two types of SLM, LC-LSM (liquid crystal-spatial light modulator) and DMD (digital micromirror device). Several modalities of Raman spectroscopy can be achieved by using LC-LSM and/or DMD, such as multi-foci Raman spectroscopy and spatially offset Raman spectroscopy (SORS). The SLMs allow the system to be flexible and efficient in collecting Raman signal, requiring no changes to the optical system or mechanical adjustment.
Basal cell carcinoma (BCC) is the most common type of cancer in the world. The very high incidence of this type of cancer has given rise to an increase in the number of new prospective treatment procedures. Previously we have described a fully automated multimodal instrument that combines autofluorescence microscopy with Raman spectroscopy for the investigation of the entire resection margins for surgically removed skin tissue samples. This multimodal spectral histopathology (MSH) instrument is capable of investigating surgical resection margins in 30 minutes, which is compatible with Mohs micrographic surgery (MMS). The instrument was first developed and optimized on spare frozen skin tissue samples obtained during MMS [1]. Here we present initial results using this MSH instrument when operated in a typical Mohs surgery clinic, using the real resected tissue. After MSH analysis, the samples were processed for frozen section histopathology, which was used to validate the MSH results. The paper aims to present the difficulties that are encountered during the implementation of the instrument into clinical practice. The operating procedure has been successfully adapted to perform measurements of fresh tissue samples intra-operatively, with an improved accuracy over frozen tissue samples.
We report the use of dielectrophoresis to fabricate in-situ probes for tip-enhanced Raman spectroscopy (TERS) based on Au nanoparticles. A typical conductive atomic force microscope (AFM) was used to functionalize iridium-coated conductive silicon probes with Au nanoparticles of 10-nm diameter. Suitable TERS probes can be rapidly produced (30 to 120 s) by applying a voltage of 10 Vpp at a frequency of 1 MHz. The technique has the advantage that the Au-based probes are ready for immediate use for TERS measurements, minimizing the risks of tip contamination and damage during handling. Scanning electron microscopy and energy dispersive x-ray spectroscopy were used to confirm the quality of the probes, and used samples of p-ATP monolayers on silver substrates were used to demonstrate experimentally TERS measurements.
The capacity of pathogens to acquire nutrients from their host cells is one of the most fundamental aspects of infection biology. Hence, measuring the patterns of nutrients’ uptake by pathogens is essential for understanding the interactions of pathogens with eukaryotic host cells. In this study, we optimized a technique that allows fast and non-destructive measurement of the amino acid Phenylalanine (Phe) acquired by the trophozoite stage of the protozoan Acanthamoeba castellanii (A. castellanii) as they engage with individual human retinal pigment epithelial cells (ARPE-19). ARPE-19 host cells were pre-saturated with Deuterated Phe (L-Phe(D8)) to replace the native substrate Phe (L-Phe). The uptake of L-Phe(D8) by A. castellanii trophozoites was measured by Raman microspectroscopy. This approach allowed us to characterize the uptake patterns of this essential amino acid into A. castellanii trophozoites at a single cell level. At 24 hours post infection (PI) A. castellanii trophozoites are capable of salvaging L-Phe(D8) from host cells. The uptake pattern was time-dependent during the first 24 hours of infection and complete substitution with L-Phe(D8) in all parasites was detected at 48 hours PI. On the other hand, isolated A. castellanii trachyzoites (grown without host cells) did not show significant uptake for L-Phe(D8) from the media; only achieved an uptake ratio of 16-18% of L-Phe(D8) from the culture medium after 24 hours. These findings demonstrate the potential of combining Raman microspectroscopy and stable isotope labelling approaches to elucidate the role of metabolism in mediating A. castellanii interaction with host cells.
KEYWORDS: Raman spectroscopy, Curium, Stem cells, Raster graphics, Principal component analysis, Signal to noise ratio, Proteins, Data modeling, Time metrology, Laser marking
Raman micro-spectroscopy (RMS) has been recently proposed for label-free phenotypic identification of human embryonic stem cells (hESC)-derived cardiomyocytes. However, the methods used for measuring the Raman spectra led to acquisition times of minutes per cell, which is prohibitive for rapid cell sorting applications. In this study we evaluated two measurement strategies that could reduce the measurement time by a factor of more than 100. We show that sampling individual cells with a laser beam focused to a line could eliminate the need of cell raster scanning and achieve high prediction accuracies (>95% specificity and >96% sensitivity) with acquisition times ∼5 seconds per cell. However, the use of commercially-available higher power lasers could potentially lead to sorting speeds of ∼10 cells per s. This would start to progress RMS to the field of cell sorting for applications such as enrichment and purification of hESC-derived cardiomyocytes
Surface-enhanced Raman spectroscopy (SERS) substrates formed by nanosphere lithography were investigated for their spatial distribution and magnitude of electric field enhancement. An integrated atomic force microscopy and Raman micro-spectroscopy system was used to establish, with high accuracy, the correlation between the local SERS mappings and substrate topography. Using a monolayer of rhodamine 6G as a probe of the local electric field, the high resolution Raman mappings, showed that the highest electric field enhancement originates from the metallic nanostructures rather than the gaps between them. The enhancement factor of the substrates is calculated from Raman spectra of the substrates covered in a monolayer of p-aminothiophenol and spatial measurements, giving a value on the order of 105. The experimental results were confirmed by theoretical calculations using the finite element method.
We investigate the potential of Raman microspectroscopy (RMS) for automated evaluation of excised skin tissue during Mohs micrographic surgery (MMS). The main aim is to develop an automated method for imaging and diagnosis of basal cell carcinoma (BCC) regions. Selected Raman bands responsible for the largest spectral differences between BCC and normal skin regions and linear discriminant analysis (LDA) are used to build a multivariate supervised classification model. The model is based on 329 Raman spectra measured on skin tissue obtained from 20 patients. BCC is discriminated from healthy tissue with 90±9% sensitivity and 85±9% specificity in a 70% to 30% split cross-validation algorithm. This multivariate model is then applied on tissue sections from new patients to image tumor regions. The RMS images show excellent correlation with the gold standard of histopathology sections, BCC being detected in all positive sections. We demonstrate the potential of RMS as an automated objective method for tumor evaluation during MMS. The replacement of current histopathology during MMS by a "generalization" of the proposed technique may improve the feasibility and efficacy of MMS, leading to a wider use according to clinical need.
To ensure the sustainability of tissue engineered products there is a need to consider the engineering and manufacturing
issues related to them particularly for the purposes of process optimization and product quality assurance. This work
describes the application of Raman spectroscopy for in process monitoring of a skin substitute and rotating orthogonal
polarization imaging to track collagen alignment in a tissue engineered tendon. The skin substitute studied is produced
from culturing fibroblasts in a fibrin matrix. Throughout the production process the fibroblasts secrete extracellular
matrix and in doing so deposit collagen in the matrix. Key to optimization of the skin substitute production process is
development of strategies to track the collagen and fibrin content. The work presented here discusses the feasibility of
Raman spectroscopy to resolve fibrin and collagen components in the skin substitutes. Collagen alignment is also
important in the engineering of many tissues, in particular tendons. Thus, this work will also investigate the ability of
rotating orthogonal polarization imaging to track collagen alignment in a tissue engineered tendon.
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