5 research outputs found
Advanced methods for enhanced sensing in biomedical Raman spectroscopy
No full textRaman spectroscopy is a powerful tool in the field of biomedicine for disease
diagnosis owing to its potential to provide the molecular fingerprint of biological
samples. However due to the inherent weak nature of the Raman process, there is a
constant quest for enhancing the sensitivity of this technique for enhanced diagnostic
efficiency. This thesis focuses on achieving this goal by integrating advanced methods
with Raman spectroscopy.
Firstly this thesis explores the applicability of a laser based fluorescence
suppression technique – Wavelength Modulated Raman Spectroscopy (WMRS) - for
suppressing the broad luminescence background which often obscure the Raman peaks.
The WMRS technique was optimized for its applications in single cell studies and tissue
studies for enhanced sensing without compromising the throughput. It has been
demonstrated that the optimized parameter would help to chemically profile single cell
within 6 s. A two fold enhancement in SNR of Raman bands was demonstrated when
WMRS was implemented in fiber Raman based systems for tissue analysis. The
suitability of WMRS on highly sensitive single molecule detection techniques such as
Surface Enhanced Raman Spectroscopy (SERS) and Surface Enhanced Resonance
Raman Spectroscopy (SERRS) was also explored. Further this optimized technique was
successfully used to address an important biological problem in the field of immunology.
This involved label-free identification of major immune cell subsets from human blood.
Later part of this thesis explores a multimodal approach where Raman
spectroscopy was combined with Optical Coherence Tomography (OCT) for enhanced
diagnostic sensitivity (>10%). This approach was used to successfully discriminate
between ex-vivo adenocarcinoma tissues and normal colon tissues.
Finally this thesis explores the design and implementation of a specialized fiber
Raman probe that is compatible with surgical environments. This probe was originally
developed to be compatible with Magnetic Resonance Imaging (MRI) environment. It
has the potential to be used for performing minimally invasive optical biopsy during
interventional MRI procedures
Optofluidic Raman sensor for simultaneous detection of the toxicity and quality of alcoholic beverages
No full textWe report a chemometric prediction of the toxicity and quality of liquor using an optofluidic sensor based upon Waveguide Confined Raman Spectroscopy (WCRS). The WCRS sensor was used to record the Raman spectra, each obtained from a 20 µl sample of a given alcoholic beverage with and acquisition time of 20 s. This was used to predict, simultaneously, both the methanol concentration (toxicity) and ethanol concentration (quality), with an accuracy of 0.1% and 0.7% by volume, respectively, using a Partial Least Squares-based chemometric model. The model sensor is shown to be capable of identifying toxic liquors, based on the test performed on different types of liquor samples
Near infrared spectroscopic analysis of single malt Scotch whisky on an optofluidic chip
No full textStandardization and quality monitoring of alcoholic beverages is an important issue in the liquor production industry. Various spectroscopic techniques have proved useful for tackling this problem. An ideal sensing device for alcoholic beverages should be able to detect the quality of alcohol with a small amount of sample at a low acquisition time using a portable and easy to use device. We propose the use of near infra-red spectroscopy on an optofluidic chip for quality monitoring of single malt Scotch whisky. This is chip upon which we have previously realized waveguide confined Raman spectroscopy. Analysis on this alignment-free, portable chip may be performed in only 2 seconds with a sample volume of only 20 µl. Using a partial least square (PLS) calibration, we demonstrate that the alcohol content in the beverage may be predicted to within a 1% prediction error. Principal component analysis (PCA) was employed for successful classification of whiskies based upon their age, type and cask. The prospect of implementing an optofluidic analogue of a conventional fiber based spectroscopic probe allows a rapid analysis of alcoholic beverages with dramatically reduced sample volumes
Fluorescence suppression using wavelength modulated Raman spectroscopy in fiber-probe-based tissue analysis
No full textThe work was funded by CR-UK/EPSRC/MRC/DoH (England) imaging programme.In the field of biomedical optics, Raman spectroscopy is a powerful tool for probing the chemical composition of biological samples. In particular, fiber Raman probes play a crucial role for in vivo and ex vivo tissue analysis. However, the high-fluorescence background typically contributed by the auto fluorescence from both a tissue sample and the fiber-probe interferes strongly with the relatively weak Raman signal. Here we demonstrate the implementation of wavelength-modulated Raman spectroscopy (WMRS) to suppress the fluorescence background while analyzing tissues using fiber Raman probes. We have observed a significant signal-to-noise ratio enhancement in the Raman bands of bone tissue, which have a relatively high fluorescence background. Implementation of WMRS in fiber-probe-based bone tissue study yielded usable Raman spectra in a relatively short acquisition time (∼30 s), notably without any special sample preparation stage. Finally, we have validated its capability to suppress fluorescence on other tissue samples such as adipose tissue derived from four different species.Peer reviewe
