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Schematic of the Raman spectroscopy system used for experimental testing of the Raman probe see text for details. Details of the probe tip are presented in Fig. 5. 10 MO, MO, microscopic objective.
Source publication
In vitro experiments have demonstrated the ability of Raman spectroscopy to diagnose a wide variety of diseases. Recent in vivo investigations performed with optical fiber probes were promising but generally limited to easily accessible organs, often requiring relatively long collection times. We have implemented an optical design strategy to utili...
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Context 1
... schematic of the experimental system used in these investigations is shown in Fig. 8. Light from an 830-nm diode laser Process Instruments, Salt Lake City, Utah is collimated by two cylindrical lenses c 1 and c 2 , directed through a bandpass filter BP; Kaiser, redirected by a gold-coated mirror M and focused onto the Raman probe excitation fiber by a 10 microscope objective Newport, Irvine, Calif.. The proximal linear ...
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Citations
... Excitation wavelengths in the near-infrared region between 785 and 1064 nm were selected to minimize the fluorescence exhibited by melanin in the skin because these effectively mask the Raman signals. In some of the studies, the autofluorescence signal was included in the measurement (Bratchenko et al, 2021;Khristoforova et al, 2019), and different fiber optic probes and classification methods were developed for some of the portable systems (Latka et al, 2013;Motz et al, 2004;Sharma et al, 2014). However, the studies were limited to skin neoplasms, and sample numbers were commonly small (range ¼ 21e518); in addition, they almost exclusively included European patient samples. ...
The exquisite sensitivity of Raman spectroscopy for detecting biomolecular changes in skin cancer has previously been explored; however, this mostly required analysis of excised tissue samples using bulky, immobile laboratory instrumentation. In this study, the technique was translated for clinical use with a portable Raman system and customized fiber optic probe and applied to differentiation of skin cancers from benign lesions and inflammatory dermatoses. The aim was to provide an easy-to-use, easy-to-manage assessment tool for clinicians to use in their daily patient examination routine to perform rapid Raman measurements of skin lesions in vivo. Using this system, >867 spectra were measured in vivo from 330 patients with a wide variety of different benign skin lesions (n = 603), inflammatory dermatoses (n = 140), and skin cancers (n = 124). Ethnicities represented were 70% European; 16% Asian; 6% Māori; 5% Pacific people; and 4% Middle East, Latin American, and African. Accurate differentiation of skin cancers from benign lesions and inflammatory dermatoses was achieved using partial least squares discriminant analysis, with area under curve for the receiver operator curves for external validation sets ranging from 0.916 to 0.958. This study shows evidence for robust clinical translation of Raman spectroscopy for rapid, accurate diagnosis of skin cancer.
... To minimize this interfering signal, Motz et al. demonstrates a method to acquire Raman spectra of biological tissues using a fiber probe that integrates one fiber for excitation and several fibers for detection of Raman scattering. To remove the interfering background signal, various bandpass filters are used at the distal end of the fiber to block the generated Raman signal from the fiber and the excitation signal from the Laser [10]. Another approach is to study the Raman bands at higher wavenumbers in the range of 2400 cm -1 -3800 cm -1 using a fiber probe, as reported by Koljenovic et al. ...
... There have been the technical approaches to avoid the high silica background. Instead of the lone fiber used for both excitation laser delivery and Raman signal collection, multiple, bundled silica fibers have been used in the fiberoptic probe to separate the excitation and collection paths [45,46]. Konorov based on a hollow-core photonic-crystal fiber (PCF) surrounded by three silica-core collection fibers [47]. ...
Although surface-enhanced Raman spectroscopy (SERS) is a powerful analytical technique with unbeaten sensitivity, the capabilities of SERS have been not fully utilized in screening applications because throughput of spectrum detection by conventional Raman instruments has been restricted due to their single-point measurement manners. Hence, this paper presents a development of a high throughput Raman screening system that employs a fiber-optic switch and a Raman probe array. In the system, a 785 nm excitation light is directed into the 1 × 8 broadband optical switching device and selectively switched to one of 8 output ports connected to the corresponding Raman probe array to deliver the light to samples under each probe. This optical switching driven probing in sequence allows us to rapidly detect Raman scattering of the multiple ( n = 8) samples in array within a short time (~ 28 s) with decent sensitivity (10 –7 M). The Raman spectroscopy of the system is validated by comparing the features of Raman spectra obtained from vitamin C tablets with those from a commercial Raman microscope and the detection sensitivity is measured with SERS substrates with different concentrations. Then, feasibility of high throughput screening is tested with a SERS chip array.
... In recent years, optical fiber technology has experienced significant advancements [23][24][25][26], and fiber-optic Raman spectroscopy has burgeoned by integrating the transmission ability of optical fiber into the fingerprint characterization capacity of Raman spectroscopy systems, providing great potential for on-site real-time monitoring [27][28][29][30][31][32][33]. However, fiber-optic Raman spectroscopy has rarely been utilized to investigate the complex chemical reactions in cementitious materials. ...
This study utilized a novel in situ fiber-optic Raman probe to continuously monitor the hydration progress of tricalcium silicate (C3S) and dicalcium silicate (C2S) without the need for sampling, from early hydration stage to later stages, and from fresh to hardened states of paste samples. By virtue of the remarkable ability of this technique in characterizing either dry or wet and crystalline or amorphous samples, the hydration processes of C3S and C2S pastes with different water-to-solid (w/s) ratios could be monitored from the start of the hydration reaction. The main hydration products, calcium silicate hydrate (C–S–H) and portlandite/calcium hydroxide (CH), have been successfully identified and continuously monitored for variations in their respective amounts in situ. The effect of w/s ratio on the hydration processes of C3S and C2S pastes was also considered. Meanwhile, the x-ray diffraction (XRD) and thermogravimetric analysis (TGA) results showed a great correlation with the in situ Raman test results about hydration products, which demonstrated the reliability of this technology. Moreover, the signal-to-noise ratio (SNR) of this Raman probe is significantly superior to existing technologies for in situ fiber-optic Raman spectroscopy. This remote fiber-optic Raman probe enables the use of Raman spectroscopy in future construction projects for on-site monitoring and evaluation of health conditions and performance of concrete structures.
... This problem has been solved by using various designs of micro endoscopes with fiber-optic probes [31,69,70]. Motz et.al [71] developed a Raman probe for tissue spectroscopy using 830 nm light incidence. As shown in Figure 3b, the central incidence fiber Komachi et al. [65]developed a narrow fiber optic Raman probe of 600 micron in diameter, which can be inserted into coronary arteries. ...
... As shown in Figure 3b, the central incidence fiber Komachi et al. [65]developed a narrow fiber optic Raman probe of 600 micron in diameter, which can be inserted into coronary arteries. They selected a probe similar to that in [71], but with a reduction in the number and dimensions of the optical fibers. The ball lens was also excluded as shown in Figure 3c. ...
Introduction
Fiber optic probe based in-vivo spectroscopy techniques are fast and highly objective methods for intraoperative diagnoses and minimally invasive surgical interventions for all procedures where endoscopic observations are carried out for cancers of different types. The Raman spectral features provide molecular fingerprint-type information and can reveal the subjects’ pathological state in label-free manner, making endoscopy multiplexed fiber optic probe-based devices with the potential for translation from bench to bedside for routine applications.
Areas Covered
This review provides a general overview of different fiber-optic probes for in-vivo measurements with emphasis on Raman spectroscopy for biomedical application. Various aspects such as fiber-optic probe, radiation source, detector, and spectrometer for extracting optimum spectral features have also been discussed.
Expert opinion
: Optical spectroscopy-based fiber probe systems with “Chip-on-Tip” technology, combined with machine learning, can in the near future, become a complimentary diagnostic tool to magnetic resonance imaging (MRI), computed tomography (CT) scan, ultrasound, etc. Hyperspectral imaging and fluorescence-based devices are in the advanced stage of technology readiness level (TRL), and with advances in lasers and miniature spectroscopy systems, probe-based Raman devices are also coming up.
... An intriguing advance, proposed by Motz et al. (2004) and next developed by Kong et al. (2011), Ghenuche et al. (2012) and Pandey et al. (2017), concerns the development of tailored optical fiber probes for delivery and collection of light to and from the tissue interface. The ultimate achievement on optical fiber-probe based Raman instrument lead to measure reliably the Raman signal from a tissue spot in a lighted room (Motz et al., 2004;Kong et al., 2011;Ghenuche et al., 2012;Pandey et al., 2017). ...
... An intriguing advance, proposed by Motz et al. (2004) and next developed by Kong et al. (2011), Ghenuche et al. (2012) and Pandey et al. (2017), concerns the development of tailored optical fiber probes for delivery and collection of light to and from the tissue interface. The ultimate achievement on optical fiber-probe based Raman instrument lead to measure reliably the Raman signal from a tissue spot in a lighted room (Motz et al., 2004;Kong et al., 2011;Ghenuche et al., 2012;Pandey et al., 2017). ...
Diabetes has no well-established cure; thus, its management is critical for avoiding severe health complications involving multiple organs. This requires frequent glycaemia monitoring, and the gold standards for this are fingerstick tests. During the last decades, several blood-withdrawal-free platforms have been being studied to replace this test and to improve significantly the quality of life of people with diabetes (PWD). Devices estimating glycaemia level targeting blood or biofluids such as tears, saliva, breath and sweat, are gaining attention; however, most are not reliable, user-friendly and/or cheap. Given the complexity of the topic and the rise of diabetes, a careful analysis is essential to track scientific and industrial progresses in developing diabetes management systems. Here, we summarize the emerging blood glucose level (BGL) measurement methods and report some examples of devices which have been under development in the last decades, discussing the reasons for them not reaching the market or not being really non-invasive and continuous. After discussing more in depth the history of Raman spectroscopy-based researches and devices for BGL measurements, we will examine if this technique could have the potential for the development of a user-friendly, miniaturized, non-invasive and continuous blood glucose-monitoring device, which can operate reliably, without inter-patient variability, over sustained periods.
... However, studies have shown that background signals generated within the fiber mask the returning Raman signals [5]. To exclude contamination by the Raman light generated within the fiber, light from the sample is returned to the spectrometer through a separate fiber or fibers [18] (Figure 1b). The nanometallic structures are distributed as a 'cloud' within the sample [19][20][21]. ...
Raman Spectroscopy is a well-known method for identifying molecules by their spectroscopic “fingerprint”. In Surface Enhanced Raman Scattering (SERS), the presence of nanometallic surfaces in contact with the molecules enormously enhances the spectroscopic signal. Raman enhancing surfaces are often fabricated lithographically or chemically, but the throughput is low and the equipment is expensive. In this work a SERS layer was formed by the self-assembly of silver nanospheres from a hexane suspension onto an imprinted thermoplastic sheet (PET). In addition, the SERS layer was transferred and securely bonded to other surfaces. This is an important attribute for probes into solid specimen. Raman spectra were obtained with Rhodamine 6G (R6G) solution concentrations ranging from 1 mm to 1 nm. The methods described here produced robust and sensitive SERS surfaces with inexpensive equipment, readily available materials, and with no chemical or lithographic steps. These may be critical concerns to laboratories faced with diminishing funding resources.
... In Situ pueden ser sistemas portátiles, de resolución variable y, de preferencia, de bajo costo, mientras que los equipos para las mediciones In Vitro son mas precisos, por lo que su uso esta restringido a los laboratorios especializados. Estas considerables diferencias entre las mediciones dan origen a variaciones considerables en los resultados obtenidos y sobre todo en el costo final del estudio o experimento a realizar [38,39,40,41,42,43]. ...
... Motz et al. [64] have developed a small diameter Raman probe with integrated filters and a spherical lens to minimise low priority signals. In as little as one second, the probe can show the spectra of arteries and breast tissue at different stages of pathology, which is clinically useful. ...
Nowadays, there is an interest in biomedical and nanobiotechnological studies, such as studies on carotenoids as antioxidants and studies on molecular markers for cardiovascular, endocrine, and oncological diseases. Moreover, interest in industrial production of microalgal biomass for biofuels and bioproducts has stimulated studies on microalgal physiology and mechanisms of synthesis and accumulation of valuable biomolecules in algal cells. Biomolecules such as neutral lipids and carotenoids are being actively explored by the biotechnology community. Raman spectroscopy (RS) has become an important tool for researchers to understand biological processes at the cellular level in medicine and biotechnology. This review provides a brief analysis of existing studies on the application of RS for investigation of biological, medical, analytical, photosynthetic, and algal research, particularly to understand how the technique can be used for lipids, carotenoids, and cellular research. First, the review article shows the main applications of the modified Raman spectroscopy in medicine and biotechnology. Research works in the field of medicine and biotechnology are analysed in terms of showing the common connections of some studies as caretenoids and lipids. Second, this article summarises some of the recent advances in Raman microspectroscopy applications in areas related to microalgal detection. Strategies based on Raman spectroscopy provide potential for biochemical-composition analysis and imaging of living microalgal cells, in situ and in vivo. Finally, current approaches used in the papers presented show the advantages, perspectives, and other essential specifics of the method applied to plants and other species/objects.
... Next, the spectra were smoothed by using a Savitsky-Golay filter (5th order, frame size 7). The wavenumber range between 800 and 1730 cm −1 was chosen for analysis, as the Raman background of silica/quartz fibers is strong from 600 cm −1 up to the quartz peak at 800 cm −1 [59,60], and the range 1730-1800 cm −1 was considered irrelevant for differentiation of tissues in this study. In fact, Raman vibrational modes are tabulated only up to 1756 cm −1 by Talari et al. and Movasaghi et al. [61]. ...
Most oral injuries are diagnosed by histopathological analysis of invasive and time-consuming biopsies. This analysis and conventional clinical observation cannot identify biochemically altered tissues predisposed to malignancy if no microstructural changes are detectable. With this in mind, detailed biochemical characterization of normal tissues and their differentiation features on healthy individuals is important in order to recognize biomolecular changes associated with early tissue predisposition to malignant transformation. Raman spectroscopy is a label-free method for characterization of tissue structure and specific composition. In this study, we used Raman spectroscopy to characterize the biochemistry of in vivo oral tissues of healthy individuals. We investigated this biochemistry based on the vibrational modes related to Raman spectra of four oral subsites (buccal, gingiva, lip and tongue) of ten volunteers as well as with principal component (PC) loadings for the difference between the four types of oral subsites. Therefore, we determined the biochemical characteristics of each type of healthy oral subsite and those corresponding to differentiation of the four types of subsites. In addition, we developed a spectral reference of oral healthy tissues of individuals in the Brazilian population for future diagnosis of early pathological conditions using real-time, noninvasive and label-free techniques such as Raman spectroscopy.
