As one type of spatially offset Raman spectroscopy(SORS), inverse SORS is particularly suited to in vivo biomedical measurements due to its ring-shaped illumination scheme. To explain inhomogeneous Raman scattering du...As one type of spatially offset Raman spectroscopy(SORS), inverse SORS is particularly suited to in vivo biomedical measurements due to its ring-shaped illumination scheme. To explain inhomogeneous Raman scattering during in vivo inverse SORS measurements, the light–tissue interactions when excitation and regenerated Raman photons propagate in skin tissue were studied using Monte Carlo simulation. An eight-layered skin model was first built based on the latest transmission parameters. Then, an open-source platform, Monte Carlo e Xtreme(MCX), was adapted to study the distribution of 785 nm excitation photons inside the model with an inverse spatially shifted annular beam. The excitation photons were converted to emission photons by an inverse distribution method based on excitation flux with spatial offsets Δs of 1 mm, 2 mm, 3 mm and 5 mm. The intrinsic Raman spectra from separated skin layers were measured by continuous linear scanning to improve the simulation accuracy. The obtained results explain why the spectral detection depth gradually increases with increasing spatial offset, and address how the intrinsic Raman spectrum from deep skin layers is distorted by the reabsorption and scattering of the superficial tissue constituents. Meanwhile, it is demonstrated that the spectral contribution from subcutaneous fat will be improved when the offset increases to 5 mm, and the highest detection efficiency for dermal layer spectral detection could be achieved when Δs = 2 mm. Reasonably good matching between the calculated spectrum and the measured in vivo inverse SORS was achieved, thus demonstrating great utility of our modeling method and an approach to help understand the clinical measurements.展开更多
The limited penetration of photons in biological tissue restricts the deep-tissue detection and imaging application.The micro-scale spatially offset Raman spectroscopy(micro-SORS)with an optical fiber probe,colleting ...The limited penetration of photons in biological tissue restricts the deep-tissue detection and imaging application.The micro-scale spatially offset Raman spectroscopy(micro-SORS)with an optical fiber probe,colleting photons from deeper regions by offsetting the position of laser excitation from the collection optics in a range of hundreds of microns,shows great potential to be integrated with endoscopy for inside-body noninvasive detection by circumventing this restric-tion,particularly with the combination of surface-enhanced Raman spectroscopy(SERS).However,a detailed tissue penetration study of micro-SORS in combination with SERS is still lacking.Herein,we compared the signal decay of enhanced Raman nanotags through the tissue phantom of agarose gel and the biological tissue of porcine muscle in the near-infrared(NIR)region using a portable Raman spectrometer with a micro-SORS probe(2.1 mm in diameter)and a conventional hand-held probe(9.7mm in diameter).Two kinds of Raman nanotags were prepared from gold nanorods decorated with the nonresonant(4-nitrobenzenethiol)or resonant Raman reporter molecules(IR-780 iodide).The SERS measurements show that the penetration depths of two Raman nanotags are both over 2 cm in agarose gel and 3 mm in porcine muscle.The depth could be improved to over 4 cm in agarose gel and 5 mm in porcine tissue when using the micro-SORS system.This demonstrates the superiority of optical-fiber micro-SORS system over the conventional Raman detection for the detection of nanotags in deeper layers in the turbid medium and biological tissue,offering the possibility of combining the micro-SORS technique with SERS for noninvasive in vivo endoscopy-integrated clinical application.展开更多
The purpose of this study is to examine optical spatial frequency spectroscopy analysis(SFSA)combined with visible resonance Raman(VRR)spectroscopic method,for thefirst time,to discriminate human brain metastases of l...The purpose of this study is to examine optical spatial frequency spectroscopy analysis(SFSA)combined with visible resonance Raman(VRR)spectroscopic method,for thefirst time,to discriminate human brain metastases of lung cancers adenocarcinoma(ADC)and squamous cell carcinoma(SCC)from normal tissues.A total of 31 label-free micrographic images of three type of brain tissues were obtained using a confocal micro-Raman spectroscopic system.VRR spectra of the corresponding samples were synchronously collected using excitation wavelength of 532 nm from the same sites of the tissues.Using SFSA method,the difference in the randomness of spatial frequency structures in the micrograph images was analyzed using Gaussian functionfitting.The standard deviations,calculated from the spatial frequencies of the micrograph images were then analyzed using support vector machine(SVM)classifier.The key VRR biomolecularfingerprints of carotenoids,tryptophan,amide II,lipids and proteins(methylene/methyl groups)were also analyzed using SVM classifier.All three types of brain tissues were identified with high accuracy in the two approaches with high correlation.The results show that SFSA–VRR can potentially be a dual-modal method to provide new criteria for identifying the three types of human brain tissues,which are on-site,real-time and label-free and may improve the accuracy of brain biopsy.展开更多
Measurement and comparison of NaNO3 powder concealed in opaque and semi-transparent plastic bottles are carried out through conventional Raman spectroscopy and spatially offset Raman spectroscopy individually. The act...Measurement and comparison of NaNO3 powder concealed in opaque and semi-transparent plastic bottles are carried out through conventional Raman spectroscopy and spatially offset Raman spectroscopy individually. The action mechanism why the spatially offset Raman spectroscopy can effectively detect the medium concealed in the non-transparent bottle is analyzed. The spatially offset Raman spectroscopy breaks through the detection neck of the conventional Raman spectroscopy (the detection depth is small and cannot detect the ingredient of the subsurface under non-transparent medium), and the measurement and identification of the substance concealed in the non-transparent medium (opaque/semi-transparent plastic) bottle have been realized.展开更多
Stress index of tetrahedron （SIT） was defined to describe the topological connectivities among various sili- con-oxygen tetrahedra （SiOT） in anionic clusters of binary silicate crystals, glasses, and melts. It was...Stress index of tetrahedron （SIT） was defined to describe the topological connectivities among various sili- con-oxygen tetrahedra （SiOT） in anionic clusters of binary silicate crystals, glasses, and melts. It was found that the value of SIT was well correlated with the wavenumber of Raman active symmetric stretching vibration of non-bridging oxygen of SiOT. The spatial fractional dimension of hyperfine structure was introduced while comparative analysis was made with the value of SIT. It can be concluded that the concepts of SIT, vibrational wavenumber, and spatial fractional dimension were inherently and holographically correlated and exhibit isomorphic representations of complex structure of binary silicates. Experimental Raman spectra of binary silicates with different alkali cations were investigated. It was demonstrated that alkali cations have little effect on the vibrational wavenumber of symmetric stretching of non-bridging oxygen （NBO） of SiOT, but remarkably affect its Raman active optical cross section, as was consensus resulted from ab initio calculation. It can also be concluded that the spatial fractional dimension of binary silicate is predominantly determined by the hyperfine structure of the anionic clusters and little affected by alkali cations, although the species of anionic clusters and their distributions were originally assigned by the content of alkali oxides. And Raman optical activity extinct effect of isolated SiOT at high basicity should be considered while being applied to quantitatively analysis.展开更多
Laser-assisted manufacturing(LAM)is a technique that performs machining of materials using a laser heating process.During the process,temperatures can rise above over 2000°C.As a result,it is crucial to explore t...Laser-assisted manufacturing(LAM)is a technique that performs machining of materials using a laser heating process.During the process,temperatures can rise above over 2000°C.As a result,it is crucial to explore the thermal behavior of materials under such high temperatures to understand the physics behind LAM and provide feedback for manufacturing optimization.Raman spectroscopy,which is widely used for structure characterization,can provide a novel way to measure temperature during LAM.In this review,we discuss the mechanism of Raman-based temperature probing,its calibration,and sources of uncertainty/error,and how to control them.We critically review the Raman-based temperature measurement considering the spatial resolution under near-field optical heating and surface structure-induced asymmetries.As another critical aspect of Raman-based temperature measurement,temporal resolution is also reviewed to cover various ways of realizing ultrafast thermal probing.We conclude with a detailed outlook on Raman-based temperature probing in LAM and issues that need special attention.展开更多
基金Project supported by the National Natural Science Foundation of China (Grant No. 61911530695)the Key Research and Development Project of Shaanxi Province, China (Grant No. 2023-YBSF-671)。
文摘As one type of spatially offset Raman spectroscopy(SORS), inverse SORS is particularly suited to in vivo biomedical measurements due to its ring-shaped illumination scheme. To explain inhomogeneous Raman scattering during in vivo inverse SORS measurements, the light–tissue interactions when excitation and regenerated Raman photons propagate in skin tissue were studied using Monte Carlo simulation. An eight-layered skin model was first built based on the latest transmission parameters. Then, an open-source platform, Monte Carlo e Xtreme(MCX), was adapted to study the distribution of 785 nm excitation photons inside the model with an inverse spatially shifted annular beam. The excitation photons were converted to emission photons by an inverse distribution method based on excitation flux with spatial offsets Δs of 1 mm, 2 mm, 3 mm and 5 mm. The intrinsic Raman spectra from separated skin layers were measured by continuous linear scanning to improve the simulation accuracy. The obtained results explain why the spectral detection depth gradually increases with increasing spatial offset, and address how the intrinsic Raman spectrum from deep skin layers is distorted by the reabsorption and scattering of the superficial tissue constituents. Meanwhile, it is demonstrated that the spectral contribution from subcutaneous fat will be improved when the offset increases to 5 mm, and the highest detection efficiency for dermal layer spectral detection could be achieved when Δs = 2 mm. Reasonably good matching between the calculated spectrum and the measured in vivo inverse SORS was achieved, thus demonstrating great utility of our modeling method and an approach to help understand the clinical measurements.
基金This work was financially supported by National Natural Science Foundation of China(Nos.81871401 and 81901786)China Postdoctoral Science Foundation(Nos.2018M640395 and 2019T120343)+3 种基金the Science and Technology Commission of Shanghai Municipality(No.19441905300)Innovation Research Plan supported by Shanghai Municipal Education Commission(No.ZXWF082101)Shanghai Jiao Tong University(Nos.YG2017MS54 and YG2019QNA28)the Shanghai Key Laboratory of Gynecologic Oncology.
文摘The limited penetration of photons in biological tissue restricts the deep-tissue detection and imaging application.The micro-scale spatially offset Raman spectroscopy(micro-SORS)with an optical fiber probe,colleting photons from deeper regions by offsetting the position of laser excitation from the collection optics in a range of hundreds of microns,shows great potential to be integrated with endoscopy for inside-body noninvasive detection by circumventing this restric-tion,particularly with the combination of surface-enhanced Raman spectroscopy(SERS).However,a detailed tissue penetration study of micro-SORS in combination with SERS is still lacking.Herein,we compared the signal decay of enhanced Raman nanotags through the tissue phantom of agarose gel and the biological tissue of porcine muscle in the near-infrared(NIR)region using a portable Raman spectrometer with a micro-SORS probe(2.1 mm in diameter)and a conventional hand-held probe(9.7mm in diameter).Two kinds of Raman nanotags were prepared from gold nanorods decorated with the nonresonant(4-nitrobenzenethiol)or resonant Raman reporter molecules(IR-780 iodide).The SERS measurements show that the penetration depths of two Raman nanotags are both over 2 cm in agarose gel and 3 mm in porcine muscle.The depth could be improved to over 4 cm in agarose gel and 5 mm in porcine tissue when using the micro-SORS system.This demonstrates the superiority of optical-fiber micro-SORS system over the conventional Raman detection for the detection of nanotags in deeper layers in the turbid medium and biological tissue,offering the possibility of combining the micro-SORS technique with SERS for noninvasive in vivo endoscopy-integrated clinical application.
基金This research is supported by The Air Force Medical Center,China and in part of The Institute for Ultrafast Spectroscopy and Lasers(IUSL),the City College of the City University of New York.The authors would like to thank Mr.C.Y.Zhang,Mr.M.Z.Fan and Dr.X.H.Ni for their assistance in the experiments and suggestions concerning this paper.
文摘The purpose of this study is to examine optical spatial frequency spectroscopy analysis(SFSA)combined with visible resonance Raman(VRR)spectroscopic method,for thefirst time,to discriminate human brain metastases of lung cancers adenocarcinoma(ADC)and squamous cell carcinoma(SCC)from normal tissues.A total of 31 label-free micrographic images of three type of brain tissues were obtained using a confocal micro-Raman spectroscopic system.VRR spectra of the corresponding samples were synchronously collected using excitation wavelength of 532 nm from the same sites of the tissues.Using SFSA method,the difference in the randomness of spatial frequency structures in the micrograph images was analyzed using Gaussian functionfitting.The standard deviations,calculated from the spatial frequencies of the micrograph images were then analyzed using support vector machine(SVM)classifier.The key VRR biomolecularfingerprints of carotenoids,tryptophan,amide II,lipids and proteins(methylene/methyl groups)were also analyzed using SVM classifier.All three types of brain tissues were identified with high accuracy in the two approaches with high correlation.The results show that SFSA–VRR can potentially be a dual-modal method to provide new criteria for identifying the three types of human brain tissues,which are on-site,real-time and label-free and may improve the accuracy of brain biopsy.
文摘Measurement and comparison of NaNO3 powder concealed in opaque and semi-transparent plastic bottles are carried out through conventional Raman spectroscopy and spatially offset Raman spectroscopy individually. The action mechanism why the spatially offset Raman spectroscopy can effectively detect the medium concealed in the non-transparent bottle is analyzed. The spatially offset Raman spectroscopy breaks through the detection neck of the conventional Raman spectroscopy (the detection depth is small and cannot detect the ingredient of the subsurface under non-transparent medium), and the measurement and identification of the substance concealed in the non-transparent medium (opaque/semi-transparent plastic) bottle have been realized.
基金This work was financially supported by the National Natural Science Foundation of China (Nos. 50334040, 40203001, and 50334050) and Shanghai Research Center for Advanced Materials (No. 98JC14018).
文摘Stress index of tetrahedron （SIT） was defined to describe the topological connectivities among various sili- con-oxygen tetrahedra （SiOT） in anionic clusters of binary silicate crystals, glasses, and melts. It was found that the value of SIT was well correlated with the wavenumber of Raman active symmetric stretching vibration of non-bridging oxygen of SiOT. The spatial fractional dimension of hyperfine structure was introduced while comparative analysis was made with the value of SIT. It can be concluded that the concepts of SIT, vibrational wavenumber, and spatial fractional dimension were inherently and holographically correlated and exhibit isomorphic representations of complex structure of binary silicates. Experimental Raman spectra of binary silicates with different alkali cations were investigated. It was demonstrated that alkali cations have little effect on the vibrational wavenumber of symmetric stretching of non-bridging oxygen （NBO） of SiOT, but remarkably affect its Raman active optical cross section, as was consensus resulted from ab initio calculation. It can also be concluded that the spatial fractional dimension of binary silicate is predominantly determined by the hyperfine structure of the anionic clusters and little affected by alkali cations, although the species of anionic clusters and their distributions were originally assigned by the content of alkali oxides. And Raman optical activity extinct effect of isolated SiOT at high basicity should be considered while being applied to quantitatively analysis.
基金We are grateful for the financial support of National Key R&D Program of China(Nos.2O18YFEO2O5OOO and 2O19YFAO9O58OO for R W)Program for Professor of Special Appointment(Eastern Scholar)at Shanghai Institutions of Higher Learning and China Scholarship Council(S X),National Natural Science Foundation of China(No.5157614 for Y Y)and US National Science Foundation(CBET193O866 for X W).
文摘Laser-assisted manufacturing(LAM)is a technique that performs machining of materials using a laser heating process.During the process,temperatures can rise above over 2000°C.As a result,it is crucial to explore the thermal behavior of materials under such high temperatures to understand the physics behind LAM and provide feedback for manufacturing optimization.Raman spectroscopy,which is widely used for structure characterization,can provide a novel way to measure temperature during LAM.In this review,we discuss the mechanism of Raman-based temperature probing,its calibration,and sources of uncertainty/error,and how to control them.We critically review the Raman-based temperature measurement considering the spatial resolution under near-field optical heating and surface structure-induced asymmetries.As another critical aspect of Raman-based temperature measurement,temporal resolution is also reviewed to cover various ways of realizing ultrafast thermal probing.We conclude with a detailed outlook on Raman-based temperature probing in LAM and issues that need special attention.
