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1.IntroductionOver the past decade, the nonlinear optical methods have become widely used tools for biomolecular detection, medical diagnosis in cells or tissues at the micrometer and nanometer level.1 Advancement of these optical methods promotes and enhances basic research in biology, pharmacy, and medicine.2–4 Compared with the optical method, radiation is usually applied for imaging modalities, including x-rays, computed tomography, plain radiography, magnetic resonance imaging, and other nuclear imaging methods.5 However, these techniques are costly and emit radiation. For disease detection and diagnoses and cells development process, optical imaging methods can provide molecular information on human tissues with noninvasive, real-time, accurate, sensitive, and economic properties, as discussed in recent reviews.6 When human diseases develop, cells and tissues are used to study the genetics, drug screening, and disease control via optical imaging techniques.7–9 Among optical imaging technologies, the nonlinear optical methods have great advantages such as noninvasiveness, depth penetration, high sensitivity, and ultrahigh resolution. The nonlinear signal is generated via nonlinear optical microscopy in a small area (measured in nanometers) in the focal plane of the objective lens using a pico- or femtosecond near-infrared pulsed excited laser. This technology noninvasively enables tissue depth penetration, image sensitivity, and high resolution, as discussed in recent reviews.10–12 Combined various fluorescent dye labels13,14 and two-photon excited fluorescence (TPEF) microscopy are potentially used in laboratories and clinics to analyze live cells and accurately localize and completely resect live tumors.15 Live cells and tissues also can be imaged without external labeling by directly tracking different chemical bonds or proteins with nonlinear optical microscopes such as stimulated Raman scatting (SRS),16–19 coherent anti-Stokes Raman scattering (CARS), TPEF, second harmonic generation (SHG), and sum frequency generation (SFG), among other techniques. In this review, we will discuss several nonlinear methods began to be used in cells and tissues optics, such as SRS,16,20 CARS,8,21 TPEF,22 SHG,23 SFG,24 and multiple combinations of techniques. Although it is not comprehensive, an overview of nonlinear optics method applications with representative references is given in Table 1. Table 1Representative example applications of nonlinear optical microscopy.
2.Single Experimental MethodsIn both nonlinear microscopy and confocal laser scanning microscopy, a vibrating mirror scans the sample with focused laser beams.35 In confocal laser scanning microscopy, a high-resolution optical sectioning image is obtained with pinhole apertures. In biology and medicine, optical microscopy is restricted by phototoxicity. Each measurement often necessitates the minimum average energy of an excited laser to avoid phototoxicity. Compared to linear processes, nonlinear processes can provide momentary extremely high pulsed excited light with low average energy on a live sample. Near-infrared excitation light is typically used in nonlinear excitation microscopy and can also decrease the phototoxicity. Using infrared light can minimize scattering in live cells and tissues. All of these effects increase the penetration depth of nonlinear microscopes. The technology and theories of nonlinear optical microscopy have made significant contributions to biological research and medical diagnoses.36 The potential applications of these nonlinear optical microscopes are in the fields of biology and medicine. An energy-level diagram of a variety of nonlinear optical processes, including TPEF, SHG, SFG, CARS, and SRS, is shown in Fig. 1. To accurately study nonlinear optical microscopy, the relationship between polarization and electric field strength is used to precisely describe nonlinear optical microscopy using the following equation:37 where , , and are the linear, second-order, and third-order susceptibility, respectively. is the permittivity of free space. The second-order nonlinear optics are described using the following equation:37SHG and SFG are labeled as and . The third-order nonlinear optics (CARS and SRS) are described using the following equations:37 2.1.Two-Photon Excited FluorescenceTPEF microscopy is one of the traditional fluorescence imaging techniques. Due to its nonlinear optical effects, the penetration depth can reach 1 mm in live tissue with high resolution and high sensitivity. Combining TPEF microscopy with fluorescence materials can provide rapid techniques to diagnose and monitor a variety of diseases using encoded fluorescent proteins, exogenous dyes, and nanomaterials.25 A picosecond or femtosecond beam is focused on the sample using a scanning microscope to generate a fluorescence signal (Fig. 2). TPEF microscopy uses exogenous markers to detect and diagnose live cancer cells’ phenotypic changes, metabolic activity, and protein expression.38 Live ovarian cancer cells have been studied using TPEF microscopy to detect -galactosidase with lysosome-targetable and two-photon fluorescent probe FC-, which are important for the diagnosis of primary ovarian cancer (Fig. 3).25 2.2.Second-Harmonic GenerationIn general, for the second-order nonlinear optical techniques of three-wave mixing, the generation of a w3 photo has to emit one w1 and one w2 photon (). When w1 equals w2, it is defined as SHG (Fig. 1); otherwise, it is defined as SFG (Fig. 1).39 SHG occurs when an incident laser beam passes through a noncentrosymmetric and highly ordered medium such as tendons, axons, and striated muscle. Due to the nonabsorptive effects of nonlinear processes, SHG inhibits photobleaching.40 SHG was discovered by Franken in 1961.41 Because it uses the same laser scanning microscope and laser source with an additional proper narrow band filter, SHG can be combined with other nonlinear equipment. SHG is suitable for the collagen, microtubules, and muscles in live tissues and cells42 and is widely applied for biological research, medical diagnoses,43 and medicine.10,29,23,42,44 SHG microscopy has been used to measure the muscles’ contractile integrity via sarcomeric myosin imaging. Previous studies found that the muscle contractile integrity and neuromuscular health are strongly correlated in mice (Fig. 4).44 2.3.Coherent Anti-Stokes Raman ScatteringCARS is one of the most powerful Raman techniques for imaging molecular vibrations in live cells and tissues as discussed in recent reviews.3,45,46–50 Similar to SRS, CARS is also generated by four-wave mixing with a three-order nonlinear effect, and these work together in the same process. However, unlike SRS, anti-Stokes signal is used for molecular imaging, and a variation in the pump intensity is applied in SRS microscopy.51 Collinear picosecond or femtosecond beams (pump and Stokes) are focused on the sample using a scanning microscope to generate anti-Stokes signals (Fig. 5). Similar to SRS, CARS microscopy is widely applied for imaging live cancer cells,31,52 probing the interactions between live cells and plasmas,53 investigating intracellular lipid storage and dynamics in live tissues,54 and assessing lipid uptake in live stem cells during differentiation,30 with the same source, ease of use, real-time, label-free, and ultrahigh resolution. CARS is used to image lipids and measure their number and size to analyze their effects on hormone-treated breast and prostate cancer cells as shown in Fig. 6. 2.4.Stimulated Raman ScatteringSRS is a form of Raman scattering. Similar to Raman, it uses femtosecond or picosecond lasers to directly image the vibrational fingerprints of live cells and tissues. SRS is also a special case of four-wave mixing with the three-order nonlinear effect. SRS can provide high-speed, ultrahigh resolution, high-sensitivity, free label, real-time, and three-dimensional55 properties to image the distribution of specific molecules56 and monitor glucose metabolic activity,2 intracellular drug uptake,19,32,57,58 and image the vibration of newly synthesized proteins,18,59 image multiple proteins in situ,16,60,61 detect brain tumors,20 and probe the interactions between nanoparticles and live cancer cells.62 Based on the configuration of CARS microscopy, electro-optical modulators or acousto-optic modulators and lock-in amplifiers are added to the Stokes beam and photomultiplier tube, respectively, to generate an SRS signal (Fig. 7). Macrophages are among the most important white blood cells in the immune systems of animals. They phagocytose cancer cells and cell debris, among other functions. SRS microscopy was first used to characterize the different uptake kinetics of d31-palmitic acid by macrophages between individual cells as shown in Fig. 8. 3.Multiple Experimental MethodsPicosecond or femtosecond pulsed laser and multi- or two-photon scanning microscopes are used in SRS and CARS. Many useful signals can be applied to biological research and medical diagnosis, such as TPEF, SHG, and SFG. 3.1.Two Methods3.1.1.TPEF and SHGBoth TPEF and SHG are second-order nonlinear processes with minimum device, single incident lasers, and the same optical system.10,29,23 The distribution of alpha-actinin with fluorescence drugs and sarcomeric structures in live embryonic cardiomyocytes is imaged using TPEF and SHG channels, respectively. This second-order nonlinear optical technique can effectively reveal long-term structural changes in the live DiO-stained myofibrillogenesis of a single cardiomyocyte using real-time, high-resolution, and high-speed (4 SPF) features as shown in Fig. 9. 3.1.2.SRS and TPEFTPEF and SRS microscopy are combined with new features to image live cells and tissues. They can provide similar quality images with the same organelles of live cells as shown in Fig. 10.22 Deferent organelles can also be imaged using TPEF and SRS, respectively. In a recent study, the distribution of lipid droplets and the endoplasmic reticulum was obtained in cancer cells in situ. The spatial–temporal dynamics of lipid droplets and the endoplasmic reticulum in live cancer cells can be monitored to study organelle dynamics and metabolism as shown in Fig. 10(d).63 3.1.3.CARS and TPEFDue to the spectra overlap of TPEF and CARS signals, they cannot be easily separated. Using the correct wavelength of the pump and probe source solves this problem. As female gametocytes and germ cells are involved in reproduction, oocytes are the earliest stages of mammals. As with early embryos, they are widely used to study genetic diseases, cloned animals, genetic breeding, organ transplantation, and cell differentiation mechanisms. Lipid droplets store fatty acids and play a significant role in the preimplantation development of oocytes. Combined CARS and differential interference contrast (DIC) microscopy have been used to quantitatively image lipids in live mouse oocytes and early embryos at different stages of cell division as shown in Fig. 11. 3.2.Three MethodsWith the appropriate filters, fluorescent labels, and excited wavelengths, three or more types of nonlinear optic microscopy can be combined in the same scanning microscope. The results indicate that these multiple processes are advantageous for imaging live tissues or animals.7,24 Caenorhabditis elegans, a free-living (nonparasitic) transparent nematode (roundworm) in length, is widely used in genetics and developmental biology, behavior and neurobiology, aging and longevity, human genetic diseases, pathogen and biological interactions, drug screening, animal emergency response, and other fields. CARS, SFG, and TPEF have been used to study the muscle of live C. elegans using a scanning microscope with an excited laser as shown in Fig. 13. 4.ConclusionWe have summarized the principles, applications, and advantages of individual and combination of several types of nonlinear optical microscopy, including SRS, TPEF, SHG, and SFG. The experimental results indicate that these multiple processes are of great advantage for imaging live tissues or animals, C. elegans. The nonlinear optical microscopy can monitor specific molecules and proteins inside cells and tissues in three dimensions with high sensitivity and ultrahigh resolution. Our review can promote further understanding of the advanced application of combination of these types of nonlinear optical microscopy for biophotonics. AcknowledgmentsThis work was supported by the National Natural Science Foundation of China (Grant Nos. 91436102, 11374353, 11474141, 51401239, and 11704058), Fundamental Research Funds for the Central Universities in USTB, and National Basic Research Program of China (Grant No. 2016YFA0200802). ReferencesL. Opilik, T. Schmid and R. Zenobi,
“Modern Raman imaging: vibrational spectroscopy on the micrometer and nanometer scales,”
Annu. Rev. Anal. Chem., 6
(1), 379
–398
(2013). https://doi.org/10.1146/annurev-anchem-062012-092646 SCIEAS 0036-8075 Google Scholar
W. Hong et al.,
“Antibiotic susceptibility determination within one cell cycle at single-bacterium level by stimulated Raman metabolic imaging,”
Anal. Chem., 90 3737
–3743
(2018). https://doi.org/10.1021/acs.analchem.7b03382 ANCHAM 0003-2700 Google Scholar
R. E. Kast et al.,
“Emerging technology: applications of Raman spectroscopy for prostate cancer,”
Cancer Metastasis Rev., 33
(2), 673
–693
(2014). https://doi.org/10.1007/s10555-013-9489-6 Google Scholar
J. Bradley et al.,
“Quantitative imaging of lipids in live mouse oocytes and early embryos using CARS microscopy,”
Development, 143
(12), 2238
–2247
(2016). https://doi.org/10.1242/dev.129908 Google Scholar
S. Ayyachamy and V. S. Manivannan,
“Distance measures for medical image retrieval,”
Int. J. Imaging Syst. Technol., 23
(1), 9
–21
(2013). https://doi.org/10.1002/ima.v23.1 IJITEG 0899-9457 Google Scholar
R. H. Wilson, K. Vishwanath and M. Mycek,
“Optical methods for quantitative and label-free sensing in living human tissues: principles, techniques, and applications,”
Adv. Phys., 1
(4), 523
–543
(2016). https://doi.org/10.1080/23746149.2016.1221739 Google Scholar
H. Segawa et al.,
“Multimodal imaging of living cells with multiplex coherent anti-Stokes Raman scattering (CARS), third-order sum frequency generation (TSFG) and two-photon excitation fluorescence (TPEF) using a nanosecond white-light laser source,”
Anal. Sci., 31
(4), 299
–305
(2015). https://doi.org/10.2116/analsci.31.299 ANSCEN 0910-6340 Google Scholar
C. L. Evans et al.,
“Chemical imaging of tissue in vivo with video-rate coherent anti-Stokes Raman scattering microscopy,”
Proc. Natl. Acad. Sci. U. S. A., 102
(46), 16807
–16812
(2005). https://doi.org/10.1073/pnas.0508282102 Google Scholar
T. Hellerer et al.,
“Monitoring of lipid storage in Caenorhabditis elegans using coherent anti-Stokes Raman scattering (CARS) microscopy,”
Proc. Natl. Acad. Sci. U. S. A., 104
(37), 14658
–14663
(2007). https://doi.org/10.1073/pnas.0703594104 Google Scholar
P. J. Campagnola et al.,
“High-resolution nonlinear optical imaging of live cells by second harmonic generation,”
Biophys. J., 77
(6), 3341
–3349
(1999). https://doi.org/10.1016/S0006-3495(99)77165-1 BIOJAU 0006-3495 Google Scholar
A. D. Hofemeier et al.,
“Label-free nonlinear optical microscopy detects early markers for osteogenic differentiation of human stem cells,”
Sci. Rep., 6 26716
(2016). https://doi.org/10.1038/srep26716 SRCEC3 2045-2322 Google Scholar
W. Min et al.,
“Coherent nonlinear optical imaging: beyond fluorescence microscopy,”
Annu. Rev. Phys. Chem., 62
(1), 507
–530
(2011). https://doi.org/10.1146/annurev.physchem.012809.103512 ARPLAP 0066-426X Google Scholar
K. Svoboda and R. Yasuda,
“Principles of two-photon excitation microscopy and its applications to neuroscience,”
Neuron, 50
(6), 823
–839
(2006). https://doi.org/10.1016/j.neuron.2006.05.019 NERNET 0896-6273 Google Scholar
H. W. Liu et al.,
“Molecular engineering of two-photon fluorescent probes for bioimaging applications,”
Methods Appl. Fluores., 5
(1), 012003
(2017). https://doi.org/10.1088/2050-6120/aa61b0 Google Scholar
C. Vinegoni et al.,
“Measurement of drug-target engagement in live cells by two-photon fluorescence anisotropy imaging,”
Nat. Protoc., 12 1472
–1497
(2017). https://doi.org/10.1038/nprot.2017.043 1754-2189 Google Scholar
F. Hu et al.,
“Bioorthogonal chemical imaging of metabolic activities in live mammalian hippocampal tissues with stimulated Raman scattering,”
Sci. Rep., 6 39660
(2016). https://doi.org/10.1038/srep39660 SRCEC3 2045-2322 Google Scholar
L. Zhang and W. Min,
“Bioorthogonal chemical imaging of metabolic changes during epithelial–mesenchymal transition of cancer cells by stimulated Raman scattering microscopy,”
J. Biomed. Opt., 22 1
–7
(2017). https://doi.org/10.1117/1.JBO.22.10.106010 JBOPFO 1083-3668 Google Scholar
L. Wei et al.,
“Vibrational imaging of newly synthesized proteins in live cells by stimulated Raman scattering microscopy,”
Proc. Nat. Acad. Sci. U. S. A., 110
(28), 11226
–11231
(2013). https://doi.org/10.1073/pnas.1303768110 Google Scholar
B. G. Saar et al.,
“Video-rate molecular imaging in vivo with stimulated Raman scattering,”
Science, 330
(6009), 1368
–1370
(2010). https://doi.org/10.1126/science.1197236 SCIEAS 0036-8075 Google Scholar
M. Ji et al.,
“Rapid, label-free detection of brain tumors with stimulated Raman scattering microscopy,”
Sci. Transl. Med., 5
(201), 201ra119
(2013). https://doi.org/10.1126/scitranslmed.3005954 STMCBQ 1946-6234 Google Scholar
B. F. M. Romeike et al.,
“Coherent anti-Stokes Raman scattering and two photon excited fluorescence for neurosurgery,”
Clin. Neurol. Neurosurg., 131 42
–46
(2015). https://doi.org/10.1016/j.clineuro.2015.01.022 CNNSBV 0303-8467 Google Scholar
X. Li et al.,
“Mitochondrial imaging with combined fluorescence and stimulated Raman scattering microscopy using a probe of the aggregation-induced emission characteristic,”
J. Am. Chem. Soc., 139
(47), 17022
–17030
(2017). https://doi.org/10.1021/jacs.7b06273 JACSAT 0002-7863 Google Scholar
S. Awasthi et al.,
“Multimodal SHG-2PF imaging of microdomain Ca2+-contraction coupling in live cardiac myocytes,”
Circ. Res., 118
(2), e19
(2016). https://doi.org/10.1161/CIRCRESAHA.115.307919 CIRUAL 0009-7330 Google Scholar
H. Kim et al.,
“Coherent Raman imaging of live muscle sarcomeres assisted by SFG microscopy,”
Sci. Rep., 7
(1), 9211
(2017). https://doi.org/10.1038/s41598-017-09571-w SRCEC3 2045-2322 Google Scholar
J. Huang et al.,
“A lysosome-targetable and two-photon fluorescent probe for imaging endogenous -galactosidase in living ovarian cancer cells,”
Sens. Actuators B, 246 833
–839
(2017). https://doi.org/10.1016/j.snb.2017.02.158 SABCEB 0925-4005 Google Scholar
F. Tian et al.,
“Monitoring peripheral nerve degeneration in ALS by label-free stimulated Raman scattering imaging,”
Nat. Commun., 7 13283
(2016). https://doi.org/10.1038/ncomms13283 NCAOBW 2041-1723 Google Scholar
L. Zhou et al.,
“Molecular engineering of d-A-d-based non-linearity fluorescent probe for quick detection of thiophenol in living cells and tissues,”
Sens. Actuators B, 244 958
–964
(2017). https://doi.org/10.1016/j.snb.2017.01.079 SABCEB 0925-4005 Google Scholar
H. Wang et al.,
“Coherent anti-Stokes Raman scattering imaging of axonal myelin in live spinal tissues,”
Biophys. J., 89
(1), 581
–591
(2005). https://doi.org/10.1529/biophysj.105.061911 BIOJAU 0006-3495 Google Scholar
H. Liu et al.,
“Myofibrillogenesis in live neonatal cardiomyocytes observed with hybrid two-photon excitation fluorescence-second harmonic generation microscopy,”
J. Biomed. Opt., 16
(12), 126012
(2011). https://doi.org/10.1117/1.3662457 JBOPFO 1083-3668 Google Scholar
C. Di Napoli et al.,
“Quantitative spatiotemporal chemical profiling of individual lipid droplets by hyperspectral CARS microscopy in living human adipose-derived stem cells,”
Anal. Chem., 88
(7), 3677
–3685
(2016). https://doi.org/10.1021/acs.analchem.5b04468 ANCHAM 0003-2700 Google Scholar
M. C. Potcoava et al.,
“Raman and coherent anti-Stokes Raman scattering microscopy studies of changes in lipid content and composition in hormone-treated breast and prostate cancer cells,”
J. Biomed. Opt., 19
(11), 111605
(2014). https://doi.org/10.1117/1.JBO.19.11.111605 Google Scholar
C. W. Freudiger et al.,
“Label-free biomedical imaging with high sensitivity by stimulated Raman scattering microscopy,”
Science, 322
(5909), 1857
–1861
(2008). https://doi.org/10.1126/science.1165758 Google Scholar
C. W. Freudiger et al.,
“Highly specific label-free molecular imaging with spectrally tailored excitation-stimulated Raman scattering (STE-SRS) microscopy,”
Nat. Photonics, 5 103
–109
(2011). https://doi.org/10.1038/nphoton.2010.294 PSSABANPAHBY 1862-63001749-4885 Google Scholar
C. Stiebing et al.,
“Real-time Raman and SRS imaging of living human macrophages reveals cell-to-cell heterogeneity and dynamics of lipid uptake,”
J. Biophotonics, 10
(9), 1217
–1226
(2017). https://doi.org/10.1002/jbio.201600279 Google Scholar
R. Li et al.,
“Optical characterizations of two-dimensional materials using nonlinear optical microscopies of CARS, TPEF, and SHG,”
Nanophotonics, 7
(5), 873
–881
(2018). https://doi.org/10.1515/nanoph-2018-0002 Google Scholar
W. W. Mantulin, B. R. Masters and P. T. C. So,
“Handbook of biomedical nonlinear optical microscopy,”
J. Biomed. Opt., 14
(1), 019901
(2009). https://doi.org/10.1117/1.3077566 JBOPFO 1083-3668 Google Scholar
R. W. Boyd, Chapter 1: The Nonlinear Optical Susceptibility, in Nonlinear Optics, 1
–67 3rdAcademic Press, Burlington
(2008). Google Scholar
Z. Liu et al.,
“A new fluorescent probe with a large turn-on signal for imaging nitroreductase in tumor cells and tissues by two-photon microscopy,”
Biosens. Bioelectron., 89 853
–858
(2017). https://doi.org/10.1016/j.bios.2016.09.107 BBIOE4 0956-5663 Google Scholar
A. V. Petukhov et al.,
“Energy exchange in second-order nonlinear optics in centrosymmetric media,”
Phys. Status Solidi A, 170
(2), 417
–422
(1999). https://doi.org/10.1002/(ISSN)1521-396X Google Scholar
A. H. Reshak and C. R. Sheue,
“Second harmonic generation imaging of the deep shade plant Selaginella erythropus using multifunctional two-photon laser scanning microscopy,”
J. Microsc., 248
(3), 234
–244
(2012). https://doi.org/10.1111/jmi.2012.248.issue-3 JRSPAFJMICAR 0377-04860022-2720 Google Scholar
A. E. Hill et al.,
“Generation of optical harmonics,”
Phys. Rev. Lett., 7
(4), 118
–119
(1961). https://doi.org/10.1103/PhysRevLett.7.118 PRLTAO 0031-9007 Google Scholar
X. Chen et al.,
“Second harmonic generation microscopy for quantitative analysis of collagen fibrillar structure,”
Nat. Protoc., 7 654
–669
(2012). https://doi.org/10.1038/nprot.2012.009 1754-2189 Google Scholar
C. Macias-Romero et al.,
“Probing rotational and translational diffusion of nanodoublers in living cells on microsecond time scales,”
Nano Lett., 14
(5), 2552
–2557
(2014). https://doi.org/10.1021/nl500356u NALEFD 1530-6984 Google Scholar
S. V. Plotnikov et al.,
“Measurement of muscle disease by quantitative second-harmonic generation imaging,”
J. Biomed. Opt., 13
(4), 044018
(2008). https://doi.org/10.1117/1.2967536 Google Scholar
J. Cheng and X. S. Xie,
“Coherent anti-Stokes Raman scattering microscopy: instrumentation, theory, and applications,”
J. Phys. Chem. B, 108
(3), 827
–840
(2004). https://doi.org/10.1021/jp035693v JPCBFK 1520-6106 Google Scholar
C. L. Evans and X. S. Xie,
“Coherent Anti-Stokes Raman scattering microscopy: chemical imaging for biology and medicine,”
Annu. Rev. Anal. Chem., 1
(1), 883
–909
(2008). https://doi.org/10.1146/annurev.anchem.1.031207.112754 Google Scholar
H. Kano et al.,
“Hyperspectral coherent Raman imaging: principle, theory, instrumentation, and applications to life sciences,”
J. Raman Spectrosc., 47
(1), 116
–123
(2015). https://doi.org/10.1002/jrs.4853 Google Scholar
J. Cheng et al.,
“An epi-detected coherent anti-Stokes raman scattering (E-CARS) microscope with high spectral resolution and high sensitivity,”
J. Phys. Chem. B, 105
(7), 1277
–1280
(2001). https://doi.org/10.1021/jp003774a JRSPAFJPCBFK 0377-04861520-6106 Google Scholar
J. Cheng et al.,
“Laser-scanning coherent anti-Stokes Raman scattering microscopy and applications to cell biology,”
Biophys. J., 83
(1), 502
–509
(2002). https://doi.org/10.1016/S0006-3495(02)75186-2 BIOJAU 0006-3495 Google Scholar
C. Krafft, B. Dietzek and J. Popp,
“Raman and CARS microspectroscopy of cells and tissues,”
Analyst, 134
(6), 1046
–1057
(2009). https://doi.org/10.1039/b822354h ANLYAG 0365-4885 Google Scholar
M. Müller and A. Zumbusch,
“Coherent anti-Stokes Raman scattering microscopy,”
ChemPhysChem, 8
(15), 2156
–2170
(2007). https://doi.org/10.1002/(ISSN)1439-7641 CPCHFT 1439-4235 Google Scholar
K. Ishitsuka et al.,
“Identification of intracellular squalene in living algae, Aurantiochytrium mangrovei with hyper-spectral coherent anti-Stokes Raman microscopy using a sub‐nanosecond supercontinuum laser source,”
J. Raman Spectrosc., 48
(1), 8
–15
(2016). https://doi.org/10.1002/jrs.v48.1 Google Scholar
R. Furuta et al.,
“Intracellular-molecular changes in plasma-irradiated budding yeast cells studied using multiplex coherent anti-Stokes Raman scattering microscopy,”
Phys. Chem. Chem. Phys., 19
(21), 13438
–13442
(2017). https://doi.org/10.1039/C7CP00489C PPCPFQ 1463-9076 Google Scholar
S. Daemen et al.,
“Microscopy tools for the investigation of intracellular lipid storage and dynamics,”
Mol. Metab., 5
(3), 153
–163
(2016). https://doi.org/10.1016/j.molmet.2015.12.005 Google Scholar
X. Chen et al.,
“Volumetric chemical imaging by stimulated Raman projection microscopy and tomography,”
Nat. Commun., 8 15117
(2017). https://doi.org/10.1038/ncomms15117 NCAOBW 2041-1723 Google Scholar
R. Long et al.,
“Two-color vibrational imaging of glucose metabolism using stimulated Raman scattering,”
Chem. Commun., 54
(2), 152
–155
(2018). https://doi.org/10.1039/C7CC08217G Google Scholar
W. J. Tipping et al.,
“Imaging drug uptake by bioorthogonal stimulated Raman scattering microscopy,”
Chem. Sci., 8
(8), 5606
–5615
(2017). https://doi.org/10.1039/C7SC01837A 1478-6524 Google Scholar
T. Ito, Y. Obara and K. Misawa,
“Single-beam phase-modulated stimulated Raman scattering microscopy with spectrally focused detection,”
J. Opt. Soc. Am. B, 34
(5), 1004
–1015
(2017). https://doi.org/10.1364/JOSAB.34.001004 JOBPDE 0740-3224 Google Scholar
L. Wei et al.,
“Live-cell imaging of alkyne-tagged small biomolecules by stimulated Raman scattering,”
Nat. Methods, 11 410
–412
(2014). https://doi.org/10.1038/nmeth.2878 1548-7091 Google Scholar
X. Zhang et al.,
“Label-free live-cell imaging of nucleic acids using stimulated Raman scattering microscopy,”
ChemPhysChem, 13
(4), 1054
–1059
(2012). https://doi.org/10.1002/cphc.201100890 CPCHFT 1439-4235 Google Scholar
W. Yang et al.,
“Simultaneous two-color stimulated Raman scattering microscopy by adding a fiber amplifier to a 2 ps OPO-based SRS microscope,”
Opt. Lett., 42
(3), 523
–526
(2017). https://doi.org/10.1364/OL.42.000523 OPLEDP 0146-9592 Google Scholar
L. Zhang et al.,
“Label-free, quantitative imaging of MoS2-nanosheets in live cells with simultaneous stimulated Raman scattering and transient absorption microscopy,”
Adv. Biosyst., 1
(4), 1700013
(2017). https://doi.org/10.1002/adbi.201700013 Google Scholar
C. Zhang et al.,
“Quantification of lipid metabolism in living cells through the dynamics of lipid droplets measured by stimulated Raman scattering imaging,”
Anal. Chem., 89
(8), 4502
–4507
(2017). https://doi.org/10.1021/acs.analchem.6b04699 ANCHAM 0003-2700 Google Scholar
BiographyRui Li received his PhD from the Department of Physics of Dalian University, China, in 2014. From 2009 to 2012, he worked as an exchanged student at the Department of Electronic Engineering, University of Texas at Arlington. Since 2014, he has worked as a lecturer at the Department of Physics of Dalian University of Technology, China. His current research interests focus on surface enhancement Raman scattering and coherent anti-stokes Raman scattering microscopy. Xinxin Wang is the PhD candidate supervised by Professor Mengtao Sun, at the School of Mathematics and Physics, University of Science and Technology Beijing, China. Her current research interests focus on one and two photon absorptions, fluorescence, and Raman spectra. Yi Zhou is the PhD candidate supervised by Professor Rui Li, at Dalian University of Technology. His current research interests focus on one and two photon absorptions, fluorescence, and Raman spectra. Huan Zong is a PhD candidate supervised by Professor Mengtao Sun, at the School of Mathematics and Physics, University of Science and Technology Beijing, China. Her current research interests focus on one and two photon absorptions, fluorescence, and Raman spectra. Maodu Chen received his PhD in 2003 from Dalian Institute of Chemical Physics, Chinese Academy of Sciences (CAS). From 2003 to 2005, he worked as a postdoc at the Department of Chemical Physics, Northwestern University. Since 2005, he has worked as an associate professor at the Department of Physics of Dalian University of Technology. In 2010, he became a full professor at Dalian University of Technology, China. Mengtao Sun received his PhD in 2003 from the Dalian Institute of Chemical Physics, CAS. From 2003 to 2006, he worked as a postdoc at the Department of Chemical Physics, Lund University. Since 2006, he has worked as an associate professor at the Institute of Physics, CAS. In 2016, he became a full professor at the University of Science and Technology Beijing. His current research interests focus on nonlinear optical microscopy, such as CARS, TPEF, and SHG, applied in biophtonics and two-dimensional materials. |