scholarly journals Comparison of Different Polarization Sensitive Second Harmonic Generation Imaging Techniques

2019 ◽  
Vol 2 (2) ◽  
pp. 49 ◽  
Author(s):  
Mehdi Alizadeh ◽  
Masood Ghotbi ◽  
Pablo Loza-Alvarez ◽  
David Merino
Keyword(s):  
Second Harmonic Generation ◽  
Harmonic Generation ◽  
Second Harmonic ◽  
Imaging Techniques ◽  
Image Plane ◽  
Excitation Beam ◽  
Non Invasive ◽  
Second Harmonic Generation Imaging ◽  
First Time

Polarization sensitive second harmonic generation (pSHG) microscopy is an imaging technique able to provide, in a non-invasive manner, information related to the molecular structure of second harmonic generation (SHG) active structures, many of which are commonly found in biological tissue. The process of acquiring this information by means of pSHG microscopy requires a scan of the sample using different polarizations of the excitation beam. This process can take considerable time in comparison with the dynamics of in vivo processes. Fortunately, single scan polarization sensitive second harmonic generation (SS-pSHG) microscopy has also been reported, and is able to generate the same information at a faster speed compared to pSHG. In this paper, the orientation of second harmonic active supramolecular assemblies in starch granules is obtained on by means of pSHG and SS-pSHG. These results are compared in the forward and backward directions, showing a good agreement in both techniques. This paper shows for the first time, to the best of the authors’ knowledge, data acquired using both techniques over the exact same sample and image plane, so that they can be compared pixel-to-pixel.

scholarly journals Observations of intracellular second-harmonic generation imaging in black phosphorus nanosheets

2020 ◽  
pp. 2041006
Author(s):  
Xiao Peng ◽  
Yiwan Song ◽  
Zheng Peng ◽  
Kaixuan Nie ◽  
Hao Liu ◽  
...  
Keyword(s):  
Second Harmonic Generation ◽  
Harmonic Generation ◽  
Photothermal Therapy ◽  
Second Harmonic ◽  
Black Phosphorus ◽  
Prolonged Incubation ◽  
Second Harmonic Generation Imaging ◽  
Poor Stability

Functionalized black phosphorus (BP) nanosheets have been considered as promising nanoagents in cancer therapy due to their excellent photothermal conversion efficiency. However, it is still difficult to visually monitor the dynamic localization of BP nanoagents in cancer cells. In this paper, we systematically studied the second-harmonic generation (SHG) signals originating from exfoliated BP nanosheets. Interestingly, under the excitation of a high frequency pulsed laser at 950 nm, the SHG signals of BP nanosheets in vitro are almost undetectable because of their poor stability. However, the intracellular SHG signals from BP nanosheets could be measured by in vivo optical [Formula: see text]imaging due to the efficient enrichment of living HeLa cells. Moreover, the SHG signal intensity from BP nanosheets increases with the prolonged incubation time. It can be expected that the BP nanosheets could be a promising intracellular SHG nanoprobe employed for visually in vivo biomedical imaging in practical cancer photothermal therapy (PIT).

scholarly journals Applications of Second-Harmonic Generation Imaging Microscopy in Ovarian and Breast Cancer

2015 ◽  
Vol 7 ◽  
pp. PMC.S13214 ◽  
Author(s):  
Karissa Tilbury ◽  
Paul J. Campagnola
Keyword(s):  
Ovarian Cancer ◽  
Second Harmonic Generation ◽  
Harmonic Generation ◽  
Second Harmonic ◽  
Imaging Techniques ◽  
Great Sensitivity ◽  
Fiber Morphology ◽  
Breast And Ovarian Cancer ◽  
Epithelial Cancers ◽  
Computationally Intensive

In this perspective, we discuss how the nonlinear optical technique of second-harmonic generation (SHG) microscopy has been used to greatly enhance our understanding of the tumor microenvironment (TME) of breast and ovarian cancer. Striking changes in collagen architecture are associated with these epithelial cancers, and SHG can image these changes with great sensitivity and specificity with submicrometer resolution. This information has not historically been exploited by pathologists but has the potential to enhance diagnostic and prognostic capabilities. We summarize the utility of image processing tools that analyze fiber morphology in SHG images of breast and ovarian cancer in human tissues and animal models. We also describe methods that exploit the SHG physical underpinnings that are effective in delineating normal and malignant tissues. First we describe the use of polarization-resolved SHG that yields metrics related to macromolecular and supramolecular structures. The coherence and corresponding phase-matching process of SHG results in emission directionality (forward to backward), which is related to sub-resolution fibrillar assembly. These analyses are more general and more broadly applicable than purely morphology-based analyses; however, they are more computationally intensive. Intravital imaging techniques are also emerging that incorporate all of these quantitative analyses. Now, all these techniques can be coupled with rapidly advancing miniaturization of imaging systems to afford their use in clinical situations including enhancing pathology analysis and also in assisting in real-time surgical determination of tumor margins.

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