Raman Spectroscopy and its Application in Nanostructures
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Raman Spectroscopy and its Application in Nanostructures is an original and timely contribution to a very active area of physics and materials science research. This book presents the theoretical and experimental phenomena of Raman spectroscopy, with specialized discussions on the physical fundamentals, new developments and main features in low-dimensional systems of Raman spectroscopy. In recent years physicists, materials scientists and chemists have devoted increasing attention to low-dimensional systems and as Raman spectroscopy can be used to study and analyse such materials as carbon nanotubes, quantum wells, silicon nanowires, etc.
XX is the XXth reference in the list of references. Since he has been interested in the research of Raman spectroscopy. As shown in Figure 5 , the morphologies of BF10cells without treatment with IBMX 0 h were mainly elliptical and spindle-shaped, which is consistent with that of an immature melanocyte [ 29 ]. Novel green synthesis of gold nanoparticles using Citrullus lanatus rind and investigation of proteasome inhibitory activity, antibacterial, and antioxidant potential. Thus, this book not only introduces these important new branches of Raman spectroscopy from both a theoretical and practical view point, but the resulting effects are fully explored and relevant representative models of Raman spectra are described in-depth with the inclusion of theoretical calculations, when appropriate.
Recent scientific and technological developments have resulted in the applications of Raman spectroscopy to expand. These developments are vital in providing information for a very broad field of applications: Thus, this book not only introduces these important new branches of Raman spectroscopy from both a theoretical and practical view point, but the resulting effects are fully explored and relevant representative models of Raman spectra are described in-depth with the inclusion of theoretical calculations, when appropriate.
Chemical Kinetics and Reaction Dynamics. The Thermodynamics of Phase and Reaction Equilibria. Advances in Atomic Physics. Structural Methods in Molecular Inorganic Chemistry. Advances in Quantum Chemistry. Orbital Interactions in Chemistry. Molecular Thermodynamics of Fluid-Phase Equilibria. Handbook of Sputter Deposition Technology. Solar Cells Based on Colloidal Nanocrystals. Transport in Laser Microfabrication.
Raman Spectroscopy and its Application in Nanostructures
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Fundamentals of Fluorescence Microscopy. Fundamentals of Mass Spectrometry. Reviews in Fluorescence Electronic Properties of Organic Conductors. Fundamental Physics in Particle Traps. Recent Progress in Silicon-based Spintronic Materials. X-ray Studies on Electrochemical Systems. Then, the treated cells were placed under the Raman microscope and stimulated with nm laser power: SERS-based analysis of the generation and secretion of intracellular melanin: At different time points 0, 6, 12, and 24 h , intracellular nanocomposites were structured in situ and quickly detected by SERS imaging under streamline scanning mode with 2 s exposure.
To verify the reducibility of melanin, a test-tube experiment was performed with industrially synthesized melanin and silver—ammonia complex as precursors. Figure 1 A,B shows the morphological characterization of the melanin—Ag nanocomposites. Deep black silver nanoparticles were of different sizes nm on average , and a number of protrusions outside of the deep black particles were observed. In TEM images with higher magnification, the Ag-nanostructure was built by various smaller silver nanoparticles. Non-stacked silver particles were deposited, thereby forming protrusions on the surface.
The light gray substance outside of the Ag nanostructure is composed of attached melanin molecules. EDX spectroscopy revealed that aside from the widely existing Ag, three elements namely, C, O, and N are also present, further proving the successful synthesis of melanin—Ag nanocomposites. Characterization of the nanostructures. Figure 2 shows the absorption spectra and Raman spectra of the nanomaterial within the UV-Vis range. The absorption spectra within the UV-Vis range shows a clear absorption peak of melanin—Ag near nm, thereby indicating the formation of Ag nanostructures.
The absorption value shows a slowing trend as the wavelength increases, and this trend is consistent with the changes in melanin. After silver nanoparticles were attached, very clear SERS signals were detected, and the SERS spectral peaks belong to the molecular structure of melanin; e. This finding suggests that the strong SERS signals of melanin—Ag can be effectively used for the rapid detection and imaging of intracellular melanin.
Moreover, such SERS signals are adjustable. By properly controlling the dose of silver ions in the reaction, melanin—Ag nanocomposites exhibiting different Raman enhancement features were obtained. A Raman spectra under Surface-enhanced Raman scattering SERS spectra of melanin—Ag nanocomposites prepared with different volumes of silver—ammonia complex under Test-tube experiments confirmed the reducibility of melanin for the synthesis of noble metal nanoparticles, and the produced melanin—Ag nanocomposites displayed good intrinsic SERS signals.
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In view of this, the nanocomposites were fabricated in situ in melanocytes, and the distribution and content of intracellular melanin was then detected by the SERS technique. Under the Raman experimental conditions, conventional Raman imaging cannot obtain identifiable melanin Raman signals Figure 4 B.
In addition, the imaging speed is fast, taking only 0. This speed far outpaces conventional Raman imaging techniques tens of minutes and even several hours [ 27 , 28 ]. The distribution of melanin SERS signals reveals that the signals of melanin mainly exist in the cytoplasm, while few are observed in the nucleus. This finding is consistent with the actual distribution of melanin in the cells.
Within the region a from the cytoplasm to the nucleus which is rich in endoplasmic reticulum , the acquired SERS spectral signal is very strong. However, only background signal is observed in the nucleus region b. In the cytoplasm c at the distant end of the cell from the endoplasmic reticulum, a small amount of melanin is detected.
These observations indicate that melanin is unevenly distributed in the cell. Exploring the generation of melanin in the cell is of great biological significance.
At different periods of time, SERS technique was employed to analyze the generation of melanin. As shown in Figure 5 , the morphologies of BF10cells without treatment with IBMX 0 h were mainly elliptical and spindle-shaped, which is consistent with that of an immature melanocyte [ 29 ]. During this period, the synthetic amount of intracellular melanin is small and mainly distributes around the nucleus—specifically within the region of the rough endoplasmic reticulum where melanin is synthesized [ 30 ]. At 6 h after IBMX treatment, cell morphology starts to change significantly. Elongated dendrites start to form, thereby indicating that BF10 cells begin to mature under the action of the melanin-stimulating hormone.
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During this period, intracellular melanin is mainly distributed around the nucleus. However, the amount of melanin does not increase, and a small fraction starts to transfer out along the dendrites, thereby indicating that melanocytes mainly change in terms of morphology within the first 6 h.
After that, the BF10 cells treated with IBMX experience a period of rapid biochemical changes, including the melanin content and the cellular contour. At 12 h, the cells form numerous thin dendrites. Simultaneously, a large amount of intracellular melanin is synthesized, and the SERS signal intensity of melanin in the endoplasmic reticulum is significantly enhanced.
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A good deal of melanin is also observed in the dendrites, indicating that melanin continued to move outside along the dendrites. At 24 h after IBMX treatment, the morphology of BF10 cells is significantly influenced, exhibiting less clear contours and with dendrites partially disconnected from the cell body. Intracellular melanin is mainly concentrated in the cell periphery, awaiting transportation from the cells. Part of the melanin is secreted in the form of membrane-bound vesicles [ 31 ]. Melanin secreted from the cells is also found in the extracellular matrix.
Ten SERS spectral lines in the melanocytes were randomly extracted at different periods, and the average SERS integrated intensities were calculated to quantitatively analyze the changes of intracellular melanin. As shown in Figure 6 , at 6 h after IBMX treatment, the SERS signal intensity of intracellular melanin weakened, probably because the cells during this period significantly changed in morphology, thereby producing numerous dendrites and enlarging the cell area. However, during this period, the synthetic amount of intracellular melanin is smaller, and a small amount of melanin move outside along the dendrites, thereby ultimately leading to a lower distribution density of melanin.
After 24 h, the intracellular melanin significantly decreases, indicating that during this period the melanocytes mainly secreted melanin, but only a small amount of melanin was synthesized, despite having or synthesizing little melanin. Melanin is an important molecule in the human body that performs essential biomedical functions.
We firstly synthesized the melanin—Ag nanocomposites in the solution experiment without adding any other reducing agents. Moreover, as melanin is bonded with Ag nanoparticles, the Raman signals of melanin-Ag nanoparticles were also significantly enhanced. By using this method, the melanin—Ag nanocomposites were fabricated in situ intracellularly, and intracellular melanin was detected by Raman imaging based on the SERS features. This method featured high sensitivity and fast speed, and its scanning speed was much faster than that of conventional Raman imaging.
Moreover, the content of intracellular melanin could be quantitatively analyzed by using SERS signals. The generation and secretion of intracellular melanin under the action of the melanin-stimulating hormone could also be successfully traced using this SERS technique. The proposed SERS technique in melanin detection can be a potentially powerful detection tool for detecting the biological functions of melanin and associated diseases.
Haixin Dong did the experiments, data analysis and wrote this paper. Zhiming Liu and Zhouyi Guo provided the original ideas, revision of the manuscript. National Center for Biotechnology Information , U. Journal List Nanomaterials Basel v. Published online Mar Find articles by Haixin Dong. Find articles by Zhiming Liu. Find articles by Huiqing Zhong. Find articles by Hui Yang. Find articles by Yan Zhou. Find articles by Yuqing Hou.
Find articles by Jia Long. Find articles by Jin Lin. Find articles by Zhouyi Guo. Author information Article notes Copyright and License information Disclaimer. Received Dec 23; Accepted Mar This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution CC BY license http: This article has been cited by other articles in PMC. Abstract Melanin plays an indispensable role in the human body. Introduction Melanin is a ubiquitous pigment in the biological system, and is one of the most important chromophores in the human body.
Materials and Methods 2. Test-Tube Experiments Preparation of silver—ammonia complex: Results and Discussion 3. Synthesis and Characterization of Melanin—Ag Nanocomposites To verify the reducibility of melanin, a test-tube experiment was performed with industrially synthesized melanin and silver—ammonia complex as precursors.