Neuropeptide is one of the most diverse class of signaling molecules and has attracted great interest over the years for their role in the regulation of various physiological processes. However, there are unique challenges associated with neuropeptide derived from the study of molecular size varies greatly from peptides, low in vivo concentration, high degree of structural diversity and large number of isoforms.
As a result, much effort has been focused on the development of new techniques for studying the neuropeptides, as well as new applications geared towards learning more about endogenous peptides. Important areas for the study of neuropeptides including the structure, localization in tissues, interaction with their receptors, including ion channels, and physiological function.
Here, we discuss these aspects and related techniques, with a focus on technologies that have demonstrated the potential to advance the field in recent years. Most identification and structural information has been obtained by mass spectrometry, either alone or with confirmation from other techniques, such as nuclear magnetic resonance spectroscopy and other spectroscopic tools.
While the mass spectrometry and bioinformatics tools have proven to be the most powerful for large-scale analysis, they are still very dependent on complementary methods for confirmation. Localization in the network, for example, can be detected with imaging mass spectrometry, immunohistochemistry and radioimmunoassays. functional information has been obtained mainly from studies of behavior coupled with tissue-specific tests, electrophysiology, mass spectrometry and optogenetic tools.
Regarding receptors for neuropeptides, the discovery of ion channels directly gated by neuropeptides opens the possibility of developing a new generation of tools for neuroscience, which can be used to monitor the release of neuropeptides or to specifically modify the membrane potential of neurons. Expected future neuropeptide research will involve the integration of complementary bioanalytical technology and functional tests.
Validity of Measuring Metallic and Semiconducting Single-Walled Carbon Nanotube Fractions by Quantitative Raman Spectroscopy.
Although it is known that the Raman spectroscopic signature single-walled carbon nanotubes (SWCNTs) are very chirality dependent, using Raman spectroscopy with multiple excitation lasers as a tool to measure the fraction of metallic or semiconducting nanotubes in a sample has become a widely used method of analysis.
In this work, using electron diffraction technique as a basis, we have examined the validity of Raman spectroscopy for the quantitative evaluation of metallic fraction (M%) in single-walled carbon nanotube samples.
Our results indicate that the evaluation of Raman spectroscopy quantitative M% by using several laser line of discrete, either by using the intensity of the integrated mode of breathing radial chirality related (RBMs) or, as more commonly used in a recent study, by the statistics calculated the numbers of RBMs could misrepresentative.
In particular, we have found that the rate of occurrence of some types of RBMs in Raman spectral mapping is very dependent on the diameter distribution, resonant coupling between the energy transition and the excitation energy of the laser and Raman scattering cross-section chirality depends not only on the metal and semiconductor SWCNT fraction.
This dependency similar to that observed in the integrated intensity of RBMs. Our findings are substantially advance the understanding of the proper use of Raman spectroscopy for quantification of carbon nanotubes, which are important for the characterization of carbon nanotubes and important to guide research in SWCNT growth and their applications.