High-speed Raman imaging of cellular processes.

Raman scattering microscopy provides information about the distribution and chemical state of molecules in live cells without any labeling or modification. In recent years, the imaging speed of Raman microscopy has improved greatly owing to the development of instruments that can perform parallel acquisition of Raman spectra from multiple points. In this article, we review recent advances in high-speed hyperspectral Raman imaging and its application to observe various biological processes such as cell mitosis, apoptosis and cell differentiation.

Structured line illumination Raman microscopy.

In the last couple of decades, the spatial resolution in optical microscopy has increased to unprecedented levels by exploiting the fluorescence properties of the probe. At about the same time, Raman imaging techniques have emerged as a way to image inherent chemical information in a sample without using fluorescent probes. However, in many applications, the achievable resolution is limited to about half the wavelength of excitation light.

Dual-polarization Raman spectral imaging to extract overlapping molecular fingerprints of living cells.

Raman spectral imaging is gaining more and more attention in biological studies because of its label-free characteristic. However, the discrimination of overlapping chemical contrasts has been a major challenge. In this study, we introduce an optical method to simultaneously obtain two orthogonally polarized Raman images from a single scan of the sample.

Simultaneous imaging of protonated and deprotonated carbonylcyanide p-trifluoromethoxyphenylhydrazone in live cells by Raman microscopy.

We report the simultaneous imaging of protonated and deprotonated forms of carbonylcyanide p-trifluoromethoxy-phenylhydrazone (FCCP) molecules in live cells by Raman microscopy. Nitriles, structure-sensitive Raman tags, are used to detect the two distinct molecular structures, demonstrating the potential of Raman microscopy for structure-based imaging of bioactive small molecules.

Molecular imaging of live cells by Raman microscopy.

Raman microscopy represents an emerging class of tools for molecular imaging of live cells because of the rich information obtained by detecting molecular vibrations. Recently, several Raman imaging techniques based on the parallel detection of Raman spectra have been developed, which can achieve high spatial and temporal resolution suitable for live cell imaging. When combined with tiny Raman tags in the cellular silent region, Raman microscopy has capability to map the distribution of specific target small molecules with minimum perturbation from the tag.

Raman and SERS microscopy for molecular imaging of live cells.

Raman microscopy is a promising technology for visualizing the distribution of molecules in cells. A challenge for live-cell imaging using Raman microscopy has been long imaging times owing to the weak Raman signal. Here we present a protocol for constructing and using a Raman microscope equipped with both a slit-scanning excitation and detection system and a laser steering and nanoparticle-tracking system.

Label-free Raman observation of cytochrome c dynamics during apoptosis.

We performed label-free observation of molecular dynamics in apoptotic cells by Raman microscopy. Dynamic changes in cytochrome c distribution at the Raman band of 750 cm(-1) were observed after adding an apoptosis inducer to the cells. The comparison of mitochondria fluorescence images and Raman images of cytochrome c confirmed that changes in cytochrome c distribution can be distinguished as release of cytochrome c from mitochondria.