Imaging of macrophages by Surface Enhanced Raman Spectroscopy (SERS)

Abstract

BACKGROUND: Fluorescent dyes attached to gold nanoparticles have been shown to be efficient SERS nanosensors in studies on intracellular composition. OBJECTIVE: The cells of macrophages were incubated with gold nanoparticles (45 nm of the diameter) with the attached three fluorescent dyes, i.e. rhodamine 6G, rhodamine B or green malachite. METHODS: Surface enhanced Raman scattering effect was recorded for cells using imaging technique with an excitation wavelength at 632.8 nm. For the analysis hierarchical K-means methods were employed. RESULTS: The nanosensors were introduced to the interior of the cells showing different distribution specific for each Raman reporter. Intracellular chemical information along with SERS response of the reporter was observed for both rhodamine dyes. CONCLUSIONS: The type of the reporter plays a crucial role in the cellular uptake of nanosensors and strongly affects the detection of biomacromolecules.

Rhodamine 6G conjugated to gold nanoparticles as labels for both SERS and fluorescence studies on live endothelial cells

“…Apart from SERS bands of R6G, mean SERS spectra show the presence of marker bands of cell biomolecules assigned according to the literature, see Fig. 4 [ 8 , 9 , 29 , 30 ]. In the spectra of the cells incubated for 30 min., bands attributed to proteins and lipids (1,268, 1,278, 1,464, 1,545 cm −1 ) and the phosphate groups (419, 814 cm −1 ) are found (Fig.…”

“…Gold-supported in vitro SERS in living cells provides a tool for sensitive and structurally-selective detection of native chemicals such as DNA, proteins, lipids etc., and for monitoring their intracellular distributions. However, the distribution of bare metal nanoparticles in the cells cannot be controlled [ 7 – 9 ]. Another application of SERS for cellular studies is based on nanoprobes conjugated to Raman reporters [ 5 , 8 – 11 ].…”

“…The most commonly used reporters are organic dyes, e.g. malachite green, rhodamine B or crystal violet [ 5 – 9 ].…”

“…Therefore, the SERS- and fluorescence-based studies on the uptake of rhodamine 6G conjugated to gold nanoparticles (R6G-AuNPs) by live endothelial cells have been undertaken in our laboratory. Rhodamine 6G is a fluorophore of a high cross-section for Raman scattering used by us before in cellular studies of macrophages and endothelial cells [ 8 , 9 ]. For in vitro culture we chose EA.hy926 cells, a line derived from human umbilical vein endothelial cells.…”

Recent Progress of SERS Nanoprobe for pH Detecting and its Application in Biological Imaging

“…This information is essential for a better understanding of a wide range of physiological and metabolic processes as well as some biotechnological applications. Surface enhanced Raman scattering (SERS) has been widely used in many fields due to its unique advantages such as high sensitivity, strong specificity, good reuse ability and optical stability, especially in biological detection and biological imaging in recent years [2][3][4]. Compared with other pH detection imaging technologies, the pH probe based on SERS mainly has the following advantages: (1) There is no damage to the detected biological samples; (2) The fluorescence of biological system and the Raman signal of water can be ignored; (3) There will be no quenching or photobleaching.…”