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19 June 2003 Development of a novel Raman tweezers setup for single-cell studies
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It has recently been shown that the combination of Raman spectroscopy and optical tweezers constitute a powerful tool for biological studies. Raman spectra of single cells immobilized in a sterile surrounding can then be recorded without the risk of surface-induced morphological cell changes. Further, the complete cellular environment can be changed while measuring dynamics in real time. We here introduce a novel Raman tweezers set-up ideal for resonance Raman studies of single cells. The system differs from earlier set-ups in that two separate laser beams, used for trapping and Raman excitation, are combined in a double-microscope configuration. This has the advantage that the wavelength and power of the trapping and probe beam can be adjusted individually, for example in order to optimize the functionality of the set-up or to record resonance Raman profiles from the same trapped cell. Further, the tweezers can be removed from the system without affecting the spectrometer configuration. Trapping is achieved by tightly focusing IR diode laser radiation (830 nm) through an inverted oil immersion objective with high numerical aperture (NA = 1.25), while Raman scattering is excited by the lines of an ArKr ion-laser. The backscattered Raman signal is collected by a single-grating spectrometer equipped with a microscope and a 60x water-immersion objective (NA = 0.9). The functionality of the system is demonstrated by measurements of trapped single functional erythrocytes using differen excitation lines (488, 514.5 568.2 nm) in resonance with the heme moiety and by studying the spectral evolution during illumination.
© (2003) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Kerstin K. Ramser, Katarina I. Logg, Mattias Goksor, Jonas Enger, Mikael Kall, and Dag Hanstorp "Development of a novel Raman tweezers setup for single-cell studies", Proc. SPIE 4962, Manipulation and Analysis of Biomolecules, Cells, and Tissues, (19 June 2003);


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