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Thursday, April 1, 2010

Optical Trapping of Amino Acids in Aqueous Solutions

Yasuyuki Tsuboi, Tatsuya Shoji and Noboru Kitamura

In this paper, we demonstrated that the photon forces that are generated by a near-infrared (1064 nm) focused laser beam can manipulate (optically trap) small amino acid molecules in aqueous solutions. Under observation with an optical microscope, we observed the gradual growth of a particle-like assembly of objects at the focal point during laser irradiation into an aqueous arginine solution. The observation was a molecular assembly of arginine by means of confocal Raman microspectroscopy. Such molecular assemblies were also observed for other amino acids (glycine, proline, serine, and alanine), showing that the optical manipulation technique can be extensively applied to the micromanipulation of amino acids. From experimental observations and numeral calculations, we consider that the origin of the present manipulation phenomenon is ascribed to optical trapping, not of individual molecules, but of molecular clusters of amino acids.

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