Alignment of biological microparticles by a polarized laser beam

Abstract

The optical alignment of biological samples is of great relevance to microspectrometry and to the micromanipulation of single particles. Recently, Bayoudh et al. (J. Mod. Opt. 50:1581-1590 have shown that isolated, disk-shaped chloroplasts can be aligned in a controlled manner using an in-plane-polarized Gaussian beam trap, and suggested that this is due to their nonspherical shape. Here we demonstrate that the orientation of various micrometer-sized isolated biological particles, trapped by optical tweezers, can be altered in a controlled way by changing the plane of linear polarization of the tweezers. In addition to chloroplasts, we show that subchloroplast particles of small size and irregular overall shape, aggregated photosynthetic lightharvesting protein complexes as well as chromosomes can be oriented with the linearly polarized beam of the tweezers. By using a laser scanning confocal microscope equipped with a differential polarization attachment, we also measured the birefringence of magnetically oriented granal chloroplasts, and found that they exhibit strong birefringence with large local variations, which appears to originate from stacked membranes. The size and sign of the birefringence are such that the resulting anisotropic interaction with the linearly polarized laser beam significantly contributes to the torque orienting the chloroplasts.

Second Harmonic Generation Signal from Biological Materials Using Multi-Functional Two-Photon Laser Scanning Microscopy

“…The SHG stems from chloroplasts devoid of starch, thus clearly demonstrating the generation of SH from the noncentrosymmetric membranes opposed to each other in the grana. It is known that chloroplasts exhibit strong birefringence, with high local values, mostly originating from grana and inclued starch grains (Garab et al, 2005;Goedheer, 1955). The size and sign of the birefringence are such that the resulting anisotropic interaction with a linearly polarized laser beam significantly contributes to the torque orienting the chloroplast.…”

“…SHG indicates the non-centrosymmetric nature of the chloroplast membranes especially when aggregated into grana. The chloroplast grana and intergranal membranes are exhibit strong birefringence with large variations (Pantic-Tanner and Eden, 1999;Garab et al, 2005). A low intrinsic birefringence is expected in intergranal membranes and a high birefringence where the membranes are stacked.…”

“…18. The experiment the setup momentum as well as linear momentum, the incident beam of linearly polarized laser becomes elliptically polarized and gains angular momentum after encroaching on a birefringent particle whose optical axis is not parallel to that of polarization of the light (Higurashi et al 1999;Garab et al, 2005). The resulting change in angular momentum generates a reaction optical torque.…”

Comparison of macromolecular interactions in the cell walls of hardwood, softwood and maize by fluorescence and FTIR spectroscopy, differential polarization laser scanning microscopy and X-ray diffraction

“…The confocal fluorescence intensity images were recorded on a Zeiss LSM 410 laser scanning microscope (Carl Zeiss Jena, Jena, Germany) equipped with a differential-polarization (DP) attachment (Garab et al 2005;Steinbach et al 2009). Briefly, the DP attachment modulates the polarization state of the excitation laser beam at 100 kHz between horizontally and vertically linear polarization, using a photoelastic modulator (PEM-90, Hinds Instruments).…”

Biosensing of red blood cell-derived extracellular vesicles with the advanced bright-field light optical polarization microscopy

“…Nowadays conventional transmitted light microscopy technique is useful and simple method to determine particle size, shape and structure [10,11]. A highly sensitive optical coherent microscopy (hs-OCM) based on objective-type internal reflection regarding wavelength-modulation may sufficiently improve RBC-EV determination.…”