| Summary: | 碩士 === 國立陽明大學 === 生醫光電工程研究所 === 96 === We demonstrated optical trapping and stretching of individual human erythrocytes with jumping optical tweezers which is implemented with the aid of an acousto-optic modulator (AOM).
In our implementation of the jumping optical tweezers, the focal spot of the trapping beam in a conventional stationary optical tweezers was discretely scanned between two fixed points whose distance (referred to as the jumping distance) was controlled by the voltage of the radio-frequency (Rf) driving the AOM and the scanning frequency was controlled by the modulation frequency applied to the AOM. At a scanning frequency ~ 1 k Hz, the trapped erythrocyte sensed the averaged intensity distribution of the jumping focal spots and was stably trapped and stretched along the scanning direction (as if it were trapped and stretched by a pair of parallel twin optical tweezers). Discrete scanning with AOM allows us to change the jumping distance easily and rapidly without any mechanical motion of mirrors or lenses.
We measured not only the steady-state deformation of the erythrocyte as a function of the jumping distance but also the dynamics of the deformation when the jumping distance was switched from a smaller value (~ 2.8�慆) to a larger value (~ 4.6�慆), and vice versa. In addition, we also studied how the steady-state and the dynamic viscoelastic properties were affected by treating the erythrocyte samples with N-ethylmaleimide (NEM) which is known to destroy the cytoskeleton of the erythrocytes. The dependence of the effect on NEM concentration, incubation time, and temperature was quantified.
We have thus demonstrated that the jumping optical tweezers implemented with the aid of an AOM is a convenient and power tool for the study of cell mechanics in general, and of the viscoelastic properties of erythrocytes in particular. Potential applications for medical diagnosis based on viscoelastic properties of cells can be envisioned.
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