Injection and delivery of small amount reagent in aqueous solution for cell chip was performed utilizing regeneratively
amplified femtosecond laser system. In our new trial, the reagent integrated on a solid strip are released and delivered to
targeted cells with the femutosecond laser-induced impulsive-force. The reagent was fixed in poly(vinyl alcohol) or
polystyrene film on a glass-substrate strip. When a single pulsed femtosecond laser was focused in the solution, the film
near the focal point was fragmented and the reagent was dispersed in 45-μm φ area at 50 μm from the surface of the
reagent strip. As examples cardiomyocyte beating cells of P19CL6 were bombed with epinephrine and acetylcholine,
and as a result the beating ratio of the cells were quickly stimulated and suppressed, respectively. The results
demonstrate that the present method is a promising key nano/micro technology for diagnosis and drug discovery.
We demonstrate preparations of zinc porphyrin nanoparticles by reprecipitation method and their spectroscopic
analysis by dark-field light scattering microspectroscopy. The size distribution of the prepared nanoparticles was 80-150
nm. By using dark-field illumination the nanoparticles could be observed as bright points in dark background and could
be examined by their Rayleigh scattering spectra at single particle level. The spectra differed from particle to particle,
which would be ascribed to their size and crystalline phase difference. Thus we have performed this single particle
spectroscopic technique to remove the ambiguity about the spectroscopic information owing to distributions of particles
and to improve the space selectivility. In addition, we have successfully demonstrated the detection of amine molecules
in water at single particle level. These results indicate that the detection technique using the single porphyrin
nanoparticles can be applied to chemical and biological sensors with nanometer scale.
Several kinds of manipulation of biological cells were performed utilizing regeneratively amplified femtosecond laser
system. When single-shot pulse of an amplified Ti: Sapphire femtosecond laser pulse is focused on a culture medium,
shockwave and cavitation bubble are generated with little heating. An impulsive force resulting in these phenomena was
applied to pttern specific cells form a culture substrate. Furthermore, laser trapping of cells was realized using high-repetition
rate pulses from the laser oscillator. Although the cell was trapped stably when the laser power was less than
100 mW, the cell was burst above the threshold laser power. The bursting would be due to heating inside cell, on which
the laser was focused and multiphoton absorption was induced. On the bases of these results, we propose a new
methodology to pattern biological cells, which is speedy and flexible when compared with previous micropatterning
methods.
PC12 cells, which are derived from a rat pheochromocytoma, were independently patterned utilizing an impulsive force
resulting in impulsive shockwave and cavitation bubble generation by focused femtosecond laser irradiation. Since the
PC12 cells respond reversibly to nerve growth factor by induction of the neuronal phenotype, we can assess an influence
that the impulsive force gives to the bioactivity in term of the cell differentiation. The patterned cells were accumulated
on an intact dish and cultured for 3 days. The behavior of appearance and cell differentiation was observed by multipoint
time-lapse system. On bases of these results, it was proved that the biological activity of the cell is unaffected by the
femtosecond laser patterning.
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