Proposal and Design of an on-Chip Organelle Selection: Ablation of Cell Structures with Femtosecond Laser Pulses

High focal intensity and spatial resolution are the two key features of femtosecond laser (FSL), which we wish to incorporate into microfabrication in cellular envelopes (MINCE). Here we propose MINCE equipped with FSL in selection and isolation of organelles. Conceptually, MINCE eliminates unwanted organelles of a cell, ruptures the cellular membrane, and extracts the organelle of interest from the cell. Or, it does them in an alternative order. To test the feasibility of this concept, we irradiated the cellular membranes and granules of HeLa, MEL, and KJ cells, and observed changes by morphometry and immunomicroscopy. The cellular membrane was found inert to laser ablation (cleavage and perforation), unless it was pre-stained with photosensitive dyes enhancing laser absorption. Upon sensitization and with ~75 mW laser power of, ablation of cellular membranes was confirmed by detecting small openings on the membranes. However, these openings seemed insufficient to release organelles out of the cells. When individual granules (particles of nucleolus and mitochondrion) were irradiated at <300 mW laser powers, they disappeared with a high selectivity where one of mitochondrion particles neighboring within 2 mum was targeted and eliminated. Laser elimination of nucleoli caused no morphological change in the cells. In contrast, rapid apoptosis-like cell death was observed for mitochondria. Unexpectedly, ablation of granules at >350 mW laser powers resulted in cavitation within the cell, and the growing cavity cut the cellular membrane open. This rupture of cellular membrane could be a good foundation for selective release of organelles. The cavity-assisted membrane rupture was infrequent in adherent HeLa and KJ cells, while being predominant in non-adherent MEL cells and suspended HeLa and KJ cells. This disparity may stem from distinct surface tensions between the cells. This study reinforced the possibility of MINCE-based organelle selection, and opened its op- portunity for on-chip, single-cell nanotechnology and nanomedicine