Micro-fragmentation of cells and cell cluster
Demonstration of micro-histotripsy by LGFU (scale bar = 100 μm):
The LGFU spot is fixed while the cell culture plate is slowly moved to
the upper-right direction (from a to e). The disruption zones are guided by the inner and outer circles (35 and 90 μm in diameter, respectively). A captured temporal moment (t) is shown on the right-top corner (unit: second): (a) The cultured cell cluster is shown with a target spot; (b) Under LGFU, the cluster is fragmented first at the center of LGFU spot; (c) The prolonged exposure of LGFU enlarges the fragmented zone over the periphery; (c-e) With the cluster movement, it is finally cut into two pieces.
Figure from Biomed. Opt. Express 4(8), 1442-1450 (2013)
Nature Photonics Highlight (Oct. 2013)
Micro-Ultrasonic Triggering of Drug delivery on Targeted Cells
Biomolecular drug delivery by LGFU (scale bar = 100 μm):
(a) and (b) show cells before and after LGFU treatment (here, LGFU produces a single micro-bubble on the cells (by a single pressure pulse) and then soft disturbance to open cell membranes. Drug molecules embedded in the surrounding medium penetrate across the cell membrane; here, we used propidium iodide (PI) as a model biomolecule which is membrane-impermeable nucleic-acid binding dye. Once PI enters cells, it binds DNA and RNA, dramatically enhancing its fluorescence as shown in the bottom of (b). Two images shown in the top and bottom of (b) are merged in (c).
Figure from J. Biophoton. 6, 905 (2013)
Controlled Generation of a Single Micro-Bubble by an LGFU Pulse
(High-speed laser-flash shadowgraph images)
A focused ultrasound wavefront is shown on the top left. An entire process of bubble nucleation, growth, and shrinkage is shown (scale bar = 100 μm). Detailed physics for the bubble dynamics has been reported.
Lee et al., Phys. Rev. Appl. 2, 024007 (2014); (Selected as Editor's Choice)
Dual-Frequency Focused Ultrasound System (Piezoelectric + LGFU)
Superposition of two waveforms generated optoacoustically (i.e., LGFU) and piezoelectrically. This approach enhances the pressure amplitude, still maintaining a tight focal zone. The superposed ultrasound allows free-boundary cavitation and may be effectively used for therapeutic applications.
Figure from Appl. Phys. Lett. 103, 234103 (2013)