Targeted cell immobilization by ultrasound microbeam
- 15 February 2011
- journal article
- research article
- Published by Wiley in Biotechnology & Bioengineering
- Vol. 108 (7), 1643-1650
- https://doi.org/10.1002/bit.23073
Abstract
Various techniques exerting mechanical stress on cells have been developed to investigate cellular responses to externally controlled stimuli. Fundamental mechanotransduction processes about how applied physical forces are converted into biochemical signals have often been examined by transmitting such forces through cells and probing its pathway at cellular levels. In fact, many cellular biomechanics studies have been performed by trapping (or immobilizing) individual cells, either attached to solid substrates or suspended in liquid media. In that context, we demonstrated two‐dimensional acoustic trapping, where a lipid droplet of 125 µm in diameter was directed transversely toward the focus (or the trap center) similar to that of optical tweezers. Under the influence of restoring forces created by a 30 MHz focused ultrasound beam, the trapped droplet behaved as if tethered to the focus by a linear spring. In order to apply this method to cellular manipulation in the Mie regime (cell diameter > wavelength), the availability of sound beams with its beamwidth approaching cell size is crucial. This can only be achieved at a frequency higher than 100 MHz. We define ultrasound beams in the frequency range from 100 MHz to a few GHz as ultrasound microbeams because the lateral beamwidth at the focus would be in the micron range. Hence a zinc oxide (ZnO) transducer that was designed and fabricated to transmit a 200 MHz focused sound beam was employed to immobilize a 10 µm human leukemia cell (K‐562) within the trap. The cell was laterally displaced with respect to the trap center by mechanically translating the transducer over the focal plane. Both lateral displacement and position trajectory of the trapped cell were probed in a two‐dimensional space, indicating that the retracting motion of these cells was similar to that of the lipid droplets at 30 MHz. The potential of this tool for studying cellular adhesion between white blood cells and endothelial cells was discussed, suggesting its capability as a single cell manipulator. Biotechnol. Bioeng. 2011; 108:1643–1650.This publication has 31 references indexed in Scilit:
- Optical travelator: transport and dynamic sorting of colloidal microspheres with an asymmetrical line optical tweezersApplied Physics B Laser and Optics, 2006
- Microfluidic system for dielectrophoretic separation based on a trapezoidal electrode arrayLab on a Chip, 2005
- Revealing anti-inflammatory mechanisms of soy isoflavones by flow: modulation of leukocyte-endothelial cell interactionsAmerican Journal of Physiology-Heart and Circulatory Physiology, 2005
- Optical trapping, manipulation, and sorting of cells and colloids in microfluidic systems with diode laser barsOptics Express, 2004
- Atherosclerotic plaque characterization by acoustic impedance analysis of intravascular ultrasound dataPublished by Institute of Electrical and Electronics Engineers (IEEE) ,2004
- Microtechnologies and nanotechnologies for single-cell analysisCurrent Opinion in Biotechnology, 2004
- Optical trapping and manipulation of neutral particles using lasersProceedings of the National Academy of Sciences of the United States of America, 1997
- Forces of a single-beam gradient laser trap on a dielectric sphere in the ray optics regimeBiophysical Journal, 1992
- Observation of a single-beam gradient force optical trap for dielectric particlesOptics Letters, 1986
- Acoustic Microscopy with Microwave FrequenciesAnnual Review of Materials Science, 1979