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Zhou SF, Gopalakrishnan S, Xu YH, Yang J, Lam YW, Pang SW. A Unidirectional Cell Switching Gate by Engineering Grating Length and Bending Angle. PLoS One 2016; 11:e0147801. [PMID: 26821058 PMCID: PMC4731054 DOI: 10.1371/journal.pone.0147801] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2015] [Accepted: 01/09/2016] [Indexed: 11/18/2022] Open
Abstract
On a microgrooved substrate, cells migrate along the pattern, and at random positions, reverse their directions. Here, we demonstrate that these reversals can be controlled by introducing discontinuities to the pattern. On "V-shaped grating patterns", mouse osteogenic progenitor MC3T3-E1 cells reversed predominately at the bends and the ends. The patterns were engineered in a way that the combined effects of angle- and length-dependence could be examined in addition to their individual effects. Results show that when the bend was placed closer to one end, migration behaviour of cells depends on their direction of approach. At an obtuse bend (135°), more cells reversed when approaching from the long segment than from the short segment. But at an acute bend (45°), this relationship was reversed. Based on this anisotropic behaviour, the designed patterns effectively allowed cells to move in one direction but blocked migrations in the opposing direction. This study demonstrates that by the strategic placement of bends and ends on grating patterns, we can engineer effective unidirectional switching gates that can control the movement of adherent cells. The knowledge developed in this study could be utilised in future cell sorting or filtering platforms without the need for chemotaxis or microfluidic control.
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Affiliation(s)
- Shu Fan Zhou
- Department of Electronic Engineering, City University of Hong Kong, Kowloon, Hong Kong
- Centre for Biosystems, Neuroscience, and Nanotechnology, City University of Hong Kong, Kowloon, Hong Kong
| | - Singaram Gopalakrishnan
- Centre for Biosystems, Neuroscience, and Nanotechnology, City University of Hong Kong, Kowloon, Hong Kong
- Department of Biology and Chemistry, City University of Hong Kong, Kowloon, Hong Kong
| | - Yuan Hao Xu
- Department of Electronic Engineering, City University of Hong Kong, Kowloon, Hong Kong
- Centre for Biosystems, Neuroscience, and Nanotechnology, City University of Hong Kong, Kowloon, Hong Kong
| | - Jie Yang
- Centre for Biosystems, Neuroscience, and Nanotechnology, City University of Hong Kong, Kowloon, Hong Kong
- Department of Biology and Chemistry, City University of Hong Kong, Kowloon, Hong Kong
| | - Yun Wah Lam
- Centre for Biosystems, Neuroscience, and Nanotechnology, City University of Hong Kong, Kowloon, Hong Kong
- Department of Biology and Chemistry, City University of Hong Kong, Kowloon, Hong Kong
| | - Stella W Pang
- Department of Electronic Engineering, City University of Hong Kong, Kowloon, Hong Kong
- Centre for Biosystems, Neuroscience, and Nanotechnology, City University of Hong Kong, Kowloon, Hong Kong
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Abstract
In this work, we studied the stretching of λ phage DNA molecules immobilized on an optical fiber tip attached to a force sensitive tuning fork under ac electric fields. We designed a two electrodes stretching system in a small chamber: one is a gold-coated optical fiber tip electrode, and the other is a gold-coated flat electrode. By applying a dielectrophoretic (DEP) force, the immobilized λ DNA molecules on the tip are stretched and the stretching process is monitored by a fluorescent microscope. The DNA stretching in three-dimensional space is optimized by varying electrode shape, electrode gap distance, ac frequency, and solution conductivity. By observing the vibrational amplitude change of a quartz tuning fork, we measured the effects due to Joule heating and the DEP force on the tethered DNA molecules in solution. This work demonstrates a method to manipulate and characterize immobilized λ DNA molecules on a probe tip for further study of single DNA molecules.
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Affiliation(s)
- Changbae Hyun
- Department of Physics, University of Arkansas, Fayetteville AR 72701, USA
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