Abstract
A multi-layer device, combining hydrodynamic trapping with microfluidic valving techniques, has been developed for on-chip manipulation and imaging of single cells and particles. Such a device contains a flow layer with trapping channels to capture single particles or cells and a control layer with valve channels to selectively control the trap and release processes. Particles and cells have been successfully trapped and released using the proposed device. The device enables the trapping of single particles with a trapping efficiency of greater than 95%, and allows for single particles and cells to be trapped, released and manipulated by simply controlling corresponding valves. Moreover, the trap and release processes are found to be compatible with biological samples like cells. Our device allows stable immobilisation of large numbers of single cells in a few minutes, significantly easing the experiment setup for single-cell characterisation and offering a stable platform for both single-molecule and super-resolution imaging. Proof-of-concept super- resolution imaging experiments with mouse embryonic stem cells (mESCs) have been conducted by exploiting super-resolution photoactivated localisation microscopy (PALM). Cells and nuclei were stably trapped and imaged. Centromeres of ∼200nm size could be identified with a localisation precision of <15nm.
Highlights
Super-resolution fluorescence microscopy approaches such as photoactivated localization microscopy (PALM) allows the visualisation of subcellular structures at a spatial resolution approaching that of biomolecules, and allows the study of protein dynamics within individual cells [1]
If each trap is controlled by individual valves (Fig. S1B), selectively trapping and releasing the particles/cells would be possible by activating or deactivating the corresponding valve located on top of each middle chamber. This aspect of the design is useful for single cell culturing and characterisation, as single cells can be trapped at desired positions for real-time and long-term analysis, after which the cells that are of interest can be selectively released and retrieved from the device for further processing
Cell trapping and release Mouse embryonic stem cells or their nuclei were prepared as described in Supplementary material
Summary
Super-resolution fluorescence microscopy approaches such as photoactivated localization microscopy (PALM) allows the visualisation of subcellular structures at a spatial resolution approaching that of biomolecules, and allows the study of protein dynamics within individual cells [1] They allow the 3D imaging of fluorescent proteins in cells with an accuracy far beyond the diffraction limit of visible light. Such super-resolution techniques for visualising tagged molecules within cells place strict requirements upon sample preparation and require target cells to be immobilised over an extended period of time for the highly precise imaging process [2].
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