A technique to retrieve viable cells at single cell resolution from microfluidic chips with high spatial resolution has been developed at the University of Michigan. The capability to collect and utilize small samples is a key challenge in cancer studies and personalized medicine. However, conventional cell detachment schemes, such as trypsinization or PNIPAAm-based detachment do not provide any spatial resolution; they involve blank detachment of entire cells from the substrate. Cutting edge techniques such as those using laser-absorbing films also suffer from drawbacks. Detaching cells from the special film limits spatial resolution and handling cells over the film can be challenging. Further, cell detachment based on photo-degradation of the substrate film generates acid, leading to cell toxicity. IR-triggered detachment methods on carbon nanotube (CNT) substrates show poor cell viability because of heat-induced cell necrosis under direct laser irradiation. Cell detachment using ultrasound-induced cavitation only works on Petri dishes and is not compatible with microfluidic arrangements due to acoustic attenuation by polydimethylsiloxane (PDMS).
The cell retrieval method developed at the University of Michigan uses pulsed laser beams to generate micro-bubbles on a CNT-PDMS composite film on which cells are adhered and cultured. Due to formation and collapse of bubbles within sub-seconds, cells can be detached in a non-thermal manner. This enables viable harvested cells that can be cultured again for further studies, or lysed for PCR. The technique allows for monitoring the development of cell colonies, since each chamber starts with a single cell followed by clonal cell development. The technique also allows for comparison of cells from target chambers against the entire population. Further, the technique provides the capability to selectively detach one cell at a time from a chamber, which can allow for the comparison of mRNA expression between daughter cells and progenitor cells.
- Collection and utilization of ultra-small cell samples
- Cancer diagnostics and treatment
- Genomics applications
- High cell retrieval yields
- No sample contamination
- Excellent cell-viability post-detachment
- Support for tracing cell development from progenitor cells
- High spatial resolution