Microfluidic Chips for Sorting and Synchronization C. Elegans

As a powerful model organism, C. elegans has been widely used in basic biological research. The worm has four different larval stages, and many research questions are stage-specific. Therefore, it is necessary to classify and synchronize worms according to their developmental stages.

Microfluidic technology can help you automate the research process of C. elegans, whether you want to classify worms based on their life cycle or synchronize worms based on mutations. Compared with expensive sorters, Alfa Chemistry has developed a microfluidic chip that can synchronize and sort worms in a more effective way.

Classification of C. Elegans in Microfluidic Chips

Active Approach

The use of active methods to classify nematodes in microfluidic chips requires the use of external forces, such as electricity. In the presence of an electric field, worms at different stages will show different behaviors. Moreover, mutations in the worms can cause different swimming behaviors. Based on this, mutated and unmutated worms can be classified.

Figure.1 A chip with a hexagonal arrangement of microstructures, the geometric dimensions of which are optimized for the maximum motility of the worm according to the size of the worm. Only the worm of the target size continuously swims with the maximum fluctuation frequency. In addition, the continuous directional movement of the worm can be achieved by applying an electric field along the channel. The schematics of (a) the micro-channel device and (b) the experimental setup for electrotaxis. (Han B. C, et al. 2012)

Passive Approach

The passive method does not require any external power source and can be operated according to the geometry of the microfluidic channel or usually by the fluid dynamics inside the chip. The microchannels in the chip are designed with various gap sizes, and these gaps guide worms with specific sizes to specific outlets in the chip. The microfluidic chip we developed has successfully separated larvae from adults at a speed of 200-300 worms/min and an efficiency of 94%.

Synchronization of C. Elegans in Microfluidic Chips

The synchronization of C. elegans is another advantage, which is an important feature of age-related neurodegenerative diseases, such as Parkinson's disease. Synchronizing worms off-chip requires bleaching the pregnant worms to rupture the body and release the eggs, and then cultivate the eggs on a new plate, which is time-consuming and laborious. Using our microfluidic chip, we can efficiently and economically extract eggs from mixed eggs and worm populations at a high throughput of 4200 worms per minute.

Figure.2 A high-throughput microfluidic spiral chip to screen out eggs from a mixed age nematode population. Schematic of the spiral chip device with two cross-sectional views showing a mixture of eggs and worms in the first loop and after inertial fractionation. (Sofela S, et al. 2018)

References

• Han B. C, et al. (2012). "A Sorting Strategy for C. ElegansBased on Size-Dependent Motility and Electrotaxis in a Micro-Structured Channel." Lab Chip. 12: 4128-4134.
• Sofela S, et al. (2018). "High-Throughput Sorting of Eggs for Synchronization of C. Elegans in a Microfluidic Spiral Chip." Lab Chip. 18: 679-687.

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