Microfluidic analysis

Goal

The aim of microfluidic analysis is to trap bacteria in a chip, with a continuous medium. Hence, the behaviour (e.g. GFP production) of bacteria in exponnential phase can be analyse with microscope during long acquisition (>24h).

Chip preparation

Mix gently 36 g of Polydiméthylsiloxane (PDMS,condensed formula: (C2H6OSi)n ) with 3.6 g of curring agent (which make the PDMS polymerize).
Put in a 50 mL tube and centifugate it at 13 000 for 1 minute to remove bubbles from the mixture.
Pour the mixture on the chip mould and put it under a vacuum pump.
Once there is no more bubbles that go out of the mixture, put it in the oven at 80°C for 2 hours.
Separate the different chips and make the holes of the input and outpout of channels with a punch.
Remove all the dust on chips surfaces. Then put chips and glass slides on plasma oven.
After that, put quickly the chip on glass slide and put them in the oven at 80°C for 2 hours.

Bacteria preparation

Make 30 mL of preculture of your strain of interest in LB medium with the recquired antibiotics to avoid contamination.
Let it growth overnight.
Centrifugate and resuspend the pellet in 3 mL of LB medium with the recquired antibiotics and mild detergent
Inject bacteria in the chip with needle and syringe.
Prepare 2x25 mL of LB medium with antibiotic and mild detergent and inject it in the chip.
Check your preparation with the microscope and let the bacteria growth overnight.

Figure 1: 2 Escherichia coli (TOP 10 strain) in a microfluidic trap.
At the top and bottom of the picture, the flow of medium go throught the 2 channels.

Acquisition

Wash the chip with your recquired medium (in our case: M9 with or without iron).