Back to homepage utwente.nl
Interactions between us-generated bubbles and cells
When a substrate with very small pits is submersed in a liquid, air bubbles will spontaneously form in the pits. If this is exposed to ultrasound created by a piezo elememt, the bubbles start to oscillate and eject a stream of smaller bubbles into the liquid, see Figure 1. The bubbles can have several effects, e.g. by collapse (cavitation) they may generate reactive species in the liquid.
|
|
Figure 1. Left: Schematic of the experimental setup. b) Substrate with 42 pits with microbubbles ejecting due to ultrasound exposure. |
|
In this project we are interested in studying the effects of ultrasound-generated microbubbles on living cells. Previous studies in the BIOS and POF groups have shown that the interactions between a cavitation bubble and cells (See Fig. 2a) may lead to cellular poration or lysis, as a function of the strength of the treatment, i.e. the distance between the cells and the bubble (See Fig. 2b) [1].
|
|
Figure 2: Poration/lysis of cells using a cavitation bubble created in a microfluidic environment. a) Picture of a bubble created in close vicinity to cells. b) Outcome of the experiments in terms of porated/dead or living cells after the bubble treatment. |
|
The experimental setup shown in fig. 1 (see also [2]) presents a greater level of flexibility as a broad range of operation parameters can be changed and combined so that the sonoporation treatment can be finely tuned compared to our previous approach. Therefore, we would like to consider different scenarios to study the interactions of the micro-bubbles and cells. Furthermore, two classes of phenomena, that could affect the cells, are involved in this second approach: effects caused by the reactive species generated or effects caused by purely fluidic phenomena (jetting effects). Both classes of phenomena will be studied in this project.
Scenario 1: Cells are grown on the glass cover slip placed above the bubble chamber. Effects that will be studied are: the streaming effects, jetting effects, radical chemical effect at different bubble patterns (use of one of several bubble generation sites), as well as their effect on the cells (poration, cell death…). The same experiments will be carried out in presence of radical scavengers, added in the medium/solution.
Scenario 2: Cells are grown on the bottom substrate between the pits. The effects of the micro-bubbles will be studied as a function of the cell position with respect to that of the pits, and as a function of the amount of pits present on the surface, i.e. when the pattern of bubbles change over the immobilized cells. As before, the experiments will be performed in presence or not of radical scavengers.
Scenario 3: Cells are placed in suspension in the medium introduced in the chamber. Again, the response of cells to the micro-bubble treatment will be studied in terms of cell poration/lysis, and possible stress exerted on the cells. As before, radical scavengers will be added to the solution for one series of experiments.
Assignment:
The student(s) will:
- |
study the cavitation conditions in the experimental setup |
- |
characterize the patterns described by the bubbles (dimensions of the bubbles, cloud, physical parameters, possible jetting effects) |
- |
Observe and describe the observed phenomena. |
- |
Grow cells on the substrates (glass cover slip and substrate containing the pit(s). |
- |
Study the cell poration/survival, and the eventual stress exerted on the cells (imaging of ROS production). |
Among the several applications conceivable with this set-up and the its application for cell poration, drug delivery to cells will be considered as an outcome of this project.
[1] Le Gac et al. LOC, 2007.
[2] Fernandez Rivas, et al. (2010), doi: 10.1002/anie.201005533
Starting date - From February 2011
Contact information:
ME-147, tel: +31 (0)53 489 25 94, Email: d.fernandezrivas@utwente.nl
Or
Carré 2.411, tel: +31 (0)53 489 27 22, Email: s.legac@ewi.utwente.nl
Or
Aaldert Zijlstra,
Meander 214, tel: +31 (0)53 489 27 22, Email: a.g.zijlstra@tnw.utwente.nl
