|
Project |
Micro-Systems & Control
Laboratory, NTHU |
Chemotaxis
Objectives:
How do white blood cells direct themselves to the
site of injury or inflammation? How do unicellular microorganisms find their
food and avoid hostile environments?
The common answer to all these questions is by chemotaxis.
What is “chemotaxis” ?
Today this tern is used to denote cell movement towards or way from a chemical
source, respectively. The chemical is defined as chemoattractant
or chemorepellent. According to the common, broad
definition of chemotaxis, any cell motion that is
affected by a chemical gradient in a way that results in net propagation up a chemoattractant gradient or down a chemrepellent
gradient is defined as chemotaxis. The study of chemotaxis is fundamentally important in many areas of
biology, including microbiology, caner, and immunology. Therefore, chemotaxis studies require a way to deliver chemicals to
cells in a controlled chemotactic gradient.
The diagram to show the process of neutrophil migration in the blood vessel
In most case of microfluidics, a laminar flow can be expected so that mass
transport is more difficult than turbulent flow. It is known that laminar flows
is stable and transport mass via only molecular diffusion between interfaces of
fluids. Diffusion naturally takes place in the fluid mixture of two or more
species whenever there is a concentration gradient. We
are working on a Lab-on-a chip device to achieve and study cells migration in chemotactic concentration gradient. Used the channel
geometry complicated enough to produce the stable and continued chemotatic concentration gradient.
Technical
Approach:
Our bio-micro-chip is
designed to develop a Lab-on-chip system to achieve and measure the cell
migration in a stable chemotactic concentration
gradient. It combines with the passive concentration gradient generation device
and manipulation of cells mechanism. The aim is only using
the simple and small micro-channel structure to generate a stable and smooth chemotactic concentration gradient and dielectrophoresis
(DEP) to manipulate cells to some positions which we want before observing and
measuring their behavior of chemotaxis Theoretical analyses and numerical simulation have been developed, using
the CFD simulation software and Matlab program,
including the gradient concentration, fluidic velocity flow rate, and cell migration
path.
|
The experimental setup and the
concentration gradient within our device was visualized with the fluorescent molecule FITC-dextran
(FITC is fluorescein isothiocyanate).
|
|
Cell positions at beginning (left) and end of the experiment (right) |
References:
1.
Branebjerg J et al “Fast mixing by lamination”, MEMS’96, 9th IEEE Int.
Workshop Micro Electromechanical System(
2. Wong S H et al “Investigation of mixing in a cross-shaped micromixer with static mixing elements for reaction kinetics studies”, Sensor Actuators B 95 414-24 (2003)
3. Noo Li Jeon “A parallel-gradient microfluidic chamber for quantitative analysis of breast cancer cell chemotaxis”,Springer Science+Business Media, LLC 2006
Collaboration:
Contact Information:
·
Gou-Chuan Huang ericl9834010@yahoo.com.tw
·
Wun-Hao Wu k740706@hotmail.com
·
Cheng-Hsien Liu liuch@pme.nthu.edu.tw
