GARCIA1 |
Design and
modelling of micro-magnetic traps for studies of cell-surface interactions in
live cells via force sensing. |
Type |
Experimental |
#students |
1 |
Orientation |
In a broad context, our biophysics research aims at
gaining a better understanding of dynamic cell-surface interactions in live
cells by means of combined force sensing and fluorescence microscopy with
simultaneous high temporal and high spatial resolution. We are currently
focusing on several biological problems in collaboration with life scientists
at UCL: the study of receptor-mediated HIV entry in live cells, the study of
flexibility and adhesion properties of E.coli bacterial pili and the study of
the forces involved in clathrin-mediated endocytosis. |
How |
Magnetic
forces can be used to trap and manipulate micrometre-sized particles in
solution, in tailor-made magnetic trapping potentials. The particles can be
previously functionalised and specifically attached to the biological
complexes of interest so that the magnetic traps can then be employed to
exert and measure forces relevant to the function of the molecular complexes
in the cell in order to carry out live-cell force-spectroscopy experiments at
the single-molecule level. |
What |
The project student will focus on the force-sensing and
force-exertion aspects of this research, which will ultimately lead to
controlled three-dimensional interaction with the cell-surface in our
experiments. This project will involve the design and modelling of
magnetic trap configurations for functionalised micro-particles in solution,
based on micro-fabricated wires and permanent magnets, for their future
implementation in the laboratory. The particles to trap are anisotropic
graphite/graphene micro-flakes coated with lipids for biocompatibility.
Simulating the magnetic confining potentials generated by currents in
micron-sized wires on a chip is essential for determining the minimum size of
the particles we can trap, for calibrating the traps in order to measure
forces and for determining what force levels (typically picoNewtons) we will
be able to measure in live-cell experiments. Experimentally, micro-fabricated
rectangular-cross-section wires on a chip substrate are employed to generate
large magnetic field gradients with the aim of trapping the micro-particles
at a distance of approximately 10-20 micrometres from the chip surface.
Approximating these wires as infinitely thin wires leads to oversimplified
and incorrect trapping potentials at this close proximity to the wire
surface, hence, the shape and rectangular cross-section of the wire needs to
be accounted for in order to carry out a full finite-element calculation of
the magnetic field generated by such micro-wires, close to their surface. The
student will have the opportunity to carry out this fine-element calculations
and magnetic-trap simulations (e.g. using Mathematica) to find optimal
configurations for trapping and force measurements. In principle this is a computational modelling project. If
reasonable progress is made on the modelling aspect and if the student is
interested, there will be opportunities for close involvement with the
experimental aspect of the project in the lab, for instance, testing magnetic
trap configurations. |
Special Knowlegde |
|
Supervisor |
Dr. Isabel Llorente-Garcia i.llorente-garcia@ucl.ac.uk |
References
(optional) |
http://www.ucl.ac.uk/phys/amopp/people/isabel_llorente_garcia |