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

 Programming knowledge, preferably in Mathematica.

Supervisor

  Dr. Isabel Llorente-Garcia i.llorente-garcia@ucl.ac.uk

References (optional)

http://www.ucl.ac.uk/phys/amopp/people/isabel_llorente_garcia