Seminars 2012
BIC/MacDiarmid Seminar
Wednesday 1 February, 10am
Rm 275, New Biology Research Building, University of Canterbury
Magnetic Tweezers: From Single Molecule Force Measurements to High Sensitivity Biosensors
Prof Gil Lee
Gil U Lee*, Devrim Kilinc, Peng Li, Mark Platt, Elena Martines, Julien Muzard, Ying-Fen Ran Suad Rashdan, Agata Blasiak, Conor Fields, James O’Mahony, Paul Mallee, and Robert Seher
* gil.lee@ucd.ie
Nanomedicine Centre and School of Chemistry, University College Dublin, Belfield, Ireland.
Molecular tweezers techniques provide us with the tools to study and manipulate biomolecular inter- and intramolecular interactions under non-equilibrium conditions. In this presentation I will describe three new applications of single molecule techniques. First, magnetic tweezers have been used to measure the bond lifetime-force behaviour of the protein A-IgG and apCAM specific molecular interactions with exceptionally high resolution. This has been achieved through the synthesis of superparamagnetic microparticles (SPMs) with high, uniform magnetization and the design of permanent magnets that are capable of creating high magnetic fields and field gradients. Second, resistive pulse sensing has been used to characterize the size and shape of SPMs and SPM aggregates. This technique has been used to identify the formation of clusters of SPMs through the reaction of aptamers and model analytes down to the 10 femtomolar concentration range. Third, we have developed a nonlinear magnetophoretic separation technique that uses local magnetic and hydrodynamic fields to separate SPMs. In this technique a travelling magnetic field wave was created by applying an external rotating magnetic field to an array of micro-magnets patterned on a substrate. At low frequencies, magnetic beads are shuttled between adjacent magnets with a speed that is proportional to the frequency of rotation of the field. At higher frequencies, the onset of non-linearities in the bead’s transport behaviour occur leading to the identification of certain critical frequencies above which a specific population of beads no longer moves. This critical frequency was found to be proportional to the bead’s magnetic moment and inversely proportional to its hydrodynamic drag factor. By exploiting this frequency dependence, we have demonstrated separation of magnetic beads based on fractional differences in bead diameter and magnetization. This allows us to identify multiple pathogens based on magnetic bead aggregation by tuning the external driving frequency. These new techniques promise to allow us to study biomolecular interactions under new conditions and enhance the sensitivity and specificity of diagnostic assays.
Thursday 21 February, 12.15pm
University of Canterbury – HP Seminar Room, NZi3
Life at the Bio-Nano-Interface
Dr. Volker Nock
volker.nock@canterbury.ac.nz
Electrical and Computer Engineering, University of Canterbury
The interface between man-made micro- and nanodevices and biological systems has been gaining increasing interest due to the potential impact of such devices on healthcare and medical science. In this presentation I will explore the breadth of my personal involvement in this field by introducing several current projects covering a novel laminar flow-based surface patterning method, digital microfluidics based on droplet coalescence and self-propulsion, construction of gut-like structures through stem cell tissue engineering, a device for the study of force patterns in worm locomotion, bioimprinted cell-culture scaffolds and the generation of oxygen microenvironments on chip.