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Department of Chemistry

Dr Robert Pal

Assistant Professor in the Department of Chemistry
Telephone: +44 (0) 191 33 42102

(email at robert.pal@durham.ac.uk)

Biography

Robert Pal grew up in Hungary and graduated with the Highest Achievement award in Chemistry from KLTE University of Debrecen, in 2004. Once completing his undergraduate studies he has moved to Durham to start a Ph.D with Professor David Parker on Responsive Luminescent Lanthanide systems. Completing his Ph.D in late 2007 he began to work as a Postdoctoral researcher within the Parker group, also working closely with Professor Andrew Beeby, moving away from organic chemistry towards bio-physical chemistry, spectroscopy and microscopy. In 2014 he has been awarded with a prestigious University Research Fellowship from the Royal Society to study the Development and Chemical Application of Phase Modulation Nanoscopy.

Robert is also the Technical Director of a successful University spin out company, FScan Ltd, which has developed lanthanide technology to use light energy to measure the level of citrate in seminal fluid samples. The level of citrate can be used to signal the onset and progression of prostate cancer. This technology was developed in the Department of Chemistry here in Durham, whilst clinical studies are currently under way at UCL Hospital.

Research Interests

My research interests are focused around the development of novel optical and super-resolution microscopy instrumentation (such as PhMoNa and novel liquid crystal based SIM techniques) and associated time-resolved techniques. My research group also maintains an interest in lanthanide based sensors and imaging agents, including organelle specific probes and alternative responsive stains. I also have an ongoing collaboration within the department based on Circularly Polarised Luminescence with the Beeby, Palsson and Parker groups.

Super-resolution Microscopy or ‘Nanoscopy’

 'A picture is worth more than 100 words' 

 'A picture is worth more than 100 words'

In the field of optical fluorescence microscopy, many researchers have dedicated their entire scientific carrier to develop better and improved cellular stains or associated microscopy techniques and equipment, pushing the boundaries of both signal detection and resolution. However, the intrinsic resolution of fluorescence microscopy is limited by diffraction, which determines the extension of the focused light emitted by a point source object, in other words the point spread function (PSF). In recent years, renewed have efforts emerged in optical microscopy and associated life sciences to break through the optical diffraction barrier and visualize even smaller parts of the ‘living’ cell in ‘super-resolution’. Governed by Abbé’s law (1873) the highest achievable theoretical spatial resolution (d) of a given experimental setup is dictated by the lowest applied excitation light (λexc) d = λexc./2NA (NA: numerical aperture of objective) promoting maximal achievable resolutions of ~200 nm. However, much of the fundamental biology of the cell occurs below this threshold; hence breaking this limit will allow the wide multidisciplinary scientific community to look deeper in higher resolution.

Ever since the step-changing invention of Confocal Microscopy by Minsky in 1953, attention has turned towards the development of new optical (hardware) and computer (software) based methodologies, revolutionising the way in which we investigate nanostructures. Recent years seen many refined and evolved variants of ‘Super-resolution’ techniques by improvements applied either or both to the illumination or detection process leading to improvement in both precision and resolution. No need to say this combined multidisciplinary effort have recently been recognised with the Nobel-prize awarded in Chemistry in 2014. But these new, still fundamentally diffraction limited techniques all have drawbacks too, such as limitation of suitable stains, disruptively high laser powers, slow/limited imaging speed, poor SNR due to loss of information and specialized expensive and bulky instrumentation.

Taking the above into account, the obvious conclusion for me is to introduce a novel user friendly resolution enhancing method into any LSCM microscope harnessing the already superior resolution of the confocal detection principle. A new modular super-resolution technique called Phase Modulation Nanoscopy (PhMoNa) has been developed in order to break the optical diffraction barrier in Confocal Laser Scanning Microscopy (LSCM). This technique is based on using spatially modulated illumination intensity, whilst harnessing the fluorophore’s non-linear emission response. It allows experimental resolution in both lateral and axial domains to be improved by at least a factor of 2. The work is in its initial phase, but by using a custom built Electro Optical Modulator (EOM) in conjunction with functionalised Ln(III) complexes as probes, a sub-diffraction resolution of ~60 nm was achieved of selected cellular organelles in long term live cell imaging experiments.

Selected Publications

1. Phase Modulation Nanoscopy: a simple approach to enhanced optical resolution, R. Pal, FD1777 (manuscript submitted)

2. Simple and versatile modifications allowing time gated spectral acquisition, imaging and lifetime profiling on conventional wide-field microscopes, R. Pal and A. Beeby, Methods Appl. Fluoresc., 2014, 2,037001

3. Microscopic Visualization of Metabotropic Glutamate Receptors on the Surface of Living Cells Using Bifunctional Magnetic Resonance Imaging Probes, A. Mishra, R. Mishra, S. Gottschalk, R. Pal, N. Sim, J. Engelmann, M. Goldberg and D. Parkert, ACS Chemical Neuroscience, (5) 2 Pages: 128-137

4. Comparative analysis of conjugated alkynyl chromophore-triazacyclononane ligands for sensitized emission of europium and terbium, M. Soulie, F. Latzko, E. Bourrier, V. Placide, S. J. Butler, R. Pal, P. L. Baldeck, B. Le Guennic, C. Andraud, J. M. Zwier, L. Lamarque, D. Parker, and O. Maury, Chem, Eur. J., 2014, 20(28), 8636-8646

5. Utility of tris(4-bromopyridyl) europium complexes as versatile intermediates in the divergent S-synthesis of emissive chiral probes, S. J. Butler, M. Delbianco, N. H. Evans, A. T. Frawley, R. Pal, D. Parker, R. S, Puchrin and D. S. Yufit, Dalton Transactions, 2014, 43(15), 5721-5730

6. Induced circularly polarised luminescence arising from anion or protein binding to racemic emissive lanthanide complexes, Rachel Carr, Robert Puckrin, Brian K. McMahon, Robert Pal, David Parker and Lars-Olof Pålsson, Methods Appl. Fluoresc., 2014, 2, 024007

7. EuroTracker dyes: highly emissive europium complexes as alternative organelle stains for live cell imaging, S. J. Butler, L. Lamarque, R. Pal and D. Parker, Chem. Sci., 2014, 5, 1750-1756

Publications

Journal Article

Newspaper/Magazine Article