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Spectrum of hot methane

Spectrum of hot methane in astronomical objects using a comprehensive computed line list

A powerful new model to detect life on planets outside of our solar system, more accurately than ever before, has been developed by researchers from UCL Physics & Astronomy and the University of New South Wales. More...

Publiziert: Jun 18, 2014 4:54:56 PM

Quantum Phase Transitions

"Like melting an entire iceberg with a hot poker" – UCL scientists explore the strange world of quantum phase transitions

“What a curious feeling,” says Alice in Lewis Carroll’s tale, as she shrinks to a fraction of her size, and everything around her suddenly looks totally unfamiliar. Scientists too have to get used to these curious feelings when they examine matter on tiny scales and at low temperatures: all the behaviour we are used to seeing around us is turned on its head. More...

Publiziert: May 13, 2014 4:06:57 PM

Clover leaf by Scott Robinson on Flickr

Quantum mechanics explains efficiency of photosynthesis

Light-gathering macromolecules in plant cells transfer energy by taking advantage of molecular vibrations whose physical descriptions have no equivalents in classical physics, according to the first unambiguous theoretical evidence of quantum effects in photosynthesis published today in the journal Nature Communications. More...

Publiziert: Jan 9, 2014 3:48:33 PM

Biological Physics

Dr Philip Jones, Dr. Isabel Llorente-Garcia, Dr Angus Bain, Dr Alexandra Olaya-Castro

Within the Atomic, Molecular, Optical and Positron Physics (AMOPP) group, we have a program of research aimed at applying physics techniques to biological and life science questions.

Fluorescence microscopy

Molecular complexes that perform vital functions in live cells can be labelled with fluorescent tags which emit light when illuminated by the appropriate excitation light. Fluorescence microscopy provides valuable information about the location, number and arrangement of these complexes in the cell. When carried out in live cells (in vivo), it allows dynamic monitoring maintaining the native biological context and functionality in the living cell. Videos can be acquired with spatial resolutions of a few hundred nanometres and at tens of millisecond time scales, which, after image processing involving single-particle tracking, can help elucidate the mechanisms and functions of the biological complexes of interest.

Force sensing and manipulation using optical tweezers and magnetic traps

Optical tweezers are a useful and important tool with many applications in the physical and life sciences.  By strongly focussing a laser beam, microscopic objects can be trapped and manipulated at the beam waist. The group of Dr. Phil Jones uses optical tweezers for trapping a variety of objects interesting for life sciences or soft matter, including microscopic bubbles and carbon nanotubes. More information about this research can be found in the optical tweezers website.

tweezersbubble

Magnetic traps: tailored magnetic trapping potentials can be used for confining and manipulating micrometre-sized particles in solution. The particles can be previously functionalised and attached to biological complexes so that the magnetic traps can then be employed to exert and measure forces relevant to the function of the complexes. Combined with fluorescence microscopy, this technique provides a powerful tool for studies at the single molecule level and in real time in live cells. In this way, Physics can be applied to biomedical problems important to human health, in particular, those related to cell-surface interactions. For instance, we can try to understand the forces involved in the activity of cell-surface receptor molecules, such as those key to cancer growth, immune response or viral infection. The group of Dr. Isabel Llorente-Garcia applies fluorescence microscopy and magnetic force spectroscopy and manipulation to the study of mechanisms of receptor-mediated virus entry in live cells.

Ultrafast laser spectroscopy of biological systems

Ultrafast lasers - lasers that produce pulses of light as short as a few femtoseconds (1 femtosecond is 10-15 s)- can be used in experiments for single and multi-photon induced fluorescence as a means of investigating molecular probe dynamics in biological systems.

These very short pulses of laser light can be used to measure the orientation and very fast rotation of molecules ('probes') when they are placed in an environment that restricts their motion. The probe is a chromophore, a molecule that absorbs light of one colour and re-emits is at a different one. By analysing the light emitted by the chromophore, particularly its polarisation, we can obtain information about the way the molecule is moving ('tumbling' and 'wobbling' motion), and so deduce the nature of the environment surrounding it.

Highly ordered molecular environments can commonly be found in the biological sciences, for example, in cell membranes. This technique can be used to detect and measure changes in the biological environment from changes in the motion of the probe molecules.

bainlasersbainmolecules

Dr Angus Bain works on the development of various picosecond and femtosecond laser spectroscopy techniques, as well as on novel developments in time resolved stimulated emission depletion (STED), time resolved polarised fluorescence techniques for the study of Förster resonance energy transfer (FRET) in biological systems and super resolution fluorescence microscopy via fluorescence lifetime image reconstruction with low power continuous wave stimulated emission depletion (CW STED).

Theoretical biophysics - quantum phenomena in biomolecular functions

It is well known that quantum mechanics explains the structure, stability and spectroscopy of the molecular components of living systems. What remains unknown (and controversial) is whether there are quantum coherent dynamics relevant for their biological functionality - features that have been selected by evolution. In order to achieve a theoretical understanding of the possible roles of quantum phenomena in biomolecular functions, Dr Alexandra Olaya-Castro works on theoretical studies of quantum approaches to photosynthetic complexes, non-classical features of electronic and vibrational dynamics in biomolecules, counting statistics and noise characterisation in charge and exciton transfer processes, and quantum thermodynamics of biomolecular processes.

Additional information

For more information on Biological Physics research areas and people within the Physics Department, please see:

http://www.ucl.ac.uk/phys/biophys/

http://www.ucl.ac.uk/phys/biophys/research

http://www.ucl.ac.uk/phys/biophys/staff