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Fluorescence Research

The fluorescence research that is conducted in the Nanoscale Biophotonics group covers six main topics:

1). Metal Enhanced Fluorescence ( Details here),
2). Lifetime based sensing, ( Details here)
3). Fluorescence based methods for biomedical polymer analysis (Details to be added soon),
4). Fluorescence studies of petroleum oils & Fluid inclusions ( Details here),
5). Advanced Fluorescence Microscopy and new Instrumentation development (Details below),
6). Collaborative projects.

Fluorescence Spectroscopy Laboratory

Most of the equipment is located either in a purpose built laboratory (Lab 166 in the School of Chemistry) on the ground floor of the Concourse building or in the Physical Chemistry laboratories.

The lab. is shortly (2008) going to be upgraded with some additional fluorescence instrumentation to further expand our capabilities.

Steady state systems Lifetime cuvette Lifetime microscopes Fibre optic lifetime microscope Contact Information The picture right shows one of the spectroscopy rooms with  (from left, clockwise): a PE Lambda 950 UV-Vis, a FluoTime 200 Lifetime system, a Cary Eclipse Fluorimeter, and an Oxford Instruments XRF system (Sept. 08).

 

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Fluorescence (steady state)

The steady state fluorescence measurements we do generally refer to emission, excitation, or multi-dimensional spectra collected using either the Cary or Perkin-Elmer fluorimeters. This type of spectral information is widely used in our group for the analysis of complex samples such as crude oils or bioprocesses. 

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Fluorescence Lifetimes: 

The fluorescence lifetime of a molecule can be regarded as the average time that the molecule spends in the excited state after absorption of a photon of light. For most organic molecules these lifetimes range in the nanosecond to picosecond range.

In our laboratory we study the fluorescence lifetimes of complex fluids like petroleum, biological molecules such as proteins, and organic molecules. The information from fluorescence lifetimes is very useful in understanding the photophysics and photochemistry of different molecules and how the environment influences light emission.

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Fluorescence Lifetime Imaging (FLIM):

One of the big advantages of using fluorescence lifetime instead of intensity for imaging is that the image contrast is not dependent on the intensity. This removes artifacts and makes it easier to observe environmental factors.  In our laboratory we use FLIM to study Hydrocarbon bearing Fluid Inclusions (HCFI), live cells, and polymers.


Some sample FLIM data from the inverted system is illustrated below:

The images on the left show typical fluorescence intensity images of dichlorofluorescein labeledlabelled cells, while the images on the right dhow the FLIM images (lifetime by modulation) of the cells.  The calculated lifetime in the cells is a near uniform 3.6 +/- 0.4 ns.  The images were accumulated with a residence time of 1ms/pixel, 470 nm excitation, and an emission filter cantered at 520 nm. These images show to good advantage the ability of FLIM to overcome intensity fluctuations and give a truer image of what happens in the cells. [Cells from Dr. Michael Ball].

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Fluorescence Correlation Spectroscopy (FCS):

FCS is a very sensitive measurement method which allows scientists to measure the concentration and size of molecules in living cells.  The technique measures how long it takes for single molecules to diffuse through a very small focal volume.  It is routinely used to measure concentrations in the nanomolar (10-9 M) range in living cells.

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TOTAL INTERNAL REFLECTION FLUORESCENCE (TIRF) MICROSCOPY:

TIRF allows one to image at nanometre (10-9 m) resolution using fluorescence methods.  This can be used to provide a clear picture of what happens on the surfaces of living cells.

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