Dr. Syed Arshad Hussain Wellcomes You


My recent publications

1. Langmuir-Blodgett monolayers of cationic dyes in the presence and absence of clay mineral layers: N,N’ -dioctadecyl thiacyanine, octadecyl rhodamine B and laponite.”
Syed Arshad Hussain, R. A. Schoonheydt
Langmuir (2010) [article in press]

2. Effect of nano-clay platelets on the J-aggregation of thiacyanine dye organized in Langmuir-Blodgett films
D. Bhattacharjee, Syed Arshad Hussain, S. Chakraborty, and R. A. Schoonheydt
Spectrochimica Acta Part A (2010) [article in press]

3. Fluorescence Resonance Energy Transfer between organic dyes adsorbed onto nano-clay and Langmuir–Blodgett (LB) films
Syed Arshad Hussain, S. Chakraborty, D. Bhattacharjee, R.A. Schoonheydt
Spectrochimica Acta Part A 75 (2010) 664–670

4. Reaction kinetics of organo-clay hybrid films: In-situ IRRAS, FIM and AFM studies
Syed Arshad Hussain, Md N. Islam, D. Bhattacharjee
Journal of Physics and Chemistry of Solids 71 (2010) 323–328

5. Photophysical studies of xanthene dye in alkanols and in inorganic ions
B Ganguly, R K Nath, S A Hussain and A K Panda
Indian J. Phys. 84 (6), 549-555 (2010)

6. Investigations of RhB18 langmuir monolayer by fluorescence imaging microscopy
S A Hussain, S Chakraborty and D Bhattacharjee
Indian J. Phys. 84 (6), 625-629 (2010)

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Our new paper on Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy

Paper title: Fluorescence Resonance Energy Transfer between organic dyes adsorbed onto nano-clay and Langmuir–Blodgett (LB) films
Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy
Volume 75, Issue 2, February 2010, Pages 664-670

Full text link of the article



AFM image of hectorite assembled onto quartz slide by Langmuir-Blodgett Technique

 

 



Fluorescence Resonance Energy Transfer (FRET)

The Fluorescence Resonance Energy Transfer (FRET) between two molecules is an important physical phenomenon with considerable interest for the understanding of some biological systems and with potential applications in optoelectronic and thin film device development [1, 2]. The technique of FRET, when applied to optical microscopy, permits to determine the approach between two molecules within several nanometers. FRET was first described over 50 years ago, that is being used more and more in biomedical research and drug discovery today. FRET is a distance dependant radiationless transfer of energy from an excited donor fluorophore to a suitable acceptor fluorophore, is one of few tools available for measuring nanometer scale distances and the changes in distances, both in vitro and in vivo. Due to its sensitivity to distance, FRET has been used to investigate molecular level interactions. Recent advances in the technique have led to qualitative and quantitative improvements, including increased spatial resolution, distance range and sensitivity.
The mechanism of fluorescence resonance energy transfer involves a donor fluorophore in an excited electronic state, which may transfer its excitation energy to a nearby acceptor chromophore in a non-radiative fashion through long-range dipole-dipole interactions. The theory supporting energy transfer is based on the concept of treating an excited fluorophore as an oscillating dipole that can undergo an energy exchange with a second dipole having a similar resonance frequency. In this regard, resonance energy transfer is analogous to the behavior of coupled oscillators, such as a pair of tuning forks vibrating at the same frequency. In contrast, radiative energy transfer requires emission and reabsorption of a photon and depends on the physical dimensions and optical properties of the specimen, as well as the geometry of the container and the wavefront pathways. Unlike radiative mechanisms, resonance energy transfer can yield a significant amount of structural information concerning the donor-acceptor pair.
Resonance energy transfer is not sensitive to the surrounding solvent shell of a fluorophore, and thus, produces molecular information unique to that revealed by solvent-dependent events, such as fluorescence quenching, excited-state reactions, solvent relaxation, or anisotropic measurements. The major solvent impact on fluorophores involved in resonance energy transfer is the effect on spectral properties of the donor and acceptor. Non-radiative energy transfer occurs over much longer distances than short-range solvent effects, and the dielectric nature of constituents (solvent and host macromolecule) positioned between the involved fluorophores has very little influence on the efficacy of resonance energy transfer, which depends primarily on the distance between the donor and acceptor fluorophore.
A pair of molecules that interact in such a manner that FRET occurs is often referred to as a donor-acceptor pair. The phenomenon of FRET is not mediated by photon emission. Also it does not even require that the acceptor chromophore to be fluorescent. Although in most of the applications the donor and the acceptor are fluorescent.
References:
1. V. G. KOzlov, V. Bulovic, P. E. Burrows, S. R. Forrest, Nature 389 (1997) 362
2. C. R. Cantor, P. R. Schimmel, Biophysical Chemistry Part-II, Freeman, San Francisco, 1980
3. T. Förster Discuss Farady Soc. 27 (1959) 7