The focus of the research in our Group is on the study of the dynamics of ultrafast processes that are of importance in Chemistry and Biology. The principal tools we use for this process are steady state and femtosecond-nanosecond time resolved fluorescence spectroscopy. We also use techniques like light scattering, Tunneling Electron Microscopy, Circular dichroism and Confocal Microscopy. A brief account of our present research activities and interests is provided below.
(a)Ultrafast Molecular Devices and Photoluminescent nanomaterials
We have ventured into these fields in recent times. Presently, we endeavour to understand the origin of photoluminescence of silica nanoparticles. Future plans include their modification by labeling with fluorescent dyes, with the motivation of preparing ordered structures using the nanotubes as templates. Such ordered structures are likely to behave as light-harvesting nanoantennae, with additional possibilities of application as nanobiosensors and targeted drug delivery vehicles .
(b)Dynamics of Water and Proton in Polymer electrolyte membranes (PEM)
To study the dynamics of water and hydronium ions in nafion, functionalized nafion and other proton transfer membranes for fuel cells, by using the technique of time resolved fluorescence spectroscopy. The purpose of the study is to develop an intricate molecular level understanding of these dynamics, which govern the all-important macroscopic proton conductivity of the membranes. The thermal and chemical stability of novel proton transfer membranes, prepared in the laboratory of the PI, as well as in NMRL, will be determined.
(c) Fluorescence in Biology
Fluorescence is a sensitive technique for detection of minute amounts of analytes, which has the potential
to eliminate costly and hazardous radioactive tracers. We attempt to develop and characterize novel fluorescent sensors for analytes
like chloride ions, oxygen and metal ions in trace quantities. We have investigated quinolines for sensing of halide ions with emphasis
on ion-specificity and the effect of counterions. Efforts are on to develop and characterize novel sensors with high specificity and
selectivity.
We are also trying to understand the fluorescent properties of Epicocconone, a novel protein stain, and its derivatives. It has a
prominent emission in red upon binding to proteins and a very meek fluorescence in green when it is free. In addition we are also
looking into fluorophores like Pyridylbenzimidazoles that can be good probes to measure membrane cell potential.
(d) Excited State Processes in Neat Solvents and Restricted Microenvironments
This has been the principal strength of our group in the past years. We have investigated the excited state dynamics of novel fluorophores like bipyridinediol, Lucifer yellow, with an emphasis on how they are affected by the properties of the microenvironment around the fluorophore. In the course of these studies, we have explored the role of confined water as well as charged interfaces on the dynamics of solvent mediated excited state proton transfer in 2-(2’-pyridyl) benzimidazole. This has led us to propose potential applications of this fluorophore in the study of macromolecular interactions, intracellular fluorescence imaging and water content in polymers. The changes in photophysical pathways, brought about by synthetic modification of some fluorophores, are being studied at present.
(e) Porphyrins and Chlorins
Porphyrins and chlorins are an important class of compounds that are central to important biological processes such as photosynthesis and storage and transport of oxygen. We have performed systematic studies of aggregation and photoinduced electron transfer of chlorin p6, which has led us to a series of experiments on the dynamics of ultrafast processes in novel chlorin-based systems. The purpose of these studies is to mimic photosynthetic processes and produce efficient devices for charge transport and energy storage. Another interesting aspect of these compounds is their potential application as drugs for photodynamic therapy (PDT). In order to understand their suitability in this application, it is imperative to study their aggregation properties, binding with drug delivery vehicles and cellular uptake. Such investigations are presently in progress.