Research

Present Research Interests:

• Host-guest interactions and applications in biological environments to investigate the ultrafast dynamics under constraints of polarity and flexibility.

Essential small molecules interact with the biological organelles (cells, DNA, membrane, etc.) different based on their structures and affinity towards polarity and hydrophilicity/hydrophobicity. The interactions, in turn, decide their functionality. The host-guest composites, hence, play a major role in determining the action of the small molecules into the biological milieu. We look into the dynamic modifications and modulations of these events, analyze and find out ways to control them with external stimuli.

• Synthesis and applications of metal nanoparticles and nanoclusters in drug delivery to investigate new approaches to discover and modulate compatible biomarkers and carriers.

Metal nanoparticles are intriguing owing to their own special characteristic features due to the emergence of quantum chemical properties in them because of their size and structure. Nanoparticles show surface plasmon resonance whereas nanoclusters feature radiative emission. We design and prepare noble metal based nanoclusters and nanoparticles as well as carbon nanomaterials and controllably apply them in different physicochemical areas, such as, photoinduced energy and electron transfer, harvesting the singlet and triplet energy along with ROS generation.

• Development of crystalline polymorphs for photophysical tuning and obtaining new ways of improving photoluminescence afterglow.

Research on molecular structure-property relationship is an important area because of the vivid applicability. We design molecules with or without polymorphism, look into the photophysical properties and harvest triplet exciton to cultivate TADF, RTP and LTP. Tuning the temporal afterglow and emission shift is an intriguing and explorable field.

• Fluorescence Lifetime Imaging (FLIM) and Fluorescence Correlation Spectroscopy (FCS) to investigate the heterogeneity in small molecule photophysics in various biomimicking substrates.

FLIM and FCS are two important microscopy tools to investigate molecular dynamics down to the sungle molecule resolution. We use them to look into the molecular dynamics which changes due to host-guest interactions in the solution as well as solid/film states.

Externally funded projects:

1. “Photophysical and photochemical characterization and modulation of selected fluorophores in constrained biological environments”, sanctioned by DST, Govt. of India under the Fast Track Scheme for young scientists (October 2006 – September 2009), Completed.

2.  “Physicochemical characterization of guest molecule induced cyclodextrin nanotubular suprastructures”, sanctioned by the CSIR, New Delhi (January 2009 – January 2012), Completed.

3.  “Photophysical and photochemical studies of UV-absorbing molecules”, sponsored by Unilever Ltd. (January, 2013 – December, 2013), Completed.

4.  “Nanosystem based host-guest chemistry: Characterization using fluorescence spectroscopy”, sanctioned by DST, Govt. of India (July 2012 – July 2015), Completed.

5.  “Probing the phenomenon of interaction between lipids and surfactants using fluorescence spectroscopy”, sanctioned by CSIR, New Delhi (January 2013 – January 2016), Completed.

6.  “Synthesis and characterization of carbon nanoparticle based photoinduced electron transfer molecular devices”, sanctioned by DST, SERB (January 2016 – January 2019), Completed.

7.  “Study on photoinduced electron transfer between pristine and cyclodextrin modified carbon dots and DNA duplex”, sanctioned by CSIR, New Delhi (May 2018 – April 2021), Completed.

8.  “Studies on methods to slow down the excited state dynamics of metal nanoclusters to enhance fluorescence quantum yield”, sanctioned by DST, SERB (March 2019 – February 2022), Completed.

9.  “FRET/FLIM-FRET technique to investigate the role of hydrophobic and hydrophilic gold nanoclusters in modulating vesicle fusion and determination of the thickness of lipid bilayer”, sanctioned by DST, SERB (December 2022 – December 2025), Ongoing.