Rajen Kundu

Bio: Rajen Kundu is an academic researcher from Indian Institute of Technology Guwahati. The author has contributed to research in topics: Fluorescence & AP site. The author has an hindex of 8, co-authored 16 publications receiving 221 citations. Previous affiliations of Rajen Kundu include University of Colorado Boulder & Central Mechanical Engineering Research Institute.

Installation/modulation of the emission response via click reaction.

Abstract: We have demonstrated the installation of a fluorescence property into a nonfluorescent precursor and modulation of an emission response of a pyrene fluorophore via click reaction. The synthesized fluorophores show different solvatochromicity and/or intramolecular charge transfer (ICT) feature as is revealed from the UV−visible, fluorescence photophysical properties of these fluorophores, and DFT/TDDFT calculation. We observed that some of the synthesized fluorophores showed purely ICT character while emission from some of them arose from the LE state. A structureless and solvent polarity-sensitive dual emission behavior was observed for one of the triazolylpyrene fluorophores that contains an electron-donating −NMe2 substituent (fluorophore, 7a). Conversely, triazolylpyrene with an electron-withdrawing −CN group (fluorophore, 7b) showed a solvent polarity-independent vibronic emission. The effect of ICT on the photophysical properties of these fluorophores was studied by fluorescence emission spectra and ...

Triazolyl Donor/Acceptor Chromophore Decorated Unnatural Nucleosides and Oligonucleotides with Duplex Stability Comparable to That of a Natural Adenine/Thymine Pair

Abstract: We report the design and synthesis of triazolyl donor/acceptor unnatural nucleosides via click chemistry and studies on the duplex stabilization of DNA containing two such new nucleosides. The observed duplex stabilization among the self-pair/heteropair has been found to be comparable to that of a natural A/T pair. Our observations on the comparable duplex stabilization has been explained on the basis of possible π–π stacking and/or charge transfer interactions between the pairing partners. The evidence of ground-state charge transfer complexation came from the UV–vis spectra and the static quenching of fluorescence in a heteropair. We have also exploited one of our unnatural DNAs in stabilizing abasic DNA.

Cellulose hydrogels: Green and sustainable soft biomaterials

Abstract: Cellulose is a highly abundant, green, sustainable, and biodegradable polymer. These characteristic features of cellulose make it a useful polymer for the synthesis of bio-based hydrogel/or soft material for various applications. This article is focused on the preparation of biodegradable and biocompatible cellulose-based hydrogels using different methods based on the crosslinking agents used and the solvents used for cellulose dissolution. A study on the classification of different types of hydrogels was also reported. This article also discusses the self-healing cellulose-based hydrogel, bacterial cellulose-based hydrogel and includes the use of cellulose hydrogel in agriculture, biomedical field such as wound healing, wound dressing, and tissue engineering, water purification, removal of heavy metal, and in environmentally beneficial supercapacitors.

Dye chemistry with time-dependent density functional theory

Abstract: In this perspective, we present an overview of the determination of excited-state properties of "real-life" dyes, and notably of their optical absorption and emission spectra, performed during the last decade with time-dependent density functional theory (TD-DFT). We discuss the results obtained with both vertical and adiabatic (vibronic) approximations, choosing relevant examples for several series of dyes. These examples include reproducing absorption wavelengths of numerous families of coloured molecules, understanding the specific band shape of amino-anthraquinones, optimising the properties of dyes used in solar cells, mimicking the fluorescence wavelengths of fluorescent brighteners and BODIPY dyes, studying optically active biomolecules and photo-induced proton transfer, as well as improving the properties of photochromes.

Pyrene-functionalized oligonucleotides and locked nucleic acids (LNAs): Tools for fundamental research, diagnostics, and nanotechnology

Abstract: Pyrene-functionalized oligonucleotides (PFOs) are increasingly explored as tools in fundamental research, diagnostics and nanotechnology. Their popularity is linked to the ability of pyrenes to function as polarity-sensitive and quenchable fluorophores, excimer-generating units, aromatic stacking moieties and nucleic acid duplex intercalators. These characteristics have enabled development of PFOs for detection of complementary DNA/RNA targets, discrimination of single nucleotide polymorphisms (SNPs), and generation of π-arrays on nucleic acid scaffolds. This critical review will highlight the physical properties and applications of PFOs that are likely to provide high degree of positional control of the chromophore in nucleic acid complexes. Particular emphasis will be placed on pyrene-functionalized Locked Nucleic Acids (LNAs) since these materials display interesting properties such as fluorescence quantum yields approaching unity and recognition of mixed-sequence double stranded DNA (144 references).

Optical sensor: a promising strategy for environmental and biomedical monitoring of ionic species

Abstract: Considerable amount of research has been carried out on designing and improving metal-recognition methodologies in environmental and biological media. The development of fluorescent-based techniques has proven to be an important milestone for non-invasive metal detection and quantification in a multichannel environment. Metals as natural components of the Earth's crust are generally present in trace concentrations in environmental samples, wherein humic substances have a complexation affinity toward them. Iron, zinc and copper are the 1st, 2nd and 3rd most abundant elements that are indispensable to the human body in trace amounts as they play crucial roles in many biological processes. However, unregulated amounts either an excess or deficiency may exacerbate deterioration of the vital organs and trigger the progression of complications. In addition to these three essential elements, mercury is widely considered to be one of the most hazardous pollutants and highly dangerous elements due to its recognized accumulative and toxic effects in the environment and in biological media. In the present study, we attempted to summarize all the recently developed fluorescent signaling materials for the detection of Cu2+, Fe2+/Fe3+, Zn2+ and Hg2+. The spectral shifts in the molecules on metal chelation, the mode of complexation and the stoichiometries of the resulting adducts have been discussed in detail. Furthermore, we highlight molecules that have been reported as an intracellular metal detector via bioimaging, which can be useful for the future design and development of cell-viable and membrane-permeable molecular probes.

Design strategies for bioorthogonal smart probes

Abstract: Bioorthogonal chemistry has enabled the selective labeling and detection of biomolecules in living systems. Bioorthogonal smart probes, which become fluorescent or deliver imaging or therapeutic agents upon reaction, allow for the visualization of biomolecules or targeted delivery even in the presence of excess unreacted probe. This review discusses the strategies used in the development of bioorthogonal smart probes and highlights the potential of these probes to further our understanding of biology.