BITS Faculty Publications

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Author: search.filters.author.Addy, Partha SarathiSubject: search.filters.subject.Fluorescence

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    Nontoxic Aggregation-Induced Emissive Luminogen for the Detection of Amyloid Fibrils and Cellular Protein Aggregates
    (ACS, 2023-10) Chowdhury, Rajdeep; Addy, Partha Sarathi
    Protein misfolding and aggregation resulting in amyloid formation is directly linked to various diseases. Hence, there is keen interest in developing probes for the selective detection of such misfolded aggregated proteins. In this paper, we have shown the use of a nontoxic aggregation-induced emissive luminogen (AIEgen), BIDCPV, for the selective detection of insulin amyloid fibrils and their various stages of formation. We further verified the selective response of BIDCPV toward amyloid fibrils by testing the probe against Aβ 42 peptides, which is well known to form the fibrils. Additionally, the low toxicity, efficient cellular internalization capability, and photostability make BIDCPV a unique candidate for sensing protein aggregates inside mammalian cells.
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    One-Pot Synthesis of Vinylogous Cyano Aminoaryls (VinCAs) as Benzenic Fluorophores: Tailoring Diverse Emission Colors for White Light Emitting Materials and Cell Imaging
    (ACS, 2024-05) Ghosh, Sarbani; Chowdhury, Rajdeep; Addy, Partha Sarathi
    Donor–acceptor-based organic small molecules with an electronic push–pull effect can demonstrate intramolecular charge transfer to show interesting photoluminescence properties. This is an essential criterion for designing fluorogenic probes for cell imaging studies and the development of organic light-emitting diodes. Now, to design such optical materials sometimes it is necessary to tune the band gap by controlling the energies of the highest occupied molecular orbital and lowest unoccupied molecular orbital. Typically, the band gaps could be modulated by installing unsaturated handles between electron-rich donors and electron-deficient acceptors. However, these methods are often synthetically and economically challenging due to the involvement of expensive catalysts and difficult reaction setups. In our present study, we show a straightforward, cost-effective method for obtaining a series of donor–acceptor-type Vinylogous Cyano Aminoaryls (VinCAs) with diverse emission colors. Further studies reveal that these VinCAs can serve as effective cell imaging agents, showcasing potential use in chemical biology. Additionally, these molecules could be further used to generate white light emission (WLE), showing their potential utility in advanced lighting technologies
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    A Chemoselective Rapid Azo-Coupling Reaction (CRACR) for Unclickable Bioconjugation
    (ACS, 2017) Addy, Partha Sarathi
    Chemoselective modification of complex biomolecules has become a cornerstone of chemical biology. Despite the exciting developments of the past two decades, the demand for new chemoselective reactions with unique abilities, and those compatible with existing chemistries for concurrent multisite-directed labeling, remains high. Here we show that 5-hydroxyindoles exhibit remarkably high reactivity toward aromatic diazonium ions and this reaction can be used to chemoselectively label proteins. We have previously genetically encoded the noncanonical amino acid 5-hydroxytryptophan in both E. coli and eukaryotes, enabling efficient site-specific incorporation of 5-hydroxyindole into virtually any protein. The 5-hydroxytryptophan residue was shown to allow rapid, chemoselective protein modification using the azo-coupling reaction, and the utility of this bioconjugation strategy was further illustrated by generating a functional antibody–fluorophore conjugate. Although the resulting azo-linkage is otherwise stable, we show that it can be efficiently cleaved upon treatment with dithionite. Our work establishes a unique chemoselective “unclickable” bioconjugation strategy to site-specifically modify proteins expressed in both bacteria and eukaryotes.