Discovery of a new binding site and a possible gain in neomorphic activity in R132H_IDH1 Nandeshwar, Abhipsa Sekhar Biswal, Soumit Chatterjee, Umakanta Tripathy Physical Chemistry Chemical Physics, 2026 The WT_IDH1 undergoes open-to-close conformational switching for normal catalytic function at the canonical binding site; whereas, the R132H_IDH1 forms a new binding site for possible gain in neomorphic activity.
Modulation of Photoluminescence To Detect Glutathione-Responsiveness of Phthalimide-Derived Polymeric Micelles Kalipada Manna, Padmapani Pradhan, Subha Samanta, Abhipsa Sekhar Biswal, Santosh Kumar Jana, Sukhendu Mandal, Soumit Chatterjee, Sagar Pal Biomacromolecules, 2025 The delivery of a drug payload to targeted cells using a polymeric vehicle cannot be accurately traced solely by photoluminescence emission. A multicomponent synthetic method is imperative that should integrate fluorescence change observation along with in vitro release of the therapeutic agent. The present work outlines the design, synthesis, spectroscopic characterization, theoretical approaches, GSH-triggered surface morphology observation, and in vitro release of curcumin from a phthalimide-based pPEGMA 22 - b -pPTHDS 16 copolymer micelle. This copolymer has a disulfide bond as a cleavable linker, a phthalimide group as a fluorescent marker, and curcumin as a model cargo. Disulfide cleavage, initiated by interaction with glutathione under physiological conditions, leads to the liberation of free curcumin and a simultaneous red-shift fluorescence emission (λ max = 530 nm). This promising drug delivery system demonstrates potential for theranostic applications for the targeted therapies, as it seamlessly integrates treatment and real-time imaging of drug absorption at a cellular level.
Revealing the importance of the C(1) position to modulate the photophysics and Z-scan responses of o-locked GFP chromophores Debasish Paul, Priyadarshi Sahoo, Amit Kumar Pradhan, Prasanta Kumar Datta, Arunava Sengupta, Umakanta Tripathy, Soumit Chatterjee Journal of Chemical Physics, 2025 Three novel ortho-locked (o-locked) green fluorescent protein (GFP) chromophores, which are also doubly locked, with a phenyl group at the C(1) of the imidazolinone ring and substituents with varying electronic effects at the C(9) of the benzylidene moiety, have been synthesized. All the chromophores show relatively weak but much red-shifted emissions compared to their methyl counterparts at C(1), as previously reported by us [D. Paul et al., J. Phys. Chem. B 129, 692–711 (2025)]. Quantum chemical calculations indicate that the excited state dynamics of the chromophores possess initial rotation of the phenyl, followed by proton transfer and geometry twisting. Fluorescence decays confirm an early time charge transfer from the benzylidene moiety to the electron-withdrawing substituents at C(9). The relaxation processes occur within a time range of hundreds of femtoseconds to a few picoseconds, subject to respective compounds. This study supports our earlier reported findings [D. Paul et al., J. Phys. Chem. B 129, 692–711 (2025)] that the electronic effect at C(9) significantly affects the quantum yields of o-locked GFP chromophore analogs. This study also shows that solvent viscosity and temperature play dominant roles in modulating the fluorescence intensities of o-locked GFP chromophores. Furthermore, these compounds display significantly superior nonlinear optical (NLO) properties than their methyl analogs [D. Paul et al., J. Phys. Chem. B 129, 692–711 (2025)]. These findings provide valuable insight regarding the correlation between the molecular structures of o-locked GFP chromophores and their spectroscopic nature and pave the way to structurally engineering improved fluorophores. In a nutshell, these chromophores with a phenyl group at C(1), with poor but highly red-shifted emission in solution, showing viscosity dependency on emission intensity, and high NLO properties, can be very useful in bio-imaging.
Revealing the Role of Electronic Effect to Modulate the Photophysics and Z-Scan Responses of o-Locked GFP Chromophores Debasish Paul, Priyadarshi Sahoo, Arunava Sengupta, Umakanta Tripathy, Soumit Chatterjee Journal of Physical Chemistry B, 2025 Three novel core green fluorescent protein (GFP) chromophore analogues, based on a doubly locked conformation and variable electronic effects by replacing one hydrogen with bromine, iodine, and methyl, respectively, have been synthesized to modulate the push-pull effect. These chromophores exhibited intramolecular H-bonding, as evidenced by single-crystal X-ray and 1H NMR studies. The fluorescence quantum yields (ϕf) of all of the chromophores were found to be more than an order of magnitude higher (∼0.2) than the unlocked chromophores (∼0.01). It was found that the electronic effect did affect the nonradiative rates, as the quantum yields were found to vary with respect to different analogues in the same solvents. The effect of the push-pull effect was also evident by a higher Stokes-shifted emission in the case of the methyl derivative with respect to the bromo- and iodo-analogues. Furthermore, the emission spectra of these GFP chromophores were found to show positive solvatochromism, which was supported by a quantum chemical calculation. A detailed study, correlating the observed spectral changes with various solvent functions and supported by computational results, established a facile proton transfer, followed by twisted intramolecular charge transfer (TICT) to be the major nonradiative channels of these chromophores. Besides, a completely novel usage of these chromophores was explored for the first time by studying their third-order nonlinear optical characteristics in DMSO using a single-beam Z-scan technique. All of the chromophores exhibited tunable nonlinear refraction (NLR) and nonlinear absorption (NLA) properties that depend upon different substituent groups present in the chromophores. Here, the NLR was due to the effect of self-defocusing, whereas the NLA was triggered by reverse saturable absorption, which is attributed to the two-photon absorption (TPA) process. Surprisingly, the efficiency of the TPA ability of the chromophores was found to be a function of the induced electronic effect. Hence, this work opens a new route for the utility of the ortho-locked GFP chromophores in the field of nonlinear optical applications.
Aggregation-Induced Modulation of Ground and Excited State Photophysics of 5-(tert-Butyl)-2-Hydroxy-1,3-Isophthalaldehyde (5-tBHI) Aparna Shukla, Abhipsa Sekhar Biswal, Arkaprava Chowdhury, Ritaban Halder, Soumit Chatterjee Journal of Physical Chemistry B, 2024 5-(tert-Butyl)-2-hydroxy-1,3-isophthalaldehyde (5-tBHI) is a photochromic material susceptible to either excited state proton transfer or excited state intramolecular proton transfer, depending upon the solvent. However, it has also been found to aggregate in the presence of sodium dodecyl sulfate. In this current study, based on the steady-state and time-resolved spectroscopy, supported by crystallography, quantum chemical density functional theory calculation, and molecular dynamics (MD) simulation, we report on the aggregation of this potential single benzene-based emitter (SBBE) in neat solvents as well as solid phase to modulate its photophysics. It has been found that 5-tBHI forms mixed aggregates of different orders, owing to the presence of both enolic and tautomeric forms, to yield tunable emission, although the emission intensity is quenched. These findings suggest that the intramolecular hydrogen bonding of 5-tBHI not only limits intermolecular interactions but also promotes nonradiative deactivation pathways. Hence, designing and structural engineering, with a focus to suppressing intramolecular hydrogen bonding as well as increasing through space conjugation by replacing the aldehydic moieties with bulky aliphatic or aromatic ketonic groups, can be a plausible approach to yielding improved probes with tunable emission and higher fluorescence quantum yields.
Reversible addition fragmentation chain transfer-mediated bioconjugated amphiphilic graft-block copolymer using dextran, poly (N-isopropylacrylamide), and poly (vinyl acetate) Puja Das Karmakar, Aparna Shukla, Pralay Maiti, Soumit Chatterjee, Sagar Pal Journal of Applied Polymer Science, 2021 Abstract RAFT polymerization is a well‐known approach to develop amphiphilic copolymer with less heterogeneity and narrow dispersity. Herein, an amphiphilic bioconjugated graft‐block copolymer (Dextran‐ g ‐(PNIPAAm‐ b ‐PVAc)) using dextran, N ‐isopropyl acrylamide and vinyl acetate has been developed through RAFT polymerization. The chain length of the PVAc block has been varied to obtain the copolymers with different hydrophobic segments. The lower critical solution temperature, critical micelle concentration, and micellar stability of the synthesized copolymers have been studied in details. in‐vitro cytotoxicity, as well as the in vitro release of a hydrophobic drug have been carried out to explore its suitability in the field of biomedical science. The synthesized copolymer has been found to have controlled molecular weight with narrow dispersity. It is cytocompatible toward Human cervical cancer cell line cell lines, can efficiently load a hydrophobic drug‐norfloxacin, and subsequently, release in the sustained manner as manifested from in vitro release study.
