pH-Dependent Oxidase- and Hydrolase-Mimicking Activity of Nanoceria and Its Composite with Nitrogen-Doped Carbon Quantum Dots for Sensitive Detection of Dopamine, Glutathione, and Methyl Paraoxon Yogyata Chawre, Manmohan L. Satnami, Ankita Beena Kujur, Akash Sinha, Prince Kumar Soni, Pinki Miri, Rekha Nagwanshi, Indrapal Karbhal, Kallol K. Ghosh ACS Chemical Neuroscience, 2026 Nitrogen-doped carbon quantum dot–cerium oxide (NCQD–CeO 2 ) nanocomposites were developed as an enzyme-free, multi-analyte sensing platform based on fluorescence resonance energy transfer (FRET). The sensing mechanism arises from the redox-active Ce 3+ /Ce 4+ couple of cerium oxide, which catalyzes analyte-specific reactions and generates in situ FRET acceptors that modulate NCQD fluorescence. CeO 2 nanoparticles catalyze the oxidation of dopamine to aminochrome (quinone), whose absorption overlaps with NCQD emission, resulting in fluorescence quenching in both acidic and basic conditions. Dopamine self-polymerization under basic conditions is suppressed by glutathione through its antioxidant activity, while nanoceria enhances electron-transfer kinetics. Glutathione further regulates the Ce 3+ /Ce 4+ redox equilibrium, enabling indirect detection via modulation of FRET efficiency. In the case of methyl paraoxon, CeO 2 exhibits phosphatase-like activity and catalyzes its conversion to p -nitrophenol, which acts as a FRET acceptor and quenches NCQD fluorescence. The analyte-dependent formation of distinct FRET acceptors allows selective signal transduction, establishing the NCQD–CeO 2 nanocomposite as a versatile platform for multi-analyte sensing.
Synergy of Rectangular Truncated Highly Reactive Facets of the Functional Heterometallic Oxo Cage for Enhanced Decomposition of Paraoxon Pinki Miri, Manmohan L. Satnami, Rekha Nagwanshi, Yogyata Chawre, Ankita Beena Kujur, Akash Sinha, Indrapal Karbhal, Rajiv Nayan, Kallol K. Ghosh, Sanjay Ghosh Langmuir, 2026 Here, we synthesize a highly porous (17.2 nm, pore volume = 0.1753 cm3/g) infinite 3D coordination network of hexanuclear heterometallic mixed metallic oxo cage {MoTI5O2} in which the Ti and Mo centers are interconnected via edge and corner sharing MO6 polyhedra and demonstrate its performance to destroy the organophosphorus-based nerve simulants. The superior performance arises from a synergistic interplay of multiple pathways; defect-engineered facets create unsaturated active sites that facilitate reduction processes and stabilize oxygen vacancies, while ROS-active low-index facets promote oxidative degradation through enhanced adsorption. The strongly negative surface potential (ζ = −40 mV) accelerates hydrolytic cleavage via a direct SN2 pathway (kobs = 5.41 × 10–5 s–1) driven by carboxylate functionalities coordinated to Ti centers, with nanoconfined water further enhancing P–O bond cleavage. Importantly, Mo5+ centers exhibit dual functionality by participating in oxidative hydrolysis and mimicking nitrogenase-like activity to convert p-nitrophenoxide to p-aminophenoxide ions. The confined architecture promotes efficient hole trapping, suppresses charge recombination, and enhances charge-carrier mobility, while Mo6+ incorporation into the TiO2 lattice broadens light absorption and narrows the band gap to 2.66 eV in the oxo-bridged (F)nMo−μ3/2O–Tn heterometallate. Interestingly, the water-dispersible magnetic core–shell system, (F)nMo−μ3/2O–Tn@Fe3O4, exhibits high selectivity toward phosphate moieties, enabling efficient organophosphorus removal via magnetic separation. Overall, this work establishes a powerful multimodal platform for the rapid, selective, and practical decontamination of organophosphates from environmental systems.
AI-driven design and applications of quantum dots Prince Kumar Soni, Manmohan L. Satnami, Rekha Nagwanshi, Yogyata Chawre, Ankita Beena Kujur, Akash Sinha, Pinki Miri, Indrapal Karbhal, Kallol K. Ghosh Nano Today, 2026
Diversified dimensionality of nanomaterials and their Fӧrster resonance energy transfer based applications Yogyata Chawre, Ankita B. Kujur, Pinki Miri, Akash Sinha, Prince Kumar Soni, Indrapal Karbhal, Rekha Nagwanshi, Shamsh Pervez, Manas K. Deb, Kallol K. Ghosh, Manmohan L. Satnami Advanced Sensor and Energy Materials, 2025 Förster resonance energy transfer (FRET) is a distance-dependent and non-radiative energy transfer process that has become a valuable tool in many fields such as biosensing, bioimaging, photovoltaics, and optoelectronics. Traditional FRET systems often used organic dyes as donors and acceptors, but these dyes have several drawbacks, including low stability, sensitivity to pH, and toxicity. To overcome these issues, researchers have started using nanomaterials of different shapes and sizes in FRET systems. This review explores the role of nanomaterials ranging from zero-to three-dimensional structures as both donors and acceptors in FRET. We discuss how their size, shape, and electronic properties affect the efficiency of energy transfer. Special attention is given to materials like quantum dots, up-conversion nanoparticles, metal nanoclusters, and perovskites. The review also summarizes different donor–acceptor pairs and their use in various applications such as detection, imaging, and solar energy harvesting. By connecting the dimensional features of nanomaterials with their performance, this review provides an overview of current research and future possibilities for FRET-based technologies.
Assessment of Acetylcholinesterase Activity Using the Gold Nanocluster-MnO2 Nanosheet Pair for Detection of Paraoxon Pinki Miri, Manmohan L. Satnami, Sanjay Ghosh, Rekha Nagwanshi, Indrapal Karbhal, Vishal Jain, Yogyata Chawre, Ankita Beena Kujur, Akash Sinha, Kallol K. Ghosh, Shamsh Pervez, Bhanushree Gupta ACS Applied Nano Materials, 2024 The atomically precise gold nanoclusters (AuNCs) and MnO 2 nanosheets (MnO 2 NSs) were synthesized and characterized as donor and acceptor pairs, respectively. A Förster resonance energy transfer (FRET)-based highly sensitive “turn on–off” fluorescence (FL) response was achieved owing to the strong spectral overlapping between highly bright luminescence of as-synthesized vitamin B 1 -stabilized gold nanoclusters (VB 1 –AuNCs) and absorption spectra of manganese oxide nanosheet (MnO 2 NS)-based 2D material. The AuNC–MnO 2 NSs pair was used as a probe for the assessment of enzymatic activity of acetylcholinesterase (AChE) as an effective alternative to Ellman’s reagent. Our work predicts that an abundantly hydrophilic nano gold cluster surface would be a promising material to improve the sensitivity and hydrolytic rate ( k cat ) of AChE enzymes. The reconciliation and inhibition of AChE for the hydrolysis of acetylthiocholine furnish quantitative turn “on–off” FL signals in the linear range of 0.53–1.6 × 10 –8 M of paraoxon. The excellence of this sensor is demonstrated by its exceptionally low limit of detection (LOD) of 1.6 nM and limit of quantification (LOQ) of 4.9 nM values for detection of paraoxon. The applicability of the proposed sensing system was verified using environmental (farm water) and fruit matrixes like tomato, grapes, and apple samples.
Förster Resonance Energy Transfer between Multicolor Emissive N-Doped Carbon Quantum Dots and Gold Nanorods for the Detection of H2O2, Glucose, Glutathione, and Acetylcholinesterase Yogyata Chawre, Manmohan L. Satnami, Ankita B. Kujur, Kallol K. Ghosh, Rekha Nagwanshi, Indrapal Karbhal, Shamsh Pervez, Manas K. Deb ACS Applied Nano Materials, 2023 Multicolor emissive nitrogen-doped carbon quantum dots (CQDs) were synthesized by the hydrothermal method and characterized using spectroscopic and electron microscopic techniques. Förster resonance energy transfer (FRET) between CQDs and gold nanorods (AuNRs) has been investigated that occurs due to the distinctive overlap of transverse and longitudinal bands of AuNRs with the fluorescence (FL) spectra of CQDs. Significant FL quenching (turn-off) of CQDs by AuNRs and their recovery (turn-on) have been observed due to etching of AuNRs and end-to-end assemblies that lead to the detection of biomolecules like H 2 O 2, glucose, glutathione (GSH), and acetylcholinesterase (AChE). The redox reaction of Au(0) with H 2 O 2 results in the decomposition of AuNRs to give Au(I) ions, thereby inducing the fluorescence recovery of CQDs (turn-on). The interruption of the FRET phenomenon by the production of H 2 O 2 from the reaction of glucose oxidase in the presence of glucose and a thiol-containing compound from the reaction of acetylthiocholine and the AChE enzyme causes the FL recovery of CQDs, respectively. Moreover, the assembly of AuNRs leads to the FRET disruption, and FL turn-on signals were found to be measures of GSH. In comparison to the UV–visible approach, the FL measurements through the FRET process are found to be more sensitive under the same reaction conditions. The practical applicability of the proposed sensing system has been verified using human plasma samples.
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