http://irgu.unigoa.ac.in/drs/handle/unigoa/28 2026-04-22T09:31:31Z 2026-04-22T09:31:31Z Bandekar, S.N. Vij, R. Prabhu, S. Achanta, V.G. Sahu, S. Jha, R. Sudhir, C. http://irgu.unigoa.ac.in/drs/handle/unigoa/7841 2026-04-21T10:43:51Z 2026-01-01T00:00:00Z

Plasmon-enhanced fluorescence for sensitive and selective mercury ion (Hg sup(2+)) detection Bandekar, S.N.; Vij, R.; Prabhu, S.; Achanta, V.G.; Sahu, S.; Jha, R.; Sudhir, C. Plasmon-enhanced fluorescence (PEF) has emerged as an interesting platform for biosensing and quantum applications. The strong enhancement of emission from fluorophores arises due to an increase in the excitation and radiative decay rates of fluorophores in the vicinity of the metal surface. Furthermore, the excitation of surface plasmons on the metal accentuates the enhancement mechanism. A PEF-based system combines high sensitivity, photostability, and selectivity, making it a promising candidate for environmental monitoring and for the detection of trace levels of mercury ions (Hg sup(2+)) in aqueous media. Here, we report a study on PEF of CdSe-ZnS core-shell quantum dots and Rhodamine B (RhB) using silica-coated gold nanoparticles. Our observations indicate a strong enhancement in the emission intensity of these fluorophores in the vicinity of the metal nanoparticles. Along with this increase in intensity, there is a decrease in the emitter's lifetimes when mixed with the metal nanoparticles. Our study also shows that the enhancement is maximum at the plasmonic resonance wavelength, implying that this is indeed a plasmon-enhanced process. We performed finite-difference time-domain (FDTD) simulations to numerically investigate the electric-field enhancement in the immediate vicinity of silica-coated gold nanostructures and to determine the spontaneous emission characteristics of emitters. Furthermore, we use this mechanism to detect Hg sup(2+) at ultra-low levels in aqueous media. The system leverages PEF and dynamic quenching mechanisms to achieve a limit of detection (LOD) in the femtomolar (fM) range, surpassing previously reported nanocomposite-based sensors.

2026-01-01T00:00:00Z Bandekar, S. Sudhir, C. http://irgu.unigoa.ac.in/drs/handle/unigoa/7839 2026-04-21T10:42:34Z 2025-01-01T00:00:00Z

MoS sub(2) Quantum Dots for Mercury Detection and Fluorescence Resonant Energy Transfer Bandekar, S.; Sudhir, C. In this work, we study the optical properties of MoS sub(2) quantum dots and utilize them for mercury ion detection using fluorimetry. Further, we utilize the overlap of the emission spectrum of MoS sub(2) and the excitation spectrum of Au nanoclusters for fluorescence resonant energy transfer.

2025-01-01T00:00:00Z Rane, N.C. Sudhir, C. http://irgu.unigoa.ac.in/drs/handle/unigoa/7840 2026-04-21T10:43:20Z 2026-01-01T00:00:00Z

Scanning probe microscopy study of the electronic and piezoelectric properties of multilayer graphene oxide Rane, N.C.; Sudhir, C. Graphene oxide (GO), a two-dimensional material with tunable changes in electrical, electromechanical, and surface potential behavior, presents great potential for various nanoelectronic and energy-related applications. Herein, we present a detailed nanoscale study of multilayer GO flakes utilizing multimodal scanning probe microscopy (SPM) techniques, which include Conductive atomic force microscopy (C-AFM), Piezoresponsive force microscopy (PFM), and Kelvin probe force microscopy (KPFM). The C-AFM findings of multilayer GO flakes depict charge transport in the vertical direction, with the current profiles remaining relatively stable and showing no significant lateral diffusion. We interpreted this as further evidence of defined percolation pathways combined with sp sup(2)-rich conductive domains, further facilitating charge transport. Current-voltage (I-V) spectroscopic measurements indicate that the conduction mechanisms of GO samples amount to a transition from ohmic conduction to Poole-Frenkel emission, which eventually leads to dielectric breakdown and then current saturation, displaying the structural heterogeneity inherent in GO. PFM data provides an effective out-of-plane piezoelectric coefficient (d sub(33)) of approximately 0.59 pm V sup(-1) and a coercive voltage of 3V. The amplitude data indicate switchable polarization in the butterfly-shaped polarization loop, and a 180 degrees phase reversal confirms the switchable polarization behavior. The KPFM mapping verifies a surface potential of 4.80 eV, consistent with GO being a semiconductor. This work represents the multifaceted role of multilayer GO and establishes its application in nanoelectronics, energy harvesting, and memory devices.

2026-01-01T00:00:00Z Balasubramanian, H. Poomani, K. Kandasamy, S. Hathwar, V.R. Gonnade, R.G. http://irgu.unigoa.ac.in/drs/handle/unigoa/7787 2026-02-02T11:33:52Z 2026-01-01T00:00:00Z

Exploring the interplay of electron density distribution and electrostatic potential in the interaction of nilutamide and flutamide with androgen receptors using quantum crystallography Balasubramanian, H.; Poomani, K.; Kandasamy, S.; Hathwar, V.R.; Gonnade, R.G. Prostate cancer is a malignant disease commonly found in men. Androgens support the growth and survival of prostate cancer cells. To control this growth and the spread of cancer cells, anti-androgen drugs are necessary to block androgen activity. Effective blocking of androgens depends mainly on the structure, intermolecular interactions and charge density distribution, electrostatic potential (ESP) and binding affinity of drug molecules. Nilutamide (NIL) and flutamide (FLU) are two structurally related non-steroidal anti-androgen drugs (NSAAs) which exhibit serious side effects. The present study explores the charge density distribution, electrostatic potential and intermolecular interactions of NIL and FLU determined from a high-resolution X-ray diffraction experiment and a solid-state quantum chemical theoretical study. Topological analysis of charge density reveals the electron density at the bond critical points of chemical bonds and intermolecular interactions. The electrostatic potential derived from the charge density distribution of both molecules in the crystal has been mapped, which allows a prediction of how the electrostatic interactions, hydrogen bonds, and van der Waals forces govern the binding of these two drug molecules with the androgen receptor at the electronic level. The ESP of interacting groups of both molecules in the androgen active site is approximated to the ESP of those groups in the crystals. The charge density distribution and the electrostatic potential of both molecules were compared. The difference in charge density is reflected in the ESP of NO sub(2), CF sub(3) and NH groups and the aromatic ring of both molecules, which is important for drug binding, metabolic stability and toxicity. A molecular docking simulation of both molecules with androgen receptors shows the difference in interactions and binding affinity in the binding pocket of the androgen receptor. The results of the high-resolution X-ray experiment and the advanced computational charge density study of NIL and FLU allows us to understand drug binding and is useful to relate their differing biological effects and toxicities at the electronic level. This information pertains to the design of a new potential androgen inhibitor with improved binding affinity and fewer side effects.

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