Browsing by Author "Venkatesan, Geetha"

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COMPREHENSIVE INVESTIGATION OF ANTIBACTERIAL, CYTOTOXIC, AND ANTIOXIDANT ACTIVITIES OF IPOMOEA STAPHYLINA FLOWER EXTRACT WITH ISOLATION AND CHARACTERIZATION OF BETA-SITOSTEROL (Article)
(Elsevier B.V., 2025) Narayanan, Lakshmanan; Maruthavanan T.; Vaithiyanathan R; Venkatesan, Geetha; Vivekanandan K.E; Kaliyannan, Gayathri; Kumar, Paskalis Sahaya Murphin; Bosco, Mary Sahaya Anisha John; Murugadoss, Govindhasamy; Suseem S.R
This study aims to bridge the gap by scientifically investigating the ethnopharmacological evidence surrounding the I. staphylina plant. In this research we evaluated the antibacterial and cytotoxic abilities of I. staphylina flower extracts. The extract with the highest antioxidant activity underwent cytotoxicity testing against HCT-116 cells. Further analysis confirmed the presence of Beta-sitosterol through HPTLC, followed by its isolation via column chromatography. Antibacterial tests showed significant activity against various gram-positive and gram-negative bacteria, with notable resistance against S. aureus, P. mirabilis, and P. aeruginosa. The IPFPE extract exhibited the highest inhibition against S. aureus (16 mm) and P. mirabilis (15 mm), while ethanolic extract showed potent activity against S. aureus and P. aeruginosa (16 mm, 15 mm). The anticancer study, using ethanolic and pet-ether extracts on HCT-116 colon cancer cells and assessed via the MTT assay, revealed significant reductions in cell viability due to apoptosis induced by secondary metabolites (Beta-sitosterol) and antioxidants. A significant reduction in cell viability was observed, with IC₅₀ values of 51.44 µM (IPFE) and 52.74 µM (IPFPE), a 50 % growth inhibition was observed, highlighting vigorous pro-apoptotic activity. These results underscore the potential of I. staphylina flower extracts as promising antibacterial and chemotherapeutic agents, warranting further research to validate their efficacy.
A COMPREHENSIVE REVIEW ON TAILORING FACTORS OF POROUS BISMUTH OXYHALIDE PHOTOCATALYSTS FOR WASTEWATER TREATMENT APPLICATION (Article PDF)
(Taiwan Institute of Chemical Engineers, 2025-01) Kar, Prasenjit; Sathiyan, Govindasamy; Vivekanandan, K E; Venkatesan, Geetha; Siva, Govindasamy; Subramani, Ramesh; Kandasamy, Sabariswaran
Background: Photocatalysis is a green, environmentally friendly approach for converting organic contaminants into harmless byproducts. Especially, Bismuth oxyhalides (BiOX, where X = Cl, Br and I) have emerged as promising photocatalysts for wastewater treatment due to their layered-by-layered structure, strong chemical stability and nontoxicity in compare to other metal oxides, which makes the photocatalyst advantageous for photocatalytic application. Methods: This review provides an overview of recent developments in the synthesis and application of BiOXbased porous photocatalysts for the removal of organic contaminants from wastewater. Firstly, morphologycontrolled synthesis of BiOX in degradation of organic contaminants. Then, modulation of electronic structure through doping, facet engineering and surface engineering has been highlighted for better photocatalytic applications. Furthermore, fabrication of diverse heterojunctions and co-catalyst loading upon BiOX are introduced, which can vary photocatalytic activity towards the degradation of organic contaminants. Significant findings: Finally, this review ended on the future trend and prospects of BiOX for the creation of potential high-performance photocatalysts in the near future. The porous structure of BiOX improved photocatalytic activity, pollutant degradation efficiency, visible light response charge carrier separation, and stability. Overall, bismuth oxyhalide photocatalysts have a lot of potential for effective and long-term wastewater treatment, and their development represents an important step towards addressing the global water pollution crisis.
EFFECTIVELY CONTROLLING NIR EMISSIVE PROPERTY AND THE ESIPT BEHAVIOR OF MODIFIED STYRYL DYES BY ATOMIC SUBSTITUENT: DFT/TD-DFT APPROACH (Article)
(Springer, 2025-02-24) Taneja, Shilpa; Ramasamy, Selva Kumar; Pareek, Bhawna; Venkatesan, Geetha; Periyasami, Govindasami; Sengottuvelu, Dineshkumar
Recent literature on biosensing and bioimaging has explored excited state intramolecular proton transfer (ESIPT) cyanide dyes. These classes of fluorescence dyes generally use the classical pyridinium or indolium cations acceptor units’ styrene with the ESIPT core. This work studied the photophysical and ESIPT kinetics of novel flavylium cation as an acceptor unit styrene with an ESIPT core using DFT/TD-DFT calculations. Two new ESIPT cyanine dyes, namely (E)-4-(3-(benzo[d]thiazol-2-yl)-2-hydroxystyryl)-7-(dimethylamino)-2-phenyl chromenylium (PSS) and (E)-4-(3-(benzo[d]oxazol-2-yl)-2-hydroxystyryl)-7-(dimethylamino)-2-phenylchromenylium (PSO) were designed and fully studies. This is concerned with studying changes in intramolecular hydrogen bonds, molecular orbitals at the frontier of the ESIPT process, absorption and fluorescence spectra, and excited state energy barriers. As a result, both the systems considered here can undergo an ultrafast ESIPT reaction with PSS and then PSO. Furthermore, ESIPT is more accessible in the normal enol-form first excited singlet (S1) state, with shorter hydrogen bonds. The intersystem crossing between the S1 state and the triplet (T1) state greatly influences the fluorescence efficiency of PSO and PSS. The potential energy curve and transition state energy profiles of PSS and PSO show that ultrafast ESIPT occurs in the state. Furthermore, the PSS shows less energy barriers, which leads to faster proton transfer than PSO. The current study will advance knowledge of the mechanism behind the ESIPT process and help enhance the qualities of the cyanine dye used in ESIPT.
RECENT TRENDS IN USE OF PLANT-DERIVED CARBON DOT-BASED FLUORESCENT PROBES FOR HEAVY METAL ION DETECTION AND THEIR BIOLOGICAL APPLICATIONS (Review)
(Elsevier B.V., 2025) Venkatesan, Geetha; Sathiyan, Govindasamy
Plant-derived carbon dots (CDs) have drawn a lot of interest as superior nanomaterials because of their sustainable nature, biocompatibility, and environmentally friendly synthesis, which sets them apart from other CDs made from non-renewable resources. The synthesis of CDs from natural sources such as fruits, leaves, bark, stem, flower, seed and biowaste by hydrothermal, pyrolysis, and microwave-assisted method have been investigated to modify the size and features of CDs. The plant-derived CDs exhibit greater sensitivity and selectivity, and their high photoluminescent properties makes it possible to detect physiological and ecological significant metal ions like iron (Fe³⁺), copper (Cu²⁺), lead (Pb²⁺), and mercury (Hg²⁺). This study focuses mainly on crucial elements such as absorption, emission, sensitivity, selectivity, and limits of detection of metal ions, a thorough examination of their sensing characteristics is provided. This review article comprehensively summarizes plant-based CDs with different synthesis methods, characterization techniques, metal ion sensing and its mechanism, stability and biological imaging of CDs. Additionally, we discussed the plant derived CDs for the detection of pesticides and drugs. These CDs also find extensive applications in environmental remediation by offering a sustainable alternative for detecting harmful pollutants. Beyond these sensing, their biological uses of plant-derived CDs, such as bioimaging, antioxidant activity, and therapeutic potential, are finally addressed. This review emphasizes the bright future of plant-derived CDs in biomedicine and sustainable nanotechnology, with a focus on their biological applications and improved sensing capabilities in research development