Browsing by Author "Rohit Rai"

Now showing 1 - 5 of 5

Antibacterial Photodynamic Therapy by Zn(II)-Curcumin Complex: Synthesis, Characterization, DFT Calculation, Antibacterial Activity, and Molecular Docking
(John Wiley and Sons Inc, 2024) Rajesh Kushwaha; Rohit Rai; Vedant Gawande; Virendra Singh; Ashish Kumar Yadav; Biplob Koch; Prodyut Dhar; Samya Banerjee
The increase in antibacterial drug resistance is threatening global health conditions. Recently, antibacterial photodynamic therapy (aPDT) has emerged as an effective antibacterial treatment with high cure gain. In this work, three Zn(II) complexes viz., [Zn(en)(acac)Cl] (1), [Zn(bpy)(acac)Cl] (2), [Zn(en)(cur)Cl] (3), where en=ethylenediamine (1 and 3), bpy=2,2’-bipyridine (2), acac=acetylacetonate (1 and 2), cur=curcumin monoanionic (3) were developed as aPDT agents. Complexes 1–3 were synthesized and fully characterized using NMR, HRMS, FTIR, UV-Vis. and fluorescence spectroscopy. The HOMO–LUMO energy gap (Eg), and adiabatic splittings (ΔS1−T1 and ΔS0−T1) obtained from DFT calculation indicated the photosensivity of the complexes. These complexes have not shown any potent antibacterial activity under dark conditions but the antibacterial activity of these complexes was significantly enhanced upon light exposure (MIC value up to 0.025 μg/mL) due to their light-mediated 1O2 generation abilities. The molecular docking study suggested that complexes 1–3 interact efficiently with DNA gyrase B (PDB ID: 4uro). Importantly, 1–3 did not show any toxicity toward normal HEK-293 cells. Overall, in this work, we have demonstrated the promising potential of Zn(II) complexes as effective antibacterial agents under the influence of visible light. © 2023 Wiley-VCH GmbH.
Cellulose Based Aerogels Derived From Rice Agro Wastes with Enhanced Antifungal Activity for Topical Management of Vulvovaginal Candidiasis
(John Wiley and Sons Inc, 2025) Rahul Ranjan; Smruti B. Bhatt; Rohit Rai; Shabnam Kumari; Ragini Tilak; Prodyut Dhar
With the increased cultivation of rice crop, the problem of accumulating waste biomass after harvesting is becoming a huge challenge, disposal of which through land filling and burning leads to global warming. In this work, abundantly available rice straw waste is strategically functionalized through delignification-cum-phosphorylation route to produce smart-responsive and ultra-light weight aerogels for topical management of vulvovaginal candidiasis. The prepared aerogels show low density (0.028 g cm−3), high water absorption capacity ∼2381.71%, and charge content (1850 mmol kg−1) of phosphate groups covalently linked to cellulose backbone as evident from XPS and FTIR spectroscopy studies. The aerogels with porous morphology also show cyclic mechanical compressibility and thermal stability due to presence of phosphate groups as evident from high char content (28.5% at 700 °C). The negatively charged aerogels show prolonged storage and release profile of clotrimazole with synergistically strong antifungal response against several Candida species with lowered MIC of ∼0.02µg ml−1. Interestingly, post-phosphorylation the functionalized aerogels show improved biodegradation of ∼83% within 92 days under soil conditions. This study proposes a low-cost, facile, eco-friendly, sustainable approach to convert waste rice biomass into functionalized high-performance aerogels for potential treatment of vaginal infections improving female reproductive health. © 2025 Wiley-VCH GmbH.
Cellulose-based phosphorylated bamboo with slow urea release and lower carbon footprints improves rainfed rice crop productivity in field trials
(Elsevier B.V., 2025) Rohit Rai; Rahul Ranjan; Sonal Kumari; Nirmal De; Prodyut Dhar
With unprecedented global climate changes, rice crop cultivation under rainfed conditions encounters alternate wetting and drying cycles with water and nutrient stress, which leads to poor yield, quality, and productivity. A modified cellulose-based, slow urea-releasing and water-retaining system from bamboo is developed for rainfed rice crops, to overcome such challenges to emerging rice crops and improve soil health for subsequent crop cycles. Bamboo was delignified to expose the cellulose and subsequent phosphorylation (DPB), followed by strategic urea infiltration and melting to deposit it into the microporous matrix. The melted DPB urea (MDU) presents a zone of influence of 52.5 cm3/cm3 MDU, with water retention of 72 h for supporting plant growth during water stress upto ~6 days. MDU also displays a sustained release of 45–55 % urea for ~11 days in black, red, and alluvial soils. The application of MDU in the field study of rainfed rice crops showed improved plant height (16.66 %), chlorophyll content (32 %), grain yield (230 kg/ha), nitrogen (1.60 %), and phosphate content (0.089 %) of rice grains with the presence of ureolytic microbes (Sporosarcina) for improved soil quality. Cellulose-based MDU is biodegradable (98.1 %) in soil and generates relatively lower carbon footprints during production (~70.7 % lower GWP) than non-degradable acrylamide. Cellulose from renewable forest resources like bamboo, has been modified strategically using an eco-friendly approach to enhance the rainfed rice crop yield and soil conditions creating a closed-loop circular bioeconomy with low-carbon footprints for sustainable agriculture. © 2025 Elsevier B.V.
Photodynamic Inactivation of Bacteria Using Nickel(II) Complexes with Catecholate and Phenanthroline Ligands
(John Wiley and Sons Inc, 2025) Raval Devraj Prakashchandra; Rohit Rai; Arif Ali Mandal; Prodyut Dhar; Samya Banerjee; Tukki Sarkar; Bathini Nagendra Babu
Metal complexes activated by light can combat infections by triggering the photodynamic inactivation of bacteria. Herein, we report six mixed-ligand nickel(II) complexes with the formulation [Ni(NN)2(L)] (1–6), where NN represents an N,N-donor phenanthroline ligand, specifically 1,10-phenanthroline (phen in 1, 2), dipyrido[3,2-d:2’,3’-f]quinoxaline (dpq in 3, 4), and dipyrido[3,2-a:2’,3’-c]phenazine (dppz in 5, 6), while L is an O,O donor bidentate ligand derived from catechol (cat2−, in 1, 3, 5) or esculetin (esc2−, in 2, 4, 6). The paramagnetic d8 octahedral complexes demonstrated good dark and photostability in the solution phase and exhibited significant light absorption in the visible (400–700 nm) region. When exposed to low-energy visible light, these complexes demonstrated significant photodynamic inactivation activity against both Gram-(+) Staphylococcus aureus (S. aureus) and Gram-(−) Escherichia coli (E. coli) bacteria. This resulted in minimum inhibitory concentration (MIC) values ranging from 0.31–9.49 μM. The activity was caused by the cell-damaging singlet oxygen species produced by the complexes under light exposure. Notably, the complexes showed no bacterial inhibition activity under dark conditions. This study marks the first examples of Ni(II) complexes designed for light-triggered antibacterial activity, illuminating the path for Ni(II)-based non-macrocyclic complexes for antibacterial PDT applications. © 2024 Wiley-VCH GmbH.
Polypyridyl CoII-Curcumin Complexes as Photoactivated Anticancer and Antibacterial Agents
(John Wiley and Sons Inc, 2023) Ashish Kumar Yadav; Virendra Singh; Rajesh Kushwaha; Dependu Dolui; Rohit Rai; Prodyut Dhar; Arnab Dutta; Biplob Koch; Samya Banerjee
Four new CoII complexes, [Co(bpy)2(acac)]Cl (1), [Co(phen)2(acac)]Cl (2), [Co(bpy)2(cur)]Cl (3), [Co(phen)2(cur)]Cl (4), where bpy=2,2’-bipyridine (1 and 3), phen=1,10-phenanthroline (2 and 4), acac=acetylacetonate (1 and 2), cur=curcumin monoanion (3 and 4) have been designed, synthesized and fully characterized. The X-ray crystal structures of 1 and 2 indicated that the CoN4O2 core has a distorted octahedral geometry. The photoactivity of these complexes was tuned by varying the π conjugation in the ligands. Curcumin complexes 3 and 4 had an intense absorption band near 435 nm, which made them useful as visible-light photodynamic therapy agents; they also showed fluorescence with λem≈565 nm. This fluorescence was useful for studying their intracellular uptake and localization in MCF-7 breast cancer cells. The acetylacetonate complexes (1 and 2) were used as control complexes to understand the role of curcumin. The white-light-triggered anticancer profiles of the cytosol targeting complexes 3 and 4 were investigated in detail. These non-dark toxic complexes displayed significant apoptotic photo-cytotoxicity (under visible light) against MCF-7 cells through ROS generation. The control complexes 1 and 2 did not induce significant cell death in the light or dark. Interestingly, 1-4 produced a remarkable antibacterial response upon light exposure. Overall, the reported results here can increase the boundary of the CoII-based anticancer and antibacterial drug development. © 2023 Wiley-VCH GmbH.