Browsing by Author "Dipak Rana"

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A plausible chemical mechanism of the bioactivities of mangiferin
(1996) Shibnath Ghosal; Gangadhara Rao; V. Saravanan; Nira Misra; Dipak Rana
A plausible chemical mechanism of the observed bioactivities of mangiferin, a naturally occurring C-glucosylxanthone (1), is depicted. The mechanism focuses its capacity to provide cellular protection as an antioxidant and a radical captodative agent. Mangiferin performs its antioxidant function at different levels of systemic oxidation sequence. As far as membrane lipid peroxidation and consequent immunomodulations are concerned, it acts by (i) decreasing localized O2 concentration there-by generating, in concert, mangiferin phenoxy radicals (2); (ii) by binding metal ions (Fe2+/3+) in forms 3 and 4 that will not allow the generation of such tissue damaging species as hydroxyl and highly reactive oxo-ferryl radicals; (iii) regulating polymer chain lengthening (membrane lipids) by interacting with the reactive oxygen species; (iv) chain breaking (by 2), i.e. scavanging intermediate radicals (such as lipid peroxy and alkoxy radicals) to prevent continued H abstraction from cellular lipid molecules; and (v) maintaining systemic oxidant-antioxidant balance (by 1 and 2). Chemical evidence in support of the above postulate has been sought and obtained in the form of a complex polymer (5) through the intermediates 2 to 4.
Corrigendum to “Layered double hydroxides as effective carrier for anticancer drugs and tailoring of release rate through interlayer anions” [Journal of Controlled Release 224 (2106) 186–198] (Layered double hydroxides as effective carrier for anticancer drugs and tailoring of release rate through interlayer anions (2016) 224 (186–198), (S016836591630013X), (10.1016/j.jconrel.2016.01.016))
(Elsevier B.V., 2021) Sudipta Senapati; Ravi Thakur; Shiv Prakash Verma; Shivali Duggal; Durga Prasad Mishra; Parimal Das; T. Shripathi; Mohan Kumar; Dipak Rana; Pralay Maiti
The authors regret that the initial published version of this article an error in the assembly of Fig. 7b resulted in some image duplications. The corrected Fig. 7b includes the correct images of the experiment. This correction/omission doesn't alter any conclusion of the article as quantitative analysis of the experiment has been performed through MTT assay, presented in Fig. 7a. [Figure Presented] The figure legend remains the same. The corrections made in this corrigendum do not affect the original conclusions of the article. The author's apologies for any inconvenience caused. © 2016 Elsevier B.V.
Engineered Cellular Uptake and Controlled Drug Delivery Using Two Dimensional Nanoparticle and Polymer for Cancer Treatment
(American Chemical Society, 2018) Sudipta Senapati; Rashmi Shukla; Yamini Bhusan Tripathi; Arun Kumar Mahanta; Dipak Rana; Pralay Maiti
Two major problems in chemotherapy, poor bioavailability of hydrophobic anticancer drug and its adverse side effects causing nausea, are taken into account by developing a sustained drug release vehicle along with enhanced bioavailability using two-dimensional layered double hydroxides (LDHs) with appropriate surface charge and its subsequent embedment in polymer matrix. A model hydrophobic anticancer drug, raloxifene hydrochloride (RH), is intercalated into a series of zinc iron LDHs with varying anion charge densities using an ion exchange technique. To achieve significant sustained delivery, drug-intercalated LDH is embedded in poly(ϵ-caprolactone) (PCL) matrix to develop intravenous administration and to improve the therapeutic index of the drug. The cause of sustained release is visualized from the strong interaction between LDH and drug, as measured through spectroscopic techniques, like X-ray photoelectron spectroscopy, infrared, UV-visible spectroscopy, and thermal measurement (depression of melting temperature and considerable reduction in heat of fusion), using differential scanning calorimeter, followed by delayed diffusion of drug from polymer matrix. Interestingly, polymer nanohybrid exhibits long-term and excellent in vitro antitumor efficacy as opposed to pure drug or drug-intercalated LDH or only drug embedded PCL (conventional drug delivery vehicle) as evident from cell viability and cell adhesion experiments prompting a model depicting greater killing efficiency (cellular uptake) of the delivery vehicle (polymer nanohybrid) controlled by its better cell adhesion as noticed through cellular uptake after tagging of fluorescence rhodamine B separately to drug and LDH. In vivo studies also confirm the sustained release of drug in the bloodstream of albino rats using polymer nanohybrid (novel drug delivery vehicle) along with a healthy liver vis-à-vis burst release using pure drug/drug-intercalated LDHs with considerable damaged liver. © 2018 American Chemical Society.
Functionalized poly(vinylidene fluoride) nanohybrid for superior fuel cell membrane
(Elsevier, 2015) Karun Kumar Jana; Chumki Charan; Vinod K. Shahi; Kheyanath Mitra; Biswajit Ray; Dipak Rana; Pralay Maiti
Functionalization of poly(vinylidene fluoride) (. PVDF) nanohybrid has been performed in template system using two-dimensional layered silicate and superior fuel cell membrane has been demonstrated. Sulfonation of nanohybrid has been carried out at control condition to maintain the mechanical stiffness and toughness of the membrane using chlorosulfonic acid and the results have been compared with pure PVDF. The sulfonation and its relative extent have been confirmed through NMR, FTIR and UV-vis measurements showing greater degree of functionalization in nanohybrid which arises from the specific arrangement of polymer chains on top of nanoplatelets. The structural change over from common crystallized form α- to piezoelectric β-phase in nanohybrid has been established and the amount of β-phase has been enhanced after sulfonation as evident from deconvoluted XRD patterns and DSC measurement. A plausible mechanism has been proposed for this improvement which led to the formation of smart membrane. Essential criteria of an ideal membrane have been verified through high water uptake, low permeability and hydrophilic nature by measuring contact angle. The molecular level clustering due to the attachment of sulfonate group in main chain has been explored which in turn explain the higher barrier property both for gas and liquid (fuel). Proton conductivity of functionalized nanohybrid has been found to be quite high along with significantly low methanol cross over as compared to standard Nafion membrane. I-. V characteristics of the nanohybrid membrane show high potential at low current density with considerably lower value of slope. Membrane electrode assembly using functionalized nanohybrid exhibit significantly high value of current density and prove its worth for superior fuel cell membrane using common thermoplastic polymer. © 2015 Elsevier B.V.
Gas barrier properties of polyurethane nanocomposites
(John Wiley and Sons Inc, 2023) Shruti Pandey; Pralay Maiti; Karun K. Jana; Dipak Rana; Vinod K. Aswal
Polyurethane nanocomposites with varying concentration of different fillers are produced through hot melt extrusion by using nanotalc and Cloisite 30B as fillers. The TEM images show good dispersion of 30B while moderate agglomeration in nanotalc composite. The result is supported by the respective nanostructures (exfoliated in 30B vs. intercalated in nanotalc composites). A slight decrease in degradation temperature is observed but the nanocomposites are thermally stable upto 300°C. Permeability significantly decreases for nanocomposites. Young's modulus increases with increasing filler concentration while the toughness improvement exhibits a maximum at 4 and 6 wt% of 30B and nanotalc, respectively. Halpin–Tsai model is employed to predict the mechanical properties of the composites. The mechanical, thermal and gas barrier properties are better in 30B as compared to nanotalc nanocomposites, due to greater interaction in 30B nanocomposites evident from the large shift of peak position in UV–vis and FTIR measurements along with its good dispersion. © 2023 Wiley Periodicals LLC.
Graphene as a chain extender of polyurethanes for biomedical applications
(Royal Society of Chemistry, 2016) Dinesh K. Patel; Rajesh K. Singh; Santosh K. Singh; Vinod K. Aswal; Dipak Rana; Biswajit Ray; Pralay Maiti
Amine-functionalized graphene has been chemically tagged within long-chain polyurethane molecules, using graphene as a chain extender to prepare a nanohybrid, and its novelty has been explored by comparing its properties with those of physically dispersed functionalized graphene in polyurethane based on di-ol as a chain extender. Chemical tagging has been confirmed through NMR studies and the nature of the interaction between the polymer matrix and graphene (nanofiller) is stronger in the chemically tagged nanohybrid compared to a nanohybrid prepared through physical mixture, as revealed from FTIR, UV-visible and PL spectroscopic measurement. A homogeneous dispersion of graphene platelets is achieved through a chemically tagged nanohybrid as against the agglomerated nanostructure found in a physically mixed nanohybrid. Enhancement of thermal properties and toughening of the nanohybrids is observed, whose extent is significantly higher in the chemically tagged nanohybrid due to greater interactions between the components and the uniform dispersion of nanofiller. Graphene-induced self-assembly from the nanometer scale to the micron level (step by step) was investigated through X-ray diffraction, small angle neutron scattering, atomic force microscopy and optical images in the order of nanometer, tens of nanometer, hundreds of nanometer and micron size, respectively. The effects of self-assembly on drug release and the biocompatible nature of the nanohybrids were monitored using HeLa cells, looking at cell viability, cell adhesion and fluorescence imaging. Significant sustained release of an anti-cancer drug was obtained using the chemically tagged nanohybrid and understanding gained of its kinetic behavior and mechanism. The greater biocompatibility of the chemically tagged nanohybrid was revealed through cell adhesion and fluorescence imaging, demonstrating a superior biomaterial which delivers the anti-cancer drug in a sustained manner. Hence, the developed nanohybrid is a potential biomaterial for drug delivery and tissue engineering. This journal is. © The Royal Society of Chemistry 2016.
Layered double hydroxides as effective carrier for anticancer drugs and tailoring of release rate through interlayer anions
(Elsevier B.V., 2016) Sudipta Senapati; Ravi Thakur; Shiv Prakash Verma; Shivali Duggal; Durga Prasad Mishra; Parimal Das; T. Shripathi; Mohan Kumar; Dipak Rana; Pralay Maiti
Hydrophobic anticancer drug, raloxifene hydrochloride (RH) is intercalated into a series of magnesium aluminum layered double hydroxides (LDHs) with various charge density anions through ion exchange technique for controlled drug delivery. The particle nature of the LDH in presence of drug is determined through electron microscopy and surface morphology. The release of drug from the RH intercalated LDHs was made very fast or sustained by altering the exchangeable anions followed by the modified Freundlich and parabolic diffusion models. The drug release rate is explained from the interactions between the drug and LDHs along with order-disorder structure of drug intercalated LDHs. Nitrate bound LDH exhibits greater interaction with drug and sustained drug delivery against the loosely interacted phosphate bound LDH-drug, which shows fast release. Cell viability through MTT assay suggests drug intercalated LDHs as better drug delivery vehicle for cancer cell line against poor bioavailability of the pure drug. In vivo study with mice indicates the differential tumor healing which becomes fast for greater drug release system but the body weight index clearly hints at damaged organ in the case of fast release system. Histopathological experiment confirms the damaged liver of the mice treated either with pure drug or phosphate bound LDH-drug, fast release system, vis-à-vis normal liver cell morphology for sluggish drug release system with steady healing rate of tumor. These observations clearly demonstrate that nitrate bound LDH nanoparticle is a potential drug delivery vehicle for anticancer drugs without any side effect. © 2016 Elsevier B.V. All rights reserved.
Novel shape memory behaviour in IPDI based polyurethanes: Influence of nanoparticle
(Elsevier Ltd, 2017) Satyam Srivastava; Arpan Biswas; Sudipta Senapati; Biswajit Ray; Dipak Rana; Vinod K. Aswal; Pralay Maiti
A diverse nanostructure, key to property alteration, has been observed by the insertion of two dimensional nanoparticles through in-situ polymerization. Self-assembly at the molecular level has been revealed starting from nanoscale to observable microscale in thermoplastic polyurethane using alicyclic diisocyanate and how the self-assembly behaviour changes in presence of nanoparticle. Varying dispersion of nanoparticles observed using two different fillers has been explained from the interactions point of view through spectroscopic techniques. Thermal stability and unique crystallization behaviour have been reported in presence of nanoparticles. Better dispersion of nanofillers within the matrix offers greater number of nucleating site which enhances the ordering of the polymer chains, also supported by the semi-empirical calculation. The effect of modulated nanostructure and self-assembly augmented the shape memory behaviour in polyurethanes having alicyclic diisocyanate. Enhanced shape recovery has been observed in presence of organically modified clay as opposed to layered double hydroxide. The reason for this improved shape memory behaviour in nanohybrid is explained from the exclusive crystallization of the soft segment domain leading to a proposed model for shape recovery. Finally, the recovery of different shapes (coil, spinal and straight strip) at physiological temperature (37 °C) has been demonstrated, added advantage of these materials to be used in the biomedical applications. © 2016 Elsevier Ltd
Superior biomaterials using diamine modified graphene grafted polyurethane
(Elsevier Ltd, 2016) Dinesh K. Patel; Vivek Gupta; Ashish Dwivedi; Sanjeev K. Pandey; Vinod K. Aswal; Dipak Rana; Pralay Maiti
Surface modification of graphene oxide has been performed using diamine moieties with varying chain length and subsequently chemically grafted with long chain polyurethane for wrapping up of graphene sheet with large polymer chains. Functionalization of graphene and its subsequent grafting have been verified through spectroscopic measurements like NMR, FTIR and UV–visible spectroscopy and the uniform dispersion of graphene sheet in polyurethane matrix is achieved. Nanohybrids exhibit better thermal and mechanical responses along with greater self-assembly as compared to pure polymer. Nanometer dimension molecular sheet to gradual increased size of the order of tens of nanometer, hundreds of nanometer to micron scale assembly has been captured through XRD, small angle neutron scattering, AFM and optical microscopy, respectively. Nature of self-assembly associated with stronger interactions sustain the release of embedded drug (anticancerous dexamethasone) from nanohybrid and larger size of inhomogeinities for longer spacer length further sustain the drug release and thereby able to control the release rate of drug by articulating the chemistry of graphene modifications with suitable spacer length of diamine. Biocompatibility of the nanohybrids is verified with cell line studies using human breast cancer cells MDA-MB-231in terms of cell viability, cell adhesion, fluorescence image, reactive oxygen species and mitochondrial tracker measurements indicating better responses of nanohybrid vis-à-vis pure polyurethane. Thus, the control release of the dexamethasone drug from the nanohybrids along with better biological responses clearly suggests a novel biomaterial for the drug carrier. © 2016 Elsevier Ltd