Browsing by Author "Nira Misra"

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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.
A study on acrylamide polymerization by anodic contact glow-discharge electrolysis: A novel tool
(2001) Susanta K. Sengupta; Urvashi Sandhir; Nira Misra
Contact glow-discharge electrolysis (CGDE) is an unconventional electrolytic phenomenon in which a plasma is sustained by a direct current (dc) glow-discharge between an electrode and the liquid electrolyte around it. A remarkable feature of CGDE is highly nonfaradaic chemical effects at the glow-discharge electrode. During anodic CGDE of an aqueous electrolyte, non-Faradaic yields originate mainly from reactions triggered by H and OH radicals generated in high local concentrations near the anodic plasma/liquid electrolyte interface during the process. The radical-generating potentiality of anodic CGDE was explored for the polymerization of acrylamide in aqueous media. The percentage of monomer conversion, rate of polymerization, charge efficiency, and viscometric average molar mass of the polymers produced were measured as functions of the quantities of electricity passed. The charge efficiency of the polymerization of acrylamide by anodic CGDE was at least 1 order of magnitude higher than that of ordinary electrochemically initiated polymerization. © 2001 John Wiley & Sons, Inc.
Brominated Graphene as Mimetic Peroxidase for Sulfide Ion Recognition
(American Chemical Society, 2017) Shikha Singh; Kheyanath Mitra; Aparna Shukla; Rajshree Singh; Ravi Kumar Gundampati; Nira Misra; Pralay Maiti; Biswajit Ray
Brominated graphene (GBR) with ∼3% bromine content has shown novel peroxidase mimetic activity toward 3,3′,5,5′-tetramethylbenzidine (TMB) in the presence of H2O2. Optimum activity has been observed at pH 4.48 and after a minimum ∼30 min of equilibration time. Among the different analytes studied using the sensor combining TMB, H2O2, and GBR in phosphate buffer of pH 4.48, the S2- ion has effectively shown a short duration of sensing (∼2 min) within the detection range of 0.04-1 mM. A calibration curve for S2- ion estimation has been constructed with the experimental linearity in 0.04-0.4 mM range and having the limit of detection (LOD) value of 25.3 μM. A standard addition experiment has validated the method. A paper strip sensor has been fabricated for successful detection of S2- ion. © 2016 American Chemical Society.
Cell proliferation influenced by matrix compliance of gelatin grafted poly(D,L-Lactide) three dimensional scaffolds
(Elsevier B.V., 2018) Chelladurai Karthikeyan Balavigneswaran; Sanjeev Kumar Mahto; Arun Kumar Mahanta; Rajshree Singh; Mahalingam Rajamanickam Vijayakumar; Biswajit Ray; Nira Misra
Surface and mechanical properties of the biomaterials are determinants of cellular responses. In our previous study, star-shaped poly(D,L-Lactide)-b-gelatin (ss-pLG) was reported for possessing improved cellular adhesion and proliferation. Here, we extended our investigation to establish the cellular compatibility of gelatin-grafted PDLLA with respect to mechanical properties of biological tissues. In this view, linear PDLLA-b-gelatin (l-pLG) was synthesized and tissue-level compatibility of 1-pLG and ss-pLG against fibroblasts (L929), myoblasts (C2C12) and preosteoblasts (MG-63) was examined. The cell proliferation of C2C12 was significantly higher within l-pLG scaffolds, whereas L929 showed intensified growth within ss-pLG scaffolds. The difference in cell proliferation may be attributed to the varying mechanical properties of scaffolds; where the stiffness of l-pLG scaffolds was notably higher than ss-pLG scaffolds, most likely due to the variable levels of gelatin grafting on the backbone of PDLLA. Therefore, gelatin grafting can be used to modulate mechanical property of the scaffolds and this study reveals the significance of the matrix stiffness to produce the successful 3D scaffolds for tissue engineering applications. © 2018 Elsevier B.V.
Chemical modification of poly(vinyl chloride) for blood and cellular biocompatibility
(Royal Society of Chemistry, 2015) Monika; Sanjeev Kumar Mahto; Snehashish Das; Amit Ranjan; Santosh Kumar Singh; Partho Roy; Nira Misra
Poly(vinyl chloride) (PVC) was modified with three different ionomers including thiosulphate, thiourea and sulphite for improving the biocompatibility of the polymer. All ionomers were prepared by nucleophilic substitution using a phase transfer catalyst method. The modified forms of PVC were characterized using ultraviolet-visible (UV-Vis) spectroscopy, Fourier Transform Infrared (FTIR) spectroscopy, scanning electron microscopy (SEM) and thermal gravimetric analysis (TGA). They were found to be less stable thermally compared to the untreated polymer. The biocompatibility of the polymers was evaluated by assessing their wettability via contact angle measurements and by performing hemolysis and thrombogenicity assays. Their cellular biocompatibility was evaluated by assessing their adhesion and proliferation, and by carrying out cytotoxicity assays and nuclear staining. The results reveal that modification of the polymer with the specified ionomers significantly enhances the bio- and blood-compatibility properties. This journal is © The Royal Society of Chemistry.
Colorimetric detection of hydrogen peroxide and glucose using brominated graphene
(Royal Society of Chemistry, 2017) Shikha Singh; Kheyanath Mitra; Rajshree Singh; Archana Kumari; Susanta Kumar Sen Gupta; Nira Misra; Pralay Maiti; Biswajit Ray
Very recently, we have reported a novel peroxidase mimetic material, brominated graphene (GBR) having ∼3% bromine content, which, in combination with H2O2 and 3,3′,5,5′-tetramethylbenzidine (TMB), has shown the property of S2- ion recognition (Anal. Chem., 2017, 89, 783-791). In the present work, we further have investigated the kinetic assay and colorimetric sensing ability of GBR towards hydrogen peroxide (H2O2) and glucose. The Michaelis-Menten constants (Km) and maximum initial velocities (Vmax) of GBR have been found to be 10.98 mM and 3.60 × 10-8 M s-1, respectively, for H2O2 and 0.83 mM and 0.68 × 10-8 M s-1, respectively, for TMB. A sensor combining TMB and GBR has been fabricated, which, upon addition to H2O2 or glucose with glucose oxidase solution at pH 4.48, showed colorimetrically a significant increase in the oxidation of TMB. The fabricated sensor system has displayed linearity for H2O2 and glucose estimation in the range 0.50-5.00 mM and 40-100 mM, respectively, and the corresponding limits of detection are found to be 0.417 and 28.41 mM, respectively. The present sensor system is also highly reproducible and selective. The results of real samples using this colorimetric method have been found to be comparable with the conventional auto-analyser method. © The Royal Society of Chemistry 2017.
Enhanced catalytic and antibacterial activities of silver nanoparticles immobilized on poly(N-vinyl pyrrolidone)-grafted graphene oxide
(Royal Society of Chemistry, 2015) Shikha Singh; Ravi Kumar Gundampati; Kheyanath Mitra; K. Ramesh; Medicherla V. Jagannadham; Nira Misra; Biswajit Ray
Poly(N-vinyl pyrrolidone) (PNVP)-grafted graphene oxide (GO) (GO-PNVP) has been synthesized using a GO-based macro-RAFT agent prepared via click reaction of alkyne-terminated RAFT agent (S)-2-(propynyl propionate)-(o-ethyl xanthate) and azide-functionalized GO (GO-N3). FTIR, XPS, Raman, TGA and DSC studies confirmed its formation. Silver nanoparticles are then immobilized on GO-PNVP and GO via in situ reduction of silver nitrate in the presence and absence of glucose at 40 and 95 °C, respectively. FT-IR, UV-Vis, XRD, SEM and TGA studies supported the incorporation of silver (Ag) nanoparticles. Ag nanoparticles immobilized on GO-PNVP are small, spherical and narrowly distributed (homogenous, monodisperse) compared to GO. These nanocomposites are explored as catalysts for the reduction of p-nitrophenol into p-aminophenol and also as antibacterial agents towards Gram(+) S. aureus and Gram(-) E. coli bacteria. Ag nanoparticle immobilized GO-PNVP showed efficient catalytic activity and excellent reusability along with an excellent antibacterial activity. Hence, grafting of PNVP enhances the catalytic and antibacterial properties of GO. © 2015 The Royal Society of Chemistry.
Functionalized polyvinyl chloride/layered double hydroxide nanocomposites and its thermal and mechanical properties
(John Wiley and Sons Inc., 2020) Monika Singh; Divya Somvanshi; Rajesh K. Singh; Arun K. Mahanta; Pralay Maiti; Nira Misra; Pradip Paik
In this work, to inquire the impact of layered double hydroxide (LDH) nanoclay on functionalized poly(vinyl chloride) (PVC) through solution intercalation method, four kinds of nanocomposites were prepared. Mg-AL LDH and the obtained functionalize PVC composites were characterized through FT-IR, UV–Vis spectroscopy, TEM, XRD, contact angle, DSC, and UTM. Obtained results revealed that the functionalized PVC uniformly dispersed in the layer of LDH nanoclay. It is revealed that partially intercalated and disordered structure formed in PVC/LDH, PVC-TS (thiosulfate)/LDH, and PVC-S (sulfate)/LDH nanocomposites, whereas fully exfoliated structures formed in the PVC-TU (thiourea)/LDH nanocomposites. Further, it has been observed that the ultimate tensile strength for all the polymer nanocomposites enhanced with increased in the LDH content. These nanocomposites further exhibited higher thermal stability by at least by 51°C higher than the pristine PVC. Along with these, further it has been found that the functionalized PVC/LDH nanocomposites are proved to be effective as thermal stabilizer for PVC processing. © 2020 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020, 137, 48894. © 2020 Wiley Periodicals, Inc.
Gelatin grafted poly(D,L-lactide) as an inhibitor of protein aggregation: An in vitro case study
(John Wiley and Sons Inc, 2020) Chelladurai Karthikeyan Balavigneswaran; Gaurav Kumar; Chandrasekaran Vignesh Kumar; Satheeshkumar Sellamuthu; Uvanesh Kasiviswanathan; Biswajit Ray; Vignesh Muthuvijayan; Sanjeev Kumar Mahto; Nira Misra
Amyloids are a group of proteins that are capable of forming aggregated amyloid fibrils, which is responsible for many neurodegenerative diseases including Alzheimer's disease (AD). In our previous study, synthesis and characterization of star-shaped poly(D,L-lactide)-b-gelatin (ss-pLG) have been reported. In the present work, we have extended our work to study ss-pLG against protein aggregation. To the best of our knowledge, this is the first report on the inhibition of amyloid fibrillation by protein grafted poly(D,L-lactide). Bovine serum albumin (BSA) was chosen as the model protein, which readily forms fibril under high temperature. We found that ss-pLG efficiently suppressed the fibril formation of BSA compared with gelatin (Gel), which was supported by Thioflavin T assay, circular dichroism (CD) spectroscopy and atomic force microscopy (AFM). In addition, ss-pLG significantly curtailed amyloid-induced hemolysis. We also found that incubation of ss-pLG with neuroblastoma cells (MC65) protected the cells from fibril-induced toxicity. The rescuing efficiency of ss-pLG was better than Gel, which could be attributed to the reduced lamella thickness in branched ss-pLG. These results suggest the significance of gelatin grafting, which probably allows gelatin to interact with the key residues of the amyloidogenic core of BSA effectively. © 2020 Wiley Periodicals LLC
Highly selective fluorescence 'turn off' sensing of picric acid and efficient cell labelling by water-soluble luminescent anthracene-bridged poly(: N -vinyl pyrrolidone)
(Royal Society of Chemistry, 2019) Rajshree Singh; Kheyanath Mitra; Shikha Singh; Sudipta Senapati; Vijay Kumar Patel; Sambhav Vishwakarma; Archana Kumari; Jaydeep Singh; Susanta K. Sen Gupta; Nira Misra; Pralay Maiti; Biswajit Ray
A novel, water-soluble, luminescent anthracene-bridged AA-type bi-arm poly(N-vinylpyrrolidone) (ATC-PNVP) was synthesized using a click reaction between alkyne-terminated PNVP and 9,10-bis(azidomethyl)anthracene. The resultant anthracene-bridged PNVP (ATC-PNVP) was characterized using 1H NMR, FTIR, UV-Vis, and fluorescence spectroscopic methods and GPC analysis. ATC-PNVP showed effective fluorescence properties in an aqueous medium. It showed highly selective "turn off" sensing behaviour towards picric acid, a common nitro-aromatic explosive, with a wide linear range of detection of 0.01-0.3 mM and LOD value of 0.006 mM in water. ATC-PNVP-based paper sensors also showed very effective detection of picric acid in the concentration range 0.001-1.0 mM. Its binding with bovine serum albumin (BSA) was studied using steady-state, synchronous and 3D fluorescence spectroscopy and this study showed effective quenching of the intrinsic fluorescence of BSA and occurrence of a FRET-type interaction. Furthermore, this luminescent ATC-PNVP was efficiently used as a fluorescence microscopy labelling agent in NIH-3T3 and HeLa cells, and showed greater uptake and hence better fluorescent labelling in the cytosols of the tested cells than free 9,10-bis(azidomethyl) anthracene. The cell viability study also showed a very good biocompatible and non-toxic nature of ATC-PNVP at lower working concentrations towards each of the types of cells tested. © 2019 The Royal Society of Chemistry.
In vitro biocompatibility analysis of functionalized poly(vinyl chloride)/layered double hydroxide nanocomposites
(Royal Society of Chemistry, 2018) Monika Singh; Rajesh Kumar Singh; Santosh Kumar Singh; Sanjeev Kumar Mahto; Nira Misra
The aim of this study was to examine the cytotoxicity and biocompatibility of functionalized poly(vinyl chloride) (PVC)/layered double hydroxide (LDH) nanocomposites. The biocompatibility of the LDH-based nanocomposites of thiosulphate PVC (TS-PVC), thiourea PVC (TU-PVC) and sulphite PVC (S-PVC) was assessed via haemolysis and thrombogenicity tests followed by the analysis of cellular adhesion and proliferation. The MTT assay was performed on cells in direct contact with the polymeric nanocomposites to evaluate the side effects of the biomaterials. The cellular morphology of mouse mesenchymal stem cells was also analyzed after incubation with direct contact with the functionalized polymer nanocomposites for different time periods. Although the results of the haemolysis test displayed a positive influence of LDH on the functionalized PVC compared to the neat PVC, the thrombogenic property was observed to be notably decreased, which indicated improved blood compatibility. The resulting LDH samples were also studied for their performance via fluorescence imaging of cells after incubation with the materials. The LDH-based polymers exhibited an excellent level of cytocompatibility, which validates their use as biomaterials. PVC-TU/LDH-2 and PVC-S-2 were found to be notably less cytotoxic for the tested cell type. Also, the cells were found to adhere better to the entire PVC-S/LDH nanocomposite surface. The cytotoxicity test also revealed that the PVC-TU/LDH and PVC-S/LDH nanocomposites exhibited similar responses. The fluorescence-based image analysis showed that cells were spread much more on the polymer surface containing a higher LDH weight percentage. Overall, this study provides a benchmark for the biocompatibility properties of PVC/LDH nanocomposites, which may be useful for numerous applications in the biomedical and related areas. © The Royal Society of Chemistry.
Layered double hydroxide induced advancement in joint prosthesis using bone cement: 0054he effect of metal substitution
(Royal Society of Chemistry, 2013) Govinda Kapusetti; Raghvendra Raman Mishra; Swati Srivastava; Nira Misra; Vakil Singh; Partha Roy; Santosh Kumar Singh; Chanchal Chakraborty; Sudip Malik; Pralay Maiti
Poly(methyl methacrylate) based bone cement and its nanocomposites with layered double hydroxide (LDH) have been developed with greater mechanical strength and biocompatibility as a grouting material for total joint arthroplasty. Bivalent magnesium has been replaced with trivalent aluminium with various mole ratios, keeping the layered pattern of the LDH intact, to cater for the effect of varying substitution on the property enhancement of the nanocomposites. The intercalation of polymer inside the LDH layers makes them disordered and mechanically stiffer and tougher by more than 100%. The thermal stability of bone cement has increased by more than 30 °C in the presence of 1 wt% of nanoLDH, homogenously distributed in the bone cement matrix by creating an inorganic thermal barrier out of the LDH dispersion. The improvement in the properties of the nanocomposites has been explained in terms of the strong interaction between nanoLDH and polymer. The superior bioactivity and biocompatibility of the nanocomposites, as compared to pure bone cement, has been established through hemolysis assay, cell adhesion, MTT assay and cell proliferation using fluorescence imaging. The developed nanocomposites have been used as a grouting material and significant improvements have been achieved in fatigue behaviour with gradual increment of Al substitution in the Mg:Al mole ratio in nanoLDH, demonstrating the real use of the material in the biomedical area. In vivo experiments on rabbits clearly revealed the superior efficacy of bone cement nanocomposites, over pure bone cement and a blank. © The Royal Society of Chemistry.
Mangiferin as chain transfer agent: effect on the molecular weight of poly(methyl methacrylate) and polystyrene
(Springer Verlag, 2015) Shilpa Jaiswal; Kalyan Ramesh; Govinda Kapusetti; Amit Kumar Ray; Biswajit Ray; Nira Misra
Abstract: Free radical polymerization of methyl methacrylate (MMA) and styrene (St) has been performed in N,N-dimethylformamide (DMF) at 70 °C in the presence of varying concentration of mangiferin as chain transfer agent using 2,2′-azobisisobutyronitrile (AIBN) as initiator. With increase in mangiferin concentration, molecular weight of the obtained polySt gradually decreases as expected due to the chain transfer phenomenon, but that of polyMMA interestingly increases possibly due to the preferential auto-acceleration phenomenon during MMA polymerization in the presence of higher concentration of mangiferin. The observed chain transfer constant of mangiferin for styrene polymerization is 0.14. The incorporation of mangiferin in the resultant polymers is confirmed by FTIR and UV–Vis studies.; Graphical abstract: [Figure not available: see fulltext.] © 2015, Springer-Verlag Berlin Heidelberg.
Methotrexate-loaded four-arm star amphiphilic block copolymer elicits CD8+ T cell response against a highly aggressive and metastatic experimental lymphoma
(American Chemical Society, 2015) Sumit Kumar Hira; Kalyan Ramesh; Uttam Gupta; Kheyanath Mitra; Nira Misra; Biswajit Ray; Partha Pratim Manna
We have synthesized a well-defined four-arm star amphiphilic block copolymer [poly(DLLA)-b-poly(NVP)]4 [star-(PDLLA-b-PNVP)4] that consists of d,l-lactide (DLLA) and N-vinylpyrrolidone (NVP) via the combination of ring-opening polymerization (ROP) and xanthate-mediated reversible addition-fragmentation chain transfer (RAFT) polymerization. Synthesis of the polymer was verified by 1H NMR spectroscopy and gel permeation chromatography (GPC). The amphiphilic four-arm star block copolymer forms spherical micelles in water as demonstrated by transmission electron microscopy (TEM) and 1H NMR spectroscopy. Pyrene acts as a probe to ascertain the critical micellar concentration (cmc) by using fluorescence spectroscopy. Methotrexate (MTX)-loaded polymeric micelles of star-(PDLLA15-b-PNVP10)4 amphiphilic block copolymer were prepared and characterized by fluorescence and TEM studies. Star-(PDLLA15-b-PNVP10)4 copolymer was found to be significantly effective with respect to inhibition of proliferation and lysis of human and murine lymphoma cells. The amphiphilic block copolymer causes cell death in parental and MTX-resistant Dalton lymphoma (DL) and Raji cells. The formulation does not cause hemolysis in red blood cells and is tolerant to lymphocytes compared to free MTX. Therapy with MTX-loaded star-(PDLLA15-b-PNVP10)4 amphiphilic block copolymer micelles prolongs the life span of animals with neoplasia by reducing the tumor load, preventing metastasis and augmenting CD8+ T cell-mediated adaptive immune responses. © 2015 American Chemical Society.
Modification of PVC film and study the effect of glass transition temperature and biocompatibility
(PRINTS PUBLICATIONS PVT LTD, 2011) Nira Misra; H.S. Panda; Govinda Kapusetti; Shilpa Jaaiswal; S. Chooramani Gopal; U.S. Sharma
Medical grade polyvinyl chloride) surface was modified with sodium sulfide by nucleophilic substitution of sulfur atoms in presence of a phase-transfer catalyst. Surface modified PVC was characterized with fourier transform infrared spectroscopy, scanning electron microscope, and differential scanning calorimetry. Migration or leaching of the plasticizer, di-(2-ethylhexyl) phthalate, was examined in petroleum ether followed by differential scanning calorimetry. The leaching test was also earned out with poly(ethylene glycol)-400 (PEG-400). The surface of modified PVC film was found to be extremely migration resistant of DEHP in petroleum ether and PEG-400. Clotting time measurement was performed on both modified and unmodified PVC, and observed almost equal value. It was reflected that there is no major change on its thrombogenicity. Further, blood compatibility of modified PVC was examined through haemolysis assay and suggested that it is nontoxic material for biomedical applications. © MD Publications Pvt. Ltd.
Osteoconductive Amine-Functionalized Graphene-Poly(methyl methacrylate) Bone Cement Composite with Controlled Exothermic Polymerization
(American Chemical Society, 2017) Rakesh Sharma; Govinda Kapusetti; Sayali Yashwant Bhong; Partha Roy; Santosh Kumar Singh; Shikha Singh; Chelladurai Karthikeyan Balavigneswaran; Kaushal Kumar Mahato; Biswajit Ray; Pralay Maiti; Nira Misra
Bone cement has found extensive usage in joint arthroplasty over the last 50 years; still, the development of bone cement with essential properties such as high fatigue resistance, lower exothermic temperature, and bioactivity has been an unsolved problem. In our present work, we have addressed all of the mentioned shortcomings of bone cement by reinforcing it with graphene (GR), graphene oxide (GO), and surface-modified amino graphene (AG) fillers. These nanocomposites have shown hypsochromic shifts, suggesting strong interactions between the filler material and the polymer matrix. AG-based nanohybrids have shown greater osteointegration and lower cytotoxicity compared to other nanohybrids as well as pristine bone cement. They have also reduced oxidative stress on cells, resulting in calcification within 20 days of the implantation of nanohybrids into the rabbits. They have significantly reduced the exothermic curing temperature to body temperature and increased the setting time to facilitate practitioners, suggesting that reaction temperature and settling time can be dynamically controlled by varying the concentration of the filler. Thermal stability and enhanced mechanical properties have been achieved in nanohybrids vis-à-vis pure bone cement. Thus, this newly developed nanocomposite can create natural bonding with bone tissues for improved bioactivity, longer sustainability, and better strength in the prosthesis. © 2017 American Chemical Society.
Polyvinyl alcohol/chitosan lactate composite hydrogel for controlled drug delivery
(Institute of Physics Publishing, 2019) Kaushal Kumar Mahato; Indu Yadav; RajeshKumar Singh; Monika; Bhisham Narayan Singh; Santosh Kumar Singh; Biswajit Ray; Manoj Kumar; Nira Misra
The aim of the present study was to develop composite hydrogel and its evaluation as drug delivery matrices for sustained release of hydrophilic drugs. Composite drug-loaded hydrogels were prepared by blending of chitosan lactate with polyvinyl alcohol followed by cross-linking with glutaraldehyde. This has been further characterized by Fourier transform infrared (FTIR) spectroscopy and X-ray diffraction. The developed PVA/Chitosan Lactate (PVA/CL) based hydrogels were cross-linked in order to enhance its Physico-chemical properties. Freezing bound water was measured by differential scanning Calorimetry (DSC) to analyze the cold crystallization characteristics of the hydrogel. The cell cytotoxicity, cell adhesion, hemolysis and drug release properties of PVA/CL hydrogels membrane were also investigated. In vitro cell viability of L929 cells shows that the fabricated hydrogels are compatible with cells and facilitate cells adhesion. Moreover, the sustained release of ciprofloxacin from developed drug-loaded hydrogels inhibits the growth of E. coli and thus facilitates antimicrobial activity under physiological condition. Thus, we anticipate the improved properties of the fabricated composite hydrogels might be suitable for controlled drug delivery, anti-infective coatings, and wound dressing. © 2019 IOP Publishing Ltd.
Self-assembly of Novel Poly(d,l-Lactide-co-Glycolide)-b-Poly(N-Vinylpyrrolidone) (PLGA-b-PNVP) Amphiphilic Diblock Copolymers
(Springer Verlag, 2016) K. Ramesh; Shikha Singh; Kheyanath Mitra; Dipankar Chattopadhyay; Nira Misra; Biswajit Ray
Alkyne-terminated poly(d,l-lactide-co-glycolide) (PLGA) has been synthesized via ROP at room temperature. Amphiphilic PLGA-b-poly(N-vinylpyrrolidone) (PNVP) block copolymers have been synthesized via alkyne-azide click reaction of it with azide-terminated PNVPs prepared by RAFT polymerization of NVP using an azide-terminated RAFT agent. 1H NMR and gel permeation chromatography (GPC) confirmed the formation of block copolymers. Self-assembly of these block copolymers was confirmed by fluorescence study using pyrene as a probe and supported by 1H NMR, DLS and TEM studies. Hydrophobic drug doxorubicin was successfully encapsulated at the micellar core of PLGA46-b-PNVP89 with drug-loading content (DLC) and drug-loading efficiency (DLE) of 10.8 and 43.2 %, respectively. Sustained drug release of these drug-loaded micelles was observed at both pH of 6.4 and 7.4. Faster drug release was observed at pH 6.4. Such PLGA-b-PNVP amphiphilic block copolymer may find extensive application in sustained drug delivery, specifically in antitumor drug delivery. © 2015, Springer-Verlag Berlin Heidelberg.
Self-assembly, doxorubicin-loading and antibacterial activity of well-defined ABA-type amphiphilic poly(N-vinylpyrrolidone)-b-poly(d,l-lactide)-b-poly(N-vinyl pyrrolidone) triblock copolymers
(Royal Society of Chemistry, 2016) K. Ramesh; Ravi Kumar Gundampati; Shikha Singh; Kheyanath Mitra; Ankita Shukla; Medicherla V. Jagannadham; Dipankar Chattopadhyay; Nira Misra; Biswajit Ray
A series of ABA type well-defined amphiphilic poly(N-vinylpyrrolidone) (PNVP)-b-poly(d,l-lactide)-b-PNVP triblock copolymers have been synthesized via the combination of ring opening polymerization and xanthate-mediated reversible addition-fragmentation chain transfer polymerization, and analyzed by 1H NMR spectroscopy and gel permeation chromatography. Aggregation properties of these amphiphilic triblock copolymers have been revealed by fluorescence spectroscopy, transmission electron microscopy and dynamic light scattering, and supported by 1H NMR spectroscopy. Doxorubicin (DOX) has successfully been loaded into the block copolymer micelles with a loading efficiency of 37.5%. DOX-loaded PNVP51-b-PDLLA48-b-PNVP51 block copolymer showed sustained release within 36 h. Antibacterial properties of DOX-loaded micelles have been found to be significantly effective with respect to free DOX in terms of minimum inhibitory concentration, disk diffusion assay, growth curve, bacterial reduction and enzymatic assay based on in vitro studies. © 2016 The Royal Society of Chemistry.
Study of the effect of isotacticity on some physical properties of poly(N-isopropylacrylamide)
(Springer Verlag, 2015) Chandra Sekhar Biswas; Kheyanath Mitra; Shikha Singh; Kalyan Ramesh; Nira Misra; Biswajit Maiti; Amiya Kumar Panda; Pralay Maiti; Masami Kamigaito; Yoshio Okamoto; Biswajit Ray
Some physical properties of high molecular weight linear poly(N-isopropylacrylamide)s (PNIPAM) having different isotacticities (m, meso dyad = 47, 62, 68, 81, and 88 %) have been studied. The solubility of these polymers in different solvents varied with their isotacticity. Thermal degradation of higher isotactic polymer started slightly earlier. Cloud point of these polymers in water gradually decreased with increase in m up to 68 %. Surface tension of these polymers in N,N-dimethylformamide (DMF) was slightly lower than DMF and almost independent of their isotacticity in the temperature range of 20–60 °C. But it decreased linearly with the increase in temperature. Moreover, for all polymers, it decreased very slightly with the increase in their concentrations in the range of 0.001–0.01 % (w/v). Viscosity of these polymers in DMF increased with (i) the increase in the concentration range of 1–5 % (w/v), (ii) the increase in their m values, and (iii) the decrease in the temperature in the range of 20–60 oC. © 2015, Springer-Verlag Berlin Heidelberg.