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Singh BN, Pramanik K. Fabrication and evaluation of non-mulberry silk fibroin fiber reinforced chitosan based porous composite scaffold for cartilage tissue engineering. Tissue Cell 2018; 55:83-90. [PMID: 30503064 DOI: 10.1016/j.tice.2018.10.003] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2018] [Revised: 10/26/2018] [Accepted: 10/26/2018] [Indexed: 02/06/2023]
Abstract
Lack of potential regenerative medicine to reconstruct damaged cartilage tissue has accelerated investigation and development of potential biomaterial for cartilage tissue engineering. In this study, we fabricated micron-sized non-mulberry silk fibroin fiber (SFF) using N,N-Dimethylacetamide (DMAC)/10% LiBr solution and further used to develop SFF reinforced chitosan(CH) based porous scaffold with desired pore size, porosity, swelling and structural stability. The developed scaffold was characterized for its various physico-chemical, mechanical and biological properties. The developed CH/SFF composite scaffold facilitates human mesenchymal stem cell (hMSCs) attachment, colonization and extracellular matrix deposition. Furthermore, hMSCs shows significantly higher sulfated glycosaminoglycan deposition over CH/SFF in comparison to pure chitosan scaffold (control). Immunocytochemistry studies have shown enhanced expression of collagen type II and aggrecan by hMSCs over composite scaffold than chitosan scaffold. Thus, non-mulberry silk fibroin fiber reinforced chitosan based scaffold might be suitable scaffold that can act as a potential artificial matrix for cartilage tissue engineering.
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Affiliation(s)
- B N Singh
- Center of Excellence in Tissue Engineering, Department of Biotechnology and Medical Engineering, National Institute of Technology, Rourkela, India
| | - K Pramanik
- Center of Excellence in Tissue Engineering, Department of Biotechnology and Medical Engineering, National Institute of Technology, Rourkela, India.
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Singh BN, Pramanik K. Generation of bioactive nano-composite scaffold of nanobioglass/silk fibroin/carboxymethyl cellulose for bone tissue engineering. Journal of Biomaterials Science, Polymer Edition 2018; 29:2011-2034. [DOI: 10.1080/09205063.2018.1523525] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Affiliation(s)
- B. N. Singh
- Center of Excellence in Tissue Engineering, Department of Biotechnology and Medical Engineering, National Institute of Technology Rourkela, Rourkela, India
| | - K. Pramanik
- Center of Excellence in Tissue Engineering, Department of Biotechnology and Medical Engineering, National Institute of Technology Rourkela, Rourkela, India
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Siddiqui N, Pramanik K. Improvement of cellular responses of genipin cross-linked chitosan/nano
β
-TCP composite scaffolds by surface modification with fibrin. Biomed Phys Eng Express 2018. [DOI: 10.1088/2057-1976/aacad1] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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Singh BN, Pramanik K. Development of novel silk fibroin/polyvinyl alcohol/sol–gel bioactive glass composite matrix by modified layer by layer electrospinning method for bone tissue construct generation. Biofabrication 2017; 9:015028. [DOI: 10.1088/1758-5090/aa644f] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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Singh BN, Panda NN, Mund R, Pramanik K. Carboxymethyl cellulose enables silk fibroin nanofibrous scaffold with enhanced biomimetic potential for bone tissue engineering application. Carbohydr Polym 2016; 151:335-347. [PMID: 27474575 DOI: 10.1016/j.carbpol.2016.05.088] [Citation(s) in RCA: 102] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2016] [Revised: 05/23/2016] [Accepted: 05/24/2016] [Indexed: 11/30/2022]
Abstract
Novel silk fibroin (SF) and carboxymethyl cellulose (CMC) composite nanofibrous scaffold (SFC) were developed to investigate their ability to nucleate bioactive nanosized calcium phosphate (Ca/P) by biomineralization for bone tissue engineering application. The composite nanofibrous scaffold was prepared by free liquid surface electrospinning method. The developed composite nanofibrous scaffold was observed to control the size of Ca/P particle (≤100nm) as well as uniform nucleation of Ca/P over the surface. The obtained nanofibrous scaffolds were fully characterized for their functional, structural and mechanical property. The XRD and EDX analysis depicted the development of apatite like crystals over SFC scaffolds of nanospherical in morphology and distributed uniformly throughout the surface of scaffold. Additionally, hydrophilicity as a measure of contact angle and water uptake capacity is higher than pure SF scaffold representing the superior cell supporting property of the SF/CMC scaffold. The effect of biomimetic Ca/P on osteogenic differentiation of umbilical cord blood derived human mesenchymal stem cells (hMSCs) studied in early and late stage of differentiation shows the improved osteoblastic differentiation capability as compared to pure silk fibroin. The obtained result confirms the positive correlation of alkaline phosphatase activity, alizarin staining and expression of runt-related transcription factor 2, osteocalcin and type1 collagen representing the biomimetic property of the scaffolds. Thus, the developed composite has been demonstrated to be a potential scaffold for bone tissue engineering application.
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Affiliation(s)
- B N Singh
- Department of Biotechnology and Medical Engineering, National Institute of Technology, Rourkela, India
| | - N N Panda
- Department of Biotechnology and Medical Engineering, National Institute of Technology, Rourkela, India
| | - R Mund
- Department of Biotechnology and Medical Engineering, National Institute of Technology, Rourkela, India
| | - K Pramanik
- Department of Biotechnology and Medical Engineering, National Institute of Technology, Rourkela, India.
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Uvanesh K, Sagiri SS, Senthilguru K, Pramanik K, Banerjee I, Anis A, Al-Zahrani SM, Pal K. Effect of Span 60 on the Microstructure, Crystallization Kinetics, and Mechanical Properties of Stearic Acid Oleogels: An In-Depth Analysis. J Food Sci 2015; 81:E380-7. [PMID: 26677007 DOI: 10.1111/1750-3841.13170] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2015] [Accepted: 10/27/2015] [Indexed: 11/30/2022]
Abstract
Modulation of crystallization of stearic acid and its derivatives is important for tuning the properties of stearate oleogels. The present study delineates the crystallization of stearic acid in stearate oleogels in the presence of Span 60. Microarchitecture analysis revealed that stearic acid crystals in the oleogels changed its shape from plate-like structure to a branched architecture in the presence of Span 60. Consequently, a significant variation in the mobility of the solute molecules inside the oleogel (Fluorescence recovery after photobleaching studies, FRAP analysis) was observed. Thermal analysis (gelation kinetics and DSC) revealed shortening of nucleation induction time and secondary crystallization with an increase in the Span 60 concentration. Furthermore, isosolid diagram suggested better physical stability of the formulations at higher proportions of Span 60. XRD analysis indicated that there was a decrease in the crystal size and the crystallinity of the stearic acid crystals with an increase in Span 60 concentration in the Span 60 containing oleogels. However, crystal growth orientation was unidirectional and found unaltered with Span 60 concentration (Avarmi analysis using DSC data). The mechanical study indicated a composition-dependent variation in the viscoelastic properties (instantaneous [τ1 ], intermediate [τ2 ], and delayed [τ3 ] relaxation times) of the formulations. In conclusion, Span 60 can be used to alter the kinetics of the crystallization, crystal habit and crystal structure of stearic acid. This study provides a number of clues that could be used further for developing oleogel based formulation.
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Affiliation(s)
- K Uvanesh
- the Dept. of Biotechnology and Medical Engineering, National Inst. of Technology, Rourkela, Orissa-69008, India
| | - S S Sagiri
- the Dept. of Biotechnology and Medical Engineering, National Inst. of Technology, Rourkela, Orissa-69008, India
| | - K Senthilguru
- the Dept. of Biotechnology and Medical Engineering, National Inst. of Technology, Rourkela, Orissa-69008, India
| | - K Pramanik
- the Dept. of Biotechnology and Medical Engineering, National Inst. of Technology, Rourkela, Orissa-69008, India
| | - I Banerjee
- the Dept. of Biotechnology and Medical Engineering, National Inst. of Technology, Rourkela, Orissa-69008, India
| | - Arfat Anis
- Dept. of Chemical Engineering, King Saud Univ, Riyadh, -11421, Saudi Arabia
| | - S M Al-Zahrani
- Dept. of Chemical Engineering, King Saud Univ, Riyadh, -11421, Saudi Arabia
| | - Kunal Pal
- the Dept. of Biotechnology and Medical Engineering, National Inst. of Technology, Rourkela, Orissa-69008, India
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Singh V, Pal K, Banerjee I, Pramanik K, Anis A, Al-Zahrani S. Novel organogel based lyotropic liquid crystal physical gels for controlled delivery applications. Eur Polym J 2015. [DOI: 10.1016/j.eurpolymj.2015.05.009] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
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Panda N, Bissoyi A, Pramanik K, Biswas A. Development of novel electrospun nanofibrous scaffold from P. ricini and A. mylitta silk fibroin blend with improved surface and biological properties. Materials Science and Engineering: C 2015; 48:521-32. [DOI: 10.1016/j.msec.2014.12.010] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/25/2014] [Revised: 10/12/2014] [Accepted: 12/04/2014] [Indexed: 11/30/2022]
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Anu Priya B, Senthilguru K, Agarwal T, Gautham Hari Narayana SN, Giri S, Pramanik K, Pal K, Banerjee I. Nickel doped nanohydroxyapatite: vascular endothelial growth factor inducing biomaterial for bone tissue engineering. RSC Adv 2015. [DOI: 10.1039/c5ra09560c] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023] Open
Abstract
Biomaterial induced activation of vascular endothelial growth factor (VEGF) pathway for angiogenesis is now gaining recognition as an effective option for tissue engineering.
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Affiliation(s)
- B. Anu Priya
- Department of Biotechnology & Medical Engineering
- National Institute of Technology
- Rourkela-769008
- India
| | - K. Senthilguru
- Department of Biotechnology & Medical Engineering
- National Institute of Technology
- Rourkela-769008
- India
| | - T. Agarwal
- Department of Biotechnology & Medical Engineering
- National Institute of Technology
- Rourkela-769008
- India
| | | | - S. Giri
- Department of Chemistry
- National Institute of Technology
- Rourkela-769008
- India
| | - K. Pramanik
- Department of Biotechnology & Medical Engineering
- National Institute of Technology
- Rourkela-769008
- India
| | - K. Pal
- Department of Biotechnology & Medical Engineering
- National Institute of Technology
- Rourkela-769008
- India
| | - I. Banerjee
- Department of Biotechnology & Medical Engineering
- National Institute of Technology
- Rourkela-769008
- India
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Ray SS, Asthana S, Agarwal T, Singothu S, Samal A, Banerjee I, Pal K, Pramanik K. Molecular docking and interactions of pueraria tuberosa with vascular endothelial growth factor receptors. Indian J Pharm Sci 2015; 77:439-45. [PMID: 26664060 PMCID: PMC4649782 DOI: 10.4103/0250-474x.164780] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022] Open
Abstract
Pueraria tuberosa is known for its therapeutic potentials in cardiovascular disorders, but its effect in angiogenesis has not been studied so far. In this study, a computational approach has been applied to elucidate the role of the phytochemicals in inhibition of angiogenesis through modulation of vascular endothelial growth factor receptors: Vascular endothelial growth factor receptor-1 and vascular endothelial growth factor receptor-2, major factors responsible for angiogenesis. Metabolite structures retrieved from PubChem and KNApSAcK – 3D databases, were docked using AutoDock4.2 tool. Hydrogen bond and molecular docking, absorption, distribution, metabolism and excretion and toxicity predictions were carried out using UCSF Chimera, LigPlot+ and PreADMET server, respectively. From the docking analysis, it was observed that puerarone and tuberostan had significant binding affinity for the intracellular kinase domain of vascular endothelial growth factor receptors-1 and vascular endothelial growth factor receptor-2 respectively. It is important to mention that both the phytochemicals shared similar interaction profile as that of standard inhibitors of vascular endothelial growth factor receptors. Also, both puerarone and tuberostan interacted with Lys861/Lys868 (adenosine 5’-triphosphate binding site of vascular endothelial growth factor receptors-1/vascular endothelial growth factor receptors-2), thus providing a clue that they may enforce their inhibitory effect by blocking the adenosine 5’-triphosphate binding domain of vascular endothelial growth factor receptors. Moreover, these molecules exhibited good drug-likeness, absorption, distribution, metabolism and excretion properties without any carcinogenic and toxic effects. The interaction pattern of the puerarone and tuberostan may provide a hint for a novel drug design for vascular endothelial growth factor tyrosine kinase receptors with better specificity to treat angiogenic disorders.
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Abstract
Despite marked developments in the field of cryopreservation of cells and tissues for research and therapeutic applications, post-thaw cell death remains a significant drawback faced by cryobiologists. Post cryopreservation apoptosis and necrosis are normally observed within 6 to 24 h after post-thaw culture. As a result, massive loss of cell viability and cellular function occur due to cryopreservation. However, in this new generation of cryopreservation science, scientists in this field are focusing on incorporation of apoptosis and necrosis inhibitors (zVAD-fmk, p38 MAPK inhibitor, ROCK inhibitor, etc.) to cryopreservation and post-thaw culture media. These inhibitors target and inhibit various proteins such as caspases, proteases, and kinases, involved in the cell death cascade, resulting in reduced intensity of apoptosis and necrosis in the cryopreserved cells and tissues, increased cell viability, and maintenance of cellular function; thus improved overall cryopreservation efficiency is achieved. The present article provides an overview of various cell death pathways, molecules mediating cryopreservation-induced apoptosis and the potential of certain molecules in targeting cryopreservation-induced delayed-onset cell death.
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Affiliation(s)
- A Bissoyi
- 1 Department of Biotechnology and Medical Engineering, National Institute of Technology , Rourkela, India
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Panda N, Bissoyi A, Pramanik K, Biswas A. Directing osteogenesis of stem cells with hydroxyapatite precipitated electrospun eri–tasar silk fibroin nanofibrous scaffold. Journal of Biomaterials Science, Polymer Edition 2014; 25:1440-57. [DOI: 10.1080/09205063.2014.943548] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
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Bissoyi A, Pramanik K, Panda NN, Sarangi S. Cryopreservation of hMSCs seeded silk nanofibers based tissue engineered constructs. Cryobiology 2014; 68:332-42. [DOI: 10.1016/j.cryobiol.2014.04.008] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2013] [Revised: 03/31/2014] [Accepted: 04/13/2014] [Indexed: 10/25/2022]
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Satapathy D, Sagiri S, Pal K, Pramanik K. Development of mustard oil- and groundnut oil-based span 40 organogels as matrices for controlled drug delivery. Des Monomers Polym 2013. [DOI: 10.1080/15685551.2013.869652] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022] Open
Affiliation(s)
- D. Satapathy
- Department of Biotechnology and Medical Engineering, National Institute of Technology, Rourkela, India
| | - S.S. Sagiri
- Department of Biotechnology and Medical Engineering, National Institute of Technology, Rourkela, India
| | - K. Pal
- Department of Biotechnology and Medical Engineering, National Institute of Technology, Rourkela, India
| | - K. Pramanik
- Department of Biotechnology and Medical Engineering, National Institute of Technology, Rourkela, India
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Chudhuri B, Bhadra D, Dash S, Sardar G, Pramanik K, Chaudhuri BK. Hydroxyapatite and Hydroxyapatite-Chitosan Composite from Crab Shell. J BIOMATER TISS ENG 2013. [DOI: 10.1166/jbt.2013.1126] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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Bissoyi A, Pramanik K. Effects of non-toxic cryoprotective agents on the viability of cord blood derived MNCs. Cryo Letters 2013; 34:453-465. [PMID: 24448765] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
The present work investigates the effects of a variety of natural cryoprotectants in combination on post-thaw viability and apoptosis of cryopreserved mononuclear cells (MNCs) derived from umbilical cord blood. The extracellular cryoprotectants (10 mM) namely trehalose, hydroxyl ethyl starch, polyvinyl pyrrolidine and intracellular CPAs (5 mM) like erythritol, taurine and ectoine were used to prepare different combinations of freezing medium following L9 (3(4)) Taguchi orthogonal array. Catalase, coenzyme Q10 and n-acetyl cystine (100 microg/m) were added as antioxidants. Among various combinations, freezing medium consisting of hydroxyl ethyl starch, ectoin and co-enzyme Q10 with 10% FBS is found to be most effective combination achieving maximum cell viability of 93%, 5.6% early apoptotic, 0.7% late apoptotic and 0.1% necrotic cells. SEM and phase contrast microscopy confirmed the normal cell morphology of the post-thaw cultured cells with retaining their membrane integrity. The survival rate of MNCs is higher than the rate achieved using conventional Me2SO.
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Affiliation(s)
- Akalabya Bissoyi
- Department of Biotechnology and Medical Engineering, National Institute of Technology Rourkela, India
| | - K Pramanik
- Department of Biotechnology and Medical Engineering, National Institute of Technology Rourkela, India
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Satapathy D, Biswas D, Behera B, Sagiri SS, Pal K, Pramanik K. Sunflower-oil-based lecithin organogels as matrices for controlled drug delivery. J Appl Polym Sci 2012. [DOI: 10.1002/app.38498] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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Affiliation(s)
- S. Roy
- a School of Pharmacy and Technology Management, SVKM's NMIMS University, Mumbai-400056, India
| | - K. Pal
- b Department of Biotechnology & Medical Engineering, National Institute of Technology, Rourkela-769008, Orissa, India
| | - A. Anis
- c Department of Process Engineering & Applied Science, Dalhousie University, Halifax, NS, Canada B3J2X4
| | - K. Pramanik
- d Department of Biotechnology & Medical Engineering, National Institute of Technology, Rourkela-769008, Orissa, India
| | - B. Prabhakar
- e School of Pharmacy and Technology Management, SVKM's NMIMS University, Mumbai-400056, India
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Sadanand J, Kumar A, Pramanik K. Preparation and Characterization of Poly(vinyl alcohol) Based Scaffold Using Improved Salt Leaching Method. J BIOMATER TISS ENG 2012. [DOI: 10.1166/jbt.2012.1034] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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Trupschuch S, Pramanik K, Henschler R, Muller A. Interactions of leukemic stem- and progenitor cells with embryonal stroma environment. J Stem Cells Regen Med 2007; 2:173-174. [PMID: 24692981] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Affiliation(s)
- S Trupschuch
- Institute of Medical Radiation and Cell Research, Department of Stem Cell Biology, University of Wuerzburg , Versbacher Str. 5, 97078 Wuerzburg, Germany
| | - K Pramanik
- Institute of Medical Radiation and Cell Research, Department of Stem Cell Biology, University of Wuerzburg , Versbacher Str. 5, 97078 Wuerzburg, Germany
| | - R Henschler
- Institute of Medical Radiation and Cell Research, Department of Stem Cell Biology, University of Wuerzburg , Versbacher Str. 5, 97078 Wuerzburg, Germany
| | - Am Muller
- Institute of Medical Radiation and Cell Research, Department of Stem Cell Biology, University of Wuerzburg , Versbacher Str. 5, 97078 Wuerzburg, Germany
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Mukherjee D, Paul S, Pramanik K, Paul N, Kundu S, Bandopadhyay A. Activation of PI3‐kinase and MAPK pathway regulate IGF‐ and insulin‐induced oocyte maturation in common carp, Cyprinus carpio. FASEB J 2007. [DOI: 10.1096/fasebj.21.5.a252-b] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- Dilip Mukherjee
- Department of ZoologyUniversity of KalyaniKalyani741235India
| | - S Paul
- Department of ZoologyUniversity of KalyaniKalyani741235India
| | - K Pramanik
- Department of ZoologyUniversity of KalyaniKalyani741235India
| | - N Paul
- Department of ZoologyUniversity of KalyaniKalyani741235India
| | - S Kundu
- Department of ZoologyUniversity of KalyaniKalyani741235India
| | - A Bandopadhyay
- Molecular Endocrinology Laboratory, Indian Institute of Chemical Biology4 Raja S.C. Mullick RoadKolkata700032India
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Shivakumar M, Pramanik K, Bhattacharyya I, Chakravorty A. Chemistry of metal-bound anion radicals. A family of mono- and bis(azopyridine) chelates of bivalent ruthenium. Inorg Chem 2000; 39:4332-8. [PMID: 11196929 DOI: 10.1021/ic000356b] [Citation(s) in RCA: 53] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The reaction of the dihydride [RuII(H)2(CO)(PPh3)3], 3, with excess azo-2,2'-bipyridine (abp) in boiling dry benzene has afforded the diradical bischelate [RuII(abp.-)2(CO)(PPh3)], 4, and the hydridic monochelate monoradical [RuII(abp.-)(H)(CO)(PPh3)2], 5. A similar reaction between 3 and 2-(p-chlorophenylazo)pyridine (Clpap) did not yield a bischelate, but the hydridic monoradical [RuII(Clpap.-)(H)(CO)(PPh3)2], 6, has been isolated. Upon treatment of 4-6 with NH4PF6 in a wet dichloromethane-acetonitrile medium, the one-electron-oxidized salts 4+PF6-, 5+PF6-, and 6+PF6- are isolated, H+ being the oxidizing agent. The X-ray structures of 4+PF6-.CH2Cl2, 5+PF6-.H2O, and 6+PF6- have been determined. In the monoradical 4+ the azo N-N bond lengths in the two chelate rings are 1.284(6) and 1.336(6) A, showing that the radical electron is localized in the latter ring. The half-filled extended Hückel HOMO is indeed found to be so localized, and it has a large azo character. Complexes 4-6 display radical redox couples with E1/2 in the range -0.5 to +0.10 V vs SCE. The E1/2 values qualitatively correlate with corresponding vco values (1900-2000 cm-1). The monoradicals (S = 1/2) 4+, 5, and 6 uniformly display a strong EPR signal near g = 2.00. Metal-mediated magnetic interaction makes the EPR-silent diradical 4 strongly antiferromagnetic with J = -299 cm-1. Crystal data are as follows: (4+PF6-.CH2Cl2, C40H33Cl2F6N8-OP2Ru) monoclinic, space group P2(1)/c (no. 14), a = 14.174(6) A, b = 16.451(4) A, c = 18.381(4) A, beta = 98.00(3) degrees, Z = 4; (5+PF6-.H2O, C47H41F6N4O2P3Ru) monoclinic, space group P2(1)/n (no. 14), a = 9.433(2) A, b = 38.914(17) A, c = 13.084(3) A, beta = 103.47(2) degrees, Z = 4; (6+PF6-, C48H39ClF6N3OP3Ru) monoclinic, space group P2(1)/n (no. 14), a = 10.496(5) A, b = 22.389(8) A, c = 19.720(6) A, beta = 90.53(3) degrees, Z = 4.
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Affiliation(s)
- M Shivakumar
- Department of Inorganic Chemistry, Indian Association for the Cultivation of Science, Calcutta 700 032, India
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Abstract
The reaction of [Os(H)(Br)(CO)(PPh3)3], 5, with 2-(phenylazo)pyridine (pap) in boiling dry heptane has afforded the azo anion radical complex [Os(pap.-)(Br)(CO)(PPh3)2], 6a, as the major product and [Os(pap)(H)(CO)(PPh3)2]Br, 7, as a minor byproduct. Upon replacing pap by the better pi-acceptor azo-2,2'-bipyridine (abp) in the above synthesis, the radical complex [Os(abp.-)(Br)(CO)(PPh3)2], 6b, becomes the sole product. It is proposed that 6 is formed via homolytic cleavage of the Os-H bond in 5; in the formation of 7, the Os-Br bond of 5 is heterolytically cleaved. The X-ray structures of 6b and 7.CH2Cl2 have been determined. In 6b, the N-N length is 1.35(2) A, consistent with the anion radical description; in 7.CH2Cl2 the length is 1.27(1) A. The spin-bearing extended Huckel HOMO in a model of 6 is found to be approximately 70% azo-pi* in character associated with a small metal contribution. An electronic band observed in the range 600-700 nm in solutions of 6 is assigned to the HOMO --> LUMO transition, the LUMO being 95% pyridine-pi* in character. One-electron paramagnetic 6 displays well-defined anisotropic EPR features near g = 2.00. The anisotropy arises from the metal character of HOMO and is magnified by the large spin-orbit coupling in osmium. In a moisture-free environment 6 is indefinitely stable in the solid state, but in CH2Cl2-MeCN solution 6a is rapidly oxidized by air, affording [Os(pap)(Br)(CO)(PPh3)2]+, 6a+, which has been isolated as the diamagnetic PF6- salt; 6b+PF6- has been similarly prepared. The voltammetric reduction potentials of the 6+/6 couple follow the order 6a+/6a < 6b+/6b, and the carbon monoxide stretching frequencies follow the order 6a < 6b and 6a+ < 6b+. These trends are consistent with the pi-acidity order pap < abp. Crystal data are as follows: (6b, C47H38BrN4OOsP2) monoclinic, space group P21/c (no. 14), a = 10.215(4) A, b = 17.634(7) A, c = 22.473(8) A, beta = 97.67(3) degrees , Z = 4; (7.CH2Cl2, C49H42BrCl2N3OOsP2) monoclinic, space group P2(1/n) (no. 14), a = 15.323(7) A, b = 15.201(6) A, c = 19.542(7) A, beta = 92.51(3) degrees, Z = 4.
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Affiliation(s)
- K Pramanik
- Department of Inorganic Chemistry, Indian Association for the Cultivation of Science, Calcutta
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