Browsing by Author "Dipankar Chattopadhyay"

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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.
Tadpole-shaped β-cyclodextrin-tagged poly(N-vinylpyrrolidone): Synthesis, characterization and studies of its complexation with phenolphthalein and anti tumor activities
(Royal Society of Chemistry, 2015) Niraj Kumar Vishwakarma; Vijay Kumar Patel; Sumit Kumar Hira; K. Ramesh; Prateek Srivastava; Kheyanath Mitra; Shikha Singh; Dipankar Chattopadhyay; Pralay Maiti; Nira Misra; Partha Pratim Manna; Biswajit Ray
Tadpole-shaped β-cyclodextrin-tagged poly(N-vinylpyrrolidone) (β-CD-PNVP) has been synthesised via the click reaction of alkyne-terminated PNVP and azide-functionalized β-CD. The formed polymer is characterized by 1H NMR, FTIR, and TGA study. The complexing ability of such a polymer with phenolphthalein is considerably lower with respect to that with β-CD alone. Doxorubicin (DOX)-loaded β-CD-PNVP (DOX-β-CD-PNVP) exhibits higher tumoricidal activity against a panel of tumor cell lines derived from sarcoma (U2-OS) and carcinomas (MCF-7 and HEPG2), causing significant lysis of tumor cells compared to free DOX. The formulation also demonstrates significantly higher uptake by the tumor cells and enhances apoptosis compared to free DOX. This journal is © The Royal Society of Chemistry.