Browsing by Author "Kheyanath Mitra"

Now showing 1 - 20 of 33

Biocompatible thermoresponsive N-isopropyl-N-(3-(isopropylamino)-3-oxopropyl)acrylamide-based random copolymer: synthesis and studies of its composition dependent properties and anticancer drug delivery efficiency
(Royal Society of Chemistry, 2022) Sourov Mondal; Archana Kumari; Kheyanath Mitra; Abhineet Verma; Satyen Saha; Biswajit Maiti; Ranjeet Singh; Partha Pratim Manna; Pralay Maiti; Hironobu Watanabe; Masami Kamigaito; Biswajit Ray
A new acrylamide monomer, N-isopropyl-N-(3-(isopropylamino)-3-oxopropyl)acrylamide (M3i), consisting of both isopropyl and isopropylamidopropyl moieties, has been synthesized from isopropylamine and N-isopropylacrylamide via an aza-Michael addition reaction followed by amidation with acryloyl chloride. The homopolymer of M3i (polyM3i) and a series of random copolymers of M3i and poly(ethylene glycol)methyl ether acrylate (PEGA: CH2 00000000 00000000 00000000 00000000 11111111 00000000 11111111 00000000 00000000 00000000 CHCO2(CH2CH2O)nMe, Mn = 480, n = 9 on average) with varying compositions have been synthesized via reversible addition-fragmentation chain transfer polymerization using 2-(dodecylthiocarbonothioylthio)-2-methylpropionic acid (DDMAT) as well as 1-phenylethyl phenyl dithioacetate (PEPD) as a RAFT agent. These polymers have been characterized by 1H NMR, FTIR, GPC, UV-Vis, fluorescence, TGDTA, DSC, DLS, and TEM techniques. A lower critical solution temperature (LCST) and glass transition temperature (Tg) for polyM3i prepared using DDMAT were observed at 17 and 133 °C, respectively, while for a polymer formed using PEPD, no LCST was observed until 0 °C and its observed Tg was found at 127.3 °C. The polymers are thermally stable up to 300 °C. Upon an increase in the M3i content in the copolymers, LCST decreases, Tg increases, and the apparent hydrodynamic diameter decreases. Moreover, the effects of concentration and the addition of urea and sodium chloride on the LCST of the copolymer with an LCST close to body temperature were studied. Owing to the incorporation of PEGA, a higher critical micellar concentration and larger TEM particle size of this copolymer were observed with respect to those of polyM3i. The usefulness of the micelles of the copolymers as nano-carriers for the drug doxorubicin was explored. The in vitro tumoricidal activity of the micelles of the doxorubicin-loaded copolymers was also assessed against Dalton's lymphoma cells. © 2022 The Royal Society of Chemistry.
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.
Colorimetric detection of hydrogen peroxide and cholesterol using Fe3O4-brominated graphene nanocomposite
(Springer Science and Business Media Deutschland GmbH, 2022) Jaydeep Singh; Rajshree Singh; Shikha Singh; Kheyanath Mitra; Sourov Mondal; Sambhav Vishwakarma; Biswajit Ray
Fe3O4-brominated graphene (Fe3O4-GBR) nanocomposites were synthesized via an in situ method using the precursors FeSO4.7H2O and GBR in different (1:1, 1:2, 2:1, 1:5, 1:10, 1:20, and 5:1) weight ratios at pH 11.5. The Fe3O4-GBR (1:5) nanocomposite in combination with H2O2 and 3,3′,5,5′-tetramethylbenzidine (TMB) showed swift and superior intrinsic peroxidase mimetic enzyme activity compared with the other Fe3O4-GBR composites, GBR and Fe3O4, as observed by colorimetry. It was characterized using high-resolution scanning electron microscopy (HRSEM), energy dispersive X-ray spectroscopy (EDX), Fourier transform infrared (FTIR) spectroscopy, powder X-ray diffraction (PXRD), and thermogravimetric analysis (TGA). Its catalytic activity was optimized by varying different parameters, and the optimum conditions for peroxidase mimetic activity were observed using 100 μL Fe3O4-GBR (1 mg/mL), 50 μL TMB (1 mg/mL), and 200 μL H2O2(1 mM) in 400 μL of acetate buffer of pH 2.3 at 30 °C temperature. Kinetic analysis has revealed the Michaelis–Menten kinetic behavior of peroxidase activity with Michaelis–Menten constants (Km) and maximum initial velocities (Vmax) of 0.082 mM and 14.1 nMs−1 respectively, for H2O2 and 0.086 mM and 5.1 nMs−1, respectively for TMB. The limit of detection and linear range were found to be 49.6 μM and 100–880 μM, respectively, for H2O2 and 41.9 μM and 47.6–952.3 μM, respectively, for cholesterol. On this basis, a simple, swift, sensitive, selective, and reproducible colorimetric assay to detect cholesterol levels in blood serum samples using Fe3O4-GBR nanocomposite has been developed. Thus, Fe3O4-GBR composite as compared to Fe3O4 and GBR has shown better peroxidase mimicking activity for biosensing. Graphical abstract: [Figure not available: see fulltext.] © 2022, Springer-Verlag GmbH Germany, part of Springer Nature.
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.
Doxorubicin loaded pH responsive biodegradable ABA-type Amphiphilic PEG-b-aliphatic Polyketal-b-PEG block copolymer for therapy against aggressive murine lymphoma
(Elsevier Inc., 2020) Sumit Kumar Hira; Kheyanath Mitra; Prateek Srivastava; Shikha Singh; Sambhav Vishwakarma; Ranjeet Singh; Biswajit Ray; Partha Pratim Manna
A novel ABA-type polyethylene glycol (PEG)-b-polyketal (PK)-b-PEG block copolymer was synthesized via click reactions between the monoazido-monomethoxy-PEG and dialkyne terminated aliphatic polyketal with no carboxylic/amide linkages. Formation of the novel block copolymer was confirmed by 1H NMR, GPC, TGA, and DSC studies. The formed copolymer has shown faster degradation at acidic pH. Self-assembly of this block copolymer (average size 6.2 nm) was assessed by fluorescence study using pyrene as a probe. Doxorubicin loaded block copolymeric micelles (69.9 nm) have shown pH dependent elevated drug release at pH 6.4, indicating its potential as a pH responsive nano-carrier for anticancer therapy. The nano-sized copolymer demonstrated tumoricidal activities against the lymphoma of murine and human origin with significant levels of growth inhibition and apoptosis. Therapy with doxorubicin loaded copolymer reduced the tumor size and augmented the life span of the tumor bearing animals with improved histopathological parameters, compared with the untreated control. © 2019 Elsevier Inc.
Effect of Isotacticity of Linear Poly(N-isopropylacrylamide) on its Gelation in Benzyl Alcohol
(Springer India, 2016) Chandra Sekhar Biswas; Kheyanath Mitra; Shikha Singh; Dinesh K Patel; Biswajit Maiti; Pralay Maiti; Biswajit Ray
Thermoreversible gelation of three different isotactic linear poly(N-isopropylacrylamide) (PNIPAM)s having meso dyad (m) values 62, 68 and 81% has been observed in benzyl alcohol. All the gels were transparent in nature. SEM image of the dried gels showed fibrillar network morphology. Melting temperature of the gels gradually increased with the increase in the concentration. XRD data of dry polymers and their corresponding dry gels showed shifting in the peak positions. Rheological study showed that stronger gels were formed with increasing isotacticity of PNIPAM while lower isotactic sample exhibited typical polymer melt rheology. The formation of a plunge in the storage modulus as well as in the viscosity plot at the same frequency range indicates the reversible nature of the structure breaking/reformation under frequency sweep. Moreover, the mechanical strength of the gel decreased with increase in temperature. UV-Vis kinetic study also indicated the change in the conformation and aggregation of PNIPAM chains during gelation. Molecular modelling calculation showed that the number of solvent molecules involved in forming gel (polymer-solvent compound) decreased with the increase in the isotacticity of the polymer. Gelation rate of these gels was studied as a function of temperature, concentration and isotacticity using test-tube tilting method. It increased with the increase in the concentration and isoacticity of the polymer, and with the decrease in the temperature. Critical gelation concentration of the gel gradually increased with the decrease in the isotacticity and with the increase in the temperature. All these experimental results indicated that gelation occurs presumably through polymer-solvent compound formation. [Figure not available: see fulltext.] © 2016, Indian Academy of Sciences.
Effect of L-menthol chain-end on the optical rotation, chirality, tacticity and thermal properties of polystyrene prepared by ATRP and polyvinylacetates prepared by RAFT polymerization: A molecular weight dependence study
(Elsevier Ltd, 2021) Sambhav Vishwakarma; Archana Kumari; Kheyanath Mitra; Shikha Singh; Zhiyi Song; Masayoshi Bando; Tamaki Nakano; Susanta Kumar Sen Gupta; Biswajit Ray
Two series of L-menthol-tagged homopolymers: one polystyrenes (PSt) and the other polyvinylacetates (PVAc) having different molecular weights have been synthesized via ATRP of styrene, and RAFT polymerization of vinyl acetate, respectively. Optical rotation study has established the magnitude of the optical rotation value for the both polymer series has been found decreasing exponentially with the increase of their molecular weights. CD study has revealed an exponential decrease in the molar ellipiticity values at 235 nm with the increase in the DPs of polymers in both the polymer systems. Formed PSts and PVAcs are atactic and slightly syndiotactic, respectively. With increase in the chain length of the polymers, glass-transition temperature (Tg) values have been found increasing exponentially in both systems. Therefore, living radical polymerization using suitable ATRP initiator or, RAFT agent containing suitable chiral moiety can be useful in inducing chirality in polymers up to high chain length. © 2020 Elsevier Ltd
Effect of n-Alkyl Side Chain Length on the Thermal and Rheological Properties of PolyN-(3-(alkylamino)-N-(3-(isopropylamino)-3-oxopropyl)acrylamide) Homopolymers
(John Wiley and Sons Inc, 2021) Archana Kumari; Sambhav Vishwakarma; Kheyanath Mitra; Chuangbi Chen; Shuming Cui; Biswajit Maiti; Sourov Mondal; Chandra Sekhar Biswas; Pralay Maiti; Florian J. Stadler; Biswajit Ray
Four new N-isopropylacrylamide- and N-n-alkyl amine-based acrylamide monomers, N-(3-(alkylamino)-N-(3-(isopropylamino)-3-oxopropyl) acrylamide (Mn) (n = 4, 8, 10, 12) are successfully synthesized and polymerized via reversible addition-fragmentation chain-transfer polymerization (polyMn, n = 4, 8, 10, and 12), which are characterized by gel permeation chromatography, 1H NMR, Fourier transform infra red spectroscopy, thermo-gravimetry-differential thermal analysis, differential scanning calorimetry (DSC), and rheology. All polymers are thermally stable and undergo a two-step degradation process at ≈280 and ≈375 °C. Glass transition temperature (Tg)s of these polymers decrease gradually from 99.6 to 52.5 °C with increasing n-alkyl side chain length. The rheology of these polymers in melt state agrees to a typical Rouse-melt behavior and allows for confirming the Tg determined from DSC. Benzyl alcohol solution rheology proves a weak structural build-up, in particular for polyM12. Comparison of the quantum chemical calculations of polyMns with n = 4–8 reveals increase in backbone helicity with increasing n-alkyl side chain length. © 2021 Wiley-VCH GmbH.
Effect of tacticity and molecular weight on the rheological properties of poly(N -isopropylacrylamide) gels in benzyl alcohol
(Society of Rheology, 2017) Chandra Sekhar Biswas; Yuhang Wu; Qiao Wang; Lei Du; Kheyanath Mitra; Biswajit Ray; Zhi-Chao Yan; Bing Du; Florian J. Stadler
Two series of different isotactic poly(N-isopropylacrylamide) of number average molar masses (Mn) ∼ 100 000, 200 000 and narrow molar mass distribution are prepared by reversible addition fragmentation chain transfer polymerization. Their thermoreversible, physical gels are prepared in benzyl alcohol and rheologically characterized to assess the effect of tacticity and molar masses on the rheological properties. In general, higher tacticity, higher molar mass, and higher concentration lead to stiffer gels and a sol-gel transition at a higher temperature. The results are interpreted based on partial phase separation leading to stiff but labile spongelike structures. The tacticity influences the strength of the phase separation tendency. Concentration and molar mass determine how far reaching and how connected these domains are. © 2017 The Society of Rheology.
Electrochemical sensing of hydrogen peroxide using brominated graphene as mimetic catalase
(Elsevier Ltd, 2017) Shikha Singh; Monali Singh; Kheyanath Mitra; Rajshree Singh; Susanta Kumar Sen Gupta; Ida Tiwari; Biswajit Ray
Recently we have reported the peroxidase mimicking ability of metal free brominated graphene (GBR) (Analytical Chemistry, 89, 783–791, 2017) at a pH less than 7.2. Here we report the novel catalase mimicking ability of GBR via electrochemical (electro-oxidation) detection of hydrogen peroxide (H2O2) at pH ≥ 7.2. We have fabricated successfully a low cost electrochemical sensor using GBR coated glassy carbon electrode (GCE) [(GBR-GCE)-working electrode] and showed its excellent cyclic voltametry (CV) response towards electro-oxidation of hydrogen peroxide (H2O2), which is so far shown by electrodes made of platinum-group metals like Pt, Ir, Ru etc. Thus, GBR has exhibited the dual mimicking ability as peroxidase and also as catalase under different conditions. A plausible mechanism of sensing of hydrogen peroxide has been proposed involving the formation of perhydroxyl radical (HO2˙) facilitated by GBR-GCE as the electrode. Calibration curves for H2O2 detection using both CV and differential pulse voltametry (DPV) techniques have been constructed over 0.1–10 mM linearity range with the limits of detection of 0.048 and 0.063 mM, respectively. This fabricated electrochemical sensor is highly selective, specific and its response current is least affected by the presence of interfering analytes. The results are found highly reproducible and the use of GBR has also minimized the problem and specificity associated with natural enzymes, as it can easily be stored at room temperature. Real samples have also been successfully analyzed using our fabricated sensor. © 2017 Elsevier Ltd
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.
Fabrication and evaluation of a self-standing reduced graphene-tungsten oxides hybrid electrode for acidic water splitting
(Elsevier Ltd, 2022) Prerna Tripathi; Amit Kumar Verma; Anju Vishwakarma; Kheyanath Mitra; Biswajit Ray; A.S.K. Sinha; Shikha Singh
Efficient and sustained hydrogen production via acidic water splitting is of great importance in the electrolyzer industry. Here, we have designed and synthesized a self-assembled, freestanding, three dimensional (3D) reduced graphene-non-noble tungsten oxide (SA-GWO) electrode with high comprehensive acidic electrolysis performance. Adsorption isotherm suggested the formation of mesoporous structural design within a 3D self-assembled SA-GWO architecture electrode. Bi-functional (HER and OER) activity has been displayed by SA-GWO electrodes at the combined full potential of 1.9 V and attains the standard 10 mA/cm2 (1 M H2SO4, 28 °C). Remarkably, it exhibits OER activity in the acidic medium, which is so far very limited. The tafel slope and the exchange current density for the HER process are observed to be 117 mV/decade and 1.73 × 10−3 mA/cm2, respectively, at 28 °C. Importantly, the production rate of hydrogen is found to increase with increasing temperature. HER is highly dominated by the Volmer route. Gas liberated at the respective electrode has been tested via gas chromatography (GC) analysis. SA-GWO supports the faradaic efficiency of 73 and 52% for HER and OER, respectively. Tafel slope for OER appeared to be very high owing to its complex mechanistic pathway. Disintegration of 3D monoclinic WO3 and the formation of 2D nanochannels like nanostructure have been distinctly observed in SEM micro images, when the electrode is subjected to cathodic HER reaction (−0.5 V, 1 M H2SO4). Most importantly, the WO3 polymorph typically responsible for the distinct mechanism of HER and OER action in 1 M H2SO4 has been identified and proven. Moreover, the 3D SA-GWO electrode as HER possesses great endurance and incomparable stability in acidic media. © 2022 Hydrogen Energy Publications LLC
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.
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 Anticancer Drug Delivery Using Amphiphilic Poly(N-vinylpyrrolidone)-b-Polyketal-b-Poly(N-vinylpyrrolidone) Block Copolymer as Micellar Nanocarrier
(Wiley-Blackwell, 2018) Kheyanath Mitra; Sumit Kumar Hira; Shikha Singh; Niraj Kumar Vishwakarma; Sambhav Vishwakarma; Uttam Gupta; Partha Pratim Manna; Biswajit Ray
We have first synthesized acid-degradable alkyne-terminated aliphatic polyketal and thereof synthesized novel pH-responsive double hydrophilic amphiphilic block copolymer of poly(N-vinyl pyrrolidone) (PNVP) and aliphatic polyketal (PK) (PNVP-b-PK-b-PNVP via click chemistry upon reaction with azide-terminated PNVP. Formation of block copolymer is confirmed by proton nuclear magnetic resonance, gel permeation chromatography, thermogravimetry, differential scanning calorimetry, and fluorescence spectroscopy techniques. pH-dependent degradation study of the block copolymer shows faster degradation at lower pH. Transmission electron microscopy (TEM) has revealed the formation of tiny (∼3.8 nm) micellar nanoparticles. Loading of the anticancer drugs doxorubicin (Dox) and imatinib in the micelle is confirmed from UV-Visible, and TEM studies. Drug release study from drug-loaded micelles has shown that imatinib is being released faster than Dox and both systems have shown higher load release at acidic pH of 6.4. Doxorubicin- and imatinib- loaded micelles demonstrate significant tumoricidal properties against parental and drug resistant human erythroleukemia K-562 and Dalton's lymphoma cells with respect to enhanced cellular uptake, cytotoxicity and growth inhibition. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
L-menthol-based initiators for atom transfer radical polymerization of styrene
(John Wiley and Sons Inc., 2019) Sambhav Vishwakarma; Archana Kumari; Kheyanath Mitra; Shikha Singh; Rajshree Singh; Jaydeep Singh; Susanta K. Sen Gupta; Biswajit Ray
Two new atom transfer radical polymerization (ATRP) initiators, 2-isopropyl-5-methylcyclohexyl 2-bromopropanoate (1) and 2-Isopropyl-5-methylcyclohexyl 2-bromo-2-methylpropanoate (2), have been synthesized by the reaction of 2-bromopropanoyl bromide and 2-bromo-2-methylpropanoyl bromide, respectively, with L-menthol and characterized by 1H and 13C NMR and FTIR spectroscopic studies. ATRP of styrene has successfully been carried out in a control manner using these initiators along with catalyst/ligand system consisting of Cu(I)Br/N,N,N/,N/,N//-pentamethyldiethylenetriamine. Polymerizations have yielded polystyrenes (PSts) of controlled molecular weight with low polydispersity index having a menthyl end group, as confirmed by 1H NMR and gel permeation chromatography [GPC]. The controlled nature of the polymerization has also been confirmed by kinetic study of the polymerization process monitored via 1H NMR and GPC. Initiator 2 has evolved as most efficient among the two. The obtained end-functional PSt has also been used as a macroinitiator for homochain extension with styrene and heterochain extension with methyl methacrylate to produce PSt-b-PMMA, showing the living nature of the polymerization process. In comparison with the PSt sample prepared using widely used initiator ethyl-2-bromo-isobutyrate with almost the same molecular weight and polydispersity, initiator 2-made L-menthyl-capped PSt has shown higher light transmission properties of its dichloromethane solution at ~259 nm, higher thermal stability, lower glass transition temperature, a broad melting temperature, and higher surface roughness over its film. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019, 136, 47964. © 2019 Wiley Periodicals, Inc.
L-menthol-based xanthate mediator for RAFT polymerization of vinyl acetate
(Taylor and Francis Inc., 2020) Sambhav Vishwakarma; Archana Kumari; Kheyanath Mitra; Shikha Singh; Rajshree Singh; Jaydeep Singh; Susanta K. Sen Gupta; Biswajit Ray
A xanthate RAFT agent 2-isopropyl-5-methylcyclohexyl 2-(ethoxycarbonothioyl)thio) propanoate has been synthesized via the reactions of L-menthol with 2-bromo-propionyl bromide in THF in the presence of triethylamine leading to the formation of 2-isopropyl-5-methylcyclohexyl 2-bromopropanoate followed by its reaction with potassium-O-ethyl xanthate in ethanol at room temperature and characterized by 1H, 13C NMR and FTIR. RAFT polymerization of vinyl acetate (VAc) using it has resulted in the formation of well-defined polyVAc in controlled manner. This is evidenced by (i) the observation of the pseudo first order kinetics upto ∼90% conversion, (ii) linear increment of molecular weight (unimodal GPC chromatogram) of the polymer keeping its PDI low with the progress of the reaction upto ∼90% conversion, (iii) the linear increment of the molecular weight of the polymers with low PDI on increasing monomer loading, (iv) chain-end analysis of the polymer using 1H NMR confirming the presence of the RAFT agent fragment at the polymer chain-ends, and (v) successful homo- and hetero-chain extension with VAc and NVP, respectively. L-Menthyl-capped polyvinyl acetate has shown higher (i) light transmission properties of its dichloromethane solution at ∼277 nm, (ii) thermal stability, and (iii) glass transition temperature in comparison to its non-L-Menthyl-capped homolog. © 2019, © 2019 Taylor & Francis Group, LLC.
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.
Polymerization of 1-(2-Propynyl)-3-methylimidazolium Bromide using Cyclometalated Pd(II) Catalysts and Study of the Interaction of Ensuing Oligomer with BSA
(Wiley-Blackwell, 2017) Sujay Mukhopadhyay; Kheyanath Mitra; Rajendra Prasad Paitandi; Roop Shikha Singh; Shikha Singh; Biswajit Ray; Daya Shankar Pandey
Two novel cyclometalated binuclear chloro-bridged palladium based catalysts, {(PdClL1)2} (1) and {(PdClL2)2} (2) have been synthesized by reacting PdCl2 with 4-nitro-(benzylidene-(4-tert-butyl-phenyl)-amine (L1) and 4-methylester-(benzylidene-(4-tert-butyl-phenyl)-amine (L2), respectively. These have been characterized by elemental analyses, spectroscopic studies (IR, 1H, 13C NMR, ESI-MS), and their structures have been authenticated by X-ray single crystal analyses. Polymerization of ionic liquid monomer using these catalysts has been investigated. 1 exhibited best catalytic activity and each catalyst afforded both conducting and fluorescent oligomers and high molecular weight polymers. Resulting oligomers and polymers have been characterized by spectroscopic and conductivity, GPC, SEM-EDAX, PXRD studies. Oligomers are fluorescent and their emission intensity enhances upon interaction with anions. Binding behaviour of oligomers has been examined with BSA. Quenching of the intrinsic fluorescence of BSA in presence of oligomers have been studied by steady state, synchronous, and 3D fluorescence spectroscopy and changes in secondary structure quantified by CD spectroscopy. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Pyrene-tagged poly(N-vinyl pyrrolidone) as efficient nano-carrier for anticancer drug delivery
(Taylor and Francis Ltd., 2024) Kheyanath Mitra; Swapan Maity; Archismita Hajra; Shikha Singh; Sourov Mondal; Jaydeep Singh; Pralay Maiti; Biswajit Ray
Herein, we report the use of self-assembled amphiphilic pyrene-tagged poly(N-vinyl pyrrolidone) (PyPNVP) micelles as effective anticancer delivery vehicle. Self-assembly phenomenon of PyPNVP has been studied in aqueous medium. Anticancer drug doxorubicin has been encapsulated in the hydrophobic micellar core and in vitro release profiles have been explored in four different pH values (pH 7.4 − 1.4). The drug-loaded construct has shown pH-responsive higher drug release at lower pH. Anticancer activity of the construct has been studied against human squamous cell carcinoma of the cervix uteri cell line. The in vitro study has shown the highly effective tumoricidal activity. © 2023 Taylor & Francis Group, LLC.