Papers by Swapankumar Ghosh
Industrial Crops and Products, 2018
Nowadays, bio-derived cellulose nano-fibrils based nanocomposites is gaining utmost interest in t... more Nowadays, bio-derived cellulose nano-fibrils based nanocomposites is gaining utmost interest in the area of barrier films for food packaging, as reinforcing filler to make biodegradable nanocomposites with different biopolymers for various applications such as transdermal drug delivery, edible packaging and tissue scaffolding. Ultrasound-assisted preparation of hydroxypropylmethylcellulose based nanocomposites with cellulose nanofibrils were carried out following solution mixing technique. The crystalline nature of cellulose nano-fibrils has been scrutinized by X-ray diffraction study. The field emission-scanning electron micrographs of cellulose nanofibrils revealed a network of nano-fibrillar morphology. The Fourier transform infrared spectroscopy results of cellulose nano-fibrils confirmed the removal of lignin and hemicellulose from raw jute (Corchorus olitorius L.) fibres. The storage modulus and tensile properties of hydroxypropyl methylcellulose films increased up to the addition of 1.00 wt% cellulose nano-fibrils. The moisture affinity of hydrophilic hydroxypropylmethylcellulose has also been reduced at 1.00 wt% cellulose nano-fibrils loading. The impact of cellulose nano-fibrils loading on the cumulative percentage of drug release from prepared nanocomposites films has been explored accordingly. By utilizing these versatilities of cellulose nano-fibrils, the fabricated nanocomposites are expected to be highly promising in the area of packaging and transdermal drug delivery system.
Journal of Applied Sciences, 2012
RSC Adv., 2014
Uniform 6-13 nm sized 0D superparamagnetic Fe 3 O 4 nanocrystals were synthesized by an aqueous '... more Uniform 6-13 nm sized 0D superparamagnetic Fe 3 O 4 nanocrystals were synthesized by an aqueous 'coprecipitation method' under a N 2 atmosphere as a function of temperature to understand the growth kinetics. The crystal phases, surface charge, size, morphology and magnetic characteristics of assynthesized nanocrystals were characterized by XRD, Raman spectroscopy, FTIR, TG-DTA, BET surface area, dynamic light scattering along with zeta potential, HR-TEM, EDAX, vibrating sample magnetometry and Mössbauer spectroscopy. TEM investigation revealed highly crystalline spherical magnetite particles in the 8.2-12.5 nm size range. The kinetically controlled as-grown nanoparticles were found to possess a preferential (311) orientation of the cubic phase, with a highest magnetic susceptibility of $57 emu g À1. The Williamson-Hall technique was employed to evaluate the mean crystallite size and microstrain involved in the as-synthesized nanocrystals from the X-ray peak broadening. In addition to FTIR and Raman spectra, Rietveld structural refinement of XRD confirms the magnetite phase with 5-20% maghemite in the sample. VSM and Mössbauer spectral data allowed us to fit the magnetite/maghemite content to a core-shell model where the shell is 0.2-0.3 nm thick maghemite over a magnetite core. The activation energy of <10 kJ mol À1 calculated from an Arrhenius plot for the complex process of nucleation and growth by diffusion during synthesis shows the significance of the precipitation temperature in the size controlled fabrication processes of nanocrystals. Brunauer-Emmett-Teller (BET) results reveal a mesoporous structure and a large surface area of 124 m 2 g À1. Magnetic measurement shows that the particles are ferromagnetic at room temperature with zero remanence and zero coercivity. This method produced highly crystalline and dispersed 0D magnetite nanocrystals suitable for biological applications in imaging and drug delivery.
The structure of magnetite 20 1.3.4 Magnetic properties of small nanoparticles: Single domain par... more The structure of magnetite 20 1.3.4 Magnetic properties of small nanoparticles: Single domain particles 22 1.3.5 Superparamagnetism 24 1.4 Stabilisation of magnetite nanoparticles in suspension 27 1.4.1 The stability of magnetic fluids 27 1.4.2 The surface chemistry of magnetite 28 1.4.3 Steric or entropie stabilisation 30 1.4.4 Stabilisation by long chain surfactants 1.4.5 Clustering and aggregation in aqueous suspension 1.5 Synthesis of magnetite nanoparticles 34 1.5.1 The synthesis of magnetic nanoparticles by alkaline coprecipitation 3 5 1.5.2 The synthesis of magnetic nanoparticles by other methods 39 1.6 Applications of magnetic fluids 42 1.6.1 Superparamagnetic nanoparticles in nanotechnology 42 1.6.2 Magnetic nanoparticles as mediators for magnetic hyperthermia 44 VI 1.6.3 Magnetic nanoparticles as contrast agents for MRI 1.6.4 The NMR relaxation mechanism in aqueous magnetic fluids 45 46 Chapter Two-Experimental Section 2.1 Introduction 2.2 Fast field cycling NMR 2.2.1 Historical development of the technique 55 2.2.2 The field cycling experiment 2.2.3 Practical considerations 2.3 Photon correlation spectroscopy 2.3.1 Principles of the technique 2.3.2 Practical considerations 65 2.4 Other analytical techniques 2.4.1 Atomic absorption spectroscopy 2.4.2 Redox distribution of iron in iron oxide samples 2.4.3 Fatty acid determination 2.4.4 Raman spectroscopy of iron oxide samples 71 2.4.5 Electron Microscopy 71 Chapter Three-Preparation and characterisation of aqueous magnetic fluids 3.1 Introduction 3.2 Experimental 3.2.1 Uncoated nanoparticles suspended in water 73 3.2.2 DNA stabilised magnetic suspensions 3.2.3 Surfactant coated nanoparticle suspensions in water 75 3.3 Results 3.3.1 Uncoated aqueous nanoparticle suspensions 3.3.2 DNA stabilised magnetic suspensions 3.3.3 Surfactant coated nanoparticle suspensions in water VII 3.4 Discussion 3.4.1 Uncoated aqueous nanoparticle suspensions 3.4.2 DNA stabilised magnetic suspensions 3.4.3 Coated nanoparticle suspensions in water 3.5 Conclusion Chapter Four 100-Alkaline coprecipitation o f surfactant stabilised magnetic nanoparticles and their characterisation in suspension 4.1 Introduction 4.2 Experimental 4.2.1 Ammonia coprecipitation of Fe(II) and Fe(III) salts 4.2.2 Sodium chloride assisted coprecipitation 103 4.2.3 Phase transfer from aqueous suspension into heptane 103 4.2.4 Effect of chain length on relaxivity in heptane suspension 4.2.5 Phase transfer from non-aqueous suspension into water 4.2.6 Uncoated nanoparticles in organic solvents 105 4.3 Results 4.3.1 Ammonia coprecipitation 105 4.3. 2 Effect of pH on the NMRD response 4.3.3 Effect of temperature on the NMRD response 4.3.4 Sodium chloride assisted coprecipitation 4.3.5 Effect of chain length on relaxivity in heptane suspension 4.4 Discussion 4.4.1 Sodium chloride assisted and non-assisted coprecipitation 111 4.4.2 Coprecipitated magnetite in heptane 4.4.3 Effect of chain length on relaxivity in heptane suspension 4.4.4 Non aqueous magnetite suspended in aqueous suspension 4.4.5 Uncoated magnetite in water and heptane 4.5 Conclusion VIII Chapter Five-The preparation and characterisation o f non-aqueous magnetic fluids 5.1 Introduction 5.2 Experimental 5.3 Results 5.3.1 General observations 5.3.2 The effect of temperature on the reaction 5.3.3 The effect of concentration on the PCS analysis 5.3.4 NMR relaxation rate measurements 5.3.5 The effect of concentration on the NMRD analysis 5.3.6 The relaxivity of the suspensions: 5.3.7 The effect of applying ultrasonic energy to the magnetic fluids: 5.3.8 Transmission electron microscopy results 5.3.9 Raman spectroscopic study of magnetite particles 5.3.10 Redox-distribution of iron in magnetite 5.4 Discussion 141 5.4.1 The synthesis of non-aqueous magnetic fluids 5.4.2 NMRD characterisation of the non-aqueous magnetic fluids 5.4.3 Consistency of the NMRD results with SPM theory 5.4.4 Interpretation of the NMRD results with SPM theory 5.5 Conclusions Chapter Six 153-The adsorption o f coated magnetite nanoparticles on silica 6.1
Journal of Solid State Chemistry, 2011
Titania-lanthanum phosphate nanocomposites with multifunctional properties have been synthesized ... more Titania-lanthanum phosphate nanocomposites with multifunctional properties have been synthesized by aqueous sol-gel method. The precursor sols with varying TiO 2 :LaPO 4 ratios were applied as thin coating on glass substrates in order to be transparent, hydrophobic, photocatalytically active coatings. The phase compositions of the composite powders were identified by powder X-ray diffraction (XRD) and high-resolution transmission electron microscopy (HR-TEM). The anatase phase of TiO 2 in TiO 2-LaPO 4 composite precursors was found to be stable even on annealing at 800 1C. The glass substrates, coated with TL1 (TiO 2-LaPO 4 composition with 1 mol% LaPO 4) and TL50 (composite precursor containing TiO 2 and LaPO 4 with molar ratio 1:1) sols and annealed at 400 1C, produced contact angles of 741 and 921, respectively, though it is only 621 for pure TiO 2 coating. The glass substrates, coated with TL50 sol, produced surfaces with relatively high roughness and uneven morphology. The TL1 material, annealed at 800 1C, has shown the highest UV photoactivity with an apparent rate constant, k app ¼24 Â 10 À 3 min À 1 , which is over five times higher than that observed with standard Hombikat UV 100 (k app ¼ 4 Â 10 À 3 min À 1). The photoactivity combined with a moderate contact angle (85.31) shows that this material has a promise as an efficient self-cleaning precursor.
International Journal of Biological Macromolecules
Triblock poloxamer copolymer (PM) has been extensively utilized to deliver various ophthalmic pha... more Triblock poloxamer copolymer (PM) has been extensively utilized to deliver various ophthalmic pharmaceutical compounds. The aim of efficient ophthalmic drug delivery strategy is to attain the longer precorneal resident time and good bioavailability of drugs. In this pursuit, the influence of cellulose nanocrystals (CNC) on the in situ gelation behavior of PM and in vitro release of pilocarpine hydrochloride from the nanocomposites formulations was studied. The critical concentration of gelation of PM being 18% (wt/v) was dropped to 16.6% (wt/v) by the addition of a very low percentage of CNC. The reinforcing nature of CNC via H-bonding in the in situ nanocomposite gel also led to an increase in gel strength along with the sustained release of loaded drugs when compared with the pure PM gel. All formulations revealed that the drug release mechanism is controlled by the Fickian diffusion. Thus, the CNC has a significant effect on the gelation behavior, gel strength, and drug release kinetics of PM-CNC formulations.
There has been extensive utilization of poloxamer 407 (PM) for the delivery of various ophthalmic... more There has been extensive utilization of poloxamer 407 (PM) for the delivery of various ophthalmic drugs aimed at efficient ophthalmic drug delivery approach for longer precorneal residence time along with acceptable bioavail-ability of drugs. We have studied the effect of nanocellulose grafted collagen (CGC) on the performance of in situ gels based on PM for the controlled in vitro release of Ketorolac Tromethamine (KT). CGC has shown great influence evident by the reduction in PM critical gelation concentration, increased gel strength, and prolonged the release of loaded drugs compared with the virgin PM gel. The engineered nanocomposite formulations established an anomalous diffusion mechanism along with a Fickian diffusion controlled drug release for 1.5 & 1.75 w/v% CGC reinforced PM. Hence, the synthesized in situ nanocomposites are potential candidates for ophthalmic drug delivery system.
Non-toxic nanocomposites based bio-films obtained from methylcellulose (MC) can reduce environme... more Non-toxic nanocomposites based bio-films obtained from methylcellulose (MC) can reduce environmental problems associated with synthetic polymers. A new facile route for the isolation of cellulose nano-crystals (CNC) from jute waste is successfully utilized here. The fabrication of CNC reinforced MC nanocomposites by film casting technique and the studies of the effect of CNC on the properties of the MC based nanocomposites have been reported. The synthesized nanocomposites have shown improved UV resistance, mechanical, barrier, and thermal properties. FTIR results established the physicochemical compatibility between the drug, MC and CNC in nanocomposites. In vitro permeation studies performed by using Franz diffusion cell revealed diffusion mediated sustained drug release from the devices due to the presence of interaction between MC and CNC through H-bonding, electrostatic interaction between the hydrophilic polymer/CNC chains with the drug and the formation of tortuous path. The nanocomposites can be used for edible packaging and transdermal drug delivery.
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Papers by Swapankumar Ghosh