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Nazrul Islam - One of the best experts on this subject based on the ideXlab platform.
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effects of chemical conjugation of l leucine to chitosan on Dispersibility and controlled release of drug from a nanoparticulate dry powder inhaler formulation
Molecular Pharmaceutics, 2016Co-Authors: Mohammad Muhsin, Kenneth W Beagley, Vito Ferro, Graeme A. George, Hui Wang, Nazrul IslamAbstract:This study investigated l-leucine-conjugated chitosan as a drug delivery vehicle in terms of Dispersibility and controlled release from a nanoparticulate dry powder inhaler (DPI) formulation for pulmonary delivery using diltiazem hydrochloride (DH) as the model drug. DH-loaded nanoparticles of chitosan and conjugate were prepared by water-in-oil emulsification followed by glutaraldehyde cross-linking. Nanoparticles were characterized by dynamic light scattering for particle size, X-ray photoelectron spectroscopy for surface composition, and twin stage impinger for drug Dispersibility. The controlled release of DH was studied in phosphate-buffered saline (pH 7.3 ± 0.2, 37 °C) using UV spectrophotometry. The fine particle fractions of conjugated chitosan with and without drug were higher than those of nonconjugated chitosan nanoparticles. The conjugate nanoparticles were superior to those of unmodified chitosan in drug loading, entrapment efficiency, and controlled release profile. The higher Dispersibility...
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effects of chemical conjugation of l leucine to chitosan on Dispersibility and controlled release of drug from a nanoparticulate dry powder inhaler formulation
Faculty of Health; Institute of Health and Biomedical Innovation; Science & Engineering Faculty, 2016Co-Authors: Mohammad Muhsin, Kenneth W Beagley, Vito Ferro, Graeme A. George, Hui Wang, Nazrul IslamAbstract:This study investigated L-leucine conjugated chitosan as a drug delivery vehicle in terms of Dispersibility and controlled release from a nanoparticulate dry powder inhaler (DPI) formulation for pulmonary delivery using diltiazem hydrochloride (DH) as the model drug. DH-loaded nanoparticles of chitosan and conjugate were prepared by water-in-oil emulsification followed by glutaraldehyde crosslinking. Nanoparticles were characterised by dynamic light scattering (DLS) for particle size, X-ray Photoelectron Spectroscopy (XPS) for surface composition, and by Twin Stage Impinger (TSI) for drug Dispersibility. The controlled release of DH was studied in phosphate buffered saline (PBS, pH 7.3±0.2, 37 °C) using UV spectrophotometry. The fine particle fractions (FPFs) of conjugated chitosan with and without drug were higher than those of non-conjugated chitosan nanoparticles. The conjugate nanoparticles were superior to those of unmodified chitosan in drug loading, entrapment efficiency and controlled release profile. The higher Dispersibility was attributed to the amphiphilic environment of the L-leucine conjugate and hydrophobic crosslinks and the release profile reflects the greater swelling. The conjugated chitosan nanoparticles could be useful, after appropriate testing for biodegradability and toxicity, as an alternative carrier for lung drug delivery with enhanced aerosolization and prolonged drug release from nanoparticulate DPI formulations.
Jin Suk Chung - One of the best experts on this subject based on the ideXlab platform.
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Dispersibility of reduced alkylamine-functionalized graphene oxides in organic solvents
Journal of Colloid and Interface Science, 2014Co-Authors: Jinhee Jang, Viet Hung Pham, Jin Suk ChungAbstract:Abstract The alkylamine functionalization of graphene oxide is well known as an efficient approach to prepare reduced functionalized graphene oxide (RFGO) that is highly dispersible in organic solvents. Herein, we systematically investigated the effects of long-chain alkylamine functionalization of graphene oxide on the organic solvent Dispersibility and electrical conductivity of RFGO. Three kinds of alkylamines, octylamine, dodecylamine and hexadecylamine, were chosen as functionalization agents. The alkylamine functionalization of graphene oxide was characterized by X-ray photoelectron spectroscopy, Fourier transform infrared spectroscopy, Raman spectroscopy, thermogravimetric analysis and X-ray diffraction. RFGO using octylamine exhibited the best electrical conductivity of greater than 180 S/m. All of the RFGOs had excellent Dispersibility, up to 3.0 mg/mL, in organic solvents, with Hansen solubility parameters in the range of 6.3
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superior dispersion of highly reduced graphene oxide in n n dimethylformamide
Journal of Colloid and Interface Science, 2012Co-Authors: Thanh Truong Dang, Viet Hung Pham, Seung Hyun Hur, Eui Jung Kim, Byungseon Kong, Jin Suk ChungAbstract:Here, we report the effect of temperature on the extent of hydrazine reduction of graphene oxide in N,N-dimethylformamide (DMF)/water (80/20 v/v) and the Dispersibility of the resultant graphene in DMF. The highly reduced graphene oxide (HRG) had a high C/O ratio and good Dispersibility in DMF. The good Dispersibility of HRGs is due to the solvation effect of DMF on graphene sheets during the hydrazine reduction, which diminishes the formation of irreversible graphene sheet aggregates. The Dispersibility of the HRGs was varied from 1.66 to 0.38 mg/mL when the reduction temperature increased from 25 °C to 80 °C. The Dispersibility of the HRGs was inversely proportional to the electrical conductivity of the HRGs, which varied from 17,400 to 25,500 S/m. The relationships between the C/O ratio, electrical conductivity, and Dispersibility of the HRGs were determined and these properties were found to be easily controlled by manipulating the reduction temperature.
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chemical functionalization of graphene sheets by solvothermal reduction of a graphene oxide suspension in n methyl 2 pyrrolidone
Journal of Materials Chemistry, 2011Co-Authors: Viet Hung Pham, Seung Hyun Hur, Eui Jung Kim, Tran Viet Cuong, Eun Woo Shin, Jin Suk ChungAbstract:We report a simple and effective method for reducing and functionalizing graphene oxide into chemically converted graphene by solvothermal reduction of a graphene oxide suspension in N-methyl-2-pyrrolidone (NMP). Graphene oxide sheets were functionalized by free radicals generated during heating of NMP in the presence of air. The degree of functionalization was easily controlled by manipulating the reduction time. High functionalized solvothermally reduced graphene oxide (STRG) shows superior Dispersibility in various organic solvents, while slightly functionalized STRG shows excellent electrical conductivity. The superior Dispersibility of highly functionalized STRG in organic solvents was attributed to the steric effect of functionalized groups on the surface of STRG sheets. Free-standing STRG paper that was reduced for 1 h exhibited electrical conductivity as high as 21600 S m−1, while the Dispersibility of STRG that was reduced for 5 h was as high as 1.4 mg mL−1.
Claire Gaiani - One of the best experts on this subject based on the ideXlab platform.
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changes in surface chemical composition relating to rehydration properties of spray dried camel milk powder during accelerated storage
Food Chemistry, 2021Co-Authors: Trinh T Ton, Bhesh Bhandari, Claire Gaiani, Nidhi BansalAbstract:Abstract Alterations in surface chemical composition relating to rehydration properties of spray-dried camel milk powders during accelerated storage (11–33% RH, 37 °C) over 18 weeks were investigated. The results showed that the surface of the fresh spray-dried camel milk powder (t = 0) was dominated by lipids (78%), followed by proteins (16%) and lactose (6%). During storage, the surface protein and lactose content decreased while the surface lipid content increased, resulting in an increase in surface hydrophobicity and slight agglomeration of the powder, especially for powder kept at 33% RH. Although fresh camel milk powder had very poor wettability, it displayed very high Dispersibility and solubility (99%). During storage, Dispersibility and solubility declined with increasing storage time and increasing RH levels, which correlated with an increase in surface lipid content. However, at the end of the storage period, camel milk powder still retained very high solubility (>93%).
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physical and functional properties of whole milk powders prepared from concentrate partially acidified with co2 at two temperatures
International Dairy Journal, 2016Co-Authors: Leni Kosasih, Bhesh Bhandari, Sangeeta Prakash, Nidhi Bansal, Claire GaianiAbstract:Abstract Effects of carbonation of whole milk concentrate on spray dried powder properties were investigated. Concentrate acidification by CO 2 addition (2000 ppm) was found to strongly modify the functional properties (solubility, Dispersibility) and structural/physical properties (porosity, free fat) of the resulting powders. For concentrates treated at low temperature (where the majority of emulsified fat is in a solid state at 4 °C), colloidal calcium phosphate (CCP) release, casein dissociation and fat coalescence were observed. For warm CO 2 treated concentrates (30 °C) only CCP release was observed. The best functional properties (higher solubility and Dispersibility) were found for powders produced from the warm treated concentrates, which were possibly due to the high porosity and better fat globule preservation.
Jonathan N Coleman - One of the best experts on this subject based on the ideXlab platform.
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solvent exfoliation of transition metal dichalcogenides Dispersibility of exfoliated nanosheets varies only weakly between compounds
ACS Nano, 2012Co-Authors: Graeme Cunningham, Shane D Bergin, Mustafa Lotya, Clotilde S Cucinotta, Stefano Sanvito, Robert Menzel, Milo S P Shaffer, Jonathan N ColemanAbstract:We have studied the dispersion and exfoliation of four inorganic layered compounds, WS2, MoS2, MoSe2, and MoTe2, in a range of organic solvents. The aim was to explore the relationship between the chemical structure of the exfoliated nanosheets and their Dispersibility. Sonication of the layered compounds in solvents generally gave few-layer nanosheets with lateral dimensions of a few hundred nanometers. However, the dispersed concentration varied greatly from solvent to solvent. For all four materials, the concentration peaked for solvents with surface energy close to 70 mJ/m2, implying that all four have surface energy close to this value. Inverse gas chromatography measurements showed MoS2 and MoSe2 to have surface energies of ∼75 mJ/m2, in good agreement with Dispersibility measurements. However, this method suggested MoTe2 to have a considerably larger surface energy (∼120 mJ/m2). While surface-energy-based solubility parameters are perhaps more intuitive for two-dimensional materials, Hansen solubil...
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measurement of multicomponent solubility parameters for graphene facilitates solvent discovery
Langmuir, 2010Co-Authors: Yenny Hernandez, David Rickard, Shane D Bergin, Mustafa Lotya, Jonathan N ColemanAbstract:We have measured the Dispersibility of graphene in 40 solvents, with 28 of them previously unreported. We have shown that good solvents for graphene are characterized by a Hildebrand solubility parameter of δT ∼ 23 MPa1/2 and Hansen solubility parameters of δD ∼ 18 MPa1/2, δP ∼ 9.3 MPa1/2, and δH ∼ 7.7 MPa1/2. The Dispersibility is smaller for solvents with Hansen parameters further from these values. We have used transmission electron microscopy (TEM) analysis to show that the graphene is well exfoliated in all cases. Even in relatively poor solvents, >63% of observed flakes have <5 layers.
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multicomponent solubility parameters for single walled carbon nanotube solvent mixtures
ACS Nano, 2009Co-Authors: Shane D Bergin, Zhenyu Sun, David Rickard, Philip V Streich, James P Hamilton, Jonathan N ColemanAbstract:We have measured the Dispersibility of single-walled carbon nanotubes in a range of solvents, observing values as high as 3.5 mg/mL. By plotting the nanotube Dispersibility as a function of the Hansen solubility parameters of the solvents, we have confirmed that successful solvents occupy a well-defined range of Hansen parameter space. The level of Dispersibility is more sensitive to the dispersive Hansen parameter than the polar or H-bonding Hansen parameter. We estimate the dispersion, polar, and hydrogen bonding Hansen parameter for the nanotubes to be = 17.8 MPa(1/2), = 7.5 MPa(1/2), and = 7.6 MPa(1/2). We find that the nanotube Dispersibility in good solvents decays smoothly with the distance in Hansen space from solvent to nanotube solubility parameters. Finally, we propose that neither Hildebrand nor Hansen solubility parameters are fundamental quantities when it comes to nanotube-solvent interactions. We show that the previously calculated dependence of nanotube Hildebrand parameter on nanotube diameter can be reproduced by deriving a simple expression based on the nanotube surface energy. We show that solubility parameters based on surface energy give equivalent results to Hansen solubility parameters. However, we note that, contrary to solubility theory, a number of nonsolvents for nanotubes have both Hansen and surface energy solubility parameters similar to those calculated for nanotubes. The nature of the distinction between solvents and nonsolvents remains to be fully understood.
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multicomponent solubility parameters for single walled carbon nanotube solvent mixtures
ACS Nano, 2009Co-Authors: Shane D Bergin, David Rickard, Philip V Streich, James P Hamilton, Jonathan N ColemanAbstract:We have measured the Dispersibility of single-walled carbon nanotubes in a range of solvents, observing values as high as 3.5 mg/mL. By plotting the nanotube Dispersibility as a function of the Hansen solubility parameters of the solvents, we have confirmed that successful solvents occupy a well-defined range of Hansen parameter space. The level of Dispersibility is more sensitive to the dispersive Hansen parameter than the polar or H-bonding Hansen parameter. We estimate the dispersion, polar, and hydrogen bonding Hansen parameter for the nanotubes to be = 17.8 MPa1/2, = 7.5 MPa1/2, and = 7.6 MPa1/2. We find that the nanotube Dispersibility in good solvents decays smoothly with the distance in Hansen space from solvent to nanotube solubility parameters. Finally, we propose that neither Hildebrand nor Hansen solubility parameters are fundamental quantities when it comes to nanotube−solvent interactions. We show that the previously calculated dependence of nanotube Hildebrand parameter on na...
Mohammad Muhsin - One of the best experts on this subject based on the ideXlab platform.
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effects of chemical conjugation of l leucine to chitosan on Dispersibility and controlled release of drug from a nanoparticulate dry powder inhaler formulation
Molecular Pharmaceutics, 2016Co-Authors: Mohammad Muhsin, Kenneth W Beagley, Vito Ferro, Graeme A. George, Hui Wang, Nazrul IslamAbstract:This study investigated l-leucine-conjugated chitosan as a drug delivery vehicle in terms of Dispersibility and controlled release from a nanoparticulate dry powder inhaler (DPI) formulation for pulmonary delivery using diltiazem hydrochloride (DH) as the model drug. DH-loaded nanoparticles of chitosan and conjugate were prepared by water-in-oil emulsification followed by glutaraldehyde cross-linking. Nanoparticles were characterized by dynamic light scattering for particle size, X-ray photoelectron spectroscopy for surface composition, and twin stage impinger for drug Dispersibility. The controlled release of DH was studied in phosphate-buffered saline (pH 7.3 ± 0.2, 37 °C) using UV spectrophotometry. The fine particle fractions of conjugated chitosan with and without drug were higher than those of nonconjugated chitosan nanoparticles. The conjugate nanoparticles were superior to those of unmodified chitosan in drug loading, entrapment efficiency, and controlled release profile. The higher Dispersibility...
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effects of chemical conjugation of l leucine to chitosan on Dispersibility and controlled release of drug from a nanoparticulate dry powder inhaler formulation
Faculty of Health; Institute of Health and Biomedical Innovation; Science & Engineering Faculty, 2016Co-Authors: Mohammad Muhsin, Kenneth W Beagley, Vito Ferro, Graeme A. George, Hui Wang, Nazrul IslamAbstract:This study investigated L-leucine conjugated chitosan as a drug delivery vehicle in terms of Dispersibility and controlled release from a nanoparticulate dry powder inhaler (DPI) formulation for pulmonary delivery using diltiazem hydrochloride (DH) as the model drug. DH-loaded nanoparticles of chitosan and conjugate were prepared by water-in-oil emulsification followed by glutaraldehyde crosslinking. Nanoparticles were characterised by dynamic light scattering (DLS) for particle size, X-ray Photoelectron Spectroscopy (XPS) for surface composition, and by Twin Stage Impinger (TSI) for drug Dispersibility. The controlled release of DH was studied in phosphate buffered saline (PBS, pH 7.3±0.2, 37 °C) using UV spectrophotometry. The fine particle fractions (FPFs) of conjugated chitosan with and without drug were higher than those of non-conjugated chitosan nanoparticles. The conjugate nanoparticles were superior to those of unmodified chitosan in drug loading, entrapment efficiency and controlled release profile. The higher Dispersibility was attributed to the amphiphilic environment of the L-leucine conjugate and hydrophobic crosslinks and the release profile reflects the greater swelling. The conjugated chitosan nanoparticles could be useful, after appropriate testing for biodegradability and toxicity, as an alternative carrier for lung drug delivery with enhanced aerosolization and prolonged drug release from nanoparticulate DPI formulations.