Search results for "MICE"
showing 10 items of 6027 documents
Viscosimetric investigation of the interaction between sodium dodecylsulfate micelles and a polymer drug carrier
1993
Abstract The viscosities of aqueous sodium dodecyl sulfate solutions with and without α,β-poly( N -hydroxyethyl)- dl -aspartamide (PHEA), at 15, 25 and 35°C are reported. The viscosities of SDS and of PHEA aqueous solutions are discussed in terms of the parameter D [D = ( η η 0 − 1)/φ] describing the non-ideal behavior of SDS micelles and of PHEA macromolecules. The viscosities of SDS plus PHEA aqueous solutions, discussed in terms of the parameter F [ F = η rel ( PHEA ) + η rel ( SDS ) − η rel ( SDS + PHEA )] M , demonstrate the occurrence of interactions between SDS micelles and the PHEA macromolecule. Both D and F are scarcely influenced by temperature variation.
Thermodynamics ofN,N,N-octylpentyldimethyl-ammonium chloride in water-urea mixtures
1997
Specific conductivities, densities, heat capacities, and enthalpies of dilution at 25‡C were measured forN,N,N-octylpentyldimethylammonium chloride (OPAC) in water-urea mixtures at various urea concentrations mu as functions of the surfactant concentration ms. From conductivity data, the cmc and the degree of the counterion dissociation Β of the OPAC micelles were calculated. The cmc increases linearly with increasingm u while Βvs. mu is a smooth concave curve. From the experimental thermodynamic data, the apparentY Φ and partialY 2 molar properties (volumes, heat capacities, and relative enthalpies) are derived as functions of mu andm s . The effect of urea on the dependences of the differ…
Calorimetric study on the solubilization of some primary alcohols by reversed AOT micelles
1989
A calorimetric method to evaluate, at the same time, the distribution constant and the standard enthalpy of transfer of a solute partitioned between organic phase and reversed micelles is proposed. The method was applied to the partition of methanol, 1-propanol and 1-pentanol between n-heptane and AOT reversed micelles containing water at 25°C. The results show that the distribution constant decreases as the alcohol alkyl chain length increases and that the solubilization site can change as the water content of reversed AOT micelles increases. In particular, at sufficiently high water content, methanol seems to be preferably solubilized in the aqueous pseudophase whereas 1-pentanol prefers …
Thermodynamic Evidence of Cyclodextrin−Micelle Interactions
2002
The enthalpy of transfer (ΔHt) of hydroxypropyl-α-cyclodextrin (HP-α-CD), hydroxypropyl-β-cyclodextrin (HP-β-CD), and β-cyclodextrin (β-CD) from water to the aqueous C6F13CO2Na and C7F15CO2Na solutions were determined in the pre- and post-micellar regions. The behavior of the macrocycles is system specific. Generally, the magnitude of the enthalpy is influenced by several factors: (1) the alkyl chain length of the surfactant, (2) the cyclodextrin cavity and its alkylation, (3) the interactions between the free cyclodextrin and the free surfactant, (4) the host−guest equilibrium constant, (5) the host/guest stoichiometry, and (6) the micelle-cyclodextrin (free and/or complexed) interactions…
Heat capacities, volumes and solubilities of pentanol in aqueous alkyltrimethylammonium bromides
1988
Apparent molar heat capacities and volumes of pentanol, 0.05m in decyl-, tetradecyl- and hexadecyltrimethylammonium bromides micellar solutions, were measured at 25°C. They were assumed to approach the standard infinite dilution values and rationalized by means of previously reported equations following which the distribution constant between the aqueous and the micellar phase, heat capacity, and volume of pentanol in both phases are simultaneously derived. The present results show that the volume of the micellar core does not seem to have a significant effect on the apparent molar volume and heat capacity of pentanol in the micellar phase and on the free energy of transfer of pentanol from…
A simple method to prepare solid nanoparticles of water-soluble salts using water-in-oil microemulsions
2000
A new and simple method to prepare solid nanoparticles of water-soluble salts using water-in-oil microemulsions is described. In particular, starting from water/sodium bis(2-ethylhexyl)sulfosuccinate/n-heptane microemulsions carrying inside the aqueous core of the reversed micelles some water-soluble salts [CaCl2, Na2HPO4, Cu(NO3)2], after evaporation of the volatile components (water and apolar organic solvent), the resulting inorganic salt/surfactant composites were found to be totally dispersible in pure n-heptane. The presence of nanoparticles in these resuspended composites was ascertained by transmission electron microscopy observation of samples obtained by gentle evaporation of the …
Polymer−Surfactant Interactions. A Quantitative Approach to the Enthalpy of Transfer of Poly(Ethylene Glycol)s from Water to the Aqueous Sodium Perfl…
2000
The enthalpy of transfer (ΔHt) of nonionic polymers at a fixed concentration from water to aqueous substrate solutions as a function of the substrate concentration (fSmS) was determined. The substrates studied are sodium perfluorobutanoate to sodium perfluorooctanoate, and the polymers are poly(ethyleneglycol)s with molecular weights of 400 and 35 000. For the PEG 400-sodium perfluoroheptanoate−water systems, measurements were also performed at some polymer compositions. As a general feature, the enthalpy of transfer steeply changes with fSmS, reaching a maximum beyond which it decreases, tending to level off. A qualitative analysis of the enthalpy data assigned the steep increase of ΔHt to…
Aminofunctional polyethers: smart materials for applications in solution and on surfaces
2013
In recent years, biocompatible polyethers with multi-aminofunctionality have been used for a variety of applications in different fields. Both established and recently developed synthesis strategies for such polymers and applications as stimuli-responsive materials, non-viral vectors, shell crosslinked micelles and for surface functionalization are reviewed. The intriguing potential of such materials is due to both polyether and polyamine components and can thus be readily tuned by the copolymer microstructure and composition. © 2013 Society of Chemical Industry
Synthesis and biopharmaceutical characterisation of new poly(hydroxyethylaspartamide) copolymers as drug carriers.
2001
Abstract Four new poly(hydroxyethylaspartamide)-based copolymers bearing (a) poly(ethylene glycol) 2000, (b) poly(ethylene glycol) 5000, (c) poly(ethylene glycol) 2000 and hexadecylalkyl, (d) poly(ethylene glycol) 5000 and hexadecylalkyle, as pendant groups were synthesised. The copolymers were obtained by partial aminolysis of polysuccinimide with poly(ethylene glycol) and hexadecylalkyl amino derivatives followed by reaction with ethanolamine. Naked polyhydroxyaspartamide was obtained by polysuccinimide reaction with ethanolamine. The nuclear magnetic resonance, infrared, light scattering and elemental analysis allowed for the extensive physico-chemical characterisation of the carriers. T…
Long-term biodistribution study of HPMA- ran -LMA copolymers in vivo by means of 131 I-labeling
2018
Abstract Background For the evaluation of macromolecular drug delivery systems suitable pre-clinical monitoring of potential nanocarrier systems is needed. In this regard, both short-term as well as long-term in vivo tracking is crucial to understand structure-property relationships of polymer carrier systems and their resulting pharmacokinetic profile. Based on former studies revealing favorable in vivo characteristics for 18 F–labeled random (ran) copolymers consisting of N-(2-hydroxypropyl)methacrylamide (HPMA) and lauryl methacrylate (LMA) – including prolonged plasma half-life as well as enhanced tumor accumulation – the presented work focuses on their long-term investigation in the li…