1,721,067 research outputs found
Caratterizzazione termoanalitica e strutturale di modificazioni polimorfe e pseudopolimorfe del complesso molecolare tetroxoprim-sulfametrolo
No full textThermal behaviour of crystalline and non-crystalline forms of triacetyl alfa-, beta-, and gamma-cyclodextrins.
No full textStudio termoanalitico dello scambio di solvente in solvati isostrutturali del complesso tetroxoprim-sulfametrolo
No full textRelationships between structural and thermal properties of anhydrous and solvated crystalline forms of brodimoprim
No full textThe isolation and physicochemical characterization of four crystalline modifications of brodimoprim (5-[(4-bromo-3,5-dimethoxyphenyl)methyl]-2,4-pyrimidinediamine,
hereinafter BMP), a structural analog of trimethoprim (TMP), are reported. These phases include an unsolvated form of BMP, a hemihydrate (BMP0.5H2O), a 1:1 solvate containing isopropanol (BMPC3H7OH(iso)), and a hemichloroformate (BMP0.5CHCl3). Unsolvated BMP was isolated both by recrystallization from a range of common solvents as well as by thermal decomposition of the above solvates and no evidence for polymorphism was found. PXRD data indicated that the three solvates crystallize in different arrangements. Data from thermal analysis (thermogravimetry (TGA), hot stage microscopy (HSM), differential scanning calorimetry (DSC)) of the solvates containing water and iso-propanol were interpreted on the basis of their singlecrystal X-ray structures which revealed that the modes of solvent inclusion in BMP0.5H2O and BMPC3H7OH(iso) may be described as ‘isolated site’ and ‘lattice channel’ type inclusions, respectively
Effect of micelles formation and drug loading on thermal properties of Inulin-graft- Vitamin E (INVITE) polymers
Full text linkIn order to verify the effect of different processes on the starting polymers INVITE, their thermal properties have been deeply investigated. In particular, micelles from INVITE polymers, at different degrees of substitution in VITE, have been prepared by the dialysis method so obtaining three different micelle systems. The same systems have been further loaded with the hydrophobic drug curcumin with the aim to evaluate the influence of a hydrophobic drug in the micelles core. These studies are aimed to verify whether the tested systems could result stable at physiological temperatures and how the different parameters tested such as lyophilization, micelle formation or drug loading might influence the overall thermal behaviors of the systems for an optimized preparation of the subsequent formulation
Thermal studies of solvent exchange between isostructural solvates of tetroxoprim and non-isostructural solvates of brodimoprim.
No full textOrder-disorder enantiotropy, monotropy and isostructurality in a tetroxoprim-sulfametrole 1:1 molecular complex: crystallographic and thermal studies
No full textTwoenantiotropic polymorphs of a tetroxoprim (TXP)-sulfametrole (SMTR) 1:1 molecular complex monohydrate and two isostructural TXP-SMTR 1:1 molecular complex solvates with methanol and ethanol were grown and studied by X-ray diffraction and thermal methods (thermogravimetric analysis and differential scanning calorimetry). Interconversion of the polymorphic hydrates is essentially an order/disorder transition involving a substituent on the TXP molecule. These hydrated phases may be described as ‘‘nearly isostructural’’ with the methanol and ethanol solvates. Thermal data for decomposition of the solvates were rationalized on the basis of the location and topologies of solvent crystallographic sites. Solid-state properties of two monotropic polymorphs of the unsolvated TXP-SMTR 1:1 molecular complex were also investigated and the theoretical and experimental phase diagrams of the individual components were assessed. The existence of polymorphic and pseudopolymorphic forms is determined by conformational flexibility of the TXP-SMTR bimolecular complex components, a tendency for molecular disorder in TXP, the ability of the drug complex to form intricate, highly stabilized hydrogen-bonded frameworks, and the competition between nonspecific van der Waals and specific hydrogen bond interactions
Thermal and structural characterization and pharmaceutical use of peracetylated alfa, beta and gamma cyclodextrin.
No full textCHAPTER 7. Physico-chemical Characterisation of Silk-based Materials
No full textPhysico-chemical characterisation is essential to define and to assure quality, safety and efficacy of silk-based materials when intended for pharmaceutical and biomedical use. In fact, the possible interconversion and interactions between the various conformations of the fibroin and sericin, and the transitions
from the most stable crystalline forms to the metastable amorphous ones, can modify (i) the release properties of the drugs from the silk-based delivery systems, (ii) the silk-based carrier's superficial properties, determining the targeting mechanisms to the site of action. Thermal analysis and spectrophotometric methods, supported by X-ray diffraction analysis and microscopic techniques, are useful to characterise the main crystal structures and the three conformations, Silk I, Silk II and unstable Silk III, of proteins. This chapter reports some applicative examples of the analyses performed with these techniques concerning the characterisation of silk proteins and silk-based micro/nano-drug delivery systems
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