Physical studies of sugar-based surfactants / Seyed Mohammad Mirzadeh Hosseini
Phospholipids are widely used to produce delivery systems for the entrapment and release of drugs from vesicles, also called liposomes, especially for chemotherapy. The replacement of ionic phospholipids with non-ionic glycolipids may help to improve the stability of drug carriers due to stronger...
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| Format: | Thesis |
| Published: |
2017
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| Subjects: | |
| Online Access: | http://studentsrepo.um.edu.my/7229/2/All.pdf http://studentsrepo.um.edu.my/7229/6/mohammad.pdf http://studentsrepo.um.edu.my/7229/ |
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| Summary: | Phospholipids are widely used to produce delivery systems for the entrapment
and release of drugs from vesicles, also called liposomes, especially for chemotherapy.
The replacement of ionic phospholipids with non-ionic glycolipids may help to improve
the stability of drug carriers due to stronger molecular interactions. However, the
synthetic challenge for highly pure glycolipids in combination with the vast structural
diversity of carbohydrates makes a random testing of sugar head-groups for the
optimization of vesicle stability highly inefficient. On the other hand, computational
methods may be used to predict detailed interactions of the surfactants. However, this
method requires experimental validation. Of particular interest is hydrogen bonding
within the hydrophilic sugar head-group region. Unfortunately the intermolecular
hydrogen bonding between surfactants is difficult to measure. Instead, the validation of
computational results can focus on the interaction of the surfactants with water. This
study aims to determine the bound water content of glycolipids in the lamellar phase,
which is a good approximation for vesicular assemblies. In this regard, several
glycolipid molecules were synthesised and investigated. The bound water content was
examined by deuterium NMR (2H-NMR) and differential scanning calorimetry (DSC).
In the latter the melting enthalpy of free water was measured to indirectly determine the
bound water content. These experimental results are compared with computational
studies, which model the slightly curved vesicle bilayer as a multilayer analogue of the
lamellar phase. The complexity of carbohydrate stereochemistry and their hydrogen
bonding is very intriguing, and minor changes in orientation can cause significant
effects on the self-assembly. With respect to this, the stereo chemical effect of anomers
and epimers on the self-assembly of Guerbet glycosides was investigated. The
comparison of phase transition temperatures revealed a cis-trans correlation of
anomeric-epimeric pairs based on glucose and galactose, which can be explained by the
direction of hydrogen bonding of the hydroxyl group at the epimeric C-4 carbon. |
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