Understanding effects of sulphation of physical and chemical characteristics of polysaccharides: new renewable biopolymers for personal care products

Carbohydrates, derived from plant and animal sources, have many natural and commercial applications arising from their physical, chemical and interaction properties. As carbohydrate modifications have resulted in observable differences to these properties, modified samples have been used in various applications from pharmaceutical agents to emulsions and food components. Several carbohydrates will be used during this project as representative linear uncharged, linear charged and branched uncharged examples. The project will target improving NMR-based carbohydrate analysis methods, the generation of novel carbohydrate modifications and modification methods, and the measurement of the physical, chemical and interaction properties of modified samples.
Carbohydrate characterisation enables the starting material structure to be ascertained and any modification and interaction sites determined. Nuclear Magnetic Resonance (NMR) is the most powerful and versatile structural analysis method for carbohydrates and requires methodological improvements to allow individual atom assignments to be made. Combining this with additional methods, such as size exclusion chromatography and mass spectrometry, as well as recent developments in the field of carbohydrate NMR via diffusion spectroscopy, will allow comparison of those methods that are able to separate of distinguish the different sized fractions, and assist structural characterisation. These combined methods will also allow the repeating unit distribution the frequency with which these units occur to be determined.
Modifications have demonstrably affected the physical chemical and interaction properties of the carbohydrates used in this project. A panel of modifications focusing on the addition of charges to the carbohydrate via sulphation, oxidation to carboxyl groups but also reduction, will be performed on each of the carbohydrates selected. The analysis of modified products generated will be performed using the NMR-based structural analysis method developed above with the precise location of modification sites determined. Additional factors that could influence modification sites will also be investigated to determine whether specific atomic positions can be targeted when a novel method is developed rather than that achieved traditionally.
Previous carbohydrate modifications have been investigated in terms of their effect on the physical and chemical properties of the samples. The principal focus for these properties will be on rheological measurements, owing to potential application in the commercial sector by our industrial partner. Other physical and chemical properties which are important to study include solubility, viscosity, molecular mobility, deposition and cleaning. Many of these properties could be measured during a placement period in our commercial partner's laboratories as well as on the University's NMR spectrometers.
In addition to the effect that carbohydrate modification has on the physical and chemical properties of the resultant sample, effects are also evident in the ability of the carbohydrate to interact with other compounds that it may encounter. The effect that modifications have on these interactions will also be studied using several test systems for proteins, other carbohydrates and/or surfactant molecules. In certain cases, the study of interaction variability, using structural analysis methods, will be coupled with biological assays. Studying these interactions structurally will require the combination of NMR with other common methods, such as isothermal titration calorimetry and circular dichroism or differential scanning fluorimetry/calorimetry, to generate kinetics and protein stability data respectively when the modified polysaccharide is added.