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Title: Manufacture and characterization of chitosan based hyrogels for drug delivery and biomedical applications
Author: Alkayyali, Lamees Bilal Yahia
Awarding Body: Queen's University Belfast
Current Institution: Queen's University Belfast
Date of Award: 2013
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The weak rheological properties of CS solutions limit their applications in controlled delivery systems. Therefore, polyelectrolyte complex gels were prepared by blending CS with GZ in polybydric alcohols/water vehicles. In addition, CS was blended with PVA in aqueous systems containing dimethylsu1foxide (DMSO). Increasing polymer concentration enhanced the gel properties of the polymer blends. Inclusion of propylene glycol or glycerol in CS/GZ systems resulted in increasing the gel stability. Although glycerol systems showed greater stability than propylene glycol ones, the later exhibited stronger gel properties. The viscoelastic properties of these systems significantly decreased with increasing the pH of the gels resulted in increasing drug release rates. Inclusion of DMSO within PVA/CS systems resulted in their gelation. which increased with increasing DMSO content. The mechanical strength of CS films increased by including PVA, whereas incorporating DMSO resulted in plasticizing effects on the films. However, annealing of the films resulted in increasing their mechanical strength. Inclusion of PVA increased the swelling and hence drug release properties from the films, whereas increasing DMSO content decreased such properties. Another approach used to enhance the mechanical properties of CS films was by preparing interpenetrating networks (IPNs) with poly (hydroxyethylmethacrylate) p(HEMA). The resultant CS/p(HEMA) semi-IPNs exihibited greater mechanical strength comparing to CS films. Coating poiy(methacrylic acid (MAA)-co-HEMA) hydrogeIs by CS resulted in decreasing their swelling properties and hence increasing their mechanical strength. These results may enhance the potential applications ofp(MAA-co-HEMA.) hydrogels in controlled delivery systems. Hydrogels based on p(HEMA) microemulsion networks were prepared using different oils to produce controlled release systems. CS was included within these hydrogels to modify the viscosity of the oil phase and hence to study its effects on the drug release properties. Unexpectedly, inclusion of CS resulted in increasing drug release rates which increased with increasing CS content within the hydrogels.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available