title: Chemometric, physicomechanical and rheological analysis of the sol-gel dynamics and degree of crosslinking of glycosidic polymers.
abstract: The influence of calcium (Ca(2+)), zinc (Zn(2+)) and barium (Ba(2+)) ions on the sol-gel interconversion dynamics, degree of crosslinking and the matrix resilience of crosslinked alginate gelispheres was determined. The dependent compositional and operational variables of crosslinking make it a challenging task to optimize the degree of crosslinking and the physicomechanical properties of alginate gelispheres. The combinatory approach of textural profiling, assessing pertinent rheological descriptors and chemometric model analysis of the sol-gel interconversion mechanisms and energy paradigms involved during crosslinking, hydration and erosion of gelispheres was explored. Molecular structural modelling of the gelispheres provided a mechanistic understanding of the sol-gel interconversion phenomena and their influence on the degree of crosslinking, the hydrational dynamics and gelisphere formation. Rheological analysis revealed offset yield point values of 6.1 mg ml(-1) and 8.0 mg ml(-1) were computed from fitted regression curves for determining the crosslinker concentration required for combinatory crosslinkers such as Ca/Zn/Ba ions and Ba/Zn, respectively. The influence of hydration on the erosion was a direct function of the gelispheres physicomechanical strength. Textural profiling characterized the gelisphere matrices for their resilience. The various crosslinkers interacted with monomeric units at varying intensities. Ba-crosslinked gelispheres were brittle with dense polymeric networks. Zn-crosslinked gelispheres produced permeable resilient matrices when hydrated and Ca-crosslinked gelispheres demonstrated intermediate resilience with greater G/M ratio alginate grades. Chemometrical analysis explicated a potential link between several phenomena such as the type of crosslinkers employed, the static shear-rate viscosity attained, the matrix resilience and the associated sol-gel mechanisms and energy paradigms of crosslinked gelispheres.
authors.affiliation: Department of Pharmacy and Pharmacology, University of the Witwatersrand, 7 York Road, Parktown, 2193, Johannesburg, South Africa.
authors.forename: Y E
authors.initials: YE
authors.lastname: Choonara
authors.forename: V
authors.initials: V
authors.lastname: Pillay
authors.forename: N
authors.initials: N
authors.lastname: Singh
authors.forename: R A
authors.initials: RA
authors.lastname: Khan
authors.forename: V M K
authors.initials: VM
authors.lastname: Ndesendo
mesh_terms: D000464:Alginates / Q000737:chemistry*; D001672:Biocompatible Materials / Q000737:chemistry*; D020650:Combinatorial Chemistry Techniques; D003198:Computer Simulation; D003432:Cross-Linking Reagents / Q000737:chemistry*; D004548:Elasticity; D005782:Gels / Q000737:chemistry; D020723:Glucuronic Acid / Q000737:chemistry; D006027:Glycosides / Q000737:chemistry*; D006603:Hexuronic Acids / Q000737:chemistry; D008422:Materials Testing; D008956:Models, Chemical; D008958:Models, Molecular; D044367:Phase Transition; D011108:Polymers / Q000737:chemistry; D013314:Stress, Mechanical; D014783:Viscosity
chemical_list: D000464:Alginates; D001672:Biocompatible Materials; D003432:Cross-Linking Reagents; D005782:Gels; D006027:Glycosides; D006603:Hexuronic Acids; D011108:Polymers; D020723:Glucuronic Acid