12.4.2023
Doctoral thesis on utilizing pristine natural polysaccharides to develop products for humidity and temperature sensing
MSc Trung-Anh Le’s doctoral thesis in physical chemistry will be put forth for public defence at the Faculty of Science and Engineering at Åbo Akademi University.
The thesis is entitled Pristine iota-Carrageenan and Chemically Functionalized Guar gum Polysaccharides for Metal-ion Complexation and CuS-based Nanocomposite Preparation.
Public defence of the doctoral thesis takes place on Wednesday, 19 April 2023, at 1.15 PM, in Auditorium Argentum, Aurum, Henrikinkatu 2, Turku. Associate Professor Elżbieta Grządka, Maria Curie-Skłodowska University, Lublin, Poland, will serve as opponent and Associate Professor Tan Phat Huynh, Åbo Akademi University, as custos.
Summary
Natural polysaccharides are ubiquitous in nature and have been widely used in human history. To cope with climate crisis and develop a more sustainable economy, promoting the use of natural polysaccharides is of great interest. In this work, anionic iota-carrageenan (CG) polysaccharide was employed to prepare an iota-carrageenan/CuS covellite (CG/CuS) nanocomposite using a gel/liquid interface precipitation process similarly to chemobrionics. This approach showed how pristine natural polysaccharides such as CG could be effortlessly utilized to develop high-end products for humidity and temperature sensing.
Despite great potential of pristine natural polysaccharides in fabricating novel materials, chemical modifications of natural polysaccharides still play a crucial role in altering and enriching properties as well as applications of natural polysaccharides. Nucleophilic reactions of non-ionic guar gum (GG) polysaccharide were adopted in this study due to the simplicity, accessibility and diversity of chemical reaction conditions and reagents. Different nucleophilic reactions were successfully carried out in aqueous medium at room temperature without using toxic organic solvents, allowing the introduction of different organic functional groups and moieties. The chemical modification of GG by xanthate and benzoic acid groups was chosen for further study due to their great potential applications. Being a soft base according to the hard and soft acid and base (HSAB) theory, xanthate groups on guar gum-xanthate (GG-X) allowed GG-X to coordinate more strongly to a wide range of soft metal ions, which have great potential in heavy metal removal, wastewater treatment, cross-linked hydrogel preparation, etc. In addition, GG-X offered dual functionalities as a surfactant and an organic matrix in the formation of GG-X/CuS nanocomposite colloidal dispersions, which showed printability and electrical responsiveness in humidity sensing. Benzoic acid moieties contain aromatic benzene rings and carboxylic acid groups, which offer interesting intermolecular interactions, coordination chemistry and swelling properties at mildly acidic environments to GG. Guar gum-benzoic acid (GG-BA) was found biocompatible to living cells. Therefore, GG-BA could be explored further as coacervates and cross-linked hydrogels for biomedical applications, e.g., wound dressing, bioadhesives and drug delivery.
Trung-Anh Le is born in 1991 in Ho Chi Minh City, Vietnam. He can be reached by email via the address trunganhle91@gmail.com.
The doctoral thesis can be read online through the Doria publication archive.
Click here for a press photo of the doctoral student.