Influence of solvent polarity on organic solvent induced gelation in alginate hydrogels

• Main Author: Lim, Charles Kian Wee
• Other Authors: Huang Changjin
• Format: Final Year Project
• Language: English
• Published: Nanyang Technological University 2022
• Subjects: Engineering::Materials::Biomaterials; Engineering::Mechanical engineering
• Online Access: https://hdl.handle.net/10356/159041
• Institution: Nanyang Technological University

Polysaccharide hydrogels have been widely used in the biomedical field for a wide range of applications, such as scaffolding for tissue engineering, living cell encapsulation and bone and cartilage repair. In particular, sodium alginate is a naturally derived hydrogel material and has a wide applicability as biomaterials. 3D printing offers a versatile method to fabricate hydrogels into desired 3D structures on demand. However, due to the limited viscosity of sodium alginate solution, 3D printing alginate hydrogels often requires either supporting materials to hold the printed structures in place or incorporation of other polymers into the sodium alginate solution to increase the ink viscosity before the printed structures are crosslinked into physical hydrogels with divalent cations. In recent years, non-conventional methods to induce gelation in alginate hydrogels have been identified. One such method relies on the use of organic solvents. It has been observed that several different organic solvents can induce gelation in sodium alginate. However, there has yet to be a solvent parameter established for the extent of gelation induced in the hydrogel. In this project, controlled experiments were conducted to systematically investigate the suitability of solvent polarity as the solvent property responsible for inducing gelation in alginate hydrogels. Rheology testing was conducted across different concentrations of organic solvents known to induce gelation in alginate hydrogels and the corresponding sol-to-gel transition temperature was identified. Comparison is made against the polarities of the solvents. The results obtained were indicative of a trend present in the gelation induced by organic solvents, but insufficient evidence was obtained across a larger range of concentrations to conclude that solvent polarity is the key parameter towards inducing gelation in alginate hydrogels. This project proposes for further experiments to be conducted using different 3 parameters and methods to better isolate the dominant gelation mechanism and identify if there are any dominant solvent parameters influencing the gelation in alginate hydrogels.