Synthesis and behavior of click cross-linked alginate hydrogels: Effect of cross-linker length and functionality

Various bismaleimides and trismaleimides of varying molar masses, chemical architectures and functionalities were explored as cross-linkers for furan-modified alginate chains via Diels-Alder click reactions. An environmentally friendly approach is described for the preparation of hydrogels based on naturally occurring biomacromolecules, without catalysts. The behavior of the resulting polysaccharides-based hydrogels was analyzed in terms of swelling, rheological properties and drug-release efficiency, in connection with potential biomedical applications. The use of the different cross-linkers allows tuning the mechanical properties as well as the pulsatile swelling behavior of the hydrogels. When using trifunctional cross-linkers stiffer hydrogels were formed with high storage modulus whereas the chain length and the composition of the cross-linker clearly influence the swelling of the hydrogel network. In connection with drug delivery applications, release of vanillin as a traceable aromatic biobased model drug was also monitored as a function of hydrogel composition. To the best of our knowledge, for the first-time furan-modified alginates were reacted and studied with polyethylene glycol-based bis or trismaleimides with different molar masses and architectures, resulting in advanced hydrogels with different behavior.