Development of (5-(4,6-dichlorotriazinyl) aminofluorescein) DTAF-labelled polysaccharides for characterization of microstructure and phase distribution of composite hydrogel visualization of hydrogels using CLSM

Visualization of the microstructure of hydrogels and the distribution of individual components in a binary polysaccharide hydrogel is often challenging due to its high-water content (up to 99%) and the difficulty in covalent labelling of polysaccharides without important negative effects on the physio-chemical properties of the polysaccharides. The present study investigated the potential use of 5-(4,6-dichlorotriazinyl) aminofluorescein (DTAF) to label polysaccharides that carry different functional groups on the polymer backbone, especially anionic functional groups. Agar, konjac glucomannan (KGM), low acyl gellan, and kappa- and iota-carrageenan were covalently labelled with DTAF. The advantage of polysaccharide labelling with DTAF was that the labelling could be done in an aqueous environment. The results suggested that DTAF labelling had no impact on the sol-gel transition temperature and gel strength of polysaccharides. Furthermore, DTAF labelled polysaccharides could be stored as a powder at room temperature for three months, except iota-carrageenan, without losing visualization using CLSM and affecting the mechanical strength. Both hydrated and dehydrated forms of binary polysaccharide composite gels were visualized using CLSM. CLSM images enable visibility of component distribution, compatibility of the two polysaccharides and network formation of both polysaccharides of agar:KGM, agar:potato starch, and KGM:potato starch composite gels.

Automated summary

This study explored the potential use of DTAF for labeling polysaccharides with different functional groups, especially anionic functional groups, without affecting their physio-chemical properties. The results showed that DTAF labeling did not impact the gelation properties and stability of polysaccharides, while maintaining their mechanical strength and visibility.