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

Abstract

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 κ- and ι-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 ι-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.