Single chain morphology and nanofiber-like aggregates of branched β-(1→3)-d-glucan in water/dimethylsulfoxide solution

A polysaccharide coded as PR-CA was extracted from Polyporus rhinoceros and determined to be a β-(1→3)- d -glucan with multiple branches. The weight-average molecular weights ( M w ) of PR-CA in dimethylsulfoxide (DMSO) and in water were determined with static light scattering (SLS) to be 3.57   ×   10 5 and 1.79   ×   10 7 , indicating existence of the single chains in DMSO and co-existence of single chains and aggregates in water. Moreover, the stiffness of single chains of PR-CA in water was directly visualized by atomic force microscopy (AFM) and transmission electron microscopy (TEM). The hollow structure of PR-CA nanofibers with width of 30–40   nm and length of ∼350   nm formed in the water/DMSO (9:1, v:v) was demonstrated by a fluorescent probe tetraphenylethylene (TPE) via aggregation-induced emission (AIE). The formation of PR-CA nanofibers was ascribed to the parallel aggregation of the extended PR-CA chains due to the hydrogen bonding and hydrophobic interaction. This work offered valuable results for promising applications of natural branched β-glucans in the biological fields of drug inclusion, delivery and disease diagnosis.