In this study we demonstrate that chitosan solutions can be neutralised up
to physiological pH (similar to7.2) using beta -glycerol phosphate without
creating immediate gel-like precipitation and furthermore that subsequent h
eating of these solutions induces hydrogel formation. The addition of the p
articular basic salt, glycerol phosphate, provides the correct buffering an
d other physicochemical conditions including control of hydrophobic interac
tions and hydrogen bonding which are necessary to retain chitosan in soluti
on at neutral pH near 4 degreesC and Furthermore to allow gel formation upo
n heating to 37 degreesC. Rheological investigation evidenced the endotherm
ic gelation of chitosan/beta -glycerol phosphate solutions and allowed the
establishment of a sol/gel diagram. The gelation process appears to be gove
rned by delicate interplay between the pH and the temperature. The role of
beta -glycerol phosphate is discussed in the light of relevant literature p
articularly those indicating the role of glycerol and polyols in the stabil
isation of proteins and polysaccharides. (C) 2001 Elsevier Science Ltd. All
rights reserved.