Glyceraldehyde as an Efficient Chemical Crosslinker Agent for the Formation of Chitosan Hydrogels

The rheological changes that occur during the chemical gelation of semidilute solutions of chitosan in the presence of the low-toxicity agent glyceraldehyde (GCA) are presented and discussed in detail. The entanglement concentration for chitosan solutions was found to be approximately 0.2 wt.% and the rheological experiments were carried out on 1 wt.% chitosan solutions with various amounts of GCA at different temperatures (25 degrees C and 40 degrees C) and pH values (4.8 and 5.8). High crosslinker concentration, as well as elevated temperature and pH close to the pK(a) value (pH approximate to 6.3-7) of chitosan are three parameters that all accelerate the gelation process. These conditions also promote a faster solid-like response of the gel-network in the post-gel region after long curing times. The mesh size of the gel-network after a very long (18 h) curing time was found to contract with increasing level of crosslinker addition and elevated temperature. The gelation of chitosan in the presence of other chemical crosslinker agents (glutaraldehyde and genipin) is discussed and a comparison with GCA is made. Small angle neutron scattering (SANS) results reveal structural changes between chitosan solutions, incipient gels, and mature gels.

Automated summary

The rheological changes during the chemical gelation process of chitosan with the low-toxicity agent glyceraldehyde were studied. Factors such as crosslinker concentration, temperature, and pH were found to influence the gelation process. Small angle neutron scattering results showed structural changes in chitosan solutions under different conditions.