The aggregation behaviour of chitosan bioelectret in aqueous solution using a fluorescence probe

A kind of intramolecular charge-transfer compound, 3-hydroxy-6-methyl-4'-N,N-dimethylamino flavone derivatives (PF), was used to detect the self-association of chitosan bioelectret in aqueous solution. Results showed that the fluorescence intensity of PF at 430 nm increased with increasing chitosan concentration in 0.1 M acetic acid, and concomitantly, the emission at 515 nm decreased. However, no emission was observed at 515 nm after the polarization of chitosan solution and only an increase in the peak of PF at 430 nm could be found. When 0.1 M hydrochloric acid was used to dissolve chitosan and all other conditions were the same as above, the PF peak was weak and did not disappear after the chitosan solution was polarized. In addition, the effect of ionic strength on chitosan aggregation with a concentration of 5 mg ml(-1) before and after polarization was examined. The results also showed that the fluorescence intensity of the probe increased remarkably at 430 nm with increasing ionic strength after polarization of the chitosan solution. All the results indicated that polarization can promote the aggregation behaviour of chitosan in aqueous solution. (C) 1998 Chapman & Hall.