Fig. 3: PA influences the properties of chitosans in solution.

A Rheological analysis of enzymatically (CS.33^E-Ac) and chemically (CS.30 ^N-Ac-1) produced chitosan polymers prepared from 30 mg ml⁻¹ chitosan dissolved in a 5% stoichiometric excess of acetic acid at 25 °C: dependence of viscoelastic moduli G′ and G′′ and complex viscosity (η*) on the frequency (strain = 20%) of CS.30^E-Ac (upper left panel) and CS.30 ^N-Ac-1 (upper right panel); dependence of tan δ (=G′′/G′) on frequency (strain = 20%) (lower left panel) and Cox-Merz representation of η* and steady-shear viscosity (η) as a function of frequency and shear rate, respectively (lower right panel). All measurements were conducted within the linear viscoelastic region. B Circular dichroism spectroscopy of enzymatically (CS.33^E-Ac) and chemically (CS.34 ^N-Ac) produced chitosan (0.5 mg ml⁻¹ at 25 °C). C Ratio of pyrene fluorescence emission intensities (I₃₇₄/I₃₈₅) from enzymatically (CS.33^E-Ac) and chemically (CS.30 ^N-Ac) produced chitosan as a function of chitosan concentration (λ_ex = 343 nm, 2 µM pyrene, 5% stoichiometric excess of acetic acid, 100 mM NaCl, 25 °C).