Abstract

In this work, the effects of pH, salt type, and salt concentration on the viscosity behaviour of collagen solutions were investigated by a photoelectric viscometer. The results show that the viscosity behaviour as polyelectrolytes or polyampholytes depended on the charge distribution on the polypeptide chains, which can be tuned by the value of pHof the collagen solution. The intrinsic viscosity of collagen in Na2SO4 solution at pH2.0 first decreases and then increases with increasing salt concentration, while a monotonic decrease of the intrinsic viscosity of collagen is observed in NaCl solution. The intrinsic viscosity of collagen in Cr(OH)SO4 solution at pH4.0 is found to be increased first and then decreased with an increase in salt concentration, whereas an opposite trend is observed in same solution at pH2.0. We suggest that the complicated viscosity behaviour of collagen solution is attributed to the comprehensive effects of shielding, overcharging and crosslinking caused by the introduction of the different counterions. In addition, the viscosity result is also confirmed by dynamic light scattering(DLS) experiment.