Bioartificial materials based on blends of collagen and poly(acrylic acid)

The interactions between soluble collagen (C) from calf skin and poly (acry lic acid) (PAA) were studied. Mixing aqueous solutions of collagen and PAA, at various pH values (2.5-4), leads to the formation of complexes that pre cipitate in the form of insoluble aggregates. The effects of mixture compos ition, pH, and ionic strength on C/PAA complex formation were investigated by gravimetric, turbidimetric, and conductometric analysis. The experimenta l results indicate that the complexes form through electrostatic interactio ns. Homogeneous solid films with variable C/PAA ratios were obtained by cas ting from solutions in which the pH was adjusted just over the isoelectric point of collagen, thus avoiding the attractive ionic interactions responsi ble for the complexation of collagen and PAA molecules. A relevant result o btained is related to the possibility of restoring the ionic interactions b etween the two polymers inside the solid films. Mixture composition and pH appear to influence the thermal properties of both complexes and films. (C) 1999 John Wiley & Sons, Inc.