[(2->8)-N,O(9)-diacetyl-alpha-D-neuraminosyl]n polyanion
[(2->8)-n,o(9)-diacetyl-alpha-d-neuraminosyl]n polyanion
"A polyanionic polymer obtained by deprotonation of the carboxy groups of [(2->8)-N,O(9)-diacetyl-alpha-D-neuraminosyl]n; major species at pH 7.3."