US Patent 4,600,531
United States Patent and Trademark Office
University of Iowa Research Foundation (Iowa City, IA, US)
A high yield method of production of a cross-linked hemoglobin derivative suitable for use as a blood substitute and plasma expander which is cross-linked between Lys 99 Alpha1 and Lys 99 Alpha2 in high percentage by adding the cross-linker in the presence of an added polyanion which blocks competing reactions at other sites of the protein.
Walder, Joseph A. Production of alpha-alpha cross-linked hemoglobins in high yield. US Patent 4,600,531 filed March 18, 1985 and issued July 15, 1986. https://ir.uiowa.edu/patents/44