A new biomaterial is disclosed. The biomaterial is prepared by mixing glycosaminoglycan with a phosphoric acid, phosphate ester, or salt or derivative thereof under the action of a catalyst in a liquid reaction medium at a pH of 2.1 to 4.9. The obtained material is capable of enhancing the immunological resistance in human and in animals, treating diseases in human and in animals caused by viruses or bacteria, strengthening the anti-stress ability of animals, improving the appetite of animals, promoting the growth of animals, inhibiting the growth of tumor, lowering blood fat level, as well as preventing and treating viral diseases in plants.
