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US 6,627,749 B1Granted
Powdered oxidized cellulose
AssigneeUniversity of Iowa Research Foundation
InventorVijay Kumar
Life of this patent
Estimating the term…
Abstract
A controlled chemical method to produce oxidized cellulose in high yields (75-95%) and different levels of oxidation (carboxyl content <25.6%, w/w), suitable for use as an immobilizing matrix or carrier for drugs, chemicals, and biological macromolecules, has been developed by reacting a cellulose material with a mixture of phosphoric acid and nitric acid and a small but adequate amounts of sodium nitrite at room temperature for a period until the desired oxidation level is obtained.
Claims21
A method of making an oxidized cellulose containing carboxyl groups comprising:
- soaking a source of cellulose in a reaction mixture containing an amount of concentrated phosphoric acid and concentrated nitric acid to form an acid mixture;
- thereafter adding sodium nitrite to the acid mixture to form an oxidizing mixture;
- allowing the sodium nitrite to react with the acid mixture for a period of time of up to about 48 hours, said reaction occurring at a temperature ranging between 15-28° C.;
- terminating the reaction by adding an excess of water to the oxidizing mixture;
- and filtering the oxidized cellulose from the oxidizing mixture, said oxidized cellulose having a degree of polymerization of 82 or less, and a degree of crystallinity of 38% or less.
2 more elements
Oxidized cellulose;
- said oxidized cellulose having a degree of polymenzation of 82 or less, and a degree of crystallinity of 38% or less.
A pharmaceutical comprising:
- a drug;
- and oxidized cellulose;
- said oxidized cellulose having a degree of polymerization of 82 or less, and a degree of crystallinity of 38% or less.
Dependencies are inferred from the claim text.