Polysaccharide composition and methods of isolation of the emulsion stabilizing cationic polyelectrolytic polysaccharide
The present invention relates to purification and use of a novel emulsion stabilizing polysaccharide. In particular, a polyelectrolyte exopolysaccharide with high molecular weight comprising a high molecular weight polymer with a tri-saccharide repeating unit is disclosed. In one aspect of the invention, methods are directed to isolating and purifying a high molecular weight exopolysaccharide (EPS) from a cell supernatant. In another aspect, methods are disclosed for isolating a lipopolysaccharide (LPS) and a high molecular weight Acinetobacter polyelectrolyte exopolysaccharide (APE) from Acinetobacter bacteria. Compositions are also directed to lipid nanoparticles comprising a therapeutic agent encapsulated by a high molecular weight polysaccharide and nanoparticles comprising a therapeutic agent bound to a cationic polysaccharide cross-linked with a polyanion.
1. A lipid nanoparticle comprising a therapeutic agent dispersed within a lipid core surrounded by an encapsulating high molecular weight polysaccharide, wherein the polysaccharide has trisaccharide repeating units, a molecular weight greater than 3MDa, and is a polyelectrolytic exopolysaccharide isolated from Acinetobacter bacteria.
2. The nanoparticle of claim 1 , wherein the size of the particle is less than 1 micrometer.
3. The nanoparticle of claim 1 , wherein the size of the particle ranges from about 500 nm to about 100 nm.
4. The nanoparticle of claim 1 , wherein the lipid core comprises at least one lipid selected from the group of monoglycerides, diglycerides, triglycerides, waxes and fatty acids.
5. The nanoparticle of claim 1 , wherein at least one of the trisaccharide repeating units is N-acetyl galactosamine, N-acetyl glucosamine or a derivative.
6. A method of encapsulating a hydrophobic therapeutic agent comprising dissolving the therapeutic agent in a lipid; mixing the lipid solution with an aqueous solution comprising a high molecular weight polysaccharide having trisaccharide repeating units and a molecular weight greater than 3MDa, wherein the trisaccharide repeating unit comprises formula:
wherein R 1 , R 2 and R 3 are selected from the group consisting of OH and OAc; homogenizing the resulting mixture at an elevated temperature to form an emulsion; and cooling the emulsion to form particles having a therapeutic agent dispersed within a lipid core surrounded by the high molecular weight polysaccharide.
7. The method of claim 6 , wherein the method further comprises homogenizing the mixture at a temperature above 60 degrees C.
8. The method of claim 6 , wherein the polysaccharide is a polyelectrolytic exopolysaccharide isolated from Acinetobacter bacteria.
9. The method of claim 6 , wherein the lipid comprises at least one lipid selected from the group of monoglycerides, diglycerides, triglycerides, waxes and fatty acids.
10. The method of claim 6 , wherein the step of cooling the emulsion further comprises solidifying the core lipid.
11. A therapeutic nanoparticle comprising a therapeutic agent bound together with a high molecular weight cationic polysaccharide cross-linked with a polyanion, wherein the polysaccharide comprises tri-saccharide repeating units and a molecular weight greater than 3MDa in an uncross-linked state, and wherein the trisaccharide repeating unit comprises formula:
And wherein R 1 , R 2 and R 3 are selected from the group consisting of OH and OAc.
12. The nanoparticle of claim 11 , wherein the size of the particle is less than 1 micrometer.
13. The nanoparticle of claim 11 , wherein the size of the particle ranges from about 300 nm to about 50 nm.
14. The nanoparticle of claim 11 , wherein at least one of the trisaccharide repeating units is N-acetyl galactosamine, N-acetyl glucosamine or a derivative.
15. The nanoparticle of claim 11 , wherein the polysaccharide is a polyelectrolytic exopolysaccharide isolated from Acinetobacter bacteria.
16. The nanoparticle of claim 11 , wherein the polyanion is tripolyphosphate (TPP).