Pharmaceutical composition of nanoparticles

1. A method for slow-release of a bioactive agent to an animal subject, said method comprising (1) mixing said bioactive agent with a chitosan-containing solution at a low pH that effects dispersion of said bioactive agent in the chitosan-containing solution, thus forming a liquid mixture of chitosan that is present in said chitosan-containing solution and said bioactive agent, wherein said chitosan is characterized by presence of alternating charges of protonated amine groups and hydrophobic side groups; (2) raising a pH of the liquid mixture to effectively transition said mixture to a phase of malleable hydrogel; and (3) delivering said malleable hydrogel to said animal subject, wherein a body pH transforms the malleable hydrogel to a solid complex, said complex thus releasing said bioactive agent in a slow-release mode to said animal subject.

2. The method of claim 1 , wherein said chitosan is N-palmitoyl chitosan.

3. The method of claim 1 , wherein said chitosan having the hydrophobic side groups is characterized by an enhanced pH responsiveness than a chitosan without the hydrophobic side groups.

4. The method of claim 1 , wherein said bioactive agent is a drug for chemotherapy.

5. The method of claim 1 , wherein the delivering step comprises using a conduit to deliver said malleable hydrogel to a target tissue of the animal subject.

6. The method of claim 5 , wherein said conduit is selected from the group consisting of a needle, an endoscope, a syringe, a catheter, a tube, a channel, a pipe, and a duct.

7. The method of claim 5 , wherein said target tissue is an aneurysmal site of a blood vessel.

8. The method of claim 1 , wherein said bioactive agent is an anti-diabetic compound.

9. The method of claim 8 , wherein said anti-diabetic compound is selected from the group consisting of insulin, an insulin analog, mitofusin 1, mitofusin 2, GLP-1, a GLP-1 analog, an insulin sensitizer, an insulin secretagogue, an inhibitor of dipeptidyl peptidase 4, metformin, alpha-glucosidase inhibitors, amylin analog, sodium-glucose co-transporter type 2 (SGLT2) inhibitors, benfluorex, tolrestat, and combinations thereof.

10. The method of claim 1 , wherein said hydrophobic side groups comprise N-palmitoyl groups.

11. The method of claim 1 , wherein said hydrophobic side groups comprise palmitoyl chains that are conjugated or covalently bond to the N molecule of the amine groups of said chitosan.

12. The method of claim 1 , wherein a ratio of said hydrophobic side groups to said protonated amine groups is from 1 to 30.

13. The method of claim 1 , wherein a ratio of said hydrophobic side groups to said protonated amine groups is from 1 to 15.

14. The method of claim 1 , wherein a ratio of said hydrophobic side groups to said protonated amine groups is from 1 to 5.

15. The method of claim 1 , wherein said liquid mixture further comprises a negatively charged substrate.

16. The method of claim 1 , wherein said bioactive agent is selected from the group consisting of proteins, peptides, nucleosides, nucleotides, antiviral agents, antineoplastic agents, antibiotics, and anti-inflammatory drugs.

17. The method of claim 1 , wherein said bioactive agent is selected from the group consisting of calcitonin, cyclosporin, oxytocin, tyrosine, enkephalin, tyrotropin releasing hormone, follicle stimulating hormone, luteinizing hormone, growth hormone, vasopressin analogs, catalase, superoxide dismutase, interleukin-II, interferon, colony stimulating factor, tumor necrosis factor, melanocyte-stimulating hormone, and an Alzheimer antagonist for treating Alzheimer's discascs.