Nanoparticle formulations

1. A method for the preparation of a population of biologically active nanoparticles comprising one or more MYC-containing polypeptides, the method comprising:

(a) solubilizing MYC-containing polypeptides in a solubilization solution comprising a concentration of a denaturing agent to provide solubilized MYC-containing polypeptides, wherein the concentration of the denaturing agent is from about 1 M to about 10 M;

(b) performing a first refolding step on the solubilized MYC-containing polypeptides with a first refold buffer comprising about 0.35 to about 0.65 the concentration of the denaturing agent of step (a) and about 100 mM to about 1M alkali metal salt and/or alkaline metal salt for at least about 30 to 180 minutes to provide a first polypeptide mixture;

(c) performing a second refolding step on the first polypeptide mixture with a second refold buffer comprising about 0.10 to about 0.30 the concentration of the denaturing agent of step (b) and about 100 mM to 1M alkali metal salt and/or alkaline metal salt at least about 30 to 180 minutes to provide a second polypeptide mixture; and

(d) performing a third refolding step on the second polypeptide mixture with a third refold buffer comprising about 100 mM to 1M alkali metal salt and/or alkaline metal salt for at least about 30 to 180 minutes;

(e) after step (d), maintaining the MYC-containing polypeptides in the third refold buffer for a period of time sufficient to produce biologically active nanoparticles having a number average diameter of between about 80 nm and about 150 nm,

wherein contacting an anti-CD3 or anti-CD28 activated T-cell with the biologically active nanoparticles under conditions suitable for T-cell proliferation, augments one or more of the activation, survival, or proliferation of the T-cell compared with an anti-CD3 or anti-CD28 activated T-cell that is not contacted with the biologically active nanoparticles.

2. The method of claim 1 , wherein the MYC-containing polypeptide is a MYC fusion peptide comprising SEQ ID NO: 1 or 10.

3. The method of claim 1 , wherein the MYC-containing polypeptide is acetylated.

4. The method of claim 1 , wherein MYC-containing polypeptides are recombinant polypeptides.

5. The method of claim 4 , wherein the MYC-containing polypeptides are recombinant MYC-containing polypeptides isolated from a microbial host cell.

6. The method of claim 5 , wherein the microbial host cell is E. coli.

7. The method of claim 5 , wherein the microbial host cell comprises a nucleic acid encoding the MYC-containing polypeptide and an inducible promoter, or wherein the recombinant MYC-containing polypeptide from the microbial host cell is purified by affinity chromatography and/or anion exchange chromatography.

8. The method of claim 1 , wherein the MYC-containing polypeptide comprises a MYC fusion peptide, comprising a protein transduction domain linked to a MYC polypeptide.

9. The method of claim 8 , wherein the MYC fusion peptide further comprises one or more linkers that link the protein transduction domain and the MYC polypeptide.

10. The method of claim 8 , wherein the protein transduction domain sequence is a TAT protein transduction domain sequence.

11. The method of claim 10 , wherein the TAT protein transduction domain sequence is selected from the group consisting of TAT[48-57] and TAT[57-48].

12. The method of claim 1 , wherein the MYC-containing polypeptide comprises a MYC fusion peptide with the following general structure:

protein transduction domain-X-MYC sequence,

wherein -X- is a linker that links the protein transduction domain and the MYC sequence.

13. The method of claim 1 , wherein the denaturing agent comprises one or more of guanidine, guanidine hydrochloride, guanidine chloride, guanidine thiocyanate, urea, thiourea, lithium perchlorate, magnesium chloride, phenol, betain, sarcosine, carbamoyl sarcosine, taurine, dimethylsulfoxide (DMSO); wherein the solubilization solution further comprises one or more alcohols selected from the group consisting of propanol, butanol, and ethanol, one or more detergents selected from the group consisting of sodium dodecyl sulfate (SDS), N-lauroyl sarcosine, Zwittergents, non-detergent sulfobetains (NDSB), TRITON X-100, NONIDET™ P-40, the TWEEN™ series, and BRIJ™ series, and/or one or more hydroxides selected from the group consisting of sodium hydroxide and potassium hydroxide.

14. The method of claim 1 , wherein the denaturing agent comprises 6-8 M urea.

15. The method of claim 1 , wherein the alkali metal salt comprises one more of a sodium salt, a lithium salt, and a potassium salt, wherein the sodium salt comprises one or more of sodium chloride (NaCl), sodium bromide, sodium bisulfate, sodium sulfate, sodium bicarbonate, or sodium carbonate, wherein the lithium salt comprises one or more of lithium chloride, lithium bromide, lithium bisulfate, lithium sulfate, lithium bicarbonate, or lithium carbonate, and wherein the potassium salt comprises one or more of potassium chloride, potassium bromide, potassium bisulfate, potassium sulfate, potassium bicarbonate, or potassium carbonate.

16. The method of claim 1 , wherein the alkali metal salt comprises NaCl and the first, second, and/or third refold buffers comprise about 500 mM NaCl.

17. The method of claim 1 , wherein the alkaline metal salt comprises one more of a magnesium salt and a calcium salt, wherein the magnesium salt comprises one or more of magnesium chloride, magnesium bromide, magnesium bisulfate, magnesium sulfate, magnesium bicarbonate, or magnesium carbonate, and wherein the calcium salt comprises one or more of calcium chloride, calcium bromide, calcium bisulfate, calcium sulfate, calcium bicarbonate, or calcium carbonate.

18. The method of claim 1 , wherein the first refolding step, second refolding step, and/or third refolding step comprise performing the step by buffer exchange.

19. The method of claim 18 , wherein buffer exchange is performed using tangential flow filtration.

20. The method of claim 1 , wherein the first refold buffer, the second refold buffer, and/or third refold buffer each independently comprise a buffering agent, wherein the buffering agent comprises one or more of TRIS (Tris[hydroxymethyl]aminomethane), HEPPS (N-[2-Hydroxyethyl]piperazine-N′-[3-propane-sulfonic acid]), CAP SO (3-[Cyclohexylamino]-2-hydroxy-1-propanesulfonic acid), AMP (2-Amino-2-methyl-1-propanol), CAPS (3-[Cyclohexylamino]-1-propanesulfonic acid), CHES (2-[N-Cyclohexylamino]ethanesulfonic acid), arginine, lysine, and sodium borate.

21. The method of claim 20 , wherein each buffering agent is independently present at a concentration from about 1 mM to about 1M.

22. The method of claim 1 , wherein the first refold buffer, second refold buffer, and/or third refold buffer each independently comprise an oxidizing agent and a reducing agent, wherein a mole ratio of oxidizing reagent to reducing agent is from about 2:1 to about 20:1, wherein the oxidizing agent is included in a concentration from about 0.1 mM to about 10 mM, and wherein the reducing agent is included in a concentration from about 0.1 mM to about 10 mM.

23. The method of claim 22 , wherein the oxidizing agent comprises cystine, glutathione disulfide (“oxidized glutathione”), or both.

24. The method of claim 22 , wherein the reducing agent comprises one or more of beta-mercaptoethanol (BME), dithiothreitol (DTT), dithioerythritol (DTE), tris(2-carboxyethyl)phosphine, (TCEP), cysteine, cysteamine, thioglycolate, glutathione, and sodium borohydride.

25. The method of claim 1 , wherein the first, second, and/or third refold buffers further comprise glutathione and/or oxidized glutathione, wherein the first, second, and/or third refold buffers comprise 5 mM glutathione and/or 1 mM glutathione disulfide.

26. The method of claim 1 , wherein the first, second, and/or third refold buffers further comprise glycerol.

27. The composition of claim 1 , wherein the nanoparticles have an average diameter from about 100 nm and about 110 nm.

28. The method of claim 1 , wherein step (e) is performed for about 5-12 hours.

29. The method of claim 1 , wherein step (e) further comprises stirring the MYC-containing polypeptides in the third refold buffer at a speed of less than 1000 rpm.