Enhanced stability of proteins immobilized on nanoparticles
This invention is directed to the application of a previously unknown property of nanomaterials—its ability to enhance protein activity and stability at high temperatures, in organic solvents, and in polymer composites. Nanomaterials such as single-walled carbon nanotubes (SWNTs) can significantly enhance enzyme function and stability in strongly denaturing environments. Experimental results and theoretical analysis reveal that the enhancement in stability is a result of the curvature of these nanoscale materials, which suppresses unfavorable protein-protein interactions.
1. A composition comprising:
(a) nanoparticles; and
(b) proteins, wherein said proteins are bound to external surfaces of said nanoparticles and wherein each of said external surfaces has a radius of curvature that is within 1 order of magnitude of the dimensions of each of said proteins bound to said nanoparticles, wherein the stability of the bound proteins is greater than the stability of the proteins bound to surfaces of the same material as that of said nanoparticles but which forms a flat surface;
and wherein said proteins are enzymes.
2. The composition of claim 1 , wherein the composition is in a liquid medium, and wherein said liquid medium is selected from the group consisting of an aqueous medium at a temperature greater than about 40° C., less than about 10° C., an aqueous medium whose pH is less than about pH 6.5, an aqueous medium whose pH is greater than about pH 7.5, an aqueous medium with a salinity of at least about 0.3M NaCl, and a non-aqueous medium.
3. The composition of claim 1 , wherein said nanoparticles are selected from the group consisting of single-walled carbon nanotubes, multi-walled carbon nanotubes, gold or other metallic nanoparticles, semi-conducting nanoparticles, metal oxide nanoparticles, quantum dots, functionalized silica nanoparticles, and mixtures thereof.
4. The composition of claim 1 , wherein said proteins are bound to said nanoparticles through hydrophobic bonding, hydrophilic bonding, ionic bonding, covalent bonding, or non-covalent bonding.
5. An article of manufacture comprising the composition of claim 1 bound to a macroscopic surface.
6. The article of manufacture of claim 5 , wherein said macroscopic surface is selected from the group consisting of a polymer, a polymeric film, a metal, a metal alloy, and combinations thereof.
7. The article of manufacture of claim 5 , wherein said article is incorporated in a member of the group consisting of a biosensor, a biochip, a biofuel cell, a drug delivery system, an antimicrobial film, a paint antifouling film, and a lubricant antifouling film.
8. A method of making a device containing a composition which can enzymatically act on one or more substances in a solution comprising:
attaching the composition of claim 1 to a working surface of said device where said working surface will be in contact with said solution when the enzyme activity of said enzymes is desired;
thereby forming the device.
9. The method of claim 8 , wherein the solvent of said solution is selected from the group consisting of an aqueous medium at a temperature greater than about 40° C., less than about 10° C., an aqueous medium whose pH is less than about pH 6.5, an aqueous medium whose pH is greater than about pH 7.5, a liquid hydrocarbon medium, and an aqueous medium with a salinity of at least about 0.3 M NaCl.
10. The method of claim 8 , wherein said nanoparticles are selected from the group consisting of single-walled carbon nanotubes, multi-walled carbon nanotubes, gold or other metallic nanoparticles, semi-conducting nanoparticles, metal oxide nanoparticles, quantum dots, functionalized silica nanoparticles, and mixtures thereof.
11. The method of claim 8 , wherein said enzymes are bound to said nanoparticles through hydrophobic bonding, hydrophilic bonding, ionic bonding, covalent bonding, and non-covalent bonding.
12. A method of detecting an analyte in a solution comprising:
(a) contacting said solution containing said analyte with the composition of claim 1 ;
(b) allowing said enzymes to enzymatically act on said analyte, thereby forming a product that is detectable by external means; and
(c) detecting said product by said external means, thereby detecting said analyte.
13. The method of claim 12 , wherein said liquid medium is selected from the group consisting of an aqueous medium at a temperature greater than about 40° C., less than about 10° C., an aqueous medium whose pH is less than about pH 6.5, an aqueous medium whose pH is greater than about pH 7.5, a liquid hydrocarbon medium, and an aqueous medium with a salinity of at least about 0.3 M NaCl.
14. The method of claim 12 , wherein said nanoparticles are selected from the group consisting of single-walled carbon nanotubes, multi-walled carbon nanotubes, gold or other metallic nanoparticles, semi-conducting nanoparticles, metal oxide nanoparticles, quantum dots, functionalized silica nanoparticles, and mixtures thereof.
15. The method of claim 12 , wherein said enzymes are bound to said nanoparticles through hydrophobic bonding, hydrophilic bonding, ionic bonding, covalent bonding, or non-covalent bonding.
16. A method of reducing the fouling of a surface by a substance present in a solution comprising:
(a) contacting said solution containing said substance with said surface wherein a composition of claim 1 is attached to said surface; and
(b) allowing said enzymes to enzymatically degrade said substance, thereby reducing the amount of said substance in said solution and the fouling adherence of said substance to said surface.
17. The method of claim 16 , wherein said liquid medium is selected from the group consisting of an aqueous medium at a temperature greater than about 40° C., less than about 10° C., an aqueous medium whose pH is less than about pH 6.5, an aqueous medium whose pH is greater than about pH 7.5, a liquid hydrocarbon medium, and an aqueous medium with a salinity of at least about 0.3 M NaCl.
18. The method of claim 16 , wherein said nanoparticles are selected from the group consisting of single-walled carbon nanotubes, multi-walled carbon nanotubes, gold or other metallic nanoparticles, semi-conducting nanoparticles, metal oxide nanoparticles, quantum dots, functionalized silica nanoparticles, and mixtures thereof.
19. The method of claim 16 , wherein said enzymes are bound to said nanoparticles through hydrophobic bonding, hydrophilic bonding, ionic bonding, covalent bonding, or non-covalent bonding.