Self-assembled melanin particles for color production

Patent metadata

Field	Value
Publication number	US-12280349-B2
Application number	US-202217943667-A
Country	US
Kind code	B2
Filing date	Sep 13, 2022
Priority date	Nov 22, 2016
Publication date	Apr 22, 2025
Grant date	Apr 22, 2025

Abstract

In various embodiments, the present invention is directed to a facile one-pot reverse emulsion process to assemble core-shell nanoparticles (CS-SMNPs) into bright and noniridescent photonic supraballs. In one or more embodiments, the present invention is directed to core-shell nanoparticles having an inner high refractive index (RI) core and an outer low RI shell. In one or more embodiment, the present invention includes core-shell nanoparticles using high RI (˜1.74) melanin cores and low-RI (˜1.45) silica shells. In various embodiments, these nanoparticles may be self-assembled into bright and noniridescent supraballs using a scalable one-pot reverse emulsion process. According to various embodiments of the present invention, it is possible to generate a full spectrum of structural colors with the combination of only two ingredients, synthetic melanin and silica.

First claim

What is claimed is:

1. A core-shell nanoparticle capable of self assembly into a supraball for providing structural color comprising an inner high refractive index (RI) core and an outer low RI shell, wherein said inner high refractive index (RI) core comprises natural or synthetic melanin.

2. The core-shell nanoparticle of claim 1 wherein said wherein the outer low RI shell comprises silica.

3. The core-shell nanoparticle of claim 1 wherein said natural or synthetic melanin core has a diameter from about 50 nm to about 500 nm.

4. The core-shell melanin nanoparticle of claim 2 wherein said silica shell has a thickness of more than 0 nm- and 200 nm or less.

5. The nanoparticle of claim 2 , wherein the ratio of the diameter of the melanin core to the diameter of said core shell synthetic melanin particle is more than 0 and 1 or less.

6. The core-shell nanoparticle of claim 1 having a diameter of from about 50 nm to about 700 nm.

7. The nanoparticle of claim 1 having a refractive index (RI) of from about 1.40 to about 2.0.

8. The nanoparticle of claim 1 wherein said outer low RI shell comprises silica, polymers, cross linkable polymers, inorganic coatings, biological materials or a combination thereof.

9. The nanoparticle of claim 1 further comprising a surface to which a material selected from the group consisting of cross linkable polymers, polar coatings, inorganic coatings, biological materials and a combination thereof are grafted or attached.

10. A method of making the core-shell nanoparticle of claim 2 comprising:
A) preparing a synthetic melanin nanoparticle by the oxidative polymerization of dopamine in the presence of a base; and
B) depositing a silica shell (SiO 2 ) on the synthetic melanin nanoparticle to form the core-shell synthetic melanin nanoparticle of claim 2 .

11. The method of claim 10 wherein the synthetic melanin nanoparticle prepared in step A has a diameter of from about 120 nm to about 220 nm.

12. The method of claim 10 wherein the silica shell deposited on said synthetic melanin nanoparticle in step A has a thickness of in an amount greater than 0 nm and 200 nm or less.

13. The method of claim 10 wherein the step of depositing a silica shell (step B) comprises:
1) Dispersing the synthetic melanin nanoparticle in a mixture of 2-proponol and water with a volume ratio of 1:0.176;
2) Adding an ammonia solution to the dispersion of step 1; and
3) Adding tetraethyl orthosilicate (TEOS) into the mixture of step 3 to form a SiO 2 shell on the surface of SMNPs due to the hydrolysis and condensation of TEOS onto the surface of the SMNPs under a base environment.

14. The method of claim 10 wherein step 3 further comprises controlling the thickness of the silica shell deposited on said synthetic melanin nanoparticle by varying the amount of tetraethyl orthosilicate (TEOS) used to form said silica shell and/or by varying the reaction time for the hydrolysis reaction of step 3 to obtain a core-shell synthetic melanin nanoparticle that when formed into a supraball will display a desired structural color.

15. A scalable process for the production of structural colors containing the core-shell nanoparticle of claim 1 comprising:
A) preparing a plurality of core-shell nanoparticles, having a polar or nonpolar outer surface;
B) suspending said plurality of core-shell nanoparticles in a polar or non-polar liquid, depending on the polarity of the outer surface;
C) adding an amphiphilic liquid to the suspension of step B to provide a two-phase mixture having a first phase comprising the amphiphilic liquid and a second phase comprising the suspension of step B, wherein said amphiphilic liquid is not soluble in the suspension of step B but the polar or non-polar liquid in the suspension of step B is at least partially soluble in said amphiphilic liquid;
D) forming an emulsion from the two-phase mixture of step C, said emulsion having a phase comprising the amphiphilic liquid of step C and an inner phase comprising the suspension of step B;
E) allowing the polar or non-polar liquid in said plurality of droplets to be absorbed into said continuous phase to produce a plurality of supraballs comprising closely packed core-shell nanoparticles suspended in said continuous phase; and
F) removing the amphiphilic liquid to produce a powder comprising the supraballs of step E that display a structural color and contain the core-shell nanoparticles of claim 1 .

16. The scalable process for the production of structural colors of claim 15 wherein said plurality of core-shell nanoparticles in step A comprises a melanin inner core and an outer silica shell.

17. The scalable process for the production of structural colors of claim 15 wherein said plurality of core-shell nanoparticles in step A comprises a combination of two or more sets of core-shell nanoparticles, wherein each set of said two or more sets of core-shell nanoparticles would each display a different structural color if formed into a supraball.

18. The scalable process for the production of structural colors of claim 15 further comprising adding one or more nanoparticles selected from the group consisting of carbon black, inorganic pigments, quantum dots, UV stabilizers, polymer nanoparticles, inorganic particles, solid silica nanoparticles, solid synthetic melanin nanoparticles, core-shell melanin nanoparticles, and combinations thereof to the suspension of step B.

19. The scalable process for the production of structural colors of claim 15 wherein said polar or non-polar liquid is water or an aqueous solution.

20. The scalable process for the production of structural colors of claim 15 wherein said polar or non-polar liquid is primary alcohol, secondary alcohol, tertiary alcohol, anilines, 1-octanol, pentanol, hexanol, heptanol, phenols, decanol, or a combination thereof.

21. The scalable process for the production of structural colors of claim 15 wherein said plurality of core-shell nanoparticles is suspended in a non-polar liquid and steps E and F are performed in a vessel having a hydrophobic inner surface.

22. The scalable process for the production of structural colors of claim 15 wherein said plurality of core-shell nanoparticles is suspended in a polar liquid and steps D and E are performed in a vessel having a lipophobic inner surface.

23. The scalable process for the production of structural colors of claim 15 wherein the concentration of said plurality of core-shell nanoparticles in the suspension of step B is from about 1 mg/ml to about 100 mg/ml.

24. The scalable process for the production of structural colors of claim 15 wherein the step of forming an emulsion (step D) is performed using a digital vortex to disperse the suspension of step B into droplets within the amphiphilic liquid and the step of allowing the polar or non-polar liquid in said plurality of droplets to be absorbed into said continuous phase (step E) is performed by reducing the shaking speed of said digital vortex.

25. The scalable process for the production of structural colors of claim 15 wherein the amphiphilic liquid has an interfacial energy with water of from about 2 mJ/m 2 to about 55 mJ/m 2 .

26. The scalable process for the production of structural colors of claim 15 wherein the step of removing the amphiphilic liquid to produce a powder comprises:
1) Concentrating the supraballs in the suspension of step E using by centrifugat

Assignees

• Dhinojwala Ali
• Xiao Ming
• Hu Ziying
• Shawkey Matthew
• Gianneschi Nathan
• Univ Akron
• Univ Of California San Diego

Inventors

• Dhinojwala Ali
• Xiao Ming
• Hu Ziying
• Shawkey Matthew
• Gianneschi Nathan

Classifications

• C09B69/104

  containing an indole dye, including melanine derivates · CPC title

• C09B67/0007

  with inorganic coatings · CPC title

• C09B67/0005

  the pigments being nanoparticles · CPC title

• B82Y40/00

  Manufacture or treatment of nanostructures · CPC title

• B82Y30/00

  Nanotechnology for materials or surface science, e.g. nanocomposites · CPC title