Coated mesoflowers for molecular detection and smart barcode materials

1. A coated mesoflower comprising:

a metallic mesoflower core that includes a first surface, wherein the metallic mesoflower core includes at least one protrusion terminating in a tip;

a non-metallic coating that covers and is substantially conformal to the first surface such that the non-metallic coating creates an outer surface of the coated mesoflower and comprises at least one cavity, wherein the cavity comprises a space formed between the tip of the metallic mesoflower core and the non-metallic coating; and

a marker material having an optical property that is enhanced in the presence of the coated mesoflower.

2. The coated mesoflower of claim 1 , wherein the marker material is a Raman active material, a fluorescent material, or both.

3. The coated mesoflower of claim 2 , wherein the Raman active material comprises surface enhanced Raman scattering (SERS) active molecules.

4. The coated mesoflower of claim 2 , wherein the Raman active material comprises crystal violet, rhodamine 6G, methylene blue, or any combination thereof.

5. The coated mesoflower of claim 2 , wherein the fluorescent material comprises organic molecules, a semiconductor quantum dot, a rare-earth nanocrystal, a metallic quantum cluster, or any combination thereof.

6. The coated mesoflower of claim 5 , wherein the organic molecules comprise rhodamine 6G, fluorescein isothiocyanate, or any combination thereof.

7. The coated mesoflower of claim 1 , wherein the marker material is at least partially embedded in the non-metallic coating.

8. The coated mesoflower of claim 1 , wherein the marker material does not contact the first surface of the metallic mesoflower core.

9. The coated mesoflower of claim 1 , wherein the non-metallic coating comprises:

a first layer comprising the marker material; and

an overlayer that covers the first layer.

10. The coated mesoflower of claim 1 , wherein the non-metallic coating comprises at least one oxide.

11. The coated mesoflower of claim 1 , wherein the non-metallic coating comprises silicon oxide, a metal oxide, or combinations thereof.

12. The coated mesoflower of claim 1 , wherein the metallic mesoflower core comprises Au, Ag, or both Au and Ag.

13. The coated mesoflower of claim 1 , wherein the metallic mesoflower core comprises:

a core of a first metallic material; and

a shell of a second metallic material different from the first metallic material.

14. The coated mesoflower of claim 1 , wherein the non-metallic coating has a thickness of about 2 nm to about 500 nm.

15. A method of making a coated mesoflower comprising:

forming a protrusion on a metallic mesoflower core having a first surface, wherein the protrusion terminates in a tip;

covering the first surface with a non-metallic coating that is substantially conformal to the first surface, thereby creating an outer surface of the coated mesoflower;

forming a cavity in the non-metallic coating, wherein forming the cavity comprises forming a space between the tip of the metallic mesoflower core and the non-metallic coating; and

applying a marker material to the non-metallic coating, the marker material having an optical property that is enhanced in the presence of the coated mesoflower.

16. The method of claim 15 , wherein applying the marker material to the non-metallic coating comprises at least partially embedding the marker material in the non-metallic coating, and wherein the marker material does not contact the first surface of the metallic mesoflower core.

17. The method of claim 15 , wherein the covering comprises:

forming a first layer comprising the marker material; and

forming an overlayer covering the first layer.

18. The method of claim 15 , further comprising functionalizing the outer surface of the coated mesoflower.