Raman-active particles and methods of making and using them
A Raman-active particle as well as a method of making a Raman-active particle are described. The Raman-active particle includes a core particle and a coating. The coating substantially covers the core particle. A Raman-active analyte is at least partially within the coating. The method of making a Raman-active particle includes i) providing a colloidal solution comprising a core particle; ii) providing a coating or coating precursor to the colloidal solution to form a resulting solution; and iii) providing a Raman-active analyte to the resulting solution. A method of conducting an assay is also described. The method includes: i) attaching a Raman-active particle to a targeted moiety; ii) measuring the Raman spectrum of the Raman-active particle; and iii) correlating the Raman spectrum to the presence of the targeted moiety.
1. A Raman-active particle comprising:
a core particle;
a coating substantially covering the core particle; and
a plurality of Raman-active analytes at least partially within the coating and comprising analytes of different types.
2. The Raman-active particle of claim 1 , wherein the core particle comprises at least one metal selected from a group consisting of Au, Ag, Cu, Ni, Pd, Pt, Na, Al, and Cr.
3. The Raman-active particle of claim 2 , wherein the core particle comprises an Au core particle.
4. The Raman-active particle of claim 2 , wherein the core particle comprises a metallic surface.
5. The Raman-active particle of claim 1 , wherein the Raman-active particle has a diameter up to about 1000 nm.
6. The Raman-active particle of claim 1 , wherein the core particle has a diameter up to about 500 nm.
7. The Raman-active particle of claim 1 , wherein the coating has a thickness in a range from about 1 nm to about 500 nm.
8. The Raman-active particle of claim 1 , wherein the plurality of Raman-active analytes comprise at least one Raman-active analyte selected from a group consisting of 4-mercaptopyridine, 2-mercaptopyridine, trans-bis(pyridyl)ethylene, naphthalene thiol, and mercaptobenzoic acid.
9. The Raman-active particle of claim 1 , wherein the plurality of Raman-active analytes are embedded within the coating.
10. The Raman-active particle of claim 1 , wherein the plurality of Raman-active analytes are dispersed within the coating.
11. The Raman-active particle of claim 1 , wherein the coating comprises a multilayer coating.
12. The Raman-active particle of claim 1 , wherein the coating is substantially inorganic.
13. The Raman-active particle of claim 1 , wherein the coating comprises an elemental oxide, wherein at least one element of the elemental oxide comprises silicon.
14. The Raman-active particle of claim 13 , wherein the coating comprises substantially silica.
15. The Raman-active particle of claim 1 , further comprising a linker.
16. The Raman-active particle of claim 15 , wherein the linker comprises an alkoxysilane.
17. A Raman-active particle comprising:
a) a core particle comprising a metallic surface;
b) a coating substantially covering the core particle, wherein the coating comprises an elemental oxide, wherein at least one element of the elemental oxide comprises silicon; and
c) a plurality of Raman-active analytes at least partially within the coating and comprising analytes of different types.
18. The Raman-active particle of claim 17 , wherein the Raman-active particle has a diameter up to about 1000 nm.
19. The Raman-active particle of claim 17 , wherein the core particle has a diameter up to about 500 nm.
20. The Raman-active particle of claim 17 , wherein the plurality of Raman-active analytes are embedded within the coating.
21. The Raman-active particle of claim 17 , wherein the plurality of Raman-active analytes are dispersed within the coating.
22. The Raman-active particle of claim 17 , wherein the coating comprises a multilayer coating.
23. The Raman-active particle of claim 17 , further comprising a linker, wherein the linker comprises an alkoxysilane.