Granular nanoparticles having bright fluorescence and giant raman enhancements

1. A nanoparticle comprising:

a plurality of crystallites within the nanoparticle; wherein

at least some of the crystallites are about less than 3 nm in size;

the total number of photons emitted from the nanoparticle upon excitation with an excitation wavelength of the nanoparticle is at least 10 7 ,

the plurality of crystallites are separated from each other by grain boundaries, and

the nanoparticle comprises about 100 to about 10,000 grain boundaries.

2. The nanoparticle of claim 1 , wherein Raman signal for a molecule near the nanoparticle increases at least 10 7 times.

3. The nanoparticle of claim 1 , wherein the total number of photons emitted from the nanoparticle upon excitation with an excitation wavelength of the nanoparticle is at least 10 11 .

4. The nanoparticle of claim 3 , wherein Raman signal for a molecule near the nanoparticle increases at least 10 14 times.

5. The nanoparticle of claim 1 , wherein at least some of the crystallites are about less than 1 nm in size.

6. The nanoparticle of claim 1 , wherein at least some of the other crystallites are less than about 10 nm in size.

7. The nanoparticle of claim 5 , wherein said at least some of the crystallites having less than 1 nm in size result in discrete energy states that give rise to fluorescent optical transitions.

8. The nanoparticle of claim 1 , wherein the nanoparticle has a mean particle diameter of about 1 nm to about 500 nm.

9. The nanoparticle of claim 1 , wherein the nanoparticle has a mean particle diameter of about 2 nm to about 20 nm.

10. The nanoparticle of claim 1 , wherein the nanoparticle comprises a noble metal.

11. The nanoparticle of claim 1 , wherein the nanoparticle comprises a metal and the metal is selected from the group consisting of gold, silver, tantalum, platinum, palladium, rhodium, copper, and mixtures thereof.

12. The nanoparticle of claim 1 , wherein the nanoparticle further comprises an organic coating.

13. The nanoparticle of claim 12 , wherein the organic coating is selected from the group consisting of glycine, SH-PEG-SH, SH-PEG-COOH, SH-PEG-NH 2 , and mixtures thereof.

14. The nanoparticle of claim 1 , wherein the nanoparticle has a fluorescence cross-section of at least 10 −14 cm 2 .

15. A composition comprising:

a plurality of nanoparticles, at least 5% of the plurality of nanoparticle comprising the nanoparticle of claim 1 ; and

at least 5% of the plurality of nanoparticles exhibit fluorescence where the total number of photons emitted from each nanoparticle upon excitation with an excitation wavelength of the nanoparticle is at least 10 7 .

16. The composition of claim 15 , wherein at least 50% of the plurality of nanoparticles exhibit fluorescence where the total number of photons emitted from each nanoparticle upon excitation with an excitation wavelength of the nanoparticle is at least 10 7 .

17. The composition of claim 15 , wherein at least 90% of the plurality of nanoparticles exhibit fluorescence where the total number of photons emitted from each nanoparticle upon excitation with an excitation wavelength of the nanoparticle is at least 10 7 .

18. The composition of claim 15 , wherein at least 50% of the plurality of nanoparticles exhibit fluorescence where the total number of photons emitted from each nanoparticle upon excitation with an excitation wavelength of the nanoparticle is at least 10 11 .

19. The composition of claim 15 , wherein at least 90% of the plurality of nanoparticles exhibit fluorescence where the total number of photons emitted from each nanoparticle upon excitation with an excitation wavelength of the nanoparticle is at least 10 11 .

20. The composition of claim 15 , wherein at least 5% of the nanoparticles exhibit Raman enhancement where Raman signal for a molecule near an individual nanoparticle in said plurality of nanoparticles increases at least 10 7 times.

21. The composition of claim 15 , wherein at least 50% of the nanoparticles exhibit Raman enhancement where Raman signal for a molecule near an individual nanoparticle in said plurality of nanoparticles increases at least 10 7 times.

22. The composition of claim 15 , wherein at least 90% of the nanoparticles exhibit Raman enhancement where Raman signal for a molecule near an individual nanoparticle in said plurality of nanoparticles increases at least 10 7 times.

23. The composition of claim 15 , wherein at least 5% of the nanoparticles exhibit Raman enhancement where Raman signal for a molecule near an individual nanoparticle in said plurality of nanoparticles increases at least 10 14 times.

24. The composition of claim 15 , wherein at least 50% of the nanoparticles exhibit Raman enhancement where Raman signal for a molecule near an individual nanoparticle in said plurality of nanoparticles increases at least 10 14 times.

25. The composition of claim 15 , wherein at least 90% of the nanoparticles exhibit Raman enhancement where Raman signal for a molecule near an individual nanoparticle in said plurality of nanoparticles increases at least 10 14 times.

26. The composition of claim 15 , wherein each nanoparticle further comprises an organic coating.

27. The nanoparticle of claim 26 , wherein the organic coating is selected from the group consisting of glycine, SH-PEG-SH, SH-PEG-COOH, SH-PEG-NH 2 , and mixtures thereof.

28. A method for producing the nanoparticle claimed in claim 1 , the method comprising:

mixing a matrix material with a reactant capable of being thermally reduced to form the nanoparticle, wherein the matrix material has a melting temperature of at least 100° C.;

forming a mixed solid phase comprising the matrix material and the reactant; and

thermally reducing the mixed solid phase to form the nanoparticle of claim 1 .

29. The method of claim 28 , further comprising:

separating the nanoparticle from the matrix material.

30. The method of claim 29 , wherein the separating comprises dissolving the matrix material.

31. The method of claim 28 , wherein the thermally reducing is carried out at a temperature where the matrix material is in a solid phase.

32. The method of claim 28 , wherein the stoichiometric ratio of the matrix material:the reactant is from about 2:1 to about 50:1.

33. The method of claim 28 , wherein the stoichiometric ratio of the matrix material:the reactant is from about 5:1 to about 30:1.

34. The method of claim 28 , wherein the stoichiometric ratio of the matrix material:the reactant is from about 15:1 to about 25:1.

35. The method of claim 28 , wherein the reactant is a metal ion salt, wherein the metal is selected from the group consisting of copper, gold, silver, tantalum, platinum, palladium, rhodium, and mixtures thereof.

36. The method of claim 28 , wherein the matrix material is selected from the group consisting of an organic material, an inorganic material, and salts thereof.

37. The method of claim 36 , wherein the matrix material is an the organic material and the organic material is selected from the group consisting of glycine, SH-PEG-SH, SH-PEGCOOH, SH-PEG-NH 2 , and mixtures thereof.

38. A method for detecting a small molecule, the method comprising:

contacting the small molecule with the nanoparticle of claim 1 , and

measuring the Raman signal of the small molecule and the nanoparticle of claim 1 .

39. A method for generating photoemission, the method comprising:

exciting the nanoparticle of claim 1 with an electromagnetic radiation capable of generating photons the nanoparticle of claim 1 .

40. A fluorescent sensor comprising the nanoparticle of claim 1 .

41. A fluorescent biomarker comprising the nanoparticle of claim 1 .

42. A Raman sensor comprising the nanoparticle of claim 1 .