Near-infrared dyes as surface enhanced raman scattering reporters

1. A surface-enhanced Raman scattering (SERS) active nanoparticle comprising a metal or metal alloy nanoparticle and a SERS active reporter molecule covalently bound to, or adsorbed on, an outer surface of the metal or metal alloy nanoparticle, wherein the SERS active reporter molecule is selected from the group consisting of:

wherein X 1 is CR 4 or N;

r, s, and t are each independently an integer from 1 to 8;

each X 2 and X 3 is independently selected from the group consisting of C, S, and N, under the proviso that (i) when X 2 is C or S, R 5 is Z, or when X 3 is C or S, R 6 is Z, as Z is defined herein below; (ii) if both X 2 and X 3 are N at the same time, at least one of R 5 and R 6 is absent; and (iii) when X 2 is N, R 5 when present is Z′, or when X 3 is N, R 6 when present is Z′, wherein Z′ is selected from the group consisting of:

—(CH 2 ) n —X 4 ; —NR 8 —(CH 2 ) p —X 5 ; —(CH 2 ) q X 6 C(═O)—R 9 ,

wherein:

n, p, q, u, and v are each independently an integer from 1 to 8;

X 4 and X 5 are each independently selected from the group consisting of hydroxyl, amino, and thiol;

X 6 is O or NR 11 ;

wherein:

each R 1 , R 2 , R 3 , R 4 , R 5 , R 6 , R 8 , R 10 , R 11 , and Z is independently selected from the group consisting of H, alkyl, substituted alkyl, heteroalkyl, substituted heteroalkyl, cycloalkyl, substituted cycloalkyl, cycloheteroalkyl, substituted cycloheteroalkyl, aryl, substituted aryl, aralkyl, hydroxyl, alkoxyl, hydroxyalkyl, hydroxycycloalkyl, alkoxycycloalkyl, aminoalkyl, acyloxyl, alkylaminoalkyl, and alkoxycarbonyl;

R 7 is Z′;

R 9 is —(CH 2 ) m —X 7 or —(CH 2 ) m —B, wherein

m is an integer from 1 to 8;

X 7 is halogen; and

B is a binding member having a binding affinity for a ligand or analyte to be detected.

2. The SERS active nanoparticle of claim 1 , wherein the SERS-active reporter molecule is selected from the group consisting of:

wherein:

X′ is selected from the group consisting of hydroxyl, amino, and thiol.

3. The SERS active nanoparticle of claim 1 , wherein the metal is selected from the group consisting of Au, Ag, Cu, Na, Al, and Cr.

4. The SERS active nanoparticle of claim 1 , wherein the metal alloy is at least two metals selected from the group consisting of Au, Ag, Cu, Na, Al, and Cr.

5. The SERS active nanoparticle of claim 1 , wherein the metal or metal alloy nanoparticle has a diameter less than about 200 nm.

6. The SERS active nanoparticle of claim 1 , wherein the metal or metal alloy nanoparticle has a diameter between about 40 nm to about 100 nm.

7. The SERS active nanoparticle of claim 1 , wherein the SERS-active reporter molecule forms a layer on an outer surface of the metal or metal alloy nanoparticle, wherein the layer at least partially covers the outer surface of the metal or metal alloy nanoparticle and is defined by an inner surface and an outer surface.

8. The SERS active nanoparticle of claim 7 , wherein the layer of the SERS-active reporter molecule formed on the outer surface of the metal or metal alloy nanoparticle is selected from the group consisting of a submonolayer, a monolayer, and a multilayer.

9. The SERS active nanoparticle of claim 8 , further comprising an encapsulant, wherein the encapsulant is disposed on at least one of the outer surface of the metal or metal alloy nanoparticle and the outer surface of the layer of the SERS-active reporter molecule.

10. The SERS active nanoparticle of claim 9 , wherein the encapsulant comprises one or more materials selected from the group consisting of a glass, a polymer, a metal, a metal oxide, and a metal sulfide.

11. The SERS active nanoparticle of 10 , wherein the glass comprises SiO x .

12. The SERS active nanoparticle of claim 10 wherein the encapsulant has a thickness of about 1 nm to about 40 nm.

13. A kit comprising a reagent comprising one or more surface-enhanced Raman scattering (SERS) active nanoparticles, wherein the one or more SERS active nanoparticles comprises a metal or metal alloy nanoparticle having associated therewith at least one SERS-active reporter molecule covalently bound to, or adsorbed on, an outer surface of the metal or metal alloy nanoparticle, the SERS-active reporter molecule selected from the group consisting of:

wherein X 1 is CR 4 or N;

r, s, and t are each independently an integer from 1 to 8;

each X 2 and X 3 is independently selected from the group consisting of C, S, and N, under the proviso that (i) when X 2 is C or S, R 5 is Z, or when X 3 is C or S, R 6 is Z, as Z is defined herein below; (ii) if both X 2 and X 3 are N at the same time, at least one of R 5 and R 6 is absent; and (iii) when X 2 is N, R 5 when present is Z′, or when X 3 is N, R 6 when present is Z′, wherein Z′ is selected from the group consisting of:

—(CH 2 ) n —X 4 ; —NR 8 —(CH 2 ) p —X 5 ; —(CH 2 ) q X 6 C(═O)—R 9 ,

wherein:

n, p, q, u, and v are each independently an integer from 1 to 8;

X 4 and X 5 are each independently selected from the group consisting of hydroxyl, amino, and thiol;

X 6 is O or NR 11 ;

wherein:

each R 1 , R 2 , R 3 , R 4 , R 5 , R 6 , R 8 , R 10 , R 11 , and Z is independently selected from the group consisting of H, alkyl, substituted alkyl, heteroalkyl, substituted heteroalkyl, cycloalkyl, substituted cycloalkyl, cycloheteroalkyl, substituted cycloheteroalkyl, aryl, substituted aryl, aralkyl, hydroxyl, alkoxyl, hydroxyalkyl, hydroxycycloalkyl, alkoxycycloalkyl, aminoalkyl, acyloxyl, alkylaminoalkyl, and alkoxycarbonyl;

R 7 is Z′;

R 9 is —(CH 2 ) m —X 7 or —(CH 2 ) m —B, wherein

m is an integer from 1 to 8;

X 7 is halogen; and

B is a binding member having a binding affinity for a ligand or analyte to be detected.

14. The kit of claim 13 , further comprising one or more of a sample collection device, magnetic capture particles, a buffer solution, and combinations thereof.

15. The kit of claim 14 , wherein the reagent is disposed in the sample collection device.

16. The kit of claim 13 , wherein the one or more SERS active nanoparticles comprise a plurality of SERS-active nanoparticles, each having associated therewith a SERS-active reporter molecule having a distinguishable SERS response, and wherein at least one of the SERS-active reporter molecules comprises a SERS-active reporter molecule.

17. The kit of claim 13 , wherein the metal is selected from the group consisting of Au, Ag, Cu, Na, Al, and Cr.

18. The kit of claim 13 , wherein the metal alloy is at least two metals selected from the group consisting of Au, Ag, Cu, Na, Al, and Cr.