Self-assembled monolayers and methods for using the same in biosensing applications
Cross-linked amphiphile constructs that form self-assembled monolayers (SAMs) on metal surfaces such as gold surfaces are disclosed. These new SAMs generate well packed and highly oriented monolayer films on gold surfaces. A method for using the SAMs in the fabrication of biomolecule sensors is also disclosed.
1. A method of detecting a biomolecule of interest in a sample, which comprises the steps of:
(a) providing a monolayer component that comprises a self-assembled monolayer comprising a compound of Formula II:
wherein:
R 1 -R 4 are each, independently, SR a , OH, COR b , heterocyclyl, heteroaryl, CN, N 3 or halo;
R 7 is 0-2 R c groups,
X, Y, U, and V are each, independently, C 2-6 alkyl;
R a is H, C 1-20 alkyl, C(O)H, CO—(C 1-20 alkyl), SH, S(C 1-20 alkyl);
R b is C 0-20 hydroxyl, C 3-10 heterocycloalkyl, C 5-10 aryl, C 5-10 heteroaryl, or NR I R II ;
R c is alkyl, alkenyl, alkynyl, cycloalkyl, aryl, heteroaryl, hydroxyl, halo, haloalkyl, haloalkoxy, cyano, nitro, azido, amino, alkylamino, dialkylamino, carboxy, carboxyalkyl ester, carboxy aryl ester, aminocarbonyl, alkylaminocarbonyl, dialkylaminocarbonyl, sulfonyl, aminosulfonyl, alkylaminosulfonyl, dislakylaminosulfonyl, arylsulfonyl, arylsulfinyl, alkylsulfonyl, or arylsufonyl; and
R I and R II are each, independently selected from H, substituted or unsubstituted alkyl, or R I and R II come together to form a 4-10-membered substituted or unsubstituted heterocyclic ring;
(b) binding a multivalent cation to the monolayer;
(c) capturing a binding partner for the biomolecule of interest onto the monolayer, wherein the binding partner comprises a detectable marker and a first moiety capable of binding the multivalent cation;
(d) exposing the sample to the monolayer component; and
(e) detecting a signal of detectable marker.
2. The method of claim 1 , wherein the self-assembled monolayer comprises a plurality of compounds of Formula II, wherein at least about 5% of the compounds are functionalized with a second moiety capable of binding the multivalent cation.
3. The method of claim 2 , wherein the second moiety capable of binding the multivalent cation comprises a chelating molecule.
4. The method according to claim 1 , wherein at least one of R 3 or R 4 comprises a second moiety capable of binding the multivalent cation.
5. The method according to claim 4 , wherein the second moiety capable of binding the multivalent cation is a chelating molecule.
6. The method of claim 5 , wherein the chelating molecule comprises an imidazole, nitrilotriacetic acid, or 1,4,7-triazacyclononane moiety.
7. The method of claim 5 , wherein the chelating molecule is imidazole.
8. The method of claim 5 , wherein the chelating molecule is nitrilotriacetic acid.
9. The method of claim 1 , wherein the self-assembled monolayer comprises a compound selected from:
6,6′-(4,5-bis(2-(1H-imidazol-1-yl)ethyl)-1,2-phenylene)bis(hexane-1-thiol); and
((4,5-bis(2-(1H-imidazol-1-yl)ethyl)-1,2-phenylene)bis(hexane-6,1-diyl)) diethanethioate.
10. The method of claim 1 , wherein the multivalent cation is a divalent or trivalent cation.
11. The method of claim 1 , wherein the multivalent cation is a divalent cation.
12. The method of claim 11 , wherein the divalent cation is selected from Zn(II), Ni(II), or Co(II).
13. The method of claim 12 , wherein the divalent cation is Ni(II).
14. The method of claim 1 , wherein the first moiety capable of biding a multivalent cation is a chelating agent.
15. The method of claim 14 , wherein the chelating agent comprises one or more amino acids.
16. The method of claim 15 , wherein the chelating agent comprises one or more histidine amino acids.
17. The method of claim 16 , wherein the chelating agent is a histidine tag.
18. The method of claim 17 , wherein the histidine tag is hexahistidine.
19. The method of claim 1 , wherein the detectable marker is a redox molecule.
20. The method of claim 19 , wherein the redox molecule is methylene blue.
21. The method of claim 1 , wherein the binding partner is any ligand capable of binding to the biomolecule.
22. The method of claim 1 , wherein the binding partner is a peptide.
23. The method of claim 1 , wherein the method further comprises a regeneration step.
24. The method of claim 23 , wherein the regeneration comprises displacing the binding partner from the monolayer upon treatment with any reagent capable of biding the multivalent cation.
25. The method of claim 23 , wherein the regeneration comprises displacing the binding partner from the monolayer upon treatment with a chelating molecule.
26. The method of claim 1 , wherein the method is for detecting ligands such as hormones, antigens or antibodies.
27. The method of claim 26 , wherein the method is for detecting and anti-peanut antigen.
28. The method of claim 26 , wherein the method is for detecting an anti-HIV-p24 antibody.