Modification of metal nanoparticles for improved analyte detection by surface enhanced Raman spectroscopy (SERS)
A SERS active particle having a metal-containing particle and a cationic coating on the metal-containing particle, wherein the SERS active particle carries a positive charge is disclosed. Also, a SERS active particle having a metal-containing particle and a non-metallic molecule, wherein the metal-containing particle is derivatized with the non-metallic molecule is disclosed. In addition, several methods of modifying the nanoparticles surfaces of a SERS active particle and of improving the interaction between the SERS active particle and an analyte are disclosed.
1. A surface enhanced Raman spectroscopy (SERS) active particle comprising a metal-containing particle and a cationic coating on the metal-containing particle, wherein the metal-containing particle comprises a metal selected from the group consisting of silver, gold, platinum, aluminum, an oxide of aluminum, and combinations thereof, and wherein the cationic coating comprises hematite, further comprising an analyte, an aggregate of a plurality of the metal-containing particles, wherein the metal-containing particles have the cationic coating and the analyte on the metal-containing particles, and a coagulant wherein the coagulant is a salt that causes the plurality of the metal-containing particles to aggregate.
2. The SERS active particle of claim 1 , wherein the metal-containing particle comprises metallic colloids.
3. The SERS active particle of claim 1 , wherein the cationic coating comprises an adsorbed additive or a deposited additive.
4. The SERS active particle of claim 3 , wherein the adsorbed additive comprises a material selected from the group consisting of ions, a thiol-containing compound, a polymer and nanoparticles.
5. The SERS active particle of claim 4 , wherein the nanoparticles comprise an iron-containing material.
6. The SERS active particle of claim 1 , wherein the SERS active particle has as planar or curved surface.
7. The SERS active particle of claim 1 , wherein the SERS active particle carries a positive charge.
8. The SERS active particle of claim 1 , wherein the analyte comprises m-RNA, r-RNA, t-RNA, DNA, DNA-RNA duplexes, peptide nucleic acids (PNA), restriction enzymes, activators, repressors, nucleases, polymerases, histones, repair enzymes, or chemotherapeutic agents.
9. The SERS active particle of claim 1 , wherein the salt is LiCl or NaCl.