Self-assembled metal colloid monolayers

• US 5,609,907 A
• Filed: 02/09/1995
• Issued: 03/11/1997
• Est. Priority Date: 02/09/1995
• Status: Expired due to Term

• Current Assignee: Sicpa Holding SA
• Original Assignee: Penn State Research Foundation (Pennsylvania State University)
• Inventors: Natan, Michael
• Primary Examiner(s): BELL, JANYCE A
• Application Number:
  US08/386,231
• Time in Patent Office: 761 Days
• Field of Search: 427/2.12, 427/2.24, 427/301, 427/414, 427/299, 427/399, 427/404, 427/229, 427/384
• US Class Current: 427/2.12
• CPC Class Codes: B01J 13/00 Colloid chemistry, e.g. the production of colloidal materials or their solutions, not otherwise provided for; Making microcapsules or microballoons
• CPC Class Codes: B05D 1/185 applying monomolecular layers B05D1/204 takes precedence
• CPC Class Codes: B82Y 15/00 Nanotechnology for interacting, sensing or actuating, e.g. quantum dots as markers in protein assays or molecular motors
• CPC Class Codes: B82Y 30/00 Nanotechnology for materials or surface science, e.g. nanocomposites
• CPC Class Codes: B82Y 40/00 Manufacture or treatment of nanostructures

Abstract

What follows is a description of an invention for the preparation of macroscopic metal surfaces by self assembly of colloidal metal particles. Metal surfaces play a critical role in technology, and in many cases, the surface morphology dictates function. The strategy delineated herein, the use of nanometer scale colloidal particles to form two-dimensional arrays, allows control of surface morphology to a degree previously unattainable and perhaps even unimaginable.

Specific applications for metallic surfaces with controlled nanostructure include: (i) surface enhanced Raman scattering and all surface spectroscopies based on roughened metal surfaces, including second harmonic generation, surface enhanced hyperRaman scattering, surface plasmon resonance, and surface plasmonpolariton resonance; (ii) biocompatible surfaces, including those that comprise the working elements of electrochemical biosensors, substrates for matrix-assisted laser desorption ionization (MALDI) and biocompatible materials such as implants; (iii) catalysis; (iv) non-linear optical devices, including those based on second or third harmonic generation, the optical Kerr effect, etc.; and (v) electrochemical applications, including those requiring very high surface area/geometric area ratios, arrays of closely or variably spaced microelectrode arrays, and surfaces with exceptional biocompatibility and facile electron transfer properties.

Claims

1. A method for the preparation of metal colloid monolayers or submonolayers comprising the steps of:

a.) selecting a substrate

b.) coating the substrate with a bifunctional organic film to impart to said substrate a functionality that allows for bonding of metal colloid particles; and

c.) contacting the organic film coated substrate with a solution of colloid metal particles to bind said particles to the functional groups on said organic film thereby forming said monolayer or submonolayer,

said method resulting in an organic film coated substrate containing a surface layer of colloidal metal particles that are closely spaced, predominately unaggregated and confined to nearly a single plane.

2. A method according to claim 1 wherein said substrate is selected from the group consisting of glass, quartz, alumina, tin oxides, and metals.

3. A method according to claim 1 wherein said functionality is imparted either by covalent or non-covalent bonding.

4. A method according to claim 3 wherein said metal particles are coated with a protein.

5. A method according to claim 4 wherein said substrate is coated with biotin and then contacted with a colloidal metal coated with a protein and streptavidin thereby forming a colloid based biocompatible surface held together by non-covalent interactions.

6. A method according to claim 1 wherein said metal colloid submonolayers are silver or gold.

7. A method according to claim 1 wherein the size of said metal particles lies within the range 3-100 nm.

8. A method according to claim 1 wherein said contacting of the organic film with a solution of colloid metal particles is done by immersing the coated substrate into a solution of colloidal metal particles causing the particles to bind to the functional groups of the organic film coated substrate.

9. A method according to claim 1 wherein said coating is an organosilane, poly(allylamine) hydrochloride or a biotin.

10. A method according to claim 9 wherein said coating step involves surface-initiated polymerization of a bifunctional alkoxysilane having the formula (RO)₃ Si(CH₂)₃ A, where the pendent functional group A has a high affinity toward metal surfaces.

11. A method for the preparation of metal colloid monolayers or submonolayers comprising the steps of:

a.) selecting a substrate selected from the group consisting of glass, quartz, alumina, tin oxides, and metals;

b.) coating said substrate with a bifunctional organic film selected from the group consisting of organosilanes, poly(allylamine) hydrochloride, and biotin to impart to said substrate a functionality that allows for bonding of metal colloid particles; and

c.) immersing the organic film coated substrate in a solution of colloid metal particles to bind said particles to the functional groups on said organic film thereby forming said monolayer or submonolayer;

said method resulting in an organic film coated substrate containing a surface layer of colloidal metal particles that are closely spaced, predominately unaggregated and confined to nearly a single plane.

12. A method according to claim 11 wherein said colloid metal particles are selected from Au and Ag.

13. A method according to claim 11 wherein the size of said metal particles lies within the range 3-100 nm.

14. A method according to claim 11 wherein said metal particles are coated with a protein.

15. A method according to claim 14 wherein said substrate is coated with biotin and then contacted with a colloidal metal coated with a protein and streptavidin thereby forming a colloid based biocompatible surface held together by non-covalent interactions.