Sensor for use in testing biological, biochemical, chemical or environmental samples

1. A method of detecting the presence and/or quantifying the amount of a substance in a biological, biochemical, chemical or environmental sample, which comprises the steps of:

(i) measuring absorbance of uv, visible and/or infrared light by at least one sensor comprising:

(a) an optically transparent substrate having a first surface and a second surface;

(b) optionally, a layer of a first functionalized material disposed over at least a portion of said first surface of said substrate;

(c) a monolayer or sub-monolayer of a metallic material disposed over at least a portion of said first surface of said substrate or, when present, said layer of a first functionalized material, said monolayer being optically transparent and exhibiting colloidal surface plasmon resonance;

(d) optionally, a layer of a second functionalized material disposed over at least a portion of said monolayer or sub-monolayer of metallic material; and

(e) a reactive substance disposed over at least a portion of said monolayer or sub-monolayer of a metallic material or, when present, said layer of a second functionalized material, wherein said reactive substance interacts with a predetermined substance present in said biological, biochemical, chemical or environmental sample;

(ii) contacting a biological, biochemical, chemical or environmental sample with said sensor;

(iii) measuring absorbance of uv infrared and/or visible light of said sensor following contact with said biological, biochemical, chemical or environmental sample; and

(iv) determining the difference in absorbance of uv, visible and/or infrared light of said sensor before and after contacting said biological, biochemical, chemical or environmental sample, wherein a difference in absorbance indicates the presence and/or amount of said substance in, said biological, biochemical, chemical or environmental sample.

2. The method of claim 1 , wherein said monolayer or sub-monolayer of metallic material is a monolayer of metallic material.

3. The method of claim 1 , wherein said monolayer or sub-monolayer of metallic material is a sub-monolayer of metallic material.

4. The method of claim 2 , wherein said monolayer of metallic material is a self-assembled monolayer of metallic material.

5. The method of claim 2 , wherein said monolayer of metallic material is formed by chemisorption.

6. The method of any one of claims 2 – 5 , wherein said monolayer or sub-monolayer of metallic material comprises a plurality of nanoparticles of metallic material.

7. The method of any one of claims 2 – 5 , wherein said metallic material is a noble metal.

8. The method of any one of claims 2 – 5 , wherein said metallic material is selected from the group consisting of gold, silver, indium, aluminum, copper, platinum, titanium, and mixtures of any two or more thereof.

9. The method of claim 6 , wherein said nanoparticles of metallic material comprise layered core-shell particles.

10. The method of claim 9 , wherein said core-shell particles comprise silver and gold.

11. The method of any one of claims 2 – 5 , wherein said metallic material is gold.

12. The method of claim 6 , wherein said nanoparticles are of a size in the range of about 10–100 nm.

13. The method of claim 6 , wherein said nanoparticles are of a size in the range of about 40–80 nm.

14. The method of claim 6 , wherein said nanoparticles are about 60 nm.

15. The method of claim 1 , wherein said optically transparent substrate is selected from the group consisting of glass, quartz, organic films, germanium, galium arsenide, fused silica, silicone gels, polysiloxanes, tin oxide and indium-doped tin oxide.

16. The method of claim 1 , wherein said reactive substance is a member of a pair selected from the group consisting of antibody/antigen; antibody/hapten; enzyme/substrate; enzyme/cofactor; enzyme/inhibitor; binding protein/substrate; carrier protein/substrate; lectin/carbohydrate; receptor/hormone; receptor/effector; nucleic acid strand/complementary nucleic acid strand; protein/nucleic acid repressor; protein/nucleic acid inducer; ligand/cell surface receptor; and virus/ligand.

17. The method of claim 1 , wherein said first functionalized material is an organosilane or an organothiol.

18. The method of claim 1 , wherein said first functionalized material is selected from the group consisting of hydrolyzed mono-, di- and trialkoxysilanes or mono-, di- and trichlorosilane which contain at least one CN, NH 2 , 2-pyridyl, P(C 6 H 5 ) 2 and/or SH group, and carboxyl-terminated organothiols.

19. The method of claim 18 , wherein said first functionalized material is gama-aminopropyltriethoxysilane.

20. The method of claim 1 , wherein said second functionalized material is an organic compound containing one or more of the functional groups COOH, CN, NH 2 , 2-pyridyl, P(C 6 H 5 ) 2 and/or SH.

21. The method of claim 20 , wherein said second functionalized material is a carboxyl-terminated organothiol.

22. The method of claim 20 , wherein said second functionalized material is 3 -mercaptopropionic acid.