Electrical detection of the immune reaction

• US 4,920,047 A
• Filed: 05/20/1988
• Issued: 04/24/1990
• Est. Priority Date: 05/20/1988
• Status: Expired due to Fees

• Current Assignee: Japanese Foundation For Cancer Research
• Original Assignee: General Electric Company
• Inventors: Keese, Charles R., Giaever, Ivar
• Primary Examiner(s): Rosen, Sam
• Application Number:
  US07/196,718
• Time in Patent Office: 704 Days
• Field of Search: 435/817, 435/7, 435/4, 204/403, 436/525, 436/806
• US Class Current: 435/7.92
• CPC Class Codes: G01N 33/5438 Electrodes
• CPC Class Codes: Y10S 435/817 Enzyme or microbe electrode
• CPC Class Codes: Y10S 436/806 Electrical property or magnetic property

Abstract

Test method and apparatus for determining the presence of, the concentration of, or the absence of, immunologically-active substances in liquid media by measuring any change of electrical impedance of an electrode due to the presence of, or the absence of, the reaction of a product of enzyme linked immunologically-active substance and a proper enzyme substrate.

Claims

1. A method for determining the presence of, the concentration of, or the absence of, a first immunologically-active substance in a liquid medium, said method comprising the steps of:

(i) providing an electrode comprising a plurality of metal film in a small area, in the range of from about 10^-10 cm² to about 10^-2 cm², on a substrate;

(ii) adsorbing a second immunologically-active substance capable of binding said first immunologically-active substance to said electrode;

(iii) contacting said electrode having said second immunologically-active substance adsorbed thereon with a liquid medium to be analyzed for said first immunologically-active substance;

(iv) contacting said electrode with a liquid medium comprising a third immunologically-active substance linked to an enzyme and capable of binding with said second immunologically-active substance and incapable of binding with said first immunologically-active substance;

(v) contacting said electrode with a liquid medium comprising an enzyme substrate capable of reacting with said enzyme linked to said third immunologically-active substance;

(vi) immersing said electrode into a measuring solution; and

(vii) measuring electrical impedance of said electrode whereby no change or only a slight change in impedance indicates the presence of said first immunologically-active substance and a larger change indicates the absence of said first immunologically-active substance, the degree of change being proportional to the concentration of said first immunologically-active substance in said liquid medium.

2. The method of claim 1 wherein said electrode comprises a film of gold, tantalum, indium, platinum, titanium or titanium on a plastic substrate.

3. The method of claim 1 wherein said first immunologically-active substance comprises an antibody, said second immunologically active substance comprises an antigen and said third immunologically-active substance linked to an enzyme comprises an antibody linked to an enzyme.

4. The method of claim 1 wherein said first immunologically-active substance comprises an antigen said second immunologically-active substance comprises an antibody, and said third immunologically-active substance linked to an enzyme comprises an antigen linked to an enzyme.

5. The method of claim 3 wherein said antibody comprises anti-goat antibody, said antigen comprises anti-goat antigen, said antibody linked to an enzyme comprises anti-goat antibody linked to horseradish peroxidase and said enzyme substrate comprises carbazone and hydrogen peroxide.

6. A method for determining the presence of, the concentration, of or the absence of, a first immunologically-active substance in a liquid medium, said method comprising the steps of:

(i) providing an electrode comprising metal film in a small area, in the range of from about 10^-10 cm² to about 10^-2 cm² on a substrate;

(ii) adsorbing a second immunologically-active substance capable of binding said first immunologically-active substance to said electrode;

(iii) contacting said electrode having said second immunologically-active substance adsorbed thereon with a liquid medium to be analyzed for said first immunologically-active substance;

(iv) contacting said electrode with a liquid medium comprising a third immunologically active substance linked to an enzyme and capable of binding with said first immunologically-active substance and incapable of binding with said second immunologically-active substance;

(v) contacting said electrode with a liquid medium comprising an enzyme substrate capable of reacting with said enzyme linked to said third immunologically-active substance;

(vi) immersing said electrode into a measuring solution; and

(vii) measuring the electrical impedance of said electrode whereby no change in impedance indicates the absence of said first immunologically-active substance and any change in impedance indicates the presence of said first immunologically-active substance, the degree of change being proportional to the concentration of said first immunologically-active substance in said liquid medium.

7. The method of claim 6 wherein said electrode comprises globules of gold, tantalum, indium, titanium or titanium on a plastic substrate.

8. The method of claim 6 wherein said first immunologically-active substance comprises an antibody, said second immunologically-active substance comprises an antigen and third immunologically-active substance linked to an enzyme comprises an antibody linked to an enzyme.

9. The method of claim 6 wherein said first immunologically active substance comprises an antigen, said second immunologically-active substance comprises an antibody and said third immunologically-active substance linked to an enzyme comprises an antibody linked to an enzyme.