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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
First Claim
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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.

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