Method for quantitative analysis using optical fibers

A method for the quantitative analysis of an analyte in a fluid containing said analyte species and a second species which reacts with said analyte species in the presence of a catalyst, said method comprising:

• (a) providing a fiber-sheath element including:
• a fiber which transmits electromagnetic radiation;
• a first sheath element covering said fiber and formed of a material which is permeable to at least one of said analyte species and said second species and which contains a reagent which reacts with one of said analyte species and said second species to modify an electromagnetic energy transmitting characteristic of the fiber;
• and
• a second sheath element surrounding said first sheath element, said second sheath element being formed of a material which is permeable to both said analyte species and said second species and which contains a catalyst for causing a reaction between said analyte species and said second species;
• (b) contacting said element with the fluid to be analyzed thus allowing said analyte and said second species to permeate said second sheath element and to react in the presence of said catalyst, thereby diminishing the amount of the species reacting with said reagent;
• (c) transmitting electromagnetic radiation through said fiber with cumulative modification of said radiation along a length of said fiber due to the influence of said reagent;
• and
• (d) measuring the quantity of electromagnetic radiation of at least one wavelength emitted from said fiber.

A method for quantitative analysis of an antigen A1 contained in a liquid, said method comprising:

• (a) providing a fiber element capable of transmitting electromagnetic energy and defining a path for the transmission of said energy, a first sheath surrounding said fiber element and containing a first complex A2 of an antigen and an energy-modifying compound, a second sheath surrounding said first sheath, said second sheath reflecting said electromagnetic radiation and being selectively permeable to said first complex when wet, and a third sheath, surrounding said second sheath, and an antibody Ab to A1 and A2 incorporated into the material forming said third sheath;
• (b) contacting said fiber element with said liquid whereby said sheaths are wetted and antigen A1, if present, diffuses from the liquid into said third sheath to complex said antibody and said first complex diffuses reversibly across said second sheath into said third sheath and likewise complexes with said antibody to produce the following competing reversible reactions in said third sheath:
• A1+Ab.revreaction.A1-Ab (1)
• A2+Ab.revreaction.A2-Ab (2)
• (c) introducing the electromagnetic radiation into one end of said fiber whereby a portion refracts into said first sheath wherein said refracted portion reacts with said energy-modifying compound to produce a modification of the transmitted radiation which is cumulative along a length of said path and which is proportional to the amount of A1 diffusing into said fiber element.

A method for the quantitative analysis of an antigen A1 contained in a liquid, said method comprising:

• (a) providing a fiber-sheath element including a fiber which transmits electromagnetic radiation, said fiber having an index of refraction n.sub.c and being permeable to the product Y of a reaction:
• ##EQU3## wherein E is an enzyme, X is a high molecular weight compound and Y is a low molecular weight compound;
• a first sheath surrounding said fiber and being permeable to Y but not to X;
• a second sheath surrounding said first sheath and having an index of refraction n.sub.s lower than n.sub.c, said second sheath being formed of a material containing an antibody Ab immunobonded to a complex of an enzyme E and an antigen A2, and an excess of X, said second sheath being permeable to A1;
• (b) transmitting electromagnetic radiation selected for maximum modification by Y through said fiber;
• (c) wetting said second sheath with the liquid to be analyzed, whereby any antigen A1 present in the liquid diffuses into second sheath and reacts with Ab thereby displacing A2-E in proportion to the concentration of A1 in the liquid, the displaced complex A2-E catalyzing the conversion of X into Y which then diffuses into the fiber and modifies said electromagnetic radiation cumulatively along a length of said fiber.

A method for the quantitative analysis of an antigen contained in a liquid, said method comprising:

• (a) providing a fiber-sheath element including a fiber which transmits electromagnetic radiation and which is formed of a material containing an antibody Ab, for the antigen, bonded to a compound Y in the form of a complex Ab-Y, said compound Y having an energy-modifying characteristic which changes upon immunobonding of the antigen to the antibody Ab;
• and a sheath, permeable to the antigen, surrounding said fiber;
• (b) transmitting electromagnetic radiation selected for maximum modification by Y through said fiber;
• (c) wetting said sheath with the liquid to be analyzed, whereby any antigen present in the liquid diffuses through the sheath and into the fiber to immunobond with Ab thus modifying said characteristic of Y and said electromagnetic radiation cumulatively, along a length of said fiber.

A method for the quantitative analysis of an enzyme in a liquid sample, said method comprising:

• (a) providing a fiber-sheath element including a fiber which transmits electromagnetic radiation, a sheath surrounding said fiber and formed of a hydrophilic polymer and an energy modifying compound Y incorporated into and chemically bound to said polymer, said chemical bond being selectively degradable by the enzyme to be detected, said fiber being permeable to Y;
• (b) transmitting electromagnetic radiation selected for maximum modification by Y through said fiber;
• and
• (c) wetting said sheath with the liquid to be analyzed whereby any enzyme in the liquid breaks down the chemical bond between Y and the polymer, thus releasing Y for diffusion into the fiber wherein Y modifies said radiation, cumulatively, along a length of said fiber.

A method for the quantitative analysis of an analyte contained in a fluid, said method comprising:

• (a) providing a plurality of fiber-sheath elements, each of said elements including:
• (1) an electromagnetic energy transmissive fiber defining a path for transmission of electromagnetic energy, at least a portion of said fiber being formed of a material having an electromagnetic energy transmitting characteristic capable of modification by the presence of an analyte contained in the fluid;
• (2) a semipermeable sheath surrounding said fiber;
• and (3) a reagent which modifies said transmitted energy responsive to the presence of an analyte or which reacts with the analyte to form a product which modifies said transmitted energy, said elements containing said reagent in different amounts;
• (b) contacting said fiber-sheath elements with the fluid to be analyzed;
• (c) transmitting electromagnetic radiation through said fibers with cumulative modification of said radiation along a length of each of said fibers due to the influence of said reagent;
• and
• (d) taking the output of one of said fibers as a measurement of the concentration of the analyte and rejecting the output of the other fibers.