Optical sensor-based cupric reducing antioxidant capacity (CUPRAC) assay
An example embodiment is an apparatus for measuring antioxidant presence comprising a solid media, and a reagent carried by the media, the reagent reactive with at least one antioxidant to cause changes in light that is incident upon the reagent while carried by the solid media.
1. An apparatus for measuring antioxidant capacity in a biological sample comprising:
a solid media, wherein the solid media is composed of paper or woven fabrics; and,
a reagent carried by the media, wherein the reagent is comprised of copper and neocuproine (2,9-dimethyl-1,10-phenanthroline, abbreviated as Nc) chelator embedded in or adsorbed to the solid media and wherein the reagent is reactive with a number of antioxidants in a biological sample to cause changes in light that are incident upon the reagent while carried by the solid media, wherein the reagent has a standard reduction potential of about 0.6V.
2. An apparatus as defined by claim 1 wherein the changes in light comprise one or more of changes in the spectral absorbance of the reagent and changes in the reflectance of the reagent retained on a solid medium.
3. An apparatus as defined by claim 1 wherein the reagent is electrostatically immobilized on the media.
4. An apparatus as defined by claim 1 wherein the changes in light are generally linear with antioxidant concentration.
5. An apparatus as defined by claim 1 wherein the changes in light are additive for different antioxidants wherein the change indicates concentration of all antioxidants.
6. An apparatus as defined by claim 1 wherein:
the reagent comprises a Cu(II)-Nc reagent; and,
reaction of the reagent with the antioxidant comprises reduction of the Cu(II)-Nc reagent to form a Cu(I)-Nc chelate in or on the solid phase matrix.
7. An apparatus as defined by claim 1 and further comprising:
a light source for illuminating the media following reaction with the reagent; and,
an optical sensor for determining a measurement of light that is one or more of reflected from the media or transmitted through the media.
8. An apparatus as defined by claim 7 and further comprising a reference for comparing the optical sensor light measurement to, the comparison useful to determine total antioxidant capacity.
9. A solid phase antioxidant assay apparatus comprising:
a solid phase matrix, wherein the solid phase matrix is solid media composed of paper or woven fabrics;
an impregnated in the solid media copper(II)-neocuproine reagent that oxidizes one or more antioxidants as they contact the reagent, the copper(II)-neocuproine reagent undergoing a change through the copper(II)-neocuproine reduction that causes changes in light reflected from the immobilized reagent, with the changes being proportional with antioxidant concentration over a certain antioxidant concentration range, wherein the reagent has a standard reduction potential of about 0.6V;
a light source for illuminating the impregnated solid media;
a light sensor for determining a measurement of light reflected from the impregnated solid media; and,
a reference for comparing the measurement to, the comparison useful to indicate concentration of the antioxidant.