An analyte sensor comprising: an insertion tip configured for insertion below a tissue of a user, the insertion tip comprising: a working electrode comprising a sensing layer disposed thereon and a membrane layer disposed at least partially over the sensing layer; a substrate; and a counter electrode. Wherein a polymer layer comprising at least an immunosuppressant is disposed on an exterior surface of the working electrode, the substrate, or the counter electrode, the polymer layer being separate from the sensing layer and the membrane layer.

The binding specificity of at least one plasma protein suspended or dissolved in a liquid medium is altered by exposing the protein to an oxidizing agent or an electric current sufficient to alter its binding specificity. A masked protein such as an autoantibody can be recovered from blood or blood products or extracts by oxidizing the protein to change its binding specificity.

An analyte sensor comprising: an insertion tip configured for insertion below a tissue of a user, the insertion tip comprising: a working electrode comprising a sensing layer disposed thereon and a membrane layer disposed at least partially over the sensing layer; a substrate; and a counter electrode. Wherein a polymer layer comprising at least an immunosuppressant is disposed on an exterior surface of the working electrode, the substrate, or the counter electrode, the polymer layer being separate from the sensing layer and the membrane layer.