Sandwich immunoassay devices using antibodies specific to the exosomes containing target analytes

A lateral flow assay device, comprising:

• a test strip configured to receive a quantity of fluid comprising a quantity of exosomes and detect a presence of a target analyte on a surface of the exosomes;
• wherein the test strip comprises:
• a conjugate pad,
• wherein the conjugate pad is configured to contain a binding reagent to the target analyte conjugated with a label, wherein the binding reagent to the target analyte is configured to bind to a protein of the target analyte on the surface of an exosome and form an immunocomplex comprising an exosome;
• and
• wherein the conjugate pad is configured to receive the fluid after a start of a test and move the fluid by capillary action, and
• a membrane fluidly connected to the conjugate pad,
• wherein the membrane is configured to move the fluid by capillary action, and
• wherein the membrane comprises a test line comprising a set of one or more types of tetraspanin binding reagents immobilized on the test line, wherein each type of tetraspanin binding reagent is configured to bind with a corresponding type of exosome tetraspanin in an immunocomplex comprising the exosome.