the present invention relates to a composition in which a conducting polymer is doped with a dopant , and a diagnostic apparatus , and more particularly , to a composition which is used to diagnose a disease and detect a biomaterial and also used for qualification and diagnosis by effectively and non - destructively collecting a captured biomaterial . further , the composition can maximize capturing efficiency by being attached to a surface of a nano - structured scaffold and can be used as an ultrahigh - sensitive sensor using various linked bodies .