A label-free electrochemiluminescent immunosensor for glutamate decarboxylase antibody detection on AuNPs supporting interface

In this paper, we will describe a novel lable-free electrochemiluminescent (ECL) immunosensor for the detection of glutamate decarboxylase antibody (GADA) in which Au nanoparticles (AuNPs) had pre-functionalized the indium tin oxide (ITO) glass to support the sensing interface. The preparation of the basal electrode only need a simple two-step drop coating, a thin polymer of hydrolyzed 3-aminopropyl trimethoxysilane, and the AuNPs gel on the ITO substrate. The AuNPs not only enhanced the ECL signal of luminol, but also acted to immobilize the glutamate decarboxylase (GAD) to build the sensing host. This immunosensor exhibits excellent specificity, reproducibility and stability. On resultant sensor, after the direct immunoreaction, the decreased ECL intensity has a good linear regression toward the logarithm of GADA concentration in the range of 0.30 ng mL−1 to 50 ng mL−1 with a detection limit of 0.10 ng mL−1. The proposed senor has prospective capability for the clinical detection of GADA in human serums, which had important value for diagnosis and precaution of type-1 diabetes or latent autoimmune diabetes in adult (LADA).