Abstract
Hyper Immunoglobulin E syndrome (HIES) is a rare inherited inborn error of primary immunodeficiency. HIES is characterized by high levels of serum immunoglobulin E (IgE), severe eczema, which overlap with atopic dermatitis, as well as lung infections and even death. HIESs are genetically inherited by heterozygous or homozygous mutations in signal transducer and activator of transcription 3 (STAT3) or Dedicator of cytokinesis 8 (DOCK8) genes, in autosomal dominant and recessive forms, respectively. Therefore, the early detection of DOCK8 and STAT3 protein levels in humans would facilitate the early diagnosis of these disorders and thus, help in the disease management. Here, we present the development of immunosensors for the detection of DOCK8 and STAT3 using electrochemical impedance spectroscopy in a label-free format. The immunosensors were fabricated by the covalent attachment of specific antibodies for DOCK8 and STAT3 on gold electrodes via cysteamine/phenylene diisothiocyanate linkers. The detection was achieved by monitoring the change in the charge transfer resistance (R-ct) of ferro/ferricyanide redox couple upon binding of the proteins to the immunosensor surface. These biosensors enabled the detection of DOCK8 and STAT3 levels with low detection limits of 1.2 and 9.0pg/ml, respectively. The immunosensor was also applied for the detection of DOCK8 in human serum samples showing high recovery percentages which indicates great promise of this method for early diagnosis of HIES in newborn infants.