Abstract
Cystic Fibrosis (CF) and Duchenne Muscular Dystrophy (DMD) are well characterized progressive inherited diseases associated with significant morbidity and mortality. Therefore, the early, rapid and affordable diagnosis of these disorders through newborn screening is highly important for the appropriate management. Here, we report label-free impedance immunosensors for the simple screening of CF and DMD through the detection of cystic fibrosis transmembrane conductance regulator (CFTR) protein fragment and a peptide sequence for dystrophin (DMD). The biosensors were constructed by the covalent immobilization of specific antibodies for CFTR and DMD on standard gold (Au) electrodes. The immunosensors response was measured based on the change in the electrochemical impedance spectroscopy (EIS) signals after binding with the peptides. The specific recognition of the immunosensor surfaces to the target antigens leads to retardation of the access of ferriferrocyanide redox molecules to the surface and thus, enhances the charge transfer resistance (R-ct). These impedimetric immunosensors enabled sensitive, fast, selective and accurate estimation of CFTR and DMD levels within a linear range from 1.0 mu g/mL to 1 mu g/mL and 1.0 pg/mL to 10 ng/mL with lower detection limits of 0.8 and 0.7 pg/mL for CFTR and DMD, respectively. Moreover, the immunosensors were tested for the detection of CFTR and DMD in human serum showing very good agreement with enzyme-linked immunosorbent assays (ELISA). This work represents a novel low cost analytical method that aims to satisfy the unmet public health need in the early diagnosis of CF and DMD and can be extended to detect other hereditary disorders.