ALS genosensing using DNA-hybridization electrochemical biosensor based on label-free immobilization of ssDNA on Sm2O3 NPs-rGO/PANI composite

A DNA-hybridization electrochemical biosensor (DNA-HEB) has been developed using a new platform for immobilization of a 20-mer oligonucleotide. In a DNA-HEB, the signal is produced based on hybridization of a probe and its target sequence. DNA-HEB can be a cost-effective techniques be able to be miniaturized. The selected DNA sequence is related to a gene sequence encoding the Cu-Zn superoxide dismutase enzyme (SOD1) which is important in familial Amyotrophic lateral sclerosis (ALS) disease. Tris(bipyridine)ruthenium(II) chloride was utilized as an electroactive probe to detect the interactions of ssDNA and dsDNA on the electrode surface indirectly. Modifying a glassy carbon electrode with polyaniline and samarium oxide nanoparticles decorated reduced graphene oxide composite, provided a matrix for a lable-free immobilization of ssDNA and enhanced the sensor signal obtained from Fast Fourier Transform square wave voltammetry (FFT-SWV). The studies showed a good dynamic response range from 1 × 10−13 to 1 × 10−8 mol L-1 for the proposed sequence SOD1.