Electrochemical cDNA-sensing of miRNA-137 for detection of Alzheimer's disease using CuO and PEI deposited Au-Pd bimetallic nanoparticles.

• Electrochemical cDNA-sensing of Alzheimer's disease biomarker miRNA-137 is done. • The bimetallic Au-Pd nanoparticles are used on PEI@CuO/FTO as sensing platform. • cDNA-sensor responded with linear range from 1fM to 100 nM and LOD of 0.164pM. • Acceptable shelf life of one month with high reproducibility (2.5- 1.46% RSD). • Recovery was obtained ranging from 99% to 103.28% in spiked human serum sample. Alzheimer's disease (AD) is the third most predominantly occurring disease worldwide that is characterized by progressive deterioration of brain cells and change in behaviour, personality, orientation of time and space, leading to functional disability which affects the daily life of patient. We report an electrochemical complementary DNA (cDNA)-sensor for detection of AD by using blood biomarker, micro-ribonucleic acid-137 (miRNA-137). In this context, the gold-palladium/polyethyleneimine@copperoxide nanocomposite-coated fluorine tin oxide (Au-Pd/PEI@CuO/FTO) electrode is used as an immobilization platform for complementary DNA (cDNA) against the target miRNA-137. The thiolated-cDNA (Thi-cDNA) and Au-Pd bimetallic particles interact through the stable electrostatic binding. The fabricated Au-Pd/PEI@CuO/FTO was characterized by field emission scanning electron microscopy, cyclic voltammetry, and electrochemical Impendence Spectroscopy. The sensor showed response time of 20 min with the linear range of 1fM to 100 nM and limit of detection as 0.164pM. The recovery of the cDNA-sensor for spiked human serum sample ranged from 99.3 % to 103.28 % with RSD value of 0.62 % to 2.81 %. The easy-to-use procedure, cost effectiveness, compactness, long shelf life (28 days) and high selectivity of cDNA-sensor towards miRNA-137 over even the one-base pair mismatch recommends the sensor's portability and real-life usability for AD detection. [ABSTRACT FROM AUTHOR]