Development of electrochemical biosensor based on Ni-doped ZnO nanorods for detecting miRNA-21 lung cancer biomarker

Circulatory miRNA-21 has shown promise as a stable and non-invasive biomarker for early diagnosis of cancer and is highly correlated with non-small cell lung cancer. In this study, a new kind of electrochemical biosensor was fabricated using the Ni-doped ZnO nanorods directly grown onto the surface of a glassy carbon electrode (GCE) for your sensitive and selective detection of miR-21. On the modified electrode surface: polydopamine (PDA) and crosslinked with glutaraldehyde, DNA probes were immobilized using the electrostatic attraction between a phosphate group and the PDA, and then treated with a solution of bovine serum albumin (BSA) to ensure that any unbound surfaces were saturated, thus preventing non-specific interactions. Electrochemical analyses were adopted to systematically investigate the progresses of the stepwise electrode modification and the hybridization. With the increasing of self-discharge time of the laser etched carbon-paste electrode The response to current gradually drop and the charge-transfer resistance increase, which indicates that the sensing interface has been successfully assembled. Following optimization, the biosensor was capable of detecting concentrations as low as 21.30 fM with dynamic linear range of 10 ^− 6 nM to 10 ⁵ nM, good reproducibility and selectivity to the mismatch and non-complementary sequences. Crucially, recovery experiments in spiked human serum samples gave satisfactory results, confirming the clinical potential of the system. In general, the Ni doped ZnO nanorod-based biosensor provides sensitive, label-free, and low-cost detection of circulating miRNAs. Its modularity allows for simple conversion for detection of other nucleic acid-based biomarkers, implicating it as a useful diagnostic tool for early cancer diagnosis and point-of-care screening.