Al-doped ZnO Nanostars for Electrochemical miRNA-21 Biosensors

The accurate and cost-effective detection of miRNAs, which are strongly associated with numerous diseases and disorders, poses significant technical challenges due to their small size, low concentration, and sequence similarity. In this study, we address these challenges by developing an Al-doped ZnO nanostar working electrode for electrochemical biosensors targeting miRNA-21 detection, employing a simple hydrothermal growth method. The introduction of Al doping modifies the nanostructure of the nanostars, enhancing their affinity for DNA probing and enabling tunability of the working electrode’s conductivity. This enhancement is achieved through the formation of a high-density, uniformly distributed nanostar structure, leading to improved electron transfer rates and increased surface area for miRNA binding. The nanostar biosensors, optimized with the appropriate Al content, exhibit satisfactory analytical properties, including a wide linear range from 1 pM to 10 nM, a low detection limit of 3.98 pM, reproducibility, and excellent selectivity for miRNA assays. Notably, real-time detection is achievable, demonstrating promising potential for point-of-care testing.