3D printed electrode-microwell system: a novel electrochemical platform for miRNA detection.

3D printing has enabled the ability to make creative electrochemical well designs suitable for a wide field of electrochemical sensing. The demand for robust electrochemical systems is particularly high in diagnostics, where the rapid detection of emerging biomarkers associated with severe diseases is critical for rapid medical decision-making. This study is aimed at developing a fully 3D-printed electrochemical sensing device featuring a three-electrode system fabricated from conductive printing materials and incorporating a microwell as the sensing platform. The assay principle of a robust electrochemical screen-printed sensor was adapted for this platform, incorporating a well-structured design to enhance fluid control. This structure ensured the uniform distribution of reagents across the sensing surface, improving the reproducibility and consistency of measurements and enabling the reliable detection of a microRNA target associated with lung cancer. The detection process was based on the hybridization of the target miRNA with an immobilized DNA probe labeled with methylene blue as a redox mediator. The sensor was thoroughly characterized and optimized, achieving a dynamic detection range of 0.001 to 400 nM and a lower limit of detection compared to screen-printed sensors, down to the picomolar level. Furthermore, the sensor demonstrated high selectivity for the target miRNA compared to other miRNA sequences, proving its specificity. These results highlighted the potential of 3D printing technology for the development of sensitive and selective tools for biomarker detection, making it a valuable complementary method in the field of diagnostics.