Self-powered bio-chip for ultra-sensitive dual MiRNAs detection: A portable platform for cancer biomarker analysis

MicroRNAs (miRNAs) are key regulators of gene expression and play a crucial role in various biological processes. However, existing methods for miRNA detection face challenges in terms of sensitivity, specificity and ease of use. These limitations highlight the need for innovative and highly sensitive detection platforms capable of accurately quantifying miRNAs. In this work, an integrated biochip based on a self-powered sensor system developed for the ultra-sensitive detection of miRNAs-21 and miRNA-20a. The system uses a bilirubin oxidase (BOD)-supported bio-cathode and a glucose oxidase (GOD)-supported bio-anode to form a closed loop that converts chemical energy into electrical energy. The complementary chains of target miRNAs are modified on the bio-anode using a bio-conjugate amplification strategy, enabling the system to generate an electrical signal proportional to the concentration of miRNAs. The sensor has a wide linear range of 5 fmol/L to 10 nmol/L for miRNA-20a and 1 fmol/L to 10 fmol/L for miRNA-21, with low detection limits of 0.176 fmol/L and 0.138 fmol/L, respectively. These detection limits are significantly lower than those achieved by existing technologies, making our biosensor a significant advancement in the field. In addition, the sensor system is integrated into a portable chip that transmits electrical signals in real time via Bluetooth to a mobile phone interface, enabling convenient and rapid analysis.