Laser-induced graphene (LIG)-based electrochemical microfluidic chip for simultaneous analysis of multiplex microRNAs

Because a cancer process is always associated with several microRNAs (miRNAs), therefore, sensing devices that can simultaneously detect multiplex tumor-signature miRNAs are urgently needed for improving the accuracy of the early cancer diagnosis. Herein, a high-throughput electrochemical microfluidic chip (EMC) is devised for simultaneous analysis of multiplex miRNAs with high sensitivity and selectivity. Specifically, laser-induced graphene (LIG) electrode array was directly wrote on a polyimide (PI) film in a flexible fashion and further integrated with microfluidic channel to construct a EMC sensing platform. Moreover, enzyme-assisted target recycling amplification was employed to amplify the output of assistant DNA for capturing more nanoprobes to ensure the sensitivity and specificity. The feasibility and high performance of the EMS sensing platform were demonstrated by the precise multiplexed quantification of miR-21, miR-1246, and miR-155 at concentrations ranging from 0.5 to 1000 pM in a single 18 μL sample with a detection limits down to 0.17 pM, 0.24 pM, and 0.11 pM, respectively. For practical application, the expression of multiplex miRNAs in exosomes and clinical serum samples can be assessed in a single-pot assay with low sample requirement. The results showed that the expression level of three miRNAs had a high accuracy for the discrimination of breast cancer patients and healthy donors, demonstrating the great potential of EMC in miRNA-based early cancer diagnosis. Therefore, the proposed EMC sensor is an efficient lab-on-chip device for multiplex miRNAs assay, which opens new avenue for preparing EMC sensing chip for non-invasive early cancer diagnosis.