Highly efficient and scalable biomarker preconcentrator based on nanoelectrokinetics.

Micro/nanofluidics are excellent candidates for biological sample preparation. However, the limited process volume in micro/nanofluidics is the main hurdle limiting their practical applications. To date, most micro/nanofluidics have processed sample volumes of several microliters and have rarely been used to handle large-volume samples. Herein, we propose a microfluidic paper-based large-volume preconcentrator (u-LVP) for enrichment and purification of biomarkers (e.g., miRNA) using ion concentration polarization. A Nafion (ion-selective nanoporous membrane)-functionalized multilayer cellulose paper enables microscale division of milliliter-scale samples, thus electrokinetically separating and preconcentrating the biomarker in different locations within the u-LVP. By inserting collecting discs at optimal positions in the u-LVP, the enriched biomarker is simply recovered with high efficiency. With this approach, as an exemplary biomarker, miRNA-21 in human serum was separated from proteins and preconcentrated with an effective preconcentration factor exceeding 6.63 and a recovery rate above 84%. Thus, our platform offers new opportunities and benefits for biomarker, diagnostic, prognostic, and therapeutic research.