Efficient Separation of Exosomes by Aptamer-Functionalized Polyacrylamide-Polyacrylic Acid Hydrogel

High-efficiency and specific isolation of exosomes from diverse biological fluids remains a major challenge for clinical diagnostics. Herein, we developed an aptamer-functionalized dual-network hydrogel platform for the specific enrichment and non-destructive release of exosomes. This study proposes an aptamer-functionalized dual-network hydrogel technology aimed at achieving the specific separation and non-destructive release of exosomes from complex biological samples. Using a sacrificial nickel foam template, polyacrylamide and polyacrylic acid were sequentially polymerized to construct a stable, interconnected macroporous hydrogel framework, which minimized flow resistance for rapid sample permeation. To build the affinity interface, circular DNA templates were chemically crosslinked into the accessible carboxyl groups of the polyacrylic acid segments, followed by in situ rolling circle amplification (RCA) to generate long DNA concatamers rich in repetitive CD63 aptamer sequences for efficient target capture. Meanwhile, polyacrylic acid is expected to reduce the non-specific adsorption of the composite hydrogel toward contaminating proteins, thereby improving the purity of the isolated exosomes. Finally, introducing complementary DNA displacement strands enables efficient, mild vesicle release via competitive hybridization, fully preserving structural integrity and cellular uptake ability. This bio-functionalized hydrogel system provides a gentle, efficient, and reliable methodology for high-purity exosome isolation, offering a promising tool for advanced biomedical applications.