The Graphene Oxide-Anchored Releasable Aptamer Scaffold (GRAS) Technique Enables Efficient Exosome Capture and Controllable Release.

Exosomes, as key mediators of intercellular communication, exhibit promising prospects in the biomedical field, particularly in stem cell-based replacement therapy. Current exosome isolation techniques face challenges in achieving batch enrichment and nondestructive release, which severely restrict their applications. Traditional specific enrichment strategies rely primarily on antibodies; however, aptamers can specifically recognize targets and serve as effective alternatives to antibodies, offering advantages such as small molecular size, high structural stability, and low cost, making them more suitable for scalable target isolation. Herein, we established the Graphene Oxide-anchored Releasable Aptamer Scaffold (GRAS) technique targeting CD63, a characteristic surface biomarker of exosomes. Leveraging the high affinity of single-stranded nucleic acids for graphene oxide (GO), along with the specific binding capacity of aptamers, we fabricated aptamer-displayed oligonucleotide scaffolds (Apt-Scaffold) and immobilized them onto GO to prepare Apt-Scaffold@GO. This configuration allows effective presentation of the CD63 aptamer on the GO interface for specific exosome recognition and capture. Different methods were further designed to achieve efficient and controllable exosome release. Our experimental results demonstrated that the GRAS technique outperformed the gold-standard ultracentrifugation (UC) in enriching exosomes from mesenchymal stem cell (MSC) culture medium. This method enables quantitative and specific enrichment of exosomes. With simple operation, low cost, and independence on large sophisticated instruments, it provides a robust technical foundation for advancing exosome-related biomedical applications.