GO-aptamer hydrogel microneedle sensors for the on-site detection of exosomes in interstitial fluid on acupuncture treatment

Acupuncture treatment had achieved good clinical effects on treat or ameliorate chronic diseases. Exosomes are crucial for transmitting information and network regulation in acupuncture, and their content could be essential for acupuncture's effects. However, there remains a critical need for a highly sensitive approach to detect exosomes in acupuncture therapy studies, particularly for rapid and precise analysis. Herein, a graphene oxide-aptamer hydrogel microneedle sensor (GOA-HMS) was designed for exosome point of care testing (POCT) on acupuncture treatment. The sensor was fabricated by cross-linking of aminophenylboronic acid (APBA)-modified sodium alginate with chondroitin sulfate and GO nanosheets conjugated with a fluorophore-modified nucleic acid aptamer, in which GO served as a quencher. In the absence of the target exosome, the aptamer binds tightly into the GO, quenching the fluorophore labels. In the presence of exosome, the aptamer binds to the targets, causing a conformational change which alters the distance the fluorescent moieties from the GO, leading to fluorescence recovery and the generation of fluorescent signals. This sensor showed a linear range of 10⁵-10⁹ particles/mL and has a detection limit of 1 particles/mL with an excellent precision of 4.3 % (RSD) for seven repeated detections of 10⁷ particles/mL exosome, demonstrating the feasibility of both point-of-care clinical diagnostics and high throughput. Meanwhile, typical enzyme-linked immunosorbent assay (ELISA) assay further verified the measurement accuracy by this GOA-HMS. The GOA-HMS was successfully applied to exosome detection in acupuncture treatment, providing a non-invasive, in situ tool for monitoring patient responses in real-time and investigating acupuncture mechanisms.