Integrating Sulfobetaine Methacrylate Hydrogel-Modified Cellulose Triacetate Filter into a Zwitterionized Tandem Membrane System for Exosome Isolation

Purifying exosomes from various biotissue samples is critical for downstream analysis for diagnosis and prognosis because these extracellular vesicles not only carry enriched genetic materials but also play multiple roles in several diseases. This study designed an easy-to-operate exosome isolation method by integrating a zwitterionic tandem membrane system in which one of the filters was modified with sulfobetaine methacrylate (SBMA) hydrogel to prevent clogging and isolating exosomes from other biomolecules without impinging their biological contents. The surfaces of SBMA-coated cellulose triacetate (CTA) membranes were analyzed by XPS, AFM, SEM, and coating density. Their performance was investigated in terms of hydration capacity, hydrophobicity, filtration ability, and resisting unwanted adhesion. Empirical results demonstrated that surface modification with SBMA endowed the zwitterionized CTA membrane with superior antifouling properties without altering its filtration performance and also successfully isolated exosomes from other biomaterials in a sequential filtration where it was integrated with another zwitterionic membrane. The zwitterionic membrane system developed in this study could sequester exosomes secreted from HCT116 cells with high yield and innate immune traits for downstream analysis using an easy-to-operate procedure without requiring expensive instruments and trained personnel, proposing a promising approach to isolate exosomes in biological samples for further analysis.