Simple and high-efficiency cotton fiber-in-syringe solid-phase extraction of extracellular vesicles

Extracellular vesicles (EVs) are promising to provide chemical predictors toward clinical diagnosis and prognosis. However, the isolation of high-purity EVs from complex bodily fluids is a little complex. To address this issue, a choline phosphate (CP)-functionalized adsorbent, designated as SCF@CP-Et, was prepared by grafting 2-(isopropylacryloyloxy)ethyl choline phosphate (CP-Et) from the surface of sulphydryl cotton fiber (SCF) via thiol-ene click polymerization. The SCF@CP-Et indicates a high-efficiency EV enrichment capability arising from the multivalent coordination interaction between the CP groups and phosphatidylcholine (PC) on EV membrane surface, meanwhile possesses an excellent anti-protein adsorption performance derived from the abundant hydroxyl groups of cotton fiber and zwitterionic property of CP-Et. Besides, this cotton fiber is easily assembled into a cotton fiber-in-syringe solid-phase extraction (SPE) device. This device shows simple and convenient operation during the isolation of EVs from various samples, including cell culture medium, plasma and urine. Meanwhile, the released EVs can maintain their biological activity. Taking advantage of these properties, this method was employed to isolate EVs in the plasma of colorectal cancer (CRC) patients and healthy donors, and 69 up-regulated and 18 down-regulated proteins are identified by proteomics analysis. Most of these up-regulated proteins, such as TLNA, FLNA, ITGB3 and MYH9, are associated with the progression of CRC, demonstrating the potential of this carbon fiber-based SPE method in the EV-based early diagnosis of diseases.