Rapid Capture and Nondestructive Release of Extracellular Vesicles Using Aptamer-Based Magnetic Isolation

Extracellular vesicles (EVs) play important roles in cell–cell communication by transferring cargo proteins and nucleic acids between cells. Due to their small size (50–150 nm) and low density, rapid capture and nondestructive release of EVs remains a technical challenge which significantly hinders study of their biofunction and biomedical application. To address this issue, we designed a DNA aptamer-based system that enabled rapid capture and nondestructive release of EVs in 90 min with similar isolation efficiency to ultracentrifugation (around 78%). Moreover, because we designed a DNA structure-switch process to release the exosomes, the isolated EVs maintained high bioactivity in cell-uptake assay and wound-healing assays. Using this method, we can isolate EVs from clinical samples and found that the amount of MUC1 positive EVs in breast cancer patient plasma sample is significantly higher than that in healthy donors. This DNA aptamer-based magnetic isolation strategy can be potentially applied for the biofunction study of EVs and EV-based point-of-care clinical tests

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Additional file 2. Encapsulation efficiency of DOX in nanopreparations

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Additional file 6. Cell viability of MCF-7/ADR cells treated with different concentrations of blank carrier

Localized Imaging of Programmed Death-Ligand 1 on Individual Tumor-Derived Extracellular Vesicles for Prediction of Immunotherapy Response

Programmed death-ligand 1 (PD-L1) on tumor-derived small extracellular vesicles (EVs) is a biomarker for prediction of the immunotherapy response. However, conventional bulk measurement can hardly analyze the expression of PD-L1 on individual tumor-derived EVs. Herein, a method for localized imaging of tumor-derived individual EVs PD-L1 (LITIE) is developed. In this assay, EVs in plasma were directly captured on a biochip. Then the liposome-mediated membrane fusion strategy was used to image miR-21 in EVs to discriminate miR-21-positive EVs from the whole EVs populations. Subsequently, the primer exchange reaction (PER) is applied to generate localized and amplified fluorescent signals for imaging PD-L1 on identified tumor-derived EVs. When applied in clinical sample tests, the LITIE assay could effectively distinguish breast cancer patients from healthy donors or patients with benign tumors. Interestingly, in a mice melanoma model, the LITIE assay showed the ability to predict immunotherapy response even before drug treatment. Thus, we think the strategy of measuring individual tumor-derived EVs PD-L1 could serve as an alternative way for screening clinical responders suitable for immunotherapy

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Additional file 4. Cellular distribution of FAM-TD@liposome

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Additional file 3. Photos of DOX@liposome and LNSD in PBS

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Additional file 1. Size distributions of nanopreparations