小细胞外囊泡（sEV）对于细胞通讯至关重要，并且是癌症等疾病的关键生物标志物载体。然而，由于特定 sEV 结合蛋白的浓度较低以及更丰富的分散蛋白的干扰，定量和分析 sEV 表面标记物提出了重大挑战。本文介绍了免疫贾努斯颗粒 (IJPs)，这是一种新方法，可以在不到一小时的时间内直接检测 sEV，无需隔离。 IJP 的设计结合了荧光和非荧光两半，利用旋转布朗运动通过眨眼频率的变化来检测捕获的 sEV，而不受较小分散蛋白质的干扰。我们展示了低样品量下 2E5 sEVs/mL 的检测限，以及直接从血浆、血清、细胞培养基和尿液中表征 sEVs 的能力。在一项涉及 87 名受试者（包括结直肠癌、胰腺导管腺癌、胶质母细胞瘤、阿尔茨海默病和健康对照者）的小型试点研究中，我们的方法在盲法环境下准确识别了 AUC 高达 0.90-0.99 的疾病类型。与需要约24小时的正交超速离心加表面等离子共振（UC SPR）方法相比，IJP的灵敏度和动态范围提高了2个对数。

Small extracellular vesicles (sEVs) are vital for cellular communication and serve as critical biomarker carriers for diseases such as cancer. However, quantifying and profiling sEV surface markers presents significant challenges due to the low concentration of specific sEV-bound proteins and interference by more abundant dispersed proteins. This paper presents Immunojanus Particles (IJPs), a new method that enables the direct detection of sEVs in less than an hour without isolation. The design of IJPs incorporates fluorescent and non-fluorescent halves, utilizing rotational Brownian motion to detect captured sEVs through the change in the blinking rate, without interference from the smaller dispersed proteins. We demonstrate a detection limit of 2E5 sEVs/mL with low sample volumes and the capability to characterize sEVs directly from plasma, serum, cell culture media, and urine. In a small pilot study involving 87 subjects, including individuals with colorectal cancer, pancreatic ductal adenocarcinoma, glioblastoma, Alzheimer's disease, and healthy controls, our method accurately identified the type of disease with high 0.90-0.99 AUC in a blind setting. Compared with an orthogonal ultracentrifugation plus surface plasmon resonance (UC+SPR) method that requires about 24 hours, the sensitivity and dynamic range of IJP are better by 2 logs.