Department of Chemistry, Okayama University, Okayama, 700-8530, Japan.
Anal Sci. 2023 May;39(5):643-651. doi: 10.1007/s44211-022-00207-2. Epub 2022 Nov 5.
Extracellular vesicles (EVs) exist in biological fluids such as blood, urine, and cerebrospinal fluid and are promising cancer biomarkers. Attempts to isolate and analyze trace EVs, however, have been a challenge for researchers studying their functions and secretion mechanisms, which has stymied the options for diagnostic application. This study demonstrated a collection of EVs that was enhanced by gold nanoparticles (AuNPs) via the use of optical force. The collection system consists of an inverted microscope equipped with a CCD camera, a square capillary connected with a PTFE tube, and an Nd:YAG laser that generates optical force. The laser beam was focused on a capillary wall in which a cell culture medium containing EVs flowed continuously. Control of the surface charges on both the capillary wall and the AuNPs achieved the collection and retention of EVs on the capillary wall. The positively charged capillary wall retained EVs even after the laser irradiation was halted due to the negative charges inherent on the surface of EVs. Conversely, positively charged AuNPs had a strong electrostatic interaction with EVs and enhanced the optical force acting on them, which made collecting them a much more efficient process.
细胞外囊泡（EVs）存在于血液、尿液和脑脊液等生物流体中，是很有前途的癌症生物标志物。然而，试图分离和分析痕量 EVs 一直是研究其功能和分泌机制的研究人员面临的挑战，这限制了其在诊断应用中的选择。本研究通过使用光学力展示了一种由金纳米粒子（AuNPs）增强的 EVs 收集系统。该收集系统由配备 CCD 相机的倒置显微镜、与 PTFE 管相连的方形毛细管和产生光学力的 Nd:YAG 激光组成。激光束聚焦在一个毛细管壁上，其中含有 EVs 的细胞培养基连续流动。控制毛细管壁和 AuNPs 表面电荷实现了 EVs 在毛细管壁上的收集和保留。由于 EVs 表面固有的负电荷，带正电荷的毛细管壁甚至在激光照射停止后仍能保留 EVs。相反，带正电荷的 AuNPs 与 EVs 之间具有很强的静电相互作用，增强了作用在它们上的光学力，这使得收集它们的过程更加高效。
