Exosomal RNA Extraction and Characterization

DNA and RNA oligonucleotides were synthesized and purified by HPLC (Sangon Biotech Co., China). DNA Hairpins were prepared as monomers at 10 μM in the reaction buffer (20 mM Tris·HCl, 150 mM KCl, 10 mM (NH4)₂SO₄, 2.5 mM MgCl₂, 1% Triton X-100, pH 7.5) using a snap cooling procedure: heating at 95°C for 5 min followed by cooling at 0.5°C min⁻¹ to 25°C, and allowing equilibration at room temperature for 30 min before use. The working concentration of DNA was 5 μM, and the initiator was 10 nM in HCR.
Urine samples from bladder cancer patients were obtained from cancer hospital, Chinese academy of sciences, Hefei. Exosomes were isolated with polyethylene glycol (34 (link)). The exocrine morphology was characterized by transmission electron microscope (JEM-2100). Size distribution of exosomes was analysised by dynamic light scattering (Zetasizer Nano ZSP). RNA was extracted using a Total Exosome RNA Isolation Kit (Invitrogen). This study was approved by the medical ethics committee of Hefei institute of physical sciences, Chinese academy of sciences and also was performed in accordance with the ethical standards.