Abstract: A glycosylated electrochemical sensor for rapid identification and detection of breast cancer PD-L1 positive exosomes was developed. First, glycosyl-imprinted polymers (GIP) were prepared by electropolymerization using glyco-Galβ1-4GlcNAcβ1-3Galβ1-4GlcNAcβ1-3Gal overexpressed by breast cancer positive exosome glycoprotein PD-L1 as template molecules and 3-aminophenylboronic acid as functional monomers. After elution and removal of template molecules, a imprinted membrane that can specifically recognize PD-L1 positive exosomes was obtained. Potassium ferricyanide was used as a probe to measure the DPV current value of the GIP electrode. Exosomes were cleaved with RIPA to deduct free protein interference, and the change in current value ΔI was recorded. ΔI decreased with the increase of the concentration of readsorbed PD-L1-positive exosomes, and was linearly positively related with the logarithmic value of the concentration. The detection range was 2.36 × 102 ~ 1.18 × 107 Particles/mL, and the detection limit was 93 particles/mL. The method has been successfully used to detect breast cancer PD-L1-positive exosomes in clinical samples, and its spiked recoveries were 93. 82% ~ 105. 32%. The sensor could be used to screen breast cancer in clinical samples by the difference of glycosylation degree.

Key words: Exosome, Glycosyl-imprinting; Electrochemical sensor, PD-L1, Breast cancer