Trace Analysis of Multiple Tumor Exosomal PD‐L1 Based on SERS Immunoassay Platform

Abstract Immunotherapy has received wide attention in recent years as a new avenue for the effective treatment of cancer. However, due to the lack of detection limit and sensitivity of immune checkpoint molecule (such as Programmed cell death 1 ligand 1, PD‐L1) in established clinical methods, the immunotherapy evaluation during anti‐PD‐L1/PD‐1 (Programmed cell death receptor 1) treatment is difficult to be guided accurately. In this study, a highly sensitive and maneuverable Surface‐Enhanced Raman Scattering (SERS)‐based immunoassay platform is developed for the analysis of exosomal PD‐L1, a highly potential biomarker for immunotherapy. Excellent detection of exosomal PD‐L1 with good linear fit over a wide concentration range is achieved. In addition, the detection and discrimination of exosomal PD‐L1 in the peripheral blood of cancer patients and healthy controls are successfully achieved. Moreover, the platform has also been successfully used to distinguish common diseases, cancer, and healthy control (such as liver cancer, liver cirrhosis, and normal individuals). The detection platform can be successfully used for the trace detection of PD‐L1 on exosomes, which has excellent potential for clinical development in cancer diagnosis and treatment guidelines.