Visualization of tumor-associated neutrophils in malignant ascites of ovarian cancer with aptamer-decorated AIE probes

Neoadjuvant chemotherapy followed by interval debulking surgery is a recommended treatment for advanced-stage ovarian cancer (OC) patients to avoid bowel and spleen resection. Pre-operative chemotherapy requires ascites from OC patients for cytopathological examinations based on hematoxylin & eosin staining to detect tumor cells, whose low ratio make them difficult to be detected in ascites. Sensitive detection of tumor-related immunocytes (TRI) in ascites is not only indicative of underlying malignant ascites, but also could predict chemoresistance and poor overall survival of OC patients. The antibodies can only recognize immunocytes but cannot distinguish TRI. Herein, we identified an aptamer99 (Apt-99) using a fluorescence-activated cell sorting-based aptamer selection strategy, which could target tumor-related neutrophils (TRNs) with high binding affinity. In contrast, FAM-labeled Apt-99 couldn't distinguish the neutrophils in the smears of other patients' derived ascites or peritoneal lavages, such as metastatic ovarian cancer from colon carcinoma and myomas of the uterus. LC-MS/MS analysis, and the molecular docking experiments demonstrated that the target molecule of Apt-99 were S100A8&A9 heterodimers. Moreover, Apt-99-labeled aggregation-induced emission dots were facilely prepared and used for specifically visualizing the TRNs in the ascites smears. The findings indicated the diagnostic potential of Apt-99 and the possibility of further clinical trials.