A multivalent activatable aptamer probe with ultralow background signal and high sensitivity for diagnosis of lung adenocarcinoma

Abstract

Lung adenocarcinoma is the most common subtype of lung cancer. Developing a simple, rapid, and sensitive method for the detection of lung adenocarcinoma is helpful to reduce the clinical workload and facilitate clinical treatment. To detect lung adenocarcinoma cells, this study designed a multivalent activatable aptamer probe (multi-AP) using S1 aptamer that can specifically recognize A549 cells (a lung adenocarcinoma cell line). Firstly, the monovalent activatable aptamer probe (mono-AP) was designed by strand-displacement strategy and fluorescent resonance energy transfer (FRET). The multi-AP was constructed by mono-AP assembled on the nucleic acid scaffold obtained by hybridization chain reaction (HCR). The presence of the target cell activated the multi-AP, the complementary strand was released, and the fluorescence detection signal was reported based on the FRET. The multi-AP has good specificity and sensitivity for detecting A549 in different matrices and greatly reduces the background signal with the lowest detection limit of 6 cells/200 μL. Furthermore, the multi-AP could directly detect the lung adenocarcinoma cells in cytology specimens, indicating a good potential of the multi-AP in clinical cytology specimens for rapid diagnosis, such as rapid on-site cytological evaluation. Besides, the multi-AP was further modified with biotin (bio-multi-AP) and used to detect clinical cytology cell blocks, implying the value of bio-multi-AP in immunocytochemistry for accurate diagnosis of lung adenocarcinoma.