Development of a microcantilever-based biosensor for detecting Programmed Death Ligand 1

The ongoing global concern of cancer worldwide necessitates the development of advanced diagnostic and therapeutic strategies. The majority of recent detection strategies involve the employment of biomarkers. A critical biomarker for cancer immunotherapy efficacy and patient prognosis is Programmed Death Ligand 1 (PD-L1), which is a key immune checkpoint protein. PD-L1 can be particularly linked to cancer progression and therapy response. Current detection methods, such as enzyme-linked immunosorbent assay (ELISA), face limitations like high cost, time consumption, and complexity. This study introduces a microcantilever-based biosensor designed for the detection of soluble PD-L1 (sPD-L1), which has a specific association with PD-L1. The biosensor utilizes anti-PD-L1 as the sensing layer, capitalizing on the specific binding affinity between anti-PD-L1 and sPD-L1. The presence of the sensing layer was confirmed through Atomic Force Microscopy (AFM) and contact angle measurements. Binding between sPD-L1 and anti-PD-L1 induces a shift in the microcantilever's resonance frequency, which is proportional to the PD-L1 concentration. Notably, the resonance frequency shift demonstrates a robust linear relationship with the increasing biomarker concentration, ranging from 0.05 ng/ml to 500 ng/ml. The detection limit of the biosensor was determined to be approximately 10 pg/ml. The biosensor demonstrates excellent performance in detecting PD-L1 with high specificity even in complex biological matrices. This innovative approach not only provides a promising tool for early cancer diagnosis but also holds potential for monitoring immunotherapy efficacy, paving the way for personalized and effective cancer treatments.