An electrochemical biosensor for the assessment of tumor immunotherapy based on the detection of immune checkpoint protein programmed death ligand-1

Although immunotherapy is now well established in cancer management, not every patient responds. Existing methods for assessing tumor immunotherapy responses, such as immunohistochemistry of the immune checkpoint protein programmed death ligand-1 (PD-L1), require destructive tissue analysis; furthermore, real-time in vivo monitoring would be beneficial for assessing tumor responses. Here we establish an electrochemical biosensor which was developed based on molybdenum disulfide (MoS2) and multi-wall carbon nanotubes (MWCNTs) used to modify the electrode and PD-L1 antibody-quantum dot (QD) conjugate as a dual optical and electrochemical label. The compositions, electrochemical performance, specificity of nanocomposite and probe were characterized. Paving the way for clinical application, the prepared biosensor detects differences in PD-L1 levels in diverse tumor cell types, tumors derived from mice or cancer patients, and it is reproducible and selective in both phosphate-buffered saline and serum. This study demonstrates that electrochemical sensing is a desirable technology for the in-situ and dynamic determination of biomarkers on the cellular level of for the assessment of tumor immunotherapy.