ICG-labeled PD-L1-antagonistic affibody dimer for tumor imaging and enhancement of tumor photothermal-immunotherapy.

In clinical practice, tumor-targeting diagnosis and immunotherapy against programmed death ligand 1 (PD-L1) have a significant impact. In this research, a PD-L1-antagonistic affibody dimer (Z) was successfully prepared through Escherichia coli expression system, and conjugated with the photosensitizer of ICG via N-hydroxysuccinimide (NHS) ester to develop a novel tumor-targeting agent (ICG-Z) for both tumor imaging diagnosis and photothermal-immunotherapy simultaneously. In vitro, Z could specifically bind to PD-L1-positive LLC and MC38 tumor cells, and ICG-Z-mediated photothermal therapy (PTT) also showed excellent phototoxicity to these tumor cells.