Monitoring of circulating exosomal immuno checkpoint in the tumor microenvironment

Researchers report the fabrication of ultrasensitive biosensors based on Surface-enhanced Raman Spectroscopy (SERS) to detect the cancer metastasis related programmed death ligand (PD-L1) biomarker.

In this research, scientists at the Hefei Institutes of Physical Science (HFIPS) fabricated highly sensitive and specific aptamer-functionalized probes based on Au/TiO₂/Fe₃O₄ (shell/core) magnetic nanocomposites and Ag/4-ATP/Au (shell/core) SERS nanotags.

Using the “sandwich” approach, they captured the malignant exosomes between magnetic nanocomposites and SERS nanotags with which they could quantitatively measure the PD-L1 biomarker as low as 4.31 ag/mL by analyzing the Raman report signals.

Schematic representation of circulating exosomal PD-L1 detection using SERS-sandwich

In the mice model, the researchers confirmed that the proposed technique could be useful in analyzing time dependent growth of tumors by analyzing enhancement in PD-L1 expression in tumor.

Moreover, the researchers demonstrated the applicability of their work by integrating nanoparticles probes with portable Raman spectrometer to realize the PD-L1 measurement with 95% sensitivity.

Overall, the outcome of this work demonstrates the great clinical significance of PD-L1 biomarker diagnosis which in future would be helpful in monitoring the patients’ health who undergo PD-L1/PD-1 immunotherapy.

Source – Hefei Institutes of Physical Science (HFIPS)