A research team led by Prof. HUANG Qing at the Hefei Institutes of Physical Science (HFIPS) of the Chinese Academy of Sciences has reported the fabrication of ultrasensitive biosensors based on surface-enhanced Raman spectroscopy (SERS) to detect cancer metastasis-related programmed death ligand (PD-L1) biomarkers. 

The researchers prepared 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.

By making it "sandwich", they captured the malignant exosomes between magnetic nanocomposites and SERS nanotags with which they could quantitatively measure the PD-L1 biomarker by analyzing the Raman report signals.

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

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

Overall, results of this study indicate the great clinical significance of PD-L1 biomarker diagnosis which in future would be helpful in monitoring the health status of patients with PD-L1/PD-1 immunotherapy.

This work was supported by the National Natural Science Foundation of China and the Postdoctoral International Exchange Program.

Fig. 1. Schematic representation of circulating exosomal PD-L1 detection using SERS-sandwich. (Image by Muhammad)

Fig. 2. Schematic design of the experiment illustrating the preparation steps of CD63 and PD-L1 probes and detection mechanism of PD-L1 in exosomes using SERS. (Image by Muhammad)