An economical, high-throughput protein-protein interaction modulator drug screening technique based on surface-enhanced Raman scattering

Increasing identification of protein-protein interaction (PPI) targets creates opportunities for drug discovery. However, the current drug screening strategies are costly and reagent-consuming, which hinders the progress in PPI modulator drug discovery. The primary obstacle lies in the inability to achieve molecular fishing with existing technology. Herein, we present a novel high-throughput, homogeneous-phase screening assay for PPI modulator discovery called "SERScreen", based on a magnetic field-amplified surface-enhanced Raman spectroscopy (SERS). Two high-affinity proteins are fixed respectively on the magnetic beads (MBs) and the SERS tags, and the cross-linking of two nanoprobes induced by PPI enables strong SERS signals. Candidate modulators interfere with the PPI according to higher affinity toward one protein, resulting in a significant reduction in SERS intensity above the MBs. We established a potential drug screening platform for PD-1/PD-L1, and demonstrated its feasiblility not only with known inhibitors (Durvalumab and BMS-202), but also with a small-molecule combinatorial library, successfully identifying two new candidate inhibitors via the molecular fishing of SERScreen. Furthermore, the anticancer mechanism of two candidates was discussed. As an ultrasensitive, low reagent consumption (2 µL sample solution), high-throughput screening technique in the PPI modulator discovery, SERScreen offers an effective solution for molecular fishing from complex samples and displays high compatibility with automatic measurement equipment.