A SERS-based biosensor for optical monitoring of PARP1 trapping dynamics and high-throughput screening of modulators

All clinically approved PARP1 inhibitors (PARPi) share NAD + -mimetic scaffolds, limiting structural diversity and hindering the discovery of next-generation agents. Their therapeutic potency depends on PARP1 trapping, a dynamic process that remains difficult to quantify, preventing the establishment of high-throughput screening (HTS) strategies. Here, we present a rapid and high-throughput surface-enhanced Raman scattering (SERS) biosensor for direct detection of PARP1 trapping at the molecular level. The biosensor reconstitutes the PARP1/HPF1–DNA complex on a magnetically active SERS nanoprobe, where NAD + binding triggers dissociation (signal-off), while PARPi competitively stabilize the complex (signal-on). Molecules sustaining SERS signals are identified as potential trapping-enhancing modulators. This biosensor accurately reproduced the trapping profiles of eight approved PARPi and, through screening of four compound libraries, revealed Oritavancin diphosphate as a novel non–NAD + -mimetic PARP1 trapping-enhancing modulator, validated in both cell-free and cellular contexts. This SERS-based PARP1 biosensor thus provides a sensitive, rapid, and cost-efficient optical strategy for high-throughput discovery of PARP1-targeted modulators and other macromolecular interaction-based therapeutics.