Polymer‐Based Prism‐Free Nanograting SPR Imaging Enables Multiplexed Detection and Single‐Step Aptamer Binding Kinetics

Surface plasmon resonance (SPR) is a benchmark for label-free biomolecular interaction analysis, but traditional prism-based systems are costly, time-consuming, and limited in multiplexing. We present a prism-free, low-cost, single-use polymer-based Au nanograting SPR imaging (SPRi) platform using normal-incidence optics and camera-based detection. Integrated with a microarray, the platform demonstrates multiplexed analysis capability. Furthermore, the incorporation of a custom microfluidic design enables simultaneous, multi-concentration kinetic analysis in a single step. Demonstrated using thrombin-aptamer interactions with 1 s time resolution, the system yielded dissociation constants of 10.1 ± 0.05 nm (kinetic) and 8.71 ± 0.59 nm (steady-state), consistent with literature values. This approach offers high-throughput potential for aptamer screening, drug discovery, biomedical applications, and life science research.