Surface Plasmon Resonance Imaging and Microscopy Modalities for Information-Rich, Label-Free Analysis of Biomolecular Interactions and Disease Biomarkers.

Label-free imaging techniques are powerful tools for characterizing biomolecular interactions, offering important advantages over traditional fluorescence-based imaging methods. Among these approaches, surface plasmon resonance imaging (SPRi) has emerged as a particularly versatile and enabling platform owing to its simple experimental configuration, rapid data acquisition, and high imaging sensitivity. A related variant, surface plasmon resonance microscopy (SPRM), further extends the capabilities of SPR-based sensing by providing enhanced spatial resolution and expanded sensing depth, allowing interrogation of interactions at the single-particle and single-event level. The combined versatility of SPRi and SPRM has supported a wide range of applications, including molecular recognition, quantitative interaction analysis, extracellular vesicle detection, and nanobubble characterization. More recently, the integration of machine-learning approaches into both instrumental development and postacquisition data analysis has significantly enhanced the ability of SPR-based imaging techniques to address complex sample environments, enabling multiplexed, high-throughput, and information-rich measurements. This review provides a comprehensive overview of recent advances in SPRi and SPRM, with a particular emphasis on innovative methodological developments and emerging applications within the broader SPR research landscape. Key topics include advances in optical configuration, machine-learning-assisted analysis, nanoparticle and nanoscale object characterization, and the development of sensing platforms for biomarker assessment.