OS11.7.A IMAGING OF MOLECULAR BOUNDARIES IN GLIOBLASTOMAUSING PROGRAMMABLE PH-RESPONSIVE DNA NANOPROBES

Abstract BACKGROUND Precise intraoperative delineation of glioblastoma multiforme (GBM) boundaries remains a critical challenge due to its infiltrative growth pattern. Tumor-associated acidosis (extracellular pH 6.5-6.9) provides a physiological basis for molecular boundary imaging; however, existing pH-responsive probes face two fundamental limitations: (1) fixed activation thresholds (typically pH <6.5), which are incompatible with intratumoral pH heterogeneity, and (2) inadequate background suppression at physiological pH (7.2-7.4), leading to suboptimal signal-to-noise ratios for detecting microinfiltration. To address these limitations, we engineered SHADE (Shadow-Strand Hybridization-Actuated Displacement Engineering)—a DNA nanotechnology platform with dynamically tunable pH sensitivity, leveraging programmable strand displacement mechanisms. MATERIAL AND METHODS The SHADE platform’s core innovation resides in two dynamically reconfigurable DNA nanostructures: (1) Tunable acidic sensor: i-motif shadow strands modified through toehold-mediated strand displacement (TMSDR) enable precise pH threshold adjustment (6.2-7.0). (2) Alkaline filter: Hairpin shadows with programmable C-A mismatches suppress background signalsThe system was functionalized with tumor-penetrating aptamers and validated in U87 glioblastoma cells and orthotopic murine models using activatable near-infrared imaging. RESULTS In U87 models, SHADE demonstrated pH-dependent fluorescence activation correlated with glioblastoma invasion patterns. Comparative studies revealed superior margin delineation over conventional probes, particularly in regions with sub-0.4 pH unit gradients. Intraoperative simulation achieved real-time visualization of micro-infiltration zones, with signal persistence matching tumor metabolic activity. The modular design allowed rapid recalibration of pH response profiles to match individual tumor acidosis characteristics. CONCLUSION As the first dynamically programmable pH nanoswitch for glioblastoma, SHADE overcomes fundamental limitations in responsiveness window fixation. This technology establishes a framework for precision-adjustable molecular imaging, and is expected to be applied in neurosurgery navigation and residual tumor monitoring.