Building high-contrast afterglow nanoprobe using semiconducting polymer nanoparticles and CuRu nanozyme for prolonged surgical navigation

Precise real-time imaging of tumor boundary is critical for effectively and thoroughly eliminating tumor residuals during surgery to prevent recurrence. Organic afterglow luminescent probes, well known for their high signal-to-background ratio (SBR), are particularly promising for imaging in vivo. However, current afterglow imaging systems still face limitations in surgical navigation: "always-on" probes offer poor contrast between the tumor area and surrounding normal tissues, and lack the enduring imaging capability needed for complete tumor excision. In this work, we developed a novel tumor microenvironment-activated afterglow nanoprobe, denoted as FMCR, by integrating the semiconducting polymer 2-methoxy-5-(2-ethylhexyloxy)-1,4-phenylenevinylene (MEHPPV) with CuRu nanozyme for enhanced intravital afterglow imaging. The CuRu nanozyme component of FMCR exhibits robust catalase-like activity, continuously catalyzing the conversion of overexpressed hydrogen peroxide (H₂O₂) present in the tumor microenvironment to oxygen (O₂), which increased the aerobic afterglow signal distinctly. More importantly, this CuRu nanozyme could sustainably and stably produce O₂ by catalyzing endogenous H₂O₂ over the long term, greatly prolonging the decay time of afterglow imaging. In vivo experiments revealed that FMCR facilitated the imaging of subcutaneously xenografted 4T1 tumors in living mice, with a remarkable SBR of 20.18. Furthermore, guided by afterglow imaging of FMCR, surgery was performed to effectively remove intraperitoneal tumor nodules, including those as smaller as 2–4.5 mm in diameter, which demonstrated the immense potential of FMCR for precise surgical navigation.