Neuropilin-1 Targeted Dual-Modality PET/NIRF Probe for the Noninvasive In Vivo Imaging of Triple-Negative Breast Cancer

Triple-negative breast cancer (TNBC) is a serious malignancy characterized by a lack of definitive biomarkers. Research has demonstrated that neuropilin-1 (NRP-1) is highly overexpressed in breast cancer, and its expression levels are strongly associated with the occurrence, development, and prognosis of tumors, thereby positioning NRP-1 as a promising target for the diagnosis and treatment of breast cancer, particularly for TNBC. Herein, NRP-1 was employed as a molecular marker to design and synthesize a PET/NIRF dual-modality molecular probe [¹⁸F]AmBF₃-QS-1 for tumor localization and surgical navigation in TNBC. The nonradioactive NIRF probe AmBF₃-QS-1 was synthesized through the click reaction (chemical purity >95%), and the radioactive probe [¹⁸F]AmBF₃-QS-1 was synthesized via the one-step ¹⁸F-labeling method (radiochemical purity >95%, radiochemical yield >15%). The fluorescence imaging, flow cytometry, and cellular uptake studies in cancer cells with different NRP-1 expression levels were performed to verify the in vitro specificity of the probe. In vivo PET and NIRF imaging of MDA-MB-231 xenografts demonstrated excellent specificity of [¹⁸F]AmBF₃-QS-1 for tumor uptake (8.41 ± 0.86%ID/mL, 9.67 ± 2.15 × 10⁷ [p/sec/cm²/sr]/[μW/cm²]) with high-contrast ratios (5.91 ± 0.60, 2.80 ± 0.51). Additionally, ex vivo experiments showed that the probe AmBF₃-QS-1 effectively guided tumor localization for precise resection and pathological examination. Collectively, the results demonstrate the potential of [¹⁸F]AmBF₃-QS-1 as a promising dual-modality probe for noninvasive whole-body PET imaging to localize TNBC tumor as well as for NIRF imaging guidance to delineate tumor margins during surgical procedures.