Activatable Fluorescent-Photoacoustic Integrated Probes with Deep Tissue Penetration for Pathological Diagnosis and Therapeutic Evaluation of Acute Inflammation in Mice

Inflammation is associated with many diseases, so the development of an excellent near infrared fluorescent (NIRF) and photoacoustic (PA) dual-modality probe is crucial for the accurate diagnosis and efficacy evaluation of inflammation. However, most of the current NIRF/PA scaffolds are based on repurposing existing fluorescent dye platforms that exhibit non-optimal properties for both NIRF and PA signal outputs. Herein, we developed a novel dye scaffold QL-OH by optimizing the NIRF and PA signal of classical hemicyanine dyes. Based on this optimized dye, we developed the first NIRF/PA dual-mode carbon monoxide (CO) probe QL-CO for noninvasive and sensitive visualization of CO levels in deep inflammatory lesions in vivo. The novel probe QL-CO exhibited rapid and sensitive NIRF₇₇₅/PA₇₃₀ dual activation responses toward CO. In addition, the CO-activated probe QL-CO was successfully used for the diagnosis of inflammation and evaluation of anti-inflammation drug efficacy in living mice though the NIRF/PA dual-mode imaging technology for the first time. More importantly, the probe QL-CO could accurately locate the deep inflammatory lesion tissues (≈1 cm) in mice and obtain 3D PA diagnostic images with deep penetration depth and spatial resolution. Therefore, the new NIRF/PA dual-mode probe QL-CO has high potential for deep-tissue diagnosis imaging of CO in vivo. These findings may provide a new tool and approach for future research and diagnosis of CO-associated diseases.