Spatiotemporal Analysis of Enzyme Activity in Lung Cancer Tissue via Deuterated Probe-Based Mass Spectrometry-Fluorescence Dual-Modal Imaging.

As an important class of biomarkers, enzyme activity has been implicated in various diseases, making it of great importance for disease diagnosis and therapy. Thus, accurately mapping the enzyme activity in disease tissue is essential. Neutrophil elastase (NE) is a serine protease, which plays a key role in cancerous processes and metastatic activity. In this study, we developed two specific liposome-based probes, Lipo-HBMT-NE and its deuterated Lipo-DBMT-NE, designed to target the NE activity in lung cancer tissues. Upon administration into lung tissues through nasal injection, two kinds of small-molecular probes HBMT-NE and DBMT-NE were released, respectively. However, unlike HBMT-NE, only DBMT-NE enables both fluorescent imaging and mass spectrometry imaging (MSI) of NE in diseased tissues. Fluorescent imaging provides real-time monitoring of NE activity, while MSI achieves highly selective spatial mapping of individual molecules within tissues. Therefore, the integration of this deuterated probe with multiple molecular imaging techniques provides synergistic advantages, thereby enabling real and accurate mapping of enzyme activity.