Point-of-Care Monitoring for Lung Cancer from Exhaled Breath Formaldehyde via Luminescent Metal–Organic Frameworks

The identification of specific markers in exhaled gas from individuals with lung cancer has significantly enhanced the feasibility of early lung cancer screening. This paper presents the synthesis of a 2D Cu-BDC-N₂H₃ nanosheet at room temperature, which has been applied for the noninvasive diagnosis and point-of-care test (POCT) of lung cancer. During this approach, the hydrazine group in the ligand molecule was employed to enhance the intrinsic fluorescence of Cu-BDC-N₂H₃ through a Schiff base reaction with formaldehyde (HCHO), thereby reducing the detection limits of HCHO gas and aqueous solution (25 ppb and 0.316 μM). As a proof of concept, Cu-BDC-N₂H₃ was successfully applied to the early screening of lung cancer patients with an accuracy of 97.45%. The results indicate that the established breath analysis method provides a viable alternative for lung cancer screening.