An Integrated Protein Switch Fluorescent Biosensor Platform for Real-Time Landmine Detection

Traditional landmine detection technologies face limitations such as low safety, poor efficiency, and high false alarm rates, posing serious threats to lives worldwide. In this study, a bacterial cell surface-displayed protein switch fluorescent biosensor (sPSFB) and an integrated detection system are developed for the highly efficient, real-time field detection of landmines. The transcriptional regulator YhaJ specifically recognizes 2,4-dinitrotoluene (DNT) by its chemical fingerprint. DNT is a typical explosive and a major volatile component of 2,4,6-trinitrotoluene (TNT)-based landmines. The protein switch fluorescent biosensor, composed of YhaJ and circularly permuted fluorescent proteins (cpFPs), is displayed on the bacterial cell surface to enable a direct and rapid response to DNT, which induced the conformation changes and green fluorescence of the protein switch. The detection performance of sPSFB is further enhanced through systematic protein engineering. Combined with automation equipment and unmanned aerial vehicles, a complete integrated sPSFB platform is established, achieving unmanned, real-time DNT detection in field trials during daylight at stand-off distances of up to 10 m, covering an area of 63.40 m2 within 5 s. This platform demonstrates potential for applications in military reconnaissance, post-conflict landmine detection, and intelligent environmental or agricultural monitoring.