Wireless, Deep-Seeing Smart Pill: A NIR-II Fluorescence Imaging Capsule Endoscope for Gastrointestinal Cancer

Gastrointestinal cancer detection technologies are evolving; capsule endoscopy (CE) overcomes the invasiveness of tethered endoscopes. However, current CEs exhibit limited penetration depth and low SNR due to strong photon scattering, absorption, and autofluorescence in biological tissues, potentially resulting in missed deep or small lesions. This study reports a near-infrared-II fluorescent imaging capsule endoscope (NIR-II FICE), a "smart pill" designed for early gastrointestinal cancer diagnosis. NIR-II FICE can detect NIR-II-specific fluorescence signals above 900 nm from lesional tissues using the NIR-II fluorescent nanoprobe (FNP). It possesses the advantages of high sensitivity, high resolution, strong tissue penetration ability, high SNR, and high-contrast imaging. Experiments show NIR‑II FICE can detect FNP at concentrations as low as 5 µg mL^-1 and image large‑scale irregular regions and minute areas down to 100 µm. In ex vivo experiments on porcine gastric tissue, the penetration depth achieved 4 mm, with SNRs exceeding 13 dB and contrast values all greater than 0.5. In vivo experiments enabled targeted imaging of lesions in nude mice. Furthermore, a wireless-powered, magnetically controlled device ensures continuous energy and precise motion for NIR‑II FICE. To our knowledge, this is the first CE platform for NIR-II fluorescence imaging, advancing non-invasive gastrointestinal disease diagnosis/treatment and clinical research.