Moxifloxacin as a contrast agent of two-photon microscopic imaging for detecting colorectal diseases.

Since two-photon microscopy (TPM) can obtain high-resolution images at cellular and subcellular level and moxifloxacin has multiphoton fluorescence characteristic, our study aimed to explore the feasibility and diagnostic value of moxifloxacin-assisted TPM in different human colorectal diseases, including low-grade intraepithelial neoplasia (LGIN), high-grade intraepithelial neoplasia (HGIN) and cancer tissues. Excitation power for TPM imaging with and without moxifloxacin was (2.74 ± 0.16) mW and (0.28 ± 0.02) mW, respectively (p < 0.05). Whether labeled with moxifloxacin or not, images of normal, LGIN, HGIN and cancer tissues all reached the strongest signal at 30 μm from the mucosa. Normalized fluorescence intensity of TPM images with moxifloxacin was approximately 10 times stronger than that without moxifloxacin. Fluorescence signal was differed significantly in normal, LGIN, HGIN and cancer tissues with or without moxifloxacin (p < 0.05). Besides, moxifloxacin-assisted TPM could present variant tissue features with different colorectal diseases, such as the crypt opening, glandular structure, adjacent glandular space and fluorescence distribution.