Fig. 6: Construction of the malignant pleural effusion model and biodistribution of the nanoparticles injected into the pleural cavity.

a Bioluminescence analysis on day 14 after pleural injection of LLC-LUC cells into C57BL/6 mice and 4T1-LUC cells into BALB/c mice; b Ultrasound detection of metastatic tumors and pleural effusion in the pleural cavity; c Representative images of pleural cavity metastatic tumors and effusion; d, e. Measurement of IPP in healthy mice and LLC- and 4T1-MPE models at different disease stages (early and late stages). Data is represented as mean ± SD (n = 3 biologically independent animals per group). Two-tailed Student’s t-test. LLC: Normal end-expiration vs. end-inspiration, p < 0.0001 (****); early stage end-expiration vs. end-inspiration, p < 0.0001 (****); advanced stage end-expiration vs. end-inspiration, p < 0.0001 (****); end-inspiration early stage vs. advanced stage, p = 0.0003 (***); 4T1: Normal end-expiration vs. end-inspiration, p < 0.0001 (****); early stage end-expiration vs. end-inspiration, p < 0.0001 (****); advanced stage end-expiration vs. end-inspiration, p < 0.0001 (****); end-inspiration early stage vs. advanced stage, p < 0.0001 (****). f IVIS imaging over time post-intrapleural DiR-O₃P@LPYU NPs. Data is represented as mean ± SD (n = 3 biologically independent animals per group). g Representative ex vivo IVIS imaging of major organs from MPE mice receiving intrapleural DiR-O₃P@LPYU NPs. L left, R right, MFI mean fluorescence intensity, MPE malignant pleural effusion, T tumor, H heart, Li liver, Sp spleen, Lu lung, K kidney, B brain, St stomach, I intestine, IPP intrapleural pressure, IVIS in vivo imaging system.