Electrically Enhanced Intraperitoneal Drug Delivery Resolved by Fluorescence Lifetime Imaging Microscopy

Intraperitoneal delivery of nanoparticles (NPs) holds promise in the treatment of peritoneal metastases (PM), and the use of electric fields may enhance their tissue penetration. Evaluating NP delivery requires evidence of intracellular payload release, which is challenging in autofluorescent tissues. Here, we combined electromotive drug administration (EMDA) with cationic RL-100 NPs co-loaded with doxorubicin (DOX) and a near-infrared aza-BODIPY tracer, reporting carrier-associated distribution, while phasor fluorescence lifetime imaging microscopy (FLIM) characterized the molecular environment of DOX. In colorectal carcinoma, NP-delivered DOX progressed from cytoplasmic puncta to nuclear accumulation, while carrier-associated fluorescence remained cytoplasmic, supporting intracellular release. EMDA enhanced NP penetration in ex vivo human peritoneum and healthy rat peritoneum. In a syngeneic rat model of colorectal PM, both free and NP-delivered DOX remained detectable to approximately 1200 um after EMDA, compared with < 200 um after passive delivery. NP-delivered DOX remained detectable 24 h after EMDA. Whole-animal and ex vivo imaging showed the highest carrier-associated signals in tumor nodules and tumor-bearing omentum. These findings support electrically enhanced intraperitoneal delivery and a dual-reporter approach to evaluate carrier distribution, drug penetration, and intracellular release, with potential applications in other autofluorescent tissues. Together, these capabilities provide a preclinical basis for investigating NP-assisted delivery.