Multiplex In Vivo Imaging of Biodistribution and Pharmacokinetics of CoMoCAT Single-Walled Carbon Nanotubes.

Semiconducting single-walled carbon nanotubes (SWCNTs) are emerging as powerful near-infrared probes for deep-tissue imaging. While SWCNT samples involving multiple chiralities can be seen as a collection of spectrally resolved fluorophores, their multiplex imaging capabilities remain underexplored. This work presents a filter-resolved evaluation of DSPE-mPEG-coated CoMoCAT SWCNTs integrating optical characterization, biodistribution, pharmacokinetics, and toxicity studies in BALB/c mice. Band-pass filters centered at 1000, 1050, and 1100 nm are used to isolate emission from the dominant (6,5) species and coexisting (7,5) and (7,6) chiralities within the NIR-II window. Following intraperitoneal administration, longitudinal whole-body imaging (0.5-24 h) illustrates rapid systemic spread and preferential uptake in reticuloendothelial organs. Ex vivo organ analysis reveals a hierarchy of emission intensities (liver >> spleen >> lung > heart > kidney > brain > thymus) preserved across all three detection channels, suggesting a negligible influence of SWCNT chirality on biodistribution. Serum kinetics show monoexponential decay with an apparent elimination half-life of ∼2.69 h. In a 21-day toxicity study, treated animals maintain stable body mass and normal behavior, organ-level fluorescence returns to the baseline, and H&E sections of the liver, kidney, and lung reveal preserved architecture without inflammatory or fibrotic lesions. Collectively, this work defines an initial in vivo tolerability profile, safe dosing, and imaging conditions for DSPE-mPEG/CoMoCAT SWCNTs and demonstrates that filter-resolved NIR-II fluorescence can be exploited for multiplex tracking of nanotube probes in vivo, providing a foundation for future biosensing and image-guided therapeutic applications.