Funct. Mater. 2026; 33 (2): 178-187.

Amphi-PIC J-aggregates are promising luminescent systems for biomedical imaging; however, their interaction with blood components remains insufficiently understood. In this work, we systematically investigated the spectral and cellular behavior of amphi-PIC J-aggregates in aqueous solutions containing erythrocytes, leukocytes, and buffer using absorption and luminescence spectroscopy, flow cytometry, and confocal laser scanning microscopy. The spectroscopic data revealed only minor variations in spectral positions, Stokes shifts, band widths, and luminescence lifetimes between different media, indicating that the observed effects are primarily governed by dye concentration and aggregation stability rather than specific interactions with blood cells. Flow cytometry measurements confirmed minimal cellular uptake, while revealing occasional weak luminescence signals likely associated with residual aggregates adsorbed on cell surfaces. Confocal microscopy further demonstrated the absence of significant colocalization between J-aggregates and blood cells, while revealing partial agglomeration of aggregates in buffer and, to a lesser extent, in erythrocyte-containing solutions. Overall, the results indicate that amphi-PIC J-aggregates remain largely stable in blood-like environments and exhibit negligible interaction with blood cells, supporting their potential as luminescent probes for vascular imaging.