Fig. 2.

Confocal and in situ fluorescence imaging of NIR-emissive polymersomes. (A) Scanning fluorescence confocal microscope image (λ^max_em = 809 nm) of 5- to 50-μm polymer vesicles featuring membrane-dispersed NIRF PZn₃ loaded at 5 mol% concentration. (Bar, 10 μm.) (B) Cryogenic transmission electron microscope (cryo-TEM) image of 50- to 150-nm PZn₃-loaded NIR-emissive polymersomes produced by sonication and freeze–thaw extraction of a dry thin film formulation of polymer and NIRF. A mono-dispersed suspension of unilamellar vesicles was further achieved after extrusion through a pressurized membrane. (C) In situ fluorescence image of a 10-ml sample tube containing 5 ml of a mono-dispersed aqueous suspension of small (<100-nm) unilamellar PZn₃-based NIR-emissive polymersomes. The image was obtained with a Xenogen Ivis Imaging System equipped with a charge-coupled device-based camera and appropriate filters for specific NIR excitation and fluorescence detection.