Supporting Information

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Fig. 5. Comparative study of membrane loading of NIRFs in polymersomes vs. liposomes. Dry thin-film formulations deposited on Teflon consisted of a constant amount of NIRF species (10 ml of 1 mM solutions of PZn₁-PZn₅ in CH₂Cl₂ with the respective molar ratio of lipid or polymer (aliquot volume of 1 mM stock solutions in CH₂Cl₂). Medium-sized (300 nm) emissive vesicles were formed by thin-film rehydration and sonication in 2 ml of H₂O. For a constant amount of NIRF species, polymersomes are able to incorporate PZn₁ and PZn₂ in their bilayered membranes at a significantly higher molar fraction than SOPC liposomes. Additionally, they are uniquely able to incorporate the larger conjugated NIRFs PZn₃-PZn₅. (A) SOPC vs. polymer membrane loading of a benchmark porphyrin monomer PZn₁. (B) SOPC vs. polymer membrane loading of NIRF PZn₂.

Fig. 6. Relative steady-state fluorescence of PZn₃ based NIR-emissive polymersomes as a function of mol% membrane loading. Polymersome solutions containing PZn₃ at 5 mol% membrane loading were determined to possess the maximum steady-state fluorescence emission on a per-vesicle basis (see Supporting Methods in Supporting Text for a discussion of experimental procedures). Because this loading level corresponds to » 2,500 copies of emitter per 100-nm-sized polymersome (Table 1), each with a molecular e = 129,000 M^-1· cm^-1 (Fig. 3A), the calculated absorptive molar extinction coefficient per vesicle is equal to » 3.2 × 10⁸ M^-1· cm^-1 (l = 794 nm).

Fig. 7. Normalized fluorescence intensity of PZn₃-based NIR-emissive polymersomes subject to constant laser irradiation over time, displayed as a function of two different laser fluence rates (mW/cm²). Aqueous polymersomes solutions containing PZn₃ at 5 mol% membrane loading were diluted 1:10 vol:vol in glycerin to minimize diffusive currents and molecular rotational effects. The samples were placed in 2-mm spectroscopic cells, and transient electronic absorption spectra were taken at various time intervals during constant laser irradiation. The l _max ground-state bleaching signatures at each time point were then compared and normalized to yield a plot of fluorescence intensity vs. time/pump wavelength = 775 nm, probe wavelength = 805 nm (see Supporting Methods in Supporting Text for a full discussion of experimental procedure). PZn₃-based NIR-emissive polymersomes displayed a photobleaching threshold between 500- and 1,000 mW/cm².