Production of Perfluorocarbon Stabilized Dextran Emulsions

The in-house manufacture of PSDE with a W₁/PFC/W₂ structure has been described previously^{15 (link)}. Perfluorohexane (C₆F₁₄, CAS# 355-42-0, bulk boiling point: 56°C, Strem Chemicals) was used as the PFC phase. A fluorosurfactant copolymer, synthesized using a 2:1 molar ratio of Krytox 157 FSH (CAS# 51798-33-5, DuPont, Wilmington, DE, USA) and poly(ethylene glycol) bis(amine) (MW: 1000 g/mol, CAS# 24991-53-5, Alfa Aesar, Ward Hill, MA, USA), was dissolved at 2% (w/w) in PFC. The PFC solution was combined at 2:1 (v/v) with a W₁ phase containing 1.66 mg/mL Alexa Fluor 488-labeled dextran (AF₄₈₈, MW: 10,000 Da, Life Technologies, Grand Island, NY, USA) in phosphate buffered saline (PBS, Life Technologies), and then sonicated (Q55 with CL-188 immersion probe, QSonica, LLC, Newton, CT, USA) for 30 seconds while on ice. To produce PSDEs, the primary emulsion (i.e., W₁/PFC) and W₂ phase, which was 50 mg/mL Pluronic F68 (CAS# 9003–-and 10 μL/min, respectively, through a quartz microfluidic chip (Cat# 3200146, junction: 14 μm × 17 μm, Dolomite, Royston, United Kingdom), as shown in Fig. 1(A). Using a Coulter Counter (Multisizer 4, Beckman Coulter, Brea, CA, USA) with a 50 μm aperture tube, the average diameter, coefficient of variation, and concentration of PSDE were 6.3 ± 0.06 μm, 16.2 ± 0.3%, and (7.1 ± 1.1) × 10⁹ particles/mL, respectively.