3510 sonicator

Silicone oil emulsions were prepared using two techniques. “High concentration” silicone oil emulsions were created by passage of a 5% (v/v) silicone oil in deionized water mixture through an Emulsiflex^™ C5 high pressure homogenizer (Avestin, Inc., Ottawa, Canada). The protocol followed was previously described in Chisholm et al.^{39 (link)} Silicone oil emulsions that contained lower amounts of silicone oil that were approximately equivalent to the amounts found in commercial siliconized syringes, were created directly from commercially-available siliconized syringes and are referred to as “low concentration” silicone oil emulsions. BD Lo-Dose^™ U-100 insulin syringes (Becton-Dickinson, Franklin Lakes, New Jersey) were filled with 20 mM sodium phosphate buffer (pH 7.4) containing 9% (w/v) sucrose and were sonicated for 2 h using a Branson 3510 sonicator (Danbury, Connecticut) as described previously.^{39 (link)}

Low concentration silicone oil emulsions were created directly from commercially available siliconized syringes (BD Lo-Dose™ U-100 insulin syringes, Becton-Dickinson, Franklin Lakes, New Jersey). Siliconized syringes were filled with 20 mM sodium phosphate buffer (pH 7.4) containing 9% (w/v) sucrose and were sonicated for 2 h using a Branson 3510 sonicator (Danbury, Connecticut). This treatment emulsified silicone oil from the syringe barrel walls into the buffer. The resulting silicone oil-in-buffer emulsions from each syringe were then expelled into a glass vial for storage at 4°C for up to 1 h until use. Silicone oil microdroplets in the emulsions that were prepared in commercial syringes were too dilute for analysis with a Beckman Coulter LS230; instead, droplet size distributions in these samples were determined using dynamic light scattering. Samples were loaded into a 12 μL quartz fluorometer cell (Starna Cells Inc., Atascadero, California). Measurements were taken in triplicate using a DynaPro Dynamic Light Scattering instrument (Wyatt/ ProteinSolutions, Dernbach, Germany) and analyzed using Dynamics V6™ version 6.3.40 software (Proterion Corp., Piscataway, New Jersey). A minimum of 15 acquisitions of 10 seconds were collected for each sample at a controlled temperature of 20°C.